inheritance, variation and evolution Flashcards

Question

What codes for a particular amino acid?

Answer 1

* sequence of three bases is the code for a particular amino acid. * amino acids are joined together to make a protein * it is the different types and order of amino acids that determine which type of protein it is * therefore the order of bases controls the order in which amino acids are assembled to produce a particular protein

Answer 2

* alternating sugar and phosphate sections * attached to each sugar is one of the four bases

Answer 3

* repeating nucleotide units

Answer 4

* A and T * C and G

Answer 5

* the process of producing a protein from DNA * if a gene is coded to make a protein, it has been expressed

Answer 6

1. DNA contains the genetic code for making a protein, but it cannot move out of the nucleus as it is too big. 2. The two strands pull apart from each other, and mRNA nucleotides (messenger RNA: a different type of nucleotide) match to their complementary base on the strand. 3. The mRNA nucleotides themselves are then joined together, creating a new strand called the mRNA strand. This is a template of the original DNA. 4. The mRNA then moves out of the nucleus to the cytoplasm and onto structures called ribosomes. 5. At the ribosomes, the bases on the mRNA are read in threes to code for an amino acid (the first three bases code for one amino acid, the second three bases code for another etc). 6. The corresponding amino acids are brought to the ribosomes by carrier molecules. 7. These amino acids connect together to form a protein. 8. When the chain is complete the protein folds to form a unique 3D structure.

Answer 7

* enzymes * hormones * structural proteins

Answer 8

* biological catalysts that speed up the rate of reaction

Answer 9

* chemical messengers that send signals around the body

Answer 10

* strong proteins in order to form structures such as collagen

Answer 11

* change the sequences of bases in DNA * can be either: insertion, deletion, or substitution

Answer 12

* as they are read in threes, this changes the way it is read. * it may change all the amino acids coded for after this insertion.

Answer 13

* like insertions they change the way it is read. * it may change all the amino acids coded for after this deletion

Answer 14

* this will only change one amino acid in the sequence or it may not change the amino acid (as the new sequence can sometimes still code for the same amino acid)

Answer 15

* affects the way it folds and therefore the structure

Answer 16

* most mutations do not alter the protein or only do so slightly * however, some have a serious effect and can change the shape - the substrate will not fit into the active site so it cannot act as a protein - a structural protein may lose its shape

Answer 17

* in the non-coding parts of DNA that control whether the genes are expressed

Answer 18

* not all parts of DNA code for proteins. * non-coding parts of DNA can switch genes on and off * so variations in these areas of DNA may affect how genes are expressed

Answer 19

* the coding DNA that determines the proteins and their activity * the non-coding DNA that determines which genes are expressed

Answer 20

* an organism’s reproductive cell (egg in female and sperm in males), which has half the number of chromosomes (23).

Answer 21

* a structure found in the nucleus which is made up of a long strand of DNA

Answer 22

* a short section of DNA that codes for a protein, and therefore contribute to a characteristic. * some characteristics are controlled by a single gene, such as fur colour in mice and red-green colour blindness in humans. * however, most characteristics are the result of many different genes interacting.

Answer 23

* the different forms of the gene - humans have two alleles for each gene as they inherit one from each parent.

Answer 24

* only one (out of the two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed.

Answer 25

* two copies are needed for it to be expressed and for the corresponding the phenotype to be observed.

Answer 26

* hen both inherited alleles are the same (i.e. two dominant alleles or two recessive alleles).

Answer 27

* when one of the inherited alleles is dominant and the other is recessive.

Answer 28

* the combination of alleles an individual has, e.g. Aa

Answer 29

* the physical characteristics that are observed in the individual, e.g. eye colour

Answer 30

* show the inheritance of different phenotypes over generations in the same family

Answer 31

* using a punnet square diagram ____I__B___I__b__I _B__I__BB_I__Bb_I _b__I__Bb_I_bb__I

Answer 32

* uppercase for dominant * lowercase for recessive

Answer 33

* by inheriting certain alleles

Answer 34

* having extra fingers or toes * caused by dominant allel

Answer 35

* disorder of the cell membranes, resulting in thick mucus in the airways and pancreas * caused by recessive allele * both parents need to either be carriers or one must have CF themselves and the other is a carrier

Answer 36

* allows scientists to observe whether the child will have a genetic condition or not

Answer 37

* if the embryo is developed in the lab, cells can be taken from it and analysed * DNA from embryos in the womb can also be extracted

Answer 38

* reduces number of people suffering (ethical) * treating disorders is very expensive (economic) * many regulations in place to stop it getting out of hand (social)

Answer 39

* could encourage people to pick characteristics - creating designer babies (ethical). * expensive to carry out screening (economic) * may promote prejudice as it suggests that those with genetic disorders will not live a full life or are unwanted (social). * decisions about terminating a pregnancy have to be made (social). * procedure can lead to a miscarriage (social)

Answer 40

* 23 pairs

Answer 41

* 22 pairs control characteristics only, but one pair carries the genes that determine sex

Answer 42

* X and Y * Y much smaller than X

Answer 43

* can be used to show sex inheritance * 50% chance of child being male, and 50% chance of child being female ____I__X___I__X___I _X__I__XX_I__XX__I _Y__I__XY_I__XY__I

Answer 44

* Genotype * Environment

Answer 45

* Differences in the characteristics of individuals in a population is called variation

Answer 46

Variation may be due to differences in: * the genes they have inherited (genetic causes) * the conditions in which they have developed (environmental causes) * a combination of genes and the environment.

Answer 47

* The genes it inherited

Answer 48

* Genes are passed on from the parent in sex cells. * The combining of genes from the mother and father creates genetic variation. * Only identical twins have the same genotype. * There is lots of genetic variation in a population.

Answer 49

* The place it lives in

Answer 50

* The conditions the organism grows and develops in also affects its appearance. * Examples include scars in animals, or smaller and yellow leaves in plants.

Answer 51

* Sometimes characteristics can result from a combination of genetics and the environment, such as weight. * Weight depends on the food you eat but also how quickly your body breaks it down and how much it stores as fat depends on your genes.

Answer 52

* Genetic variation is introduced by mutations in the sequence of DNA. * Mutations occur continuously

Answer 53

* Most have no effect on phenotype. * Some will influence phenotype but it is unlikely that it will lead to a new phenotype. * somtehing about environment, check spec * If the mutation does determine the phenotype and it is advantageous, natural selection will mean it becomes the common phenotype relatively quickly.

Answer 54

* Evolution is a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.

Answer 55

* Theory of Evolution: All species have evolved from simple life forms that first developed more than three billion years ago.

Answer 56

* Evolution occurs because of natural selection.

Answer 57

* Mutations occur which provide variation between organisms. * If a mutation provides a survival advantage the organism is more likely to survive to breeding age. * The mutation will then be passed onto offspring. * Over many generations, the frequency of the mutation will increase within the population.

Answer 58

* If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring they have formed two new species.

Answer 59

* Selective breeding is when humans choose which organisms to breed in order to produce offspring with a certain desirable characteristic (e.g animals with more meat, plants with disease resistance or big flowers) * Selective breeding (artificial selection) is the process by which humans breed plants and animals for particular genetic characteristics. * Humans have been doing this for thousands of years since they first bred food crops from wild plants and domesticated animals. * This has been happening for many years since animals were domesticated and plants were grown for food.

Answer 60

* Parents with desired characteristics are chosen. * They are bred together. * From the offspring those with desired characteristics are bred together. * The process is repeated many times until all the offspring have the desired characteristic

Answer 61

* The characteristic can be chosen for usefulness or appearance: * Disease resistance in food crops. * Animals which produce more meat or milk. * Domestic dogs with a gentle nature. * Large or unusual flowers.

Answer 62

* The problem is that it can lead to inbreeding.

Answer 63

* Breeding those with similar desirable characteristics means it is likely you are breeding closely related individuals. * This results in the reduction of the gene pool, as the number of different alleles reduce (as they mostly have the same alleles). * This means if the environment changes or there is a new disease, the species could become extinct as they all have the same genetic make-up (so the chance of a few organisms having a survival advantage and not dying is reduced). * Another problem is that the small gene pool leads to a greater chance of genetic defects being present in offspring, as recessive characteristics are more likely to present.

Answer 64

* Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.

Answer 65

* Plant cells have been engineered for disease resistance or to have larger fruits

Answer 66

* Bacterial cells have been engineered to produce substances useful to humans, such as human insulin to treat diabetes

Answer 67

1. Genes from chromosomes are ‘cut out’ using restriction enzymes leaving ‘sticky ends’ (short sections of exposed, unpaired bases) 2. A virus or bacterial plasmid is cut using the same restriction enzyme to also create sticky ends. This also contains an antibiotic marker gene. 3. The loop and gene sticky ends are then joined together by DNA ligase enzymes 4. The combined loop is placed in a vector, such as a bacterial cell, and then allowed to multiply as it will now contain the modified gene. 5. As the bacteria grows we can see which ones are resistant to antibiotics. The colonies that are will be the bacteria that are also producing the modified gene, as they were inserted together. In plants the vector is put into meristematic cells (unspecialised cells) which can then produce identical copies of the modified plant.

Answer 68

* Genetically modified crops are engineered to be resistant to insects and to herbicides. * This will result in increased yields as less crops will die.

Answer 69

* Genetic modification in medicine include gene therapy * It may be possible to use genetic engineering to cure inherited disorders.

Answer 70

* Using genetic engineering to cure inherited disorders * Involves transferring normal genes (not faulty) into patients so the correct proteins are produced

Answer 71

* It can be very useful in medicine to mass produce certain hormones in microorganisms (bacteria and fungi) * In agriculture it can be used to improve yields by improving growth rate & introducing modifications that allow the crops to grow in different conditions, e.g. hotter or drier climates * Introducing modifications that allow plants to make their own pesticide or herbicide * Crops with extra vitamins can be produced in areas where they are difficult to obtain. * Greater yields can help solve world hunger, which is becoming an increasingly bigger issue due to population growth.

Answer 72

* GM crops might have an effect on wild flowers and therefore insects. * GM crops are infertile and these genes could spread into wild plants, leading to infertility in other species, which affects the entire environment. * Growing with herbicides and pesticides can kill insects and other plants, which would reduce biodiversity * People are worried that we do not completely understand the effects of GM crops on human health. * Genetic engineering in agriculture could lead to genetic engineering in humans. This may result in people using the technology to have designer babies. * They pose a selection pressure, which could lead to increased resistance in other species, creating super weeds and pests.

Answer 73

* Cloning is creating genetically identical copies of an organism.

Answer 74

* Tissue culture: * Cuttings: an older, easier method to produce clones

Answer 75

* It is important to preserve rare plant species or commercially in plant nurseries

Answer 76

* Plant cells are taken * They are placed in a growth medium with nutrients and hormones * They grow into new plants, and are clones as they are genetically identical to the parent

Answer 77

* Cuttings, such as a section of the stem, are taken from a plant with a desirable feature * They are planted and produce clones as they are genetically identical to the parent

Answer 78

* Embryo transplants * Adult cell cloning

Answer 79

* Sperm cells and egg cells from parents with desirable features are obtained. * In the lab, they are fertilised to form an embryo. * The embryo divides many times and is then inserted into a host mother. * The offspring which is eventually born is genetically identical (with the desirable feature) as they have genetic information from the same mother and father

Answer 80

* The nucleus is removed from an unfertilised egg cell. * The nucleus from an adult body cell, such as a skin cell, is removed and inserted into the (denucleated) egg cell. * An electric shock stimulates the egg cell to divide to form an embryo. * These embryo cells contain the same genetic information as the adult skin cell. * When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development. * The offspring born is a clone of the adult body cell

Answer 81

* Produces lots of offspring with a specific desirable feature. * The study of clones could help research into embryo development. * Can help extremely endangered species, or even bring back species that have become extinct.

Answer 82

* The gene pool is reduced through producing clones, meaning it is less likely that the population will survive if a disease arises with low diversity in the population. * Clones have a low survival rate, and tend to have some genetic problems. * It may lead to human cloning.

Answer 83

* Charles Darwin was a scientist and naturalist * He put forward the theory of evolution * This was supported by experimentation and his knowledge of geology and fossils that he discovered on a round the world expedition * Published ‘On the Origin of Species’ in 1859

Answer 84

* Variation exists within species as a result of mutations in DNA * Organisms with characteristics most suited to the environment are more likely to survive to reproductive age and breed successfully – called survival of the fittest. * The beneficial characteristics are then passed on to the next generation * Over many generations the frequency of alleles for this advantageous characteristic increase within the population

Answer 85

1. It contradicted the idea that God was the creator of all species on Earth. 2. There was not enough evidence at the time as few studies had been done on how organisms change over time. 3. The mechanism of inheritance and variation were not known at the time.

Answer 86

* Changes that occurred during the lifetime of an organism were passed onto offspring * If an individual continually repeated an action, the characteristic that allowed it to do this would develop further * For example, if a giraffe stretched to reach leaves on a tree high up, its neck would become longer allowing it to do this more easily. This characteristic would then be passed on to its offspring.

Answer 87

* Lamarck’s theory was proven wrong when it was understood that changes caused by the environment were not passed on in the sex cells.

Answer 88

* Darwin’s theory was supported by genetics as it provided a mechanism for beneficial characteristics caused by mutations to be passed on. * Fossil evidence showed how developments in organisms arose slowly.

Answer 89

* Speciation is the process of a new species developing through the selection of different alleles. * This increases the genetic variation until the new population cannot breed with those in the old population to produce fertile offspring.

Answer 90

* Alfred Russel Wallace developed the theory of speciation, and therefore evolution by natural selection.

Answer 91

* On his travels, he had the idea that the individuals who did not have characteristics to help them survive a change in the environment would die out. * He published joint studies with Darwin. * The publication of ‘On the Origin of Species’ meant Darwin received the credit for the theory * He continued to work across the world to collect evidence – one of his most important works was on warning colouration in animals * Much more evidence over time has resulted in our current understanding.

Answer 92

1. Variation exists within a population as a result of genetic mutations. 2. Alleles which provide a survival advantage are selected for through natural selection. 3. Populations of a species can become isolated, for example through physical barriers such as a rock fall preventing them from breeding together. 4. Different alleles may be advantageous in the new environment, leading to them being selected for. 5. Over time the selection of different alleles will increase the genetic variation between the two populations. 6. When they are no longer able to breed together to produce fertile offspring, a new species has formed.

Answer 93

* Gregor Mendel trained in mathematics and natural history in Vienna * Worked in the monastery gardens and observed the characteristics passed on to the next generations in plants * He carried out breeding experiments on pea plants. * He used smooth peas, wrinkled peas, green peas and yellow peas and observed the offspring to see which characteristics they had inherited

Answer 94

* Through keeping a record of everything he did and eventually publishing his work in 1866, he came to the conclusions that: * Offspring have some characteristics that their parents have because they inherit ‘hereditary units’ from each. * One unit is received from each parent. * Units can be dominant or recessive, and cannot be mixed together.

Answer 95

* Mendel was not recognised till after his death as genes and chromosomes were not yet discovered, so people could not understand.

Answer 96

* In the late 19th century behaviour of chromosomes during cell division were observed * In the 20th century, it was observed that chromosomes and Mendel's 'units' (now called genes) were located on chromosomes. * In the mid-20th century, the structure of DNA was determined and the mechanism of gene function worked out, which meant we were able to understand how genes work

Answer 97

* This scientific work by many scientists led to the gene theory being developed.

Answer 98

* Evidence for evolution is seen in: 1. Fossils: the remains of organisms from many years ago, which are found in rocks 2. Antibiotic resistance in bacteria: the selection pressure of antibiotics leads to advantageous mutations being selected for in bacteria populations so they are no longer killed when exposed to antibiotics.

Answer 99

* Fossils are the remains of organisms from millions of years ago, which are found in rocks.

Answer 100

1. Parts of organisms that have not decayed because oxygen or moisture were not present, meaning that the microbes that cause decay cannot survive. 2. Parts of the organism such as teeth, shells and bones are replaced by minerals as they decay, forming a rock structure of the original part. 3. Preserved traces such as footprints, burrows and rootlet traces (the plants roots) remain due to the ground hardening around them and forming a cast

Answer 101

* Fossils are used to show how the anatomy of organisms has changed over time. * They can be used to compare how closely related two organisms are, through looking at the number of similarities they have. * This information is used to create evolutionary trees.

Answer 102

* Most early life forms are soft-bodied and therefore decay completely, so there are few fossils of them. * Any traces left have been destroyed by geological activity.

Answer 103

* When an entire species has died out

Answer 104

1. Changes in environment which the species cannot adapt fast enough to. 2. New predators may have evolved or migrated to the area. 3. A new disease arises and there are no resistant alleles to it. 4. They have to compete with a species which has advantageous mutations for the same food source. 5. A catastrophic event can wipe out a species. 6. Destruction of habitat

Answer 105

* Bacteria are labelled resistant when they are not killed by antibiotics which previously were used as cures against them

Answer 106

* Bacteria reproduce at a fast rate. * Mutations during reproduction can result in new genes, such as the gene for antibiotic resistance. This the creation of a new strain. * Exposure to antibiotics creates a selection pressure, as those with antibiotic resistant genes survive and those without die. * As a result those with antibiotic resistance can reproduce and pass on the advantageous gene to their offspring. * This population of antibiotic resistant bacteria increases.

Answer 107

* Bacterial diseases spreads rapidly because people are not immune to these new resistant bacteria and there is no treatment for it.

Answer 108

* An example is MRSA. * Called a ‘superbug’ as it is resistant to many different types of antibiotics * Common in hospitals: spreads when doctors and nurses move to different patients

Answer 109

1. Antibiotics should not be given for viral or non-serious infections 2. Specific antibiotics should be given for specific bacteria 3. Patients should complete their course of antibiotics – if they do not some bacteria may survive and mutate to become antibiotic resistant. 4. Antibiotics should be used less in agriculture – farmers currently use them to prevent their livestock dying from disease, but this overuse leads to antibiotic resistant bacteria which are then transferred to humans when they consume the meat

Answer 110

1. Maintain high standards of hygiene in hospitals 2. Medical staff and visitors should wash hands regularly 3. Medical staff should wear disposable clothing or clothing that is regularly sterilised

Answer 111

* As the development of antibiotics is expensive and slow, it is difficult to keep up with the development of resistant strains.

Answer 112

* Classification involves putting organisms into groups depending on their structure and characteristics.

Answer 113

* Carl Linnaeus put the Linnaean system forward in the 1700s * Traditionally living things have been classified into groups depending on their structure and characteristics * Linnaeus classified living things into kingdom, phylum, class, order, family, genus and species.

Answer 114

* Binomal system

Answer 115

* The binomial system gives each organism a name which is used worldwide (overcomes language barriers). * The first part is their genus and the second part is their species. e.g. the ladybug, which has the name Harmonia (genus) axyridis (species).

Answer 116

* Developments in science such as the improvement of the microscope and increased knowledge of biochemistry (for example, RNA sequence analysis) found that some species were more distantly related than first thought * So Carl Woese added three large groups called domains above kingdoms * As evidence of internal structures became more developed due to improvements in microscopes, and the understanding of biochemical processes progressed, new models of classification were proposed. * Due to evidence available from chemical analysis there is now a ‘threedomain system’ developed by Carl Woese. In this system organisms are divided into:

Answer 117

* Archaea: primitive bacteria which live in extreme environments such as hot springs * Bacteria: true bacteria (despite having similar features to archaea) * Eukaryota: organisms who have a nucleus enclosed in membranes, includes the kingdoms protists, fungi, plants and animals

Answer 118

* Evolutionary trees are used to show how closely related organisms are. * To complete this they use classification data and fossils for extinct species.

inheritance, variation and evolution Flashcards

(144 cards)