unit 2 Flashcards
1
Q
Genetic material is made of?
A
DNA: Deoxyriboucleic acid
- contain genetic material
Genes: units of inherited information
coding for protien
2
Q
chromatin
A
- long thin fibres of dna and protien
- these fibres condense when preparing for cell division (become chromosomes)
3
Q
DNA Structure
A
double helix shape with long chains of subunits called nucleotides
sugar phosphate backbone
- deoxyribrose and phosphate group
- connected from sugar to phosphate
nitrogenous base (thymine, cytosine + adenine, guanine)
4
Q
Genes and protiens
A
- protiens are made of 20 kinda of amino acids (create a chan called polypeptides)
- 2 or more polypeptides join together to make a particular protien
- DNA specifies how to put amino acids in a particular order (called genetic code)
5
Q
Genetic code
A
it takes 3 nulcleotides to create “code words”
- each set of 3 bases is known as a “codon”
0 64 possible combination of the 4 nucleotides
6
Q
RNA
A
- also has 4 bases but thymine is not used (instead uracil)
- produces a stop codom that makes sure protien sequence is complete
7
Q
3 steps of DNA Replication
A
- unzipping and unwinding
- complementation
- linkage
8
Q
- unzipping and unwinding
A
- involves enzymes (helicase) that break hydrogen bonds between nitrogen bases that hold the two strands together
- the double helix unzips
- gyrase is the enzyme that acts as a detangler
9
Q
- complementation
A
base pairs come together
10
Q
the cell cycle
A
interphase growth stage
- 90%of the cell cycle
- cell grows in size
- cells dna duplicates
1. Gap 1 (G1)
- cell grows bigger
- at end the cell either goes into rest or S phase
2. Synthesis (S)
- DNA is replicated
- chromatin in nucleas condenses into visable chromasomes
3. Gap 2 (G2)
- prepares for cell division
11
Q
cytokinesis (cytoplasmic division)
A
- seperation of cytoplasm and formation of new daughter cells
- spindle fibres break down and disappear
- nuclear membrane forms around each set of chromosomes
- cell membrane forms (cell wall between plant cells)
12
Q
diploid number vs haploid number
A
diploid: total number of chromosomes (2n)
haploid: only contain one copy of each type of chromosome (n)
13
Q
zygotes
A
- contain chromosomes from both parents but does not contain double the number of chromosomes found in normal body cells
14
Q
function of meosis
A
- reproduction involves union of 2 cells to form a zygote
- occurs only in reproductive organs called GONADS
- it makes reproductive cells called GAMETES (haploids) (ovum or sperm)
- first part of meosis reduces the number of chromosomes from diploid to haploid (reduction division)
(human sperm cells = 23 chromosomes
somatic cells = 46 chromosomes)
15
Q
gametes
A
- each human gametes has 22 autosomes and one sex chromosome (either X or Y)
22 of them are autosomes (not directly related in the sec of the individual)
females: XX
Males: XY
16
Q
Meiosis I
A
- prophase I
- homologous chromosomes form homologous pairs
(similar chromosomes. but not identical, same genes but different forms of specific traits)
- homologous pairs form a tetrad
- come from both parent (1 each)
- chromatids crossover to exchange genes to create genetic variation - Metaphase I
- spindle fibres attaches to centromere of chromosome
- line up in the middle
- positioned randomly (independant assortment) - anaphase I
- homologous chromosomes seperate and movie to opposite sides of cell
- only one chromosome from each pair will movie to each pole of the cell - Telophase I + cytokinesis
- cell is split in half
- chromosomes are still double
after meosis I = haploid
17
Q
meiosis II
A
- identical to mitosis
- haploid (only chromatid)
- the daughter cells at the end are called gametes in animals
- in plants they are called gametes or spores
- the end product is 4, non identical haploid cells
18
Q
gametogenesis
A
production of gametes via meiosis resulting in sperm and ovum
19
Q
spermatogenesis
A
process of male gamete production in animals
20
Q
oogenesis
A
process of female gamete production in animals
21
Q
process of spermatogenesis
A
- meosis takes place in testes
- starts with diploid germ cell (embroyonic cell that can develop into a gamete) called spermatogonium
- the cell (spermatocyte) enlarges and undergoes meiosis 1 and 2
final product = 4 haploid mature spermatozoa (sperms)
22
Q
breeding season for spermatogenesis
A
- humans can occur throughout the year
- sperm production only occurs during a certain time of the year
- occurs from puberty to death
- take aproximatly 74 hours for a sperm to be created
- produces 250m sperms every day in males
23
Q
oogenesis process
A
- takes place in the ovaries
- starts with a diploid germ cell called oogonium
- cell (oocyte) enlarges and undergoes mitosis 1 and 2
- end the cytoplasm is not equally divided between daughter cells
24
Q
primary oocyte vs polar body
A
primary oocyte: the cell that receives the most cytoplasm
polar body: the other cell (not viable sex cell
- only primary oocyte becomes an ovum
- because the ovum must hold sufficient nutrients to support developing zygote in first few days after fertilization
25
identical twins vs fraternal
identical twins: one egg+one sperm = fertilized egg splits into 2
= two embryos = twins
fraternal: 2 eggs+2sperms = two embryos
= twins
26
Why did mendel use pea plants?
- pea plants go through sexual reproduction
- can self fertilize
same plant provides both female and male gametes
- can produce offspring with consistant traits for generation (true breeding)
27
different generations
P generation: parental (true breeding plants)
f1 generation: the offspring of p generation (one trait corss/monohybrid cross)
f2 generation: offspring of f1 plants (3:1 ratio/mendelian ratio)
28
law of segregation
- 2 hereditatry factors for each trait studdied (called alleles)
- inherited traits are determined by pairs factors/2 alleles of a gene
- these 2 alleles segregate into each of the gametes of the parents during meiosis so each gamete contains one of the alleles
- upon fertilization each offspring contains one allele from each parent
- the form of the trait depends on whether they inherit dominant or recessive alleles for the trait
29
alleles?
a different form of a gene
- a diploid organism have 2 alleles for each genes
30
dominant
- the form of a trait that always appears when an individual has an allele for it
31
recessive
the form of a trait that only appears when an individual has 2 alleles for it
32
genotype
- the combination of alleles for any given trait or the organisms entire genetic makeup
33
phenotype
the physical and phsiological traits of an organism or expression of a genotype
34
one trait crosses vs two trait crosses
using two traits - of inheriting one trait has an impact on the other trait
two trait = dihybrid cross
ratio was: 9:3:3:1
35
law of independent assortment
during gamete formation - the two alleles for one gene segregate or assort independently of the alleles for other genes
36
incomplete dominance
- condition in which neither of the 2 alleles for the same genes can completely conceal the presence of the other
- phenotype between dominant and recessive
- ratio is 1:2:1
- middle colour (red-pink-white)
- to represent: use superscripts for colour (C^R, C^W)
37
codominance
- both alleles are fully expressed
- both colours are fully expresses (will look mixed in colour/paterns)
- eg roan cows)
38
sickle cell anemia
- caused by a specific form of the gene that directs the synthesis of hemoglobin
- hemoglobin carries oxygen in the blood
- the hemoglobin molecule that is made in individuals with sickle cell allele leads to a C-shaped (or sickled) red blood cell
--> the blood cell cannot transport oxygen effectively and cannot pass through small blood vessels
--> can lead to blockages and tissue damages
- represented by Hb^s(sickle cell), Hb^a (normal)
- homo = sickle cell
- hetero = have trait but hardly symptoms
39
heterozygous advantage
- situation in which heterozygous individuals have an advantage over both homozygous of either form
- eg: having a sickle cell trait has more resistance to malaria
40
antigen
- carbohydrate that stimulates the body's immune system
41
human blood groups
the difference combinations of the 3 alleles produce 4 different phenotypes
- Blood type A
- Blood type B
- Blood type AB (codominant)
- Blood type O
42
multiple alleles
- a gene with more than 2 alleles
43
RH factor
- inherited protien found on the surface of red blood cells
- if your blood cells have antigen = Rh positive
- if you lack antigen = Rh negative
44
sex linked traits
traits that are controlled by genes in either the X or Y chromosomes
- linked to the genes that determine sex
- are identified by the different rates of appearance between males and females
45
sex linked genes
- the x and y chromosomes have limited amount of genetic material compared to autosomes
- the x chromosomes has about 2000 genes while the y chromosome has about 100
- the most important genes are the sex-determination of genes
males: XY
Female: XX
carriers = heterozygous
46
sex-linked traits in humans
- many are genetic disorders
- if a disorder is x linked dominant = affected males pass the allele only to daughters
- females can pass an x linked dominant allele to both sons and daughters
- x linked recessive traits affect males more than females
47
colour vision deficiency
- individuals affected by CVD have difficulty distinguishing colours
- red green CVD (x linked recessive disorder
48
hemophilia
- a condition that effects the body's ability to produce proteins involved in blood clotting
- people with hemophilia can suffer serious blood loss from simple cuts
- x linked recessive trait that affects more than 3000. individuals in Canada
- also called royal disease
49
what are karyotypes?
- set of chromosomes for each specific individual
50
process of karyotyping?
- a cell sample is collected and treated to stop cell division during metaphase is mitosis
- the sample is stained which produces a banding pattern on the chromosome that is clearly visible under a microscope
- the chromosomes are sorted and paired
- they are numbered from 1 to 22 + sex cells
-
51
point mutations
- genetic mutations in DNA
- they are mutations that have the nucleotides of DNA altered, which changes the make-up of the actual gene istelf
- base pair substitution
- base pair insertion
- base pair deletion
52
2 types of chromosomal errors during meiosis
1. changes in chromosome structure
2. changes to chromosome numeber
53
the changes in chromosome structure
- during chrossing over - chemical bonds that hold DNA together break and reform
- sometimes the chromosomes do not reform correctly
- sometimes non-homologous pairs cross over
- this produces chromosomes containing genes not normally on that chromosome
errors include
- deletion
- duplication
- inversion
- translocation
53
changes in chromosomes numbers
- sometimes homologous chromosome pairs or sister chromatids do not seperate
- non-disjunction
- occurs during anaphase 1 or 11
- dont seperate tto opposite poles but instead one pair is pulled towards the same pole
- in result = gamete sthat have too many or less chromosomes
54
Trisomies
trisomy: condition in which there is an extra chromosome due to non-disjunction
- most common trisomies are found in chromosome 21, 18, 13 as well as abnormalities in number of sex chromosomes
55
monosomies
monosomy: condition in which one chromosome is lost die to non-disfunction
- gamete is missing one chromosome of homologous pair
- turner syndrome - missing chromosome
56
Prenatal Genetic testing
- tests preformed on a fetus based on testing for genetic-based abnormalities
- involves blood tests and ultrasound
- they can provide information about potential physical and chromosomal abnormalities
- fetal proteins in mother's blood are analyzed
- fetus image
