Genetics Flashcards

Question

why do cells divide?

Answer 1

* Growth * Reproduction * Replacement of dying cells – skin, RBC * Reproduction in multi-cellular organisms – gamete formation (meiosis)

Answer 2

surface area: Volume ratio constraints

Answer 3

plant cell ## Footnote The plant cell is a type of eukaryotic cell , with different characteristics that differ from animal cells , fungaland other realms of the living: the presence of the cell wall composed of cellulose (a polymer whose basic unit is the glucose , protein and, as a result of modifications, from lignin , suberin ...) and related plasmodesmata , channels in the cell wall through which the cells of the plant are in communication with each other. the plastids , and especially the chloroplasts that, thanks to the chlorophyll allow plant cells to produce monomers of sugar (glucose) and oxygen from the CO2 exploiting the ' solar energy , said process is defined as photosynthesis . characterizing the presence of numerous vacuoles (organelles but not intracellular cavity, surrounded by a membrane, called the tonoplast ) that occupy a large part of the cell and whose main function is to keep the cell turgor . Are involved in the control of the passage of molecules from the blood to the cytosol, in the maintenance of the pH optimum of the cytosol, and perform functions of reserves of various substances. the absence of centrioles typical animal cell.

Answer 4

cell nucleus •Genetic information is contained within chromosomes – threadlike structures composed of DNA, – present in the nuclei of cells – passed to daughter cells during cell division

Answer 5

in the nucleus of cells

Answer 6

–threadlike structures composed of DNA, – present in the nuclei of cells – passed to daughter cells during cell division

Answer 7

each long bit of the 'x' shaped chromosone is called a **chromatid** ## Footnote **centromere**: the point on a chromosome by which it is attached to a spindle fibre during cell division as the central region where the two chromatids are held together and form an X shape.. **Telomere:** The end of a chromosome. The ends of chromosomes are specialized structures that are involved in the replication and stability of DNA molecules. A telomere is a length of DNA that is made up of a repeating sequence of six nucleotide bases (TTAGGG).

Answer 8

pairs of autosomes where one from each pair derived from each parent

Answer 9

sex cell; sperm or egg

Answer 10

trait that will only appear in the phenotype if organism inherits two of them; covered up by the dominant gene

Answer 11

Any chromosome other than the sex chromosomes.

Answer 12

One of four chemicals which make up the 'rungs' of DNA; A;T;C;G

Answer 13

These sequences are the code for genetic information

Answer 14

adenine is the "A". “G” for guanine, “C” for cytosine, “T” for thymine. Adenine always pairs with thymine. Cytosine always pairs with guanine.

Answer 15

Protects against 3' exonuclease

Answer 16

–are major components of most organisms–replicate through mitosis – – have 2 copies of each chromosome, ## Footnote (46 in humans) a condition known as diploid (or 2n)

Answer 17

–pass on the genetic information to the progeny – –formed by meiosis – –contain only one chromosome from each pair, ( 23 in humans) –a condition known as haploid (or n)

Answer 18

•Can carry more genetic variation•If a gene on one copy is faulty there is a back-up, heterozygote often viable. • •More potential for evolution if environment changes • •Mixture of characteristics from both parents

Answer 19

1. interphase 2. mitosis 3. cytokenesis

Answer 20

non-dividing, metabolically active. At least 90% of cycle, composed of:- G1 Phase à 1st growth phase, (Restriction point.) S Phase à DNA duplicated G2 Phase à Final growth phase

Answer 21

interphase

Answer 22

* mother cell produces two daughter cells, both identical to the mother cell. * Used for growth and repair, tissues vary:- Human skin cells divide throughout life Liver cells divide in order to repair damage Nerve cells very specialised, once mature do not divide, damage usually permanent

Answer 23

•Prophase • •Metaphase • •Anaphase • •Telophase

Answer 24

not yet started to split

Answer 25

* Chromatin condenses, chromosomes become visible. * Centrioles separate, moving to opposite sides of the nucleus. * Centrioles start to make the mitotic spindle out of microtubules. * Nucleolus disappears.

Answer 26

* Nuclear membrane fragments. * Kinetochore is formed at the centromere. * Microtubules attach at the kinetochores, the two kinetochores face in opposite directions. * Chromosomes align on equator of cell, called metaphase plate.

Answer 27

centrimeres split

Answer 28

•Chromatids have reached their destination and begin to elongate back to long thin chromatin. •Nuclear membrane and nucleolus reform •Formation of cleavage furrow where cell starts to split. Cytokinesis; division of the cytoplasm

Answer 29

division of the cytoplasm

Answer 30

23 = n (half of 46 2n=46 which is diploid) 23

Answer 31

meiosis -\> egg and sperm -\> fertilisation

Answer 32

zygote -\> mitosis + development -\> adults -\> ovaries and testes produce egg and sperm cell which are haploid

Answer 33

zygote (diploid 2n)

Answer 34

•Produces 4 daughter cells which have half the original chromosome number of mother cell. (One from each homologous pair.) Used to produce haploid (n) gametes. Reduction division •These daughter cells are not identical to the mother cell or each other. Reduction division These daughter cells are not identical to the mother cell or each other

Answer 35

Reduction division These daughter cells are not identical to the mother cell or each other part of meiosis

Answer 36

two phases: Meiosis I – Prophase I, Metaphase I, Anaphase I, Telophase I Meiosis II - Prophase II, Metaphase II, Anaphase II, Telophase II and it Requires two divisions of the nucleus and cell

Answer 37

4 haploid pollen grains in a tetrahedral shape

Answer 38

the point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis forms in prophase 1

Answer 39

interphase 1 in meiosis

Answer 40

prophase 1 in meiosis

Answer 41

metaphase 1 meiosis

Answer 42

* Nuclear membrane reforms * Original cell divides by Cytokinesis * Only one set of chromosomes present in each new cell * Known as reduction division – haploid cells produced teleophase 1 meiosis

Answer 43

prophase 2 meiosis

Answer 44

anaphase 2 meiosis

Answer 45

teleophase 2 and cytokenesis 2 note that there are now 4 daughter cells

Answer 46

mitosis is a part of asexual reproduction –easy, rapid, effective way to reproduce –useful in stable environment –lack of genetic diversity among offspring

Answer 47

meiosis –promotes genetic variability, unique combinations –useful in dynamic environment

Answer 48

gain or loss of whole sets of chromosones cells with an exact multiple of the haploid number e.g. •2 sets = polyploidy 3n = triploid, 4n = tetraploid, 6n = hexaploid

Answer 49

Gain or loss of single chromosomes Aneuploidy are cells with an uneven number of chromosomes, but not an even set. So, aneuploidy like trisomy 21 would be the same as diploid + 1 chromosome. Turner syndrome in humans is a case of aneuploidy because it's diploid - 1 or 45 chromosomes... •Aneuploidy = gain or loss of whole chromosomes. 2n + 1 or 2n – 1 This is usually due to a problem in cell division, usually in production of gametes, but can be very early in development from zygote, leading to mosaic conditions

Answer 50

* Normal for gametes. * Individuals that arise from unfertilised eggs. Eg males of certain insects ; - drones, ants, wasps. * Some fungi are haploid, plus lower plants. * Rarely seen in normal diploid organisms, due to frequent presence of lethal mutations, no spare copy, - usually fatal.

Answer 51

Patau syndrome

Answer 52

to denature the double stranded DNA

Answer 53

containing more than two paired (homologous) sets of chromosomes.

Answer 54

•Almost always lethal ## Footnote 3n; approx 15% spontaneous abortions; plus in 1/10,000 live births, but most die within a month, large head + serious abnormalities. 4n; approx 5% spontaneous abortions, rarely born alive, soon die.

Answer 55

•Does not have such severe consequences for plants; can be self fertile or reproduce asexually. Bramley apple, triploid sterile. Wheat hexaploid. Strawberry octopoid. Often associated with larger fruit in cultivated plants. Plus some wild grasses eg Spartin

Answer 56

normal meiosis All gametes hapoid, fertilisation:- n + n = 2n zygote

Answer 57

Non disjunction Meiosis 1

Answer 58

* Nondisjunction of homologous pairs of chromosomes in anaphase of meiosis 1 leads to; * 4 abnormal gametes; 2 with two copies of the chromosome, and 2 with none. * Fertilisation 2n + n = 3n; tripoid ## Footnote zero + n = n; monoploid

Answer 59

Non disjunction Meiosis 2

Answer 60

* Nondisjunction of chromosomes into chromatids leads to; * 2 abnormal gametes and 2 normal gametes. Nondisjunction happens when a pair of sex chromosomes fails to separate during the formation of a sperm (or egg). When sperm with no X chromosome unites with a normal egg to form an embryo, that embryo will have just one X chromosome (X rather than XX). As the embryo grows and the cells divide, the X chromosome will be missing from every cell of the baby's body.

Answer 61

A karyotype is simply a picture of a person's chromosomes. In order to get this picture, the chromosomes are isolated, stained, and examined under the microscope. Most often, this is done using the chromosomes in the white blood cells. A picture of the chromosomes is taken through the microscope. they are useful for * To look at chromosomes structure and number. * Dividing cells used, chromosomes shorter and more easily seen with the microscope. * Autosomes arranged and numbered in order of size, followed by sex chromosomes.

Answer 62

Trisomy 21

Answer 63

downs syndrom or trisomy 21

Answer 64

patau syndrome or trisomy 13

Answer 65

Patau syndrome or trisomy 13 note the three chromosons under 13

Answer 66

trisomy 18 or edwards syndrome

Answer 67

trisomy 18 or edwards syndrome

Answer 68

Turner syndrome X0 itis caused by a missing or incomplete X chromosome. People who have Turner syndrome develop as females. it happens through non disjunction the mother must pass the condition on, a father cannot have the condition because he only has one x chromosone

Answer 69

Klinefelters Male individual most often occurs when the genetic material in the egg splits unevenly. But it can also occur when the genetic material in the sperm splits unevenly. Even though Klinefelter syndrome is a genetic disorder, it is not passed down through families.

Answer 70

•Abnormal differentiation of gonads • •Phenotypic sex ambiguous or not in agreement with chromosomal sex, hermaphrodites Abnormalities which cause an increase in androgen and testosterone synthesis may confer a competitive advantage. Eg. Congenital Adrenal Hyperplasia

Answer 71

Easy to grow. A number of easily discernable characteristics. Controlled matings possible. Large numbers of progeny produced. Short generation time. e.g. fruit flies (4 chromosones)

Answer 72

•Egg – adult 7-10 days •100 eggs per day •Only 4 chromosomes •Easy to anaesthetise •Easily discernable characteristics Easy and cheap to maintain in laboratory fruit fly

Answer 73

* Worked on pea plants. * He did not know about genes, but postulated that ‘factors’ controlled the inheritance of characteristics, * and some factors were stronger than others. Looked at characteristics with discontinuous variation, no intermediate forms. Single gene pair controls. * Height; Tall/Short * Flower colour; Purple/White * Seed shape; Round/Wrinkled * Seed colour; Yellow/Green

Answer 74

genetic make-up of an organism.

Answer 75

characteristics that can be observed or measured

Answer 76

Gregor Mendel he found out a particular flower colour dominated when crossing pea plants

Answer 77

heterozygotes for autosomal recessive

Answer 78

dizygotic non identical twins

Answer 79

* Autosomal dominant * Autosomal recessive. * Sex linked dominant * Sex linked recessive. ## Footnote Sex linked conditions can be carried on the X or Y chromosome, usually on the X

Answer 80

Autosomal means sex of individual has no influence on inheritance of disease.

Answer 81

•an abnormality occurs when only one of the genes from one parent is abnormal • •if the parent has the disorder, the baby has a 50 percent chance of inheriting it

Answer 82

Individual needs to inherit only one copy of the defective gene

Answer 83

. Huntington’s chorea. 2. Achondroplasia. 3. Marfan syndrome

Answer 84

* Caused by stutter on DNA. * Excessive number of repeats of CAG on chromosome 4. * Brain deteriorates in middle age.•If the parent has the disorder, the baby has a 50 percent chance of inheriting it. * 12 in 100,000 approx.

Answer 85

Defect on chromosome 4. Fault in fibroblast growth factor receptor. 80% patients due to new mutation. More likely if father over 35. 1/25,000 imperfect bone development causing dwarfism

Answer 86

Defect on chromosome 15, connective tissue disorder. causing long limbs and heart defects arachnodactyl y fingers

Answer 87

autosomal dominant similar to marfan syndrome High risk of sudden death due to rupture of aortic aneurysm. Joint hypermobility Club foot Curved spine etc

Answer 88

individuals who are heterozygous for a certain gene carry two different alleles

Answer 89

individuals who are homozygous for a certain gene carry two copies of thesame allele

Answer 90

BLAST G query TRANSLATE

Answer 91

experimental demonstration that DNA is the substance that causes bacterial transformation. linking into Griffiths experiement they did studies on the chemical nature of the substance inducing transformation of pneuococcal types. At that time it was thought protein might be the hereditary material. In their paper of 1944, Avery and his colleagues suggest that DNA, rather than protein was the hereditary material of bacteria, and could be analogous to genes and/or viruses in higher organisms they discovered that the active factor when transforming dead cells into live cells is DNA

Answer 92

he proposed that material in dead bacterial cells can transform living bacterial cells, a chemical substance from one cell is capable of genetically changing another cell. He concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria. Today, we know that the "transforming principle" Griffith saw was the **DNA transformation** of the III-S strain bacteria. While the bacteria had been killed, the DNA had survived the heating process and was taken up by the II-R strain bacteria. The III-S strain DNA contains the genes that form the shielding polysaccharide part from attack. Armed with this gene, the former II-R strain bacteria were now protected from the host's immune system and could kill the host. The exact nature of the transforming principle (DNA) was confirmed in the experiments done by Avery, McLeod and McCarty and by Hershey and Chase. this showed DNA transformation r strain mouse lives (non virulent) s strain mouse dies (virulent) heat killed smooth strain mouse lives heat killed smooth strain and r strain mouse dies (living s strain found in the mouses heart)

Answer 93

the separation of DNA fragments using agarose gel electrophores

Answer 94

The predicted frequency of heterozygous individuals The Hardy–Weinberg principle, also known as the Hardy–Weinberg equilibrium, model, theorem, or law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. These influences include mate choice, mutation, selection, genetic drift, gene flow and meiotic drive.

Answer 95

blunt end In a blunt-ended molecule both strands terminate in a base pair. Blunt ends are not always desired in biotechnology since when using a DNA ligase to join two molecules into one, the yield is significantly lower with blunt ends. When performing subcloning, it also has the disadvantage of potentially inserting the insert DNA in the opposite orientation desired. On the other hand, blunt ends are always compatible with each other.

Answer 96

They are most often created by restriction endonucleases when they cut DNA. Very often they cut the two DNA strands four base pairs from each other, creating a four-base 5' overhang in one molecule and a complementary 5' overhang in the other. These ends are called cohesive since they are easily joined back together by a ligase

Answer 97

950C @ 30 seconds 600C @ 60 seconds 720C @ 120 seconds 30 cycles

Answer 98

Recombinant DNA (rDNA) molecules areDNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in biological organisms.

Answer 99

sticky end cut

Answer 100

to denature the double stranded DNA

Answer 101

u4 disassociates

Answer 102

To have cystic fibrosis, an individual must have inherited two faulty alleles from their parents; one from their father and one from their mother.

Answer 103

Alleles are different forms of a gene.

Answer 104

after birth

Answer 105

confirmed that DNA was the biomolecule that carried genetic information These experiments were to make sure that DNA was the genetic material which had been discovered by the Swiss physicianFriedrich Miescher in his experiments on white blood cells or leukocytes Hershey and Chase used T2 phage, a bacteriophage, for their experiments. The phage infects a bacterium by attaching to it and injecting its genetic material into it. They put labels on phage DNA with radioactive Phosphorus-32. They then followed the phages while they infected E. coli. They found that the radioactive element was only in the bacteria, and not in the phage. In a second experiment, they put labels on the phage protein with radioactive Sulfur-35. After the phage was attached to the bacterium, the radioactive element was found in the phage, but not in the bacteria. This showed them that genetic material which infects the bacteria is DNA.

Answer 106

5 carbon sugar deoxyribose

Answer 107

a nucleoside is a nucleobase linked to a sugar

Answer 108

- phosphate, nitrogenous base and 5 carbon sugar deoxyribose Nucleotides form the basic structural unit of nucleic acids such as DNA.

Answer 109

Kary Mullis Cycling process of:  Initial Denaturation  Denaturation - cycle 28-40 times between denaturation and extension  Annealing  Extension  Final Extension

Answer 110

Denaturation – destabilises H bonds

Answer 111

Annealing – specificity of primer to site

Answer 112

Extension – polymerase requires 3’ binding

Answer 113

Description: Fr(red) = 7/20 = 0.35 (7 red dots and 20 yellow dots, divide the lowest species by the highest species)

Answer 114

change in allele frequencies

Answer 115

the population is very large • individuals in the population mate randomly • there is no migration into or out of the population • natural selection does not act on any specific genotypes • males and females have the same allele frequencies [vs. individuals are diploid and reproduce sexually] • no mutations occur

Answer 116

* Serving the interests and wellbeing of others * Act in the best interest of the individual

Answer 117

No official misconduct • Do no harm

Answer 118

legally no

Answer 119

Human Tissue Act 2004, 2006 • Must have INFORMED CONSENT • Removal, storage and use for scheduled purpose  Human Tissue Act covers anything containing cells, (organs \> urine)  Tissues from autopsy and surgery are distinguishe

Answer 120

Biological material of human origin and any substance extracted from it, e.g. DNA

Answer 121

Transcription is the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which it encodes. he process by which DNA is copied to RNA is called transcription

Answer 122

the process of translating the sequence of messenger RNA to a sequence of amino acids during protein synthesis. the ribosome reads the sequence of the mRNA in groups of 3 bases to assemble the protein

Answer 123

solid arrows: transfers that occur in all cells Dotted arrows: transfers that occur in some cells DNA -\> RNA -\> Protein DNA to RNA through transcription, RNA to Protein through Translation

Answer 124

40% for research, diagnostics tests and drugs

Answer 125

identification purposes make many copies of an organism’s DNA sequence so a small number of organisms will become large enough to be identified

Answer 126

DNA primers attached to the end of the desired gene

Answer 127

Primers anneal when DNA is cooled, not when heated.

Answer 128

fertilisation cleavage (The zygote divides (cleaves) into two identical cells.) blastocyte formation Gastrulation Organogenesis

Answer 129

The zygote is totipotent: it can produce all the cell types needed to make a complete human.

Answer 130

Cells of the inner cell mass of blastocytes are pluripotent: they can form all cell types of the human body except tissues which support the embryo, such as the placenta. The inner cell mass is the source of one type of stem cell, embryonic stem cells.

Answer 131

Stem cells are cells that can: • Generate more specialised cell types through the process of cell differentiation. • Divide to make identical copies of themselves, a process called self-renewa

Answer 132

To provide lab-grown human or animal tissue for identifying new treatments for disease, including new drugs and other substances, rather than using animals. • To produce new human tissue and organs to replace those lost in injury or disease. See box, Organ regeneration. • To repair tissue by stimulating stem cells already in the body. • To use stem cells from patients with inherited genetic diseases (such as cystic fibrosis or some forms of Parkinson’s disease) to study how the disease develops. • To investigate human development. • To better understand diseases like cancer

Answer 133

pluripotent

Answer 134

multipotent

Answer 135

ethod of generating pluripotent stem cells by subjecting ordinary cells to certain types of stress, such as the application of a bacterial toxin, submersion in a weak acid, or physical squeezing research done by Haruko Obokata all scientists who tried to duplicate her results failed and suspicion arose that Obokata's results were due to error or fraud.

Answer 136

3 main phases: Initiation, elongation and termination

Answer 137

Transcription factors (proteins) bind to promoter regions of the DNA

Answer 138

uUracil instead of Thymine

Answer 139

u50 – 100 A residues uNo template uProtects against 3’ exonuclease uAids in transport

Answer 140

1•. Silent -\> The most frequent type of mutation, doesnt change the amino acid • •2. Non-sense -\> Changes an amino acid codon into a Stop codon: • •3. Mis-sense -\> •Changes one amino acid codon into another amino acid codon. • •Changes the primary structure of the protein. •

Answer 141

Adenine and Guanine

Answer 142

PHENOTYPIC VARIATION , Inheritance, Random Sampling

Answer 143

DNA polymorphism is any difference in the nucleotide sequence between individuals. e.g. single base pair changes, deletions, insertions, or changes in the number of copies of a DNA sequence.

Answer 144

deoxyadosine 4 monophospahte (dAMP)

Answer 145

nucleotide

Answer 146

cytosine and thymine

Answer 147

he thought compositions of DNA were different between species but consistant within all cells of an organism ## Footnote Chargaff discovered tworules that helped lead to the discovery of the double helix structure of DNA. The first rule was that in DNA the number of guanine units equals the number of cytosine units, and the number of adenine units equals the number of thymine units. This hinted at the base pair makeup of DNA. The second rule was that the relative amounts of guanine, cytosine, adenine and thymine bases varies from one species to another. This hinted that DNA rather than protein could be the genetic material.

Answer 148

Amount of A = Amount of T Amount of C = Amount of G Amount of Purine = Amount of Pyramidine Chargaff discovered tworules that helped lead to the discovery of the double helix structure of DNA. The first rule was that in DNA the number of guanine units equals the number of cytosine units, and the number of adenine units equals the number of thymine units. This hinted at the base pair makeup of DNA. The second rule was that the relative amounts of guanine, cytosine, adenine and thymine bases varies from one species to another. This hinted that DNA rather than protein could be the genetic material.

Answer 149

lead to the discorvery of the double dna helix she discovered dna has a helical structure and was working on the structure of dna

Answer 150

discovery of the molecular structure of DNA based on all its known features - the double helix DNA is composed of 2 chains of nucleotides that form a double helix shape.  The two strands are antiparallel. (C5’ to C3’)  The backbone of the DNA molecule is composed of alternating phosphate groups and sugars.  The complimentary nitrogenous bases form hydrogen bonds between the strands.  A is complimentary to T and G is complimentary to C.  Turn in helix is 34Å and 10bp B form of DNA – right handed helix  Major and Minor Groves

Answer 151

5' - 3' and backwards too for double stranded 3' - 5'

Answer 152

B DNA -\> vast majority of dna in this form A DNA -\> forms in low humidity, 11 base pairs per turn, forms in certain DNA - protein complexes, central hole (RNA - RNA + RNA - DNA) Z DNA -\> left hand helix zig zag appearance

Answer 153

sound in mrna -\> code for protein product first and last exons contain untranslated regions (UTRs) 5' exon ocontains initiator codon 3' codon contains termination codon

Answer 154

contains ribose not deoxyribose uracil not thymine mainly single stranded, can be double stranded by complimentary base pairing

Answer 155

mRNA - \> carries messages to ribosomes from DNA

Answer 156

“On top of or in addition to genetics” “Heritable, but potentially reversible, changes in gene expression that occur without changes in the DNA sequence” May change over the lifetime of an individual Influenced by environment, especially in development -

Answer 157

epigenetic marks tell your genes to switch on or off ## Footnote Through epigenetic marks, environmental factors like diet, stress and prenatal nutrition can make an imprint on genes passed from one generation to the next.

Answer 158

An enzyme DNA ligase is the a glue that joins the ends of the recombinant DNA and plasmid together

Answer 159

DNA primase is an enzyme involved in the replication of DNA. DNAprimase is a type of RNA polymerase which creates a RNA primer (later this RNA piece is removed by a 5' to 3' exonuclease); next, DNA polymerase uses the RNA primer to replicate ssDNA. Primase is an enzyme that synthesizes short RNA sequences called primers. These primers serve as a starting point for DNA synthesis. Since primase produces RNA molecules, the enzyme is a type of RNA polymerase. Primase functions by synthesizing short RNA sequences that are complementary to a single-stranded piece of DNA, which serves as its template. It is critical that primers are synthesized by primase before DNA replication can occur. This is because the enzymes that synthesize DNA, which are called DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides. Therefore, primase serves to prime and lay a foundation for DNA synthesis.

Answer 160

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell.

Answer 161

A macromolecule, usually a protein, that catalyzes biochemical reactions, lowering the activation energy and increasing the rate of reaction.

Answer 162

proteins involved in the process of converting, or transcribing, DNA into RNA

Answer 163

Promoter sequences are DNA sequences that define where transcription of a gene by RNA polymerase begins. Promoter sequences are typically located directly upstream or at the 5' end of the transcription initiation site. RNA polymerase and the necessary transcription factors bind to the promoter sequence and initiate transcription. Promoter sequences define the direction of transcription and indicate which DNA strand will be transcribed; this strand is known as the sense strand. Many eukaryotic genes have a conserved promoter sequence called the TATA box, located 25 to 35 base pairs upstream of the transcription start site. Transcription factors bind to the TATA box and initiate the formation of the RNA polymerase transcription complex, which promotes transcription.

Answer 164

A TATA box is a DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins. Transcription is a process that produces an RNA molecule from a DNA sequence. The TATA box is named for its conserved DNA sequence, which is most commonly TATAAA. Many eukaryotic genes have a conserved TATA box located 25-35 base pairs before the transcription start site of a gene. The TATA box is able to define the direction of transcription and also indicates the DNA strand to be read. Proteins called transcription factors can bind to the TATA box and recruit an enzyme called RNA polymerase, which synthesizes RNA from DNA.

Answer 165

Adenosine 5'-triphosphate, or ATP, is the principal molecule for storing and transferring energy in cells. It is often referred to as the energy currency of the cell and can be compared to storing money in a bank. ATP can be used to store energy for future reactions or be withdrawn to pay for reactions when energy is required by the cell. Animals store the energy obtained from the breakdown of food as ATP. Likewise, plants capture and store the energy they derive from light during photosynthesis in ATP molecules. ATP is a nucleotide consisting of an adenine base attached to a ribose sugar, which is attached to three phosphate groups. These three phosphate groups are linked to one another by two high-energy bonds called phosphoanhydride bonds. When one phosphate group is removed by breaking a phosphoanhydride bond in a process called hydrolysis, energy is released, and ATP is converted to adenosine diphosphate (ADP)

Answer 166

RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence, duyring the process of transcription. As complex molecule composed of protein subunits, RNA polymerase controls the process of transcription, during which the information stored in a molecule of DNA is copied into a new molecule of messenger RNA. RNA polymerases have been found in all species, but the number and composition of these proteins vary across taxa. For instance, bacteria contain a single type of RNA polymerase, while eukaryotes (multicellular organisms and yeasts) contain three distinct types. In spite of these differences, there are striking similarities among transcriptional mechanisms. For example, all species require a mechanism by which transcription can be regulated in order to achieve spatial and temporal changes in gene expression.

Answer 167

when an organism activates different phenotypes in response to its environment A highly illustrative example of phenotypic plasticity is found in the social insects, colonies of which depend on the division of their members into distinct castes, such as workers and guards.These two castes differ dramatically in appearance and behaviour. However, while these differences are genetic in basis, they are not inherited; they arise during development and depend on the manner of treatment of the eggs by the queen and the workers, who manipulate such factors as embryonic diet and incubation temperature. The genome of each individual contains all the instructions needed to develop into any one of several 'morphs', but only the genes that form part of one developmental program are activated.

Answer 168

genetic and epigenetic Genetic information: The building block for the manufacture of ALL proteins in the body Epigenetic information: How, when and where this genetic information should be used

Answer 169

The process of making RNA from DNA RNA polymerases Portion of DNA copied = Template Resulting RNA molecule = Transcript

Answer 170

Initiation, elongation and termination

Answer 171

xxy (male as only males have y chromosones) genetic condition but it is not 'inherited' from your parents. It usually happens randomly during meiosis - cell division that produces egg and sperm cells lives till adulthood (normal life span) treatment: testosterone replacement, gynaecomastia treatement, infertility treatment

Answer 172

the top is negative (lowest number) and the bottom is positive (highest number). the fragments (lines) are pushed from top to bottom and those that are the smallest move the furthest from the top and the fragments that are the largest wont move as far from the negative end. the numbers go from highest at the top (negative) to lowest at the bottom (positive) agarose gel is used for larger base pairs and SDS page is used for smaller base pairs uses an electical charge to push the fragments down the gel

Answer 173

uses an electrical current DNA is negatively charged so it goes to the cathode

Answer 174

p2+2pq+q2=1 p+q=1

Answer 175

a harmless test to determine birth defects before the baby is born used to help calculate the odds that the fetus might be born with genetic disorders, such as Down syndrome, cystic fibrosis, Tay-Sachs disease, or sickle cell anemia. risk of miscarriage

Answer 176

•an abnormality occurs when only one of the genes from one parent is abnormal The alteration is located on an autosome. ## Footnote people with the condition in each generation males and females affected in roughly equal proportions all forms of transmission present (male to female, male to male, female to male and female to female). At conception, each child has a 1 in 2 (50%) chance of inheriting the condition. Examples of autosomal dominant conditions include: Huntington disease Achondroplasia Marfan syndrome loeys dietz syndrome

Answer 177

condition that appears only in individuals who have received two copies of an altered gene, once copy from each parent. People with two copies of the altered gene are called homozygotes. Their parents, each with a single copy of the altered gene, appear normal and are called heterozygotes or carriers of the altered gene. In autosomal recessive inheritance, people with one copy of the gene alteration do not have the condition. They are said to be carriers for the autosomal recessive condition. males and females have the condition in roughly equal proportions people with the condition are usually in one sibship in one generation At conception each child of parents who are both carriers has a 1 in 4 (25%) chance of being an unaffected non-carrier; a 2 in 4 (50%) chance of being a carrier and a 1 in 4 (25%) chance of inheriting the condition. Examples of autosomal recessive conditions include: cystic fibrosis sickle-cell anaemia MCADD PKU Phenylketonurea beta-thalassaemia.

Answer 178

condition in which an alteration in one gene on the X chromosome causes the condition in males but not usually when females have one copy of the altered gene. can only be passed from the mother to son as fathers only pass on their y chromosone to the son males affected almost exclusively the gene alteration can be transmitted from female carriers to sons affected males cannot transmit the condition to their sons. conditions: haemophilia (factor 8 or 9 defective) colour blindness Duchenne muscular dystrophy.

Answer 179

The sons of a man with an X-linked dominant disorder will all be unaffected (since they receive their father's Y chromosome), and his daughters will all inherit the condition. A woman with an X-linked dominant disorder has a 50% chance of having an affected fetus with each pregnancy conditions: chondrodysplasia punctata (short stature) rickets kleinefelter syndrome Rett syndrome, incontinentia pigmenti type 2, and Aicardi syndrome

Answer 180

caused by mutations on the Y chromosone Y-linked disorders in humans can only be passed from men to their sons; females can never be affected because they do not possess Y allosomes. azoospermia hairy ear pinnae retinitis pigmentosia y chromosone infertility

Answer 181

also known as maternal inheritance, applies to genes in mitochondrial DNA. Because only egg cells contribute mitochondria to the developing embryo, only mothers can pass on mitochondrial conditions to their children. An example of this type of disorder is Leber's hereditary optic neuropathy.

Answer 182

An organism that has two different alleles for a single trait is said to be heterozygousfor that trait

Answer 183

Mendel referred to the parental generation in the cross pollination between two true-breeding plants as the P generation.

Answer 184

In the cross-pollination between a true-breeding yellow pod plant(gg) and a true-breeding green pod plant(GG), where green pod color is dominant, the resulting offspring (F1 generation) will be all green. The genotype of the F1 plants is (Gg).

Answer 185

If the green F1 plants from the green dominant, yellow recessive parental generation are allowed to self-pollinate, the resulting offspring (F2 generation) will be 1/4 yellow and 3/4 green.

Answer 186

the genotype of the unknown plant is GG

Answer 187

independant assortment the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.

Answer 188

segregation genes occur in pairs and during the process of sex cell production, the members of each pair separate so that each sperm and ovum cell receives one member of each pair.

Answer 189

DNA stop codons TAG, TAA, TGA or replace T with U for RNA UAA, UAG, or UGA to signify the end of protein synthesis

Answer 190

AUG serves two related functions: start signal for translation it codes for the incorporation of the amino acid methionine (Met) into the growing polypeptide chain

Answer 191

gene transmission

Answer 192

All of the children will be healthy since none of them can be homozygous recessive (aa). However, there will be a 50% chance at each birth that the children will be carriers (Aa). The remaining 50% will be homozygous dominant (AA).

Answer 193

The nitrogen bases are pyrimidine in structure and form a bond between their 1' nitrogen and the 1' -OH group of the deoxyribose.

Answer 194

adenine it can also have two 'NH's split off at the top instead of NH2 Its chemical formula is C5H5N5 (count the number of C's etc that appear on the structure when figuring out which nucleotide the question is showing)

Answer 195

Guanine neucleotide purine, (double-ring bases) nitrogeous base

Answer 196

pyramidines

Answer 197

an enzyme that synthesizes short RNA sequences (primers). it is a type of RNA polymerase

Answer 198

Genetic polymorphism promotes diversity within a population. It often persists over many generations because no single form has an overall advantage or disadvantage over the others regarding natural selection. A common example is the different allelic forms that give rise to different blood types in humans. •DNA level variation. • •Protein level variation. • Morphological variation

Answer 199

* Single-gene traits. * Polygenic traits.

Answer 200

•Different variants (alleles) of a single gene

Answer 201

•Different variants (alleles) of several genes

Answer 202

Dominant allele: Allele that determines the phenotype in a heterozygous condition

Answer 203

•Recessive allele: Displays no influence on the phenotype in heterozygous individuals.

Answer 204

AA and aa because they must be the same

Answer 205

Aa and aA because heterzygous means different

Answer 206

tongue rolling, widows peak and attached earlobes

Answer 207

•Phenotypic variation results from environmental influences on the genotype.

Answer 208

phenotypic because their appearance depends on the differing environments whereas if it was genotypic the non windy plant would stay the same when transferred to the windy site and the windy plant would stay the same when transferred to the non windy site

Answer 209

phenotypic the height of the plant depends on its environment (altitude in this case), if it was genotypic the plant would stay the same height regardless of altitude or environment

Answer 210

•Phenotypic variation results from environmental influences on the genotype. • •Phenotypic variation has both environmental and genotypic components. • If the genotypes are identical then any variation must result from environmental influences

Answer 211

Populations could be described genetically in terms of their phenotype frequencies, genotype frequencies, and allele frequencies his three laws of inheritance are: 1. the Law of Dominance 2. the Law of Segregation 3. the Law of Independent Assortment

Answer 212

Bb x Bb - both parent show dominant trait, but some recessive offspring will be produced (each parent carries a "b")

Answer 213

•Evolution is simply a change in frequencies of alleles in the gene pool of a population. e.g. parent 92% A and 8% a offspring become 90% A and 10% a •evolution has occurred between the generations. • •The entire population's gene pool has evolved in the direction of a higher frequency of the a allele. It was not just those individuals who inherited the a allele that evolved.

Answer 214

do a punnet square! remember f1 is two purebred plants crossed so white is the dominant from that crossing so would be Ww and pink would be ww 50% heterozygous white & 50% homozygous recessive pink

Answer 215

•Godfrey Hardy (an English mathematician) and Wilhelm Weinberg (a German physician). • •Showed in 1908 that the frequency of homozygotes and heterozygotes in a population’s gene pool stays constant from generation to generation if certain conditions were fulfilled.

Answer 216

•Evolution will not occur in a population if seven conditions are met: • •1. Mutation is not occurring. •2. Natural selection is not occurring. •3. The population is infinitely large. •4. All members of the population breed. •5. All mating is totally random. •6. Everyone produces same number of offspring. 7. There is no migration in or out of the population

Answer 217

unlikely, evolution is inevitable

Answer 218

•Mutation • •Migration • •Selection • •Mating system • •Population size [Genetic drift]

Answer 219

•used to discover the probable genotype frequencies in a population and to track their changes from one generation to another. ## Footnote p² + 2pq + q² = 1 •p + q = 1

Answer 220

p is the frequency of the dominant allele. P2 = AA, Pq = Aa (dominant) q is the frequency of the recessive allele qq = aa (recessive) •For a trait controlled by a pair of autosomal alleles (A and a):

Answer 221

p2 = p squared 2pq = 2 x p x q

Answer 222

In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation (the dominant trait). Offspring that are hybrid for a trait will have only the dominant trait in the phenotype.

Answer 223

immigration, emmigration, births and deaths

Answer 224

p = 1 - q q = 1 - p

Answer 225

•chances of all possible combinations of alleles occurring randomly is: ## Footnote (p + q)² = 1 Or, more simply: pp + pq +qp + qq = 1 p² + 2pq + q² = 1

Answer 226

the predicted frequency of homozygous dominant (AA) individuals in the population,

Answer 227

the predicted frequency of heterozygous (Aa) individuals

Answer 228

the predicted frequency of homozygous recessive (aa) individuals

Answer 229

•It is usually only possible to know the frequency of homozygous recessive individuals.•q² in the Hardy-Weinberg Equation Since they do not have the dominant trait

Answer 230

it CAN be used to find out whether evolution has occured between generations •the Hardy-Weinberg equation CANNOT determine which of the various possible causes of evolution were responsible for the changes in allele frequencies in the gene pool.

Answer 231

one way only DNA -\>transcription -\> RNA -\> Translation -\> Protein

Answer 232

the study of how genes behave in populations it involves descriptions and predictions

Answer 233

the probability of randomly encountering an item of a certain type is equal to the frequency of that type in the population the probability of rolling a 6 on a single die is 1/6

Answer 234

vast majority of DNA in this form helix makes a turn every 3.4 nm 20 base pairs per turn major groove and the minor groove, which may facilitate binding with specific proteins.

Answer 235

forms in low humidity 11 base pairs per turn forms in certain DNA protein complexes central hole (RNA - RNA + RNA - DNA)

Answer 236

left hand helix zig zag appearance One turn spans 4.6 nm, comprising 12 base pairs

Answer 237

it is a combination of molecular biology, maths and computer science in order to understand the biological significance of a variety of data

Answer 238

many uses in forensic and biological sciences

Answer 239

central dogma dash lines = special solid lines = general

Answer 240

Studies in one organism have wider relevance

Answer 241

the central dogma of molecular biology describes the flow of genetic information in cells from DNA to messenger RNA (mRNA) to protein. It states that genes specify the sequence of mRNA molecules, which in turn specify the sequence of proteins

Answer 242

3:1 its the hybrid of 1 set of traits from p generation to f1 generation

Answer 243

•Locus = site of allele on chromosome

Answer 244

co dominance or incomplete dominance

Answer 245

incomplete dominance

Answer 246

1 red cow, 2 roan cows, 1 white cow (phenotype) 1:2:1 (genotype) modified monohybrid

Answer 247

use a punnet square

Answer 248

genes close together on a chromosone show linkage •They tend to enter gametes in parental combinations •The close together, the stronger the linkage. •Recombination requires breaking of linkage as a result of crossing over during meiosis The closer the genes, the less chance of crossover occurring between them

Answer 249

double heterozygote

Answer 250

•Autosomal dominant •Autosomal recessive. •Sex linked dominant Sex linked recessive

Answer 251

autosomal dominant 1:1 1 affected 1 unaffected (50% chance)

Answer 252

* Caused by stutter on DNA. * Excessive number of repeats of CAG on chromosome 4. * Brain deteriorates in middle age.•If the parent has the disorder, the baby has a 50 percent chance of inheriting it. * 12 in 100,000 approx. autosomal dominant

Answer 253

dwarfism, autosomal dominant Defect on chromosome 4. Fault in fibroblast growth factor receptor. 80% patients due to new mutation. More likely if father over 35. 1/25,000 •imperfect bone development causing dwarfism

Answer 254

aracnodactyle hands ## Footnote Defect on chromosome 15, connective tissue disorder. causing long limbs and heart defects dilation of aorta (aorta stretches and weakens) pectus excavatum (hollow point in ribcage) marfan syndrome has no cure, but treatments can help delay or prevent complications. Treatments include medicines, surgery, and other therapies.

Answer 255

autosomal dominant similar to marfan syndrome High risk of sudden death due to rupture of aortic aneurysm. Joint hypermobility Club foot Curved spine no cure, medications and surgery

Answer 256

autosomal dominant polled = no horns

Answer 257

autosomal recessive 1 affected, 2 carriers, 1 unaffected 3 normal : 1 sufferer Phenotypes

Answer 258

autosomal recessive

Answer 259

autosomal recessive hairlessness in animals

Answer 260

autosomal recessive •Caused by deletion on chromosome 7 (in most cases) •Failure of Chloride (Cl-) ion transport. •1 in 1,800 white people. •An abnormality only occurs when both chromosomes carry abnormal genes. •If both parents are carriers, a baby has a 25 percent chance of having the disorder. ## Footnote Failure of Cl- ion transport at cell surface causes:- Lungs – thick bronchial secretions block the small airways causing inflammation Liver – thick secretions (TS) block bile duct Pancreas - TS may block gland completely Small intestine – meconium ileus Reproductive organs – infertility Sweat and salivary glands - secrete fluid with more salt than normal

Answer 261

chromosone 12 ## Footnote Defective enzyme prevents conversion of phenylalanine to tyrosine. Too much phenylalanine, too little tyrosine. Brain/nervous system fails to develop normally 1/12,000 Caucasian births. Controlled by careful diet soon after birth.

Answer 262

homologous at bottom, differential at top

Answer 263

•Disorder determined by genes on the X chromosome •Affects mainly males, have no spare copy •Sons of women who are carriers each have a one in two chance of having the disorder. •Daughters of women who are carriers have a one in two chance of being a carrier. Men with the disorder pass the gene on to all their daughters who become carriers. (Provided that the disorder is not fatal during infancy. Eg colour blindness not fatal

Answer 264

* Progressive muscle weakening. * Due to abnormal muscle protein. ## Footnote 1 in 3,500 males. Onset 3 – 5 years Also cardiomyopathy, mental disability Death 15 – 25 years

Answer 265

•Some birth defects do not follow a single gene or chromosomal abnormality pattern • •They may be due to several problems, or a combined effect of genes and the environment • •It is difficult to predict inheritance of abnormalities caused by multiple factors • examples: * heart defects, * cleft lip or cleft palate, * and neural tube defects

Answer 266

•Family tree •Screening parent’s DNA •Prenatal testing: •chorionic villus sampling •amniocentesis •

Answer 267

This problem is explained because the creeper allele is lethal in the homozygous condition and fails to develop and so is not seen. The creeper condition is caused when the individual is a heterozygote (with one normal and one creeper allele).

Answer 268

turners syndrome XO

Answer 269

For evolution to occur there must be polymorphism (variation) present in the population

Answer 270

•Point mutation:•1. Silent • •2. Non-sense • •3. Mis-sense

Answer 271

•The most frequent type of mutation. • •Mainly at third codon positions. • •Genetic code is redundant. • •Does not change the amino acid.

Answer 272

•Changes an amino acid codon into a Stop codon: • •UAA •UAG •UGA

Answer 273

•Changes one amino acid codon into another amino acid codon. • •Changes the primary structure of the protein. • •Knock-on effects on the secondary, tertiary, and quaternary structure too: • •Depending on the change in size and shape; • •Depending on the change in charge or polarity.

Answer 274

•Abnormal differentiation of gonads • •Phenotypic sex ambiguous or not in agreement with chromosomal sex, hermaphrodites ## Footnote Abnormalities which cause an increase in androgen and testosterone synthesis may confer a competitive advantage. Eg. Congenital Adrenal Hyperplasia

Answer 275

•presence of two or more chromosome patterns in the cells of a person, resulting in two or more cell lines (i.e., in humans some with 46 chromosomes, others with 47)

Answer 276

nonsense mutation, causes stop codons with mutations

Answer 277

missense mutation,

Answer 278

arginine, histidine, lysine

Answer 279

aspartic acid gluatamate acid

Answer 280

serine, threonine, glutamine, asparagine

Answer 281

proline, cysteine, glycine

Answer 282

alanine, valine, isoleucine, leucine, methionine, tryptophan, tyrosine, phenylalanine

Answer 283

glycine amino acid

Answer 284

alanine amino acid

Answer 285

valine amino acid

Answer 286

leucine, amino acid

Answer 287

isoleucine amino acid

Answer 288

semi conservative model

Answer 289

conservative model

Answer 290

the dispersive model

Answer 291

they proved watson and cricks theory of dna being semi conservative,

Answer 292

``` Identified all the components needed to replicate E.coli DNA in vitro he found the enzyme that assembles the building blocks into DNA, named DNA polymerase. This ubiquitous class of enzymes make genetically precise DNA and are essential in the replication, repair and rearrangements of DNA. ```

Answer 293

uA DNA template uMagnesium ions Enzyme – DNA polymerase III (Prokaryotes all 4 dntps - Deoxyribonucleotide triphosphate, referring to the four deoxyribonucleotides: dATP, dCTP, dGTP and dTTP. A for adenine, C for cytosine, G for guanine and T for Thymine.

Answer 294

Formation of a phosphodiester bond Between 3’OH of Deoxyribose on last nucleotide and 5’phosphate of dNTP uFinds correct dNTP ONLY synthesis 5’ to 3’ DNA polymerases are the enzymes that replicate DNA in living cells. They do this by adding individual nucleotides to the 3-prime hydroxl group of a strand of DNA. The process uses acomplementary, single strand of DNA as a template. This enzyme adds nucleotides to an existing strand

Answer 295

During DNA\* replication a DNA double helix must unwind and separate so that DNA polymerase enzymes can use each single strand as a template for the synthesis of a new double strand. Strand separation is catalyzed by a Helicase enzyme. A number of helper proteins prevent the strands from coming back together before replication is complete. Partial separation of the double helix forms a replication fork\*.

Answer 296

The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated.[1] This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses.

Answer 297

Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate of DNA strands.

Answer 298

a primosome is a protein complex responsible for creating RNA primers on single stranded DNA during DNA replication.

Answer 299

uSingle stranded binding proteins u uDNA Pol III only 5’ à 3’ u uLeading and Lagging strands ## Footnote DNA synthesis at a replication fork of a replication bubble is semidiscontinuous

Answer 300

A portion of the DNA molecule that has opened, providing a site for two replication forks.

Answer 301

The copying of DNA to pass on information

Answer 302

The noncontinuous segments of newly synthesized DNA along the lagging strand

Answer 303

The process of copying the genetic code from DNA into the form of mRNA which then leaves the cell neucleus and enters the cytoplasm where it directs the synthesis of protein

Answer 304

A sequence of DNA nucleotides that signals where transcription will begin and where RNA polymerase binds enables transcription of the gene.

Answer 305

. RNA is single-stranded, not double stranded 2. The five-carbon sugar is ribose instead of deoxyribose 3. The nitrogenous base uracil replaces the DNA base thymine

Answer 306

During replication, the DNA strand that grows discontinuously and in the direction opposite of the replication fork.

Answer 307

During replication, the strand of DNA that is synthesized continuously in the direction of the replication fork.

Answer 308

This enzyme cuts and rejoins the helix

Answer 309

This enzyme brings together the Okazaki fragments

Answer 310

This enzyme unwinds our double helix into two strands

Answer 311

A proposed mechanism of DNA replication, suggesting that segments of both parental strands act as templates for a new strand. The resulting daughter strands contain a mixture of old and newly synthesized DNA.

Answer 312

A model (born out by experimental evidence) for DNA replication in which each DNA strand acts as a template for the synthesis of a new complementary strand.

Answer 313

A proposed mechanism for DNA replication that suggested replication resulted in a DNA molecule consisting of two new, and no parental, strands. The mechanism has been disproven.

Answer 314

This type of bond holds together the two DNA strands by linking complementary nitrogenous bases; this contributes to DNA's secondary structure, a double helix

Answer 315

Bonds that link nucleotides of a DNA strand together. The 3′ and 5′ carbons of sugars of two respective nucleotide subunits are linked together, and the phosphate group of the bottom nucleotide lies in between.

Answer 316

RNA primer made by DNA primase starts replication of lagging strand (synthesis of 1st osaki fragment)

Answer 317

uMany circular DNA molecules remain so during replication u uAs strands uncoil severe tension upahead u uTopoisomerases introduce negative supercoils A nucleic acid that carries the genetic information in cells and some viruses, consisting of two long chains ofnucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine andthymine or cytosine and guanine. DNA sequences are replicated by the cell prior to cell division and may include genes,intergenic spacers, and regions that bind to regulatory proteins.

Answer 318

provide multiple copies of DNA for future experiments. •To investigate DNA/RNA/protein requires a large quantity of the nucleic acid/protein so as to perform numerous molecular biology experiments

Answer 319

DNa is isolated then inserted into a plasmid (bacterial DNA) in a process called cloning * The introduction of this ‘foreign’ DNA into the bacterial plasmid DNA will enable hundreds of copies of the ‘foreign’ DNA to be produced * The cloning of an organisms DNA with the plasmid produces Recombinant DNA * Once this recombinant DNA has been produced this can be study extensively in the lab

Answer 320

•Recombinant DNA is made by cutting a DNA fragment out of one place and inserting it into another * The ‘foreign’ (donor) DNA fragment is ‘spliced’ into a specific location in the ‘host’ DNA of the plasmid * The plasmid (containing the recombinant DNA) can then be added to a bacterial cell * Every time the bacteria copies its own DNA it will also copy the plasmid (recombinant DNA)

Answer 321

* commonly known as ‘restriction enzymes’ * Restriction endonucleases cut double stranded DNA at specific target sites * Able to cut through the DNA’s phosphate backbone •Restriction enzymes recognise palindromic sequences

Answer 322

•Palindromic = both strands have same nucleotides sequence but in anti-parallel orientation e.g. 5’ GAATTC 3’ 3’ CTTAAG 5’

Answer 323

•restriction Enzyme can produce either sticky (staggered cut) or blunt (even cut) ends

Answer 324

blunt end cut

Answer 325

staggered end cut

Answer 326

plasmids are derived from a natural plasmid found in bacteria/virus •Plasmids occur naturally: ## Footnote stable genetic elements found in bacteria, fungi and mitochondria of some plants • •Natural plasmids are used by micro-organisms to enable survival e.g make bacteria antibiotic resistant

Answer 327

autonomously * Plasmids exist and replicate independently (replicate autonomously) of the bacteria cells chromosome * When ever the bacteria replicates its own bacterial DNA, it will also replicate the plasmid DNA

Answer 328

•enable DNA cloning/gene expression of recombinant DNA - maximum expression of recombinant DNA - have an area where recombinant DNA can be introduced into the plasmid - identification of bacteria that contain the plasmid

Answer 329

ampicillin ## Footnote Allows scientists to select for bacteria that has the plasmid

Answer 330

MCS: contains different restriction sites where different restriction enzymes can cut

Answer 331

it shows a 9:3::1 ratio where **2 gene pairs** are segregating independantly the f1 x green wrinkled would be: 1 round yellow : 1 round green : 1 wrinkled yellow : 1 wrinkled green

Answer 332

1:1:1:1 1 pink mildrew resistant 1 pink mildew suseptible 1 white mildew resistant 1 pink mildew suseptible This problem illustrates linkage, which is when the two alleles are sufficiently close together on the same chromosome to mean that they tend to enter gametes in parental combination. Distances between genes on a chromosome are measured in map units. F1 backcrossed to parental plants which were doubly recessive (white seeds and susceptible to mildew). If independent assortment expect a 1 : 1 : 1 : 1 ratio Total number of bean plants counted in backcross generation = 950. 950/4 = 237.5; if a 1 : 1 : 1 : 1 ratio Observed Expected Pink, Resistant (Parental) 393 237.5 Pink, Susceptible (Recomb) 101 237.5 White, Resistant (Recomb) 89 237.5 White, Susceptible (Parental) 367 237.5 Shows more than expected Parental compared to Recombinants. Χ2 (chi squared) test to see if the difference between Observed and Expected is significant Χ2 = (393 – 237.5)2 + (101 – 237.5)2 + (89 – 237.5)2 + (367 – 237.5)2 237.5 237.5 237.5 237.5 = 101.8 + 78.5 + 92.9 + 70.6 = 348.8; 3 degrees of freedom; less than 0.005 probability; reject 1:1:1:1 hypothesis Percentage Recombinants = Map units (mu) apart of the two loci = 190/950 x 100 = 20mu apart.

Answer 333

complementary DNA complementary DNA (cDNA) is double-stranded DNA synthesized from a messenger RNA (mRNA) template in a reaction catalysed by the enzyme reverse transcriptase. cDNA is often used to clone eukaryotic genes in prokaryotes.

Answer 334

Mitochondrial DNA – is passed from mothers to both genders of her children, but only passed on by females. Males carry their mother’s mitochondrial DNA (mtDNA) but they don’t pass it on.

Answer 335

tests the Y chromosome which is passed from father to son, along, in most cases, with the surname. Only men can test for this, because only men have a Y chromosome,

Answer 336

tests the rest of the DNA provided by both parents on the 23 chromosomes, not just two direct lines, as with Y-line and mitochondrial DNA.

Answer 337

thymine neucleotide pyramidine goes with adanine

Answer 338

uracil takes the place of thymine in RNA and matches with adanine which is a purine uracil is pyramidine C4H4N2O2

Answer 339

Two of the five bases in nucleic acids, adenine (2) and guanine (3), arepurines. In DNA, these bases form hydrogen bonds with their complementary pyrimidines thymine and cytosine, respectively. This is called complementary base pairing. In RNA, the complement of adenine is uracil instead of thymine.

Answer 340

segregation of genes occurs during meiosis in eukaryotes, which is a process that produces reproductive cells called gametes. Mendel's law of segregation, states that allelepairs separate or segregate during gamete formation, and randomly unite at fertilization. gene can exist in more than one form. Organisms inherit two alleles for each trait. When sex cells are produced (by meiosis), allele pairs separate leaving each cell with a single allele for each trait. When the two alleles of a pair are different, one is dominant and the other is recessive.

Answer 341

Mendel's law of independent assortment, states that allele pairs separate independently during the formation of gametes. This means that traits are transmitted to offspring independently of one another. Mendel formulated this principle after performing dihybrid crosses between plants that differed in two traits, such as seed color and pod color. After these plants were allowed to self pollinate, he noticed that the same ratio of 9:3:3:1appeared among the offspring. Mendel concluded that traits are transmitted to offspring independently.

Answer 342

Percentage Recombinants = Map units (mu) apart of the two loci = 190/950 x 100 = 20mu apart. parentage recombinants = Pm and mP (heterozygotes)

Answer 343

Histones are globular proteins that, together with the DNA, make up the nucleosome ─ the structural unit of chromatin. Histones influence how tightly or loosely packed the chromatin is during the phase when gene transcription occurs. In this way histones influence whether genes can be transcribed. HISTONE – Small basic protein bound to DNA

Answer 344

chemical - methylation protein - histones

Answer 345

a methyl group is covalently added to the fifth carbon of the cytosine ring to form 5-methyl cytosine. ## Footnote DNA methylation occurs predominately on the CpG islands. DNA methylation is actively involved in regulating cell differentiation and function. When too much or too little methylation occurs, it can often negate a gene’s function and thus causes unwanted alterations in the cell and even result in diseases. methylation of the cytosine at CpG dinucleotides CpG neucleotides enriched at the gene promotes (CpG islands) catalysed by DNa methytransferases (DNMT)

Answer 346

Along the linear DNA chain, there are sites of DNA where a cytosine is followed by and linked via a phosphate to guanine, another nucleotide Regions of DNA that have a high density of CpG sites are called CpG islands.

Answer 347

chromatin structure

Answer 348

open the chromatin structure and activate transcription - Histone acetyl transferase (HAT) - Histone deacetylase (HDAC) reverses this

Answer 349

Acetylation methylation Phosphorylation

Answer 350

Condenses chromatin during cell cycle, but can also open it during remodelling

Answer 351

augments the repression of transcription

Answer 352

X-inactivation (also called lyonization) is a process by which one of the two copies of the Xchromosome present in female mammals isinactivated randomly (by chance) inactivated in an early embryonic cell, with fixed inactivation of that same X in all cells descended from that cell. The change that occurs with X inactivation is epigenetic: it is a heritable change in gene function without a change in the sequence of the DNA. X inactivation is not restricted to females. It also occurs in males withKlinefelter syndrome who have more than one X chromosome.

Answer 353

Dosage compensation is the process that ensures equal levels of X-linked gene products in males and females in species in which the sexes differ in the number of X chromosomes they possess. helps with x inactivation

Answer 354

cancer schizophrenia bipolar disorder fragile x mental retardation

Answer 355

aging regulation of genetranscription x chromosone inactivation autosomal chromosone imprinting cellular differentiation complex non mendalin diseases

Answer 356

nature: epigenetic marks can be inherited nuture: epigentic marks can beaccumulated : only those in germ line will be passed down

Answer 357

complete epigenetic state of a cell

Answer 358

**Transfer ribonucleic acid (tRNA)** is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAsfunction at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule.

Answer 359

**ribosomal ribonucleic acid** (rRNA) is the RNA component of the ribosome, and is essential for protein synthesis in all living organisms. (rRNA) that which together with proteins forms the ribosomes, playing a structural role and also a role in ribosomalbinding of mRNA and tRNAs..

Answer 360

**Transfer ribonucleic acid** (tRNA) is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAsfunction at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule.

Answer 361

**small nuclear RNA** (snRNA) a class of eukaryotic small RNA molecules found in the nucleus, usually as ribonucleoproteins, andapparently involved in processing heterogeneous nuclear RNA.

Answer 362

**heterogeneous nuclear RNA** (hnRNA) a diverse group of long primary transcripts formed in the eukaryotic nucleus, many of which willbe processed to mRNA molecules by splicing.

Answer 363

the 3' to 5' strand

Answer 364

uCoupled Transcription and Translation (Pro) uRNA Processing (Euk) uPolycistronic (Pro) uMonocistronic (Euk)

Answer 365

the scientific study of heredity and the variation of inherited characteristics.

Answer 366

–Substitution of one or more bases. –Deletion or Insertion. –Inversion. –Translocation.

Answer 367

•Replacement of one base with another. •Some have no effect due to redundancy of genetic code.•Eg DNA change from CCG to CCA, then mRNA changed from GGC to GGU. But amino acid still glycine, no change * May be an improvement = very rare, but evolution needs variation. * But can cause severe disability eg sickle cell anaemia 1/1,600 black African people. * Chromosome 11 affected.

Answer 368

chromosone 11 ## Footnote Due to sickle haemoglobin in homozygotes •Main effects due to: –Obstruction of blood flow by less pliable sickle cells –Anaemia caused by reduced lifespan of sickle cells (60 days instead of 120 days) Heterozygotes have less severe symptoms •Incomplete dominance A balanced polymorphism.

Answer 369

sickle cell anemia PKU •Phenylketonurea, chromosome 12. defective enzyme • •Haemophilia, X chromosome, lack of blood clotting factor. • •Duchene muscular dystrophy, X chromosome, abnormal muscle protein.

Answer 370

•Additions or losses of one or more bases. Can cause frame shift mutations

Answer 371

cystic fibrosis - •Caused by deletion on chromosome 7 (in most cases)

Answer 372

•a chromosome breaks and the piece of the chromosome turns upside down and reattaches itself•may or may not cause problems depending upon their exact structure

Answer 373

* a rearrangement of a chromosome segment from one location to another, either within the same chromosome or to another. * Eg. Robertsonian translocation leading to Down’s Syndrome – a rare cause.

Answer 374

•PHENOTYPIC VARIATION - variation among individuals in some attribute or trait. • •FITNESS VARIATION - a consistent relationship between that trait and the mating ability, fertilizing ability, fertility, fecundity, and/or survivorship. • •INHERITANCE - a consistent relationship for that trait between parents and their offspring which is at least partially independent of common environmental effects.

Answer 375

•PHENOTYPIC VARIATION - variation among individuals in some attribute or trait. • •RANDOM SAMPLING – one or other form of biological random sampling and subsequent sampling error. • •INHERITANCE - a consistent relationship for that trait between parents and their offspring which is at least partially independent of common environmental effects.

Answer 376

•Natural selection can only act when there are genotype dependent differences in the number of progeny. • •These differences may be measured by survivorship and fecundity.

Answer 377

Plasmid enters bacteria but does not recombine with DNA = episomal maintance of plasmid

Answer 378

Electrical current, high temperatures, high salt concentrations can all be used to introduce holes in bacterial cell wall

Answer 379

u1 snRNPs bind to intron

Answer 380

binds to branch point sequence (YNCURAY) upstream of splice junction

Answer 381

U4/U6 & U5 interact and combine with U1 and U2 creating a loop known as a LARIAT structure

Answer 382

U4 dissociates creating an ACTIVE SPLICEOSOME

Answer 383

the entire nucleic acid sequence that is necessary for the synthesis of a functional gene product (protein or functional RNA)

Answer 384

Double helix – antiparallel strands Minor and Major grooves 4 bases – purine and pyrimidines A/C/G/T Hydrogen bonds Phosphodiester bonds Glycosidic bonds Alternate forms – A/B/Z

Answer 385

Complex of DNA, histones and non-histone proteins from which eukaryotic chromosomes are formed.

Answer 386

NUCLEOSOME – Repeating unit; 8 histones surrounded by 145 nucleotide pairs. Joined to next with linked DNA ~55bp

Answer 387

CHROMATOSOME – Nucleosome, linker and H1 histone

Answer 388

Evolutionary biologists to study the variations between human and other species in order to specify the possible relationships between them. – Molecular anthropologists and genetic genealogists to examine mtDNA of various populations to map out ancestry and migration during the years. – Forensic scientists - HV1 and HV2 are hypervariable regions which are often used for human identification in cases of ancient DNA or highly degraded DNA samples.

Answer 389

neucleotide adanine dAMP - deoxyadonosine 5' - monophosphate

Answer 390

neucleotide cytosine deoxycytidine 5'monophosphate dCMP

Answer 391

guanine neucleotide deoxyguanosine 5' monophosphate dGMP

Answer 392

thymine neucleotide deoxythymidine 5' monophosphate dTMP

Answer 393

Does not contain genetic material (some exceptions in viruses)  Broader range of functions  Therefore replication not required  Intermediate between genes and protein formation (mRNA)  Adaptor between codons (tRNA)  Ribosomal RNA (rRNA) associates with a set of proteins to form ribosomes  Fold to form regions of double helix  Stem and loop formation

Answer 394

phosphodiester bond

Answer 395

Mechanism of replication: separation of strands, specific coupling of free nucleic acids ## Footnote First, the double stranded DNA must separate, or unwind. To do this: ``` DNA gyrase (class II topoisomerase) is responsible for uncoiling the DNA ahead of the replication fork. Helicase is responsible for unwinding the DNA at the replication fork. Single-strand binding protein (SSB) is responsible for keeping the DNA unwound after the helicase. SSBs stabilize single-stranded DNA by binding to it. ``` Next, you start making DNA that is complementary to the newly unwound/separated DNA. Note, all biological DNA synthesis occurs from the 5' to the 3' end. Primase gets this started by laying down a short RNA primer on the unwound DNA. The primer is made of RNA, but is complementary to the DNA sequence. Later, this RNA is replaced with DNA. DNA polymerase then takes over and makes DNA that is complementary to the unwound DNA. DNA synthesis occurs on both strands of the unwound DNA. The synthesis that proceeds in the direction of the replication fork is the leading strand. The synthesis that proceeds in the opposite direction to the replication fork is the lagging strand. The lagging strand contains Okazaki fragments. Finally, RNA primers are replaced with DNA by a special DNA polymerase. The Okazaki fragments in the lagging strands are then stitched together by DNA ligase. DNA synthesis is bidirectional: 2 replication forks form and proceeds in opposite directions (like an expanding bubble). Biological DNA synthesis always proceeds from the 5' end to the 3' end. DNA polymerase has proof-reading activity, which means it corrects any mistakes (mutations) it makes. Replication occurs once every cell generation, during the S phase. (Cell division may occur twice in meiosis, but replication still occurs once only)

Answer 396

Annealing (biology), in genetics, means for complementary sequences of single-stranded DNA or RNA to pair by hydrogen bonds to form a double-stranded polynucleotide.

Answer 397

Dictionary definition – Moral Principles  What is ‘right’ and ‘wrong’  Are we more ethical now than 50 years ago?  Why?  “Those who do not learn from history are doomed to repeat it” – George Santayana

Answer 398

A disagreement about what to do  A conflict between moral principles

Answer 399

Serving the interests and wellbeing of others • Act in the best interest of the individual

Answer 400

do no harm, no official misconduct

Answer 401

To make informed decisions • All persons treated equally • Confidentiality • Voluntary participation • Protect participants

Answer 402

consent No coercion or inducement • No payment or reward (?) • No influence by researcher • No influence by family informed consent • What the research is for • Benefits/Risks • Presented in understandable manner • Time to consider and decide

Answer 403

leagally no morally - undecided

Answer 404

This problem illustrates epistasis which is when the expression of one gene is influenced by another non-allelic gene. In order to develop the purple colour the plants must each have at least one of each dominant allele. It gives a modified dihybrid ratio.

Answer 405

when the expression of one gene is influenced by another non-allelic gene.

Answer 406

RNA polymerase

Genetics Flashcards

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