Genetics Flashcards

1
Q

Meiosis I

A

2n2x -> n2x

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2
Q

Meiosis II

A

n2x -> n

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3
Q

G1

A
  • homologous chromosomes

- 2n1x

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4
Q

G2

A
  • passed through replication already
  • 2n2x
  • replicated homologous chromosomes
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5
Q

prophase I

A
  • mitotic prophase +
  • synapsis to form the tetrad (pairing of homologous chromosomes)
  • crossing over may occur between the homologous chromosomes
  • recombination
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6
Q

all female gametes

A
  • arrested in prophase I until they are ovulated
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7
Q

metaphase I

A
  • tetrads (replicated homologous chromosomes) align at the metaphase plate
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8
Q

anaphase I

A
  • separate the homologous chromosomes

- begin cytokinesis

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9
Q

telophase I

A
  • partial reversal of mitotic prophase
  • finish cytokinesis
  • DNA may (rarely) decondense but usually remains condensed
  • usually the nuclear envelope doesn’t reform
  • spindle fibers break down
  • haploid with replicated copies (n2x)
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10
Q

prophase II

A
  • haploid with replicated copies -> haploid

- n2x -> n

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11
Q

metaphase II

A
  • align the replicated copies
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12
Q

female secondary oocyte

A
  • locked in metaphase II after ovulation until fertilization triggers completion
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13
Q

anaphase II

A
  • separate the replicated copies

- separate the sister chromatids

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14
Q

end result of meiosis

A
  • 4 cells
  • 2n2x -> n2x (in 2 cells) -> n (in 4 cells)
  • very different from each other and from parent cell
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15
Q

nondisjunction

A
  • failure of the DNA to separate during gamete formation
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16
Q

failure during anaphase I

A
  • 4 abnormal gametes
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17
Q

failure during anaphase II

A
  • 2 normal and 2 abnormal gametes
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18
Q

gene

A
  • piece of DNA that codes for a protein/RNA

- includes regulatory regions

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19
Q

allele

A
  • form of a gene
  • 1 person = 2 alleles
  • population = 2x # of alleles
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20
Q

trait

A
  • physical expression (phenotype)
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21
Q

polymorphic

A
  • a trait with several variations
  • hair color
  • can’t have several versions of insulin
22
Q

polygenic

A
  • multiple genes code for 1 trait

- genes for total body height

23
Q

pleotropic

A
  • 1 gene = many traits
24
Q

incomplete dominance

A
  • heterozygous offspring of homozygous parents display a blended phenotype
  • pink flowers (RR and WW) red and white
25
two tip offs that you are dealing with nonclassical dominance
- blended phenotype | - two upper case letters in the genotype
26
codominance
- both alleles are fully expressed - human ABO blood group gene - codes for a protein on the surface of a red blood cell
27
Rh factor
- classically dominant - R = makes Rh proteins (+) - r = doesn't make Rh proteins (-)
28
universal donor
- O- | - no proteins to trigger reaction
29
universal acceptor
- AB+ - all proteins are recognized - already have Rh factor so won't attack something coming in with it.
30
Epistasis
- dominance between different genes - expression of 1 gene depends on expression of another gene - albino gene prevents expression of pigment genes
31
Mendel's Laws
- law of segregation | - law of independent assortment
32
law of segregation
- alleles are separated during gamete formation | - occurs during anaphase I and anaphase II
33
law of independent assortment
- how one pair of alleles separates is independent of how other pairs separate. - comes down to randomness of how chromosomes line up at metaphase I
34
homozygote x same homozygote
- 100% parents genotype and phenotype
35
homozygote x homozygote recessive
- 100% heterozygous and 100% dominant phenotype
36
heterozygote x homozygote dom/rec
- 50% heterozygous: 50% homozygous parent | - 50% dominant: 50% homozygous parent
37
heterozygote x heterozygote
- 25% homozygous dominant: 50% heterozygous: 25% homozygous recessive - 75% dominant: 25% recessive
38
rule of multiplication
- when the question asks "and" or "both - probability (A and B) = prob (A) x prob (B) - always gives you a smaller number
39
rule of addition
- when the question asks "either" or "or" - probability (A or B) = prob (A) + prob (B) - (prob A x prob B) - always gives you a bigger number
40
when they mention possible sex of offspring
- really watch out for this! - multiply by 1/2 at the end! - they already say they have a son or daughter there is no need to multiply by 1/2
41
linked genes
- genes are found close together on the same chromosome | - might not sort independently
42
recombination frequency
recombinants _____________ total # of offspring - higher the RF the greater the distance between genes
43
Hardy Weinberg equations
- p + q = 1 (allele frequency in entire population) - pp + 2pq + qq = 1 (genotype frequency) homo hetero recessive
44
5 conditions for which the equations hold true
- large population - random mating - no mutation - no migration - no natural selection
45
how long to reach new equilibrium if old one is disturbed
1 generation to reach a new equilibrium
46
exception to mendel's law of independent assortment
- genes found on the same chromosome might not sort independently - also called linked genes
47
Phenotype ratio for dihybrid (double heterozygote) cross for expected unlinked ratio
- 9 dom/dom - 3 dom/rec - 3 rec/dom - 1 rec/rec
48
if actual ratio does not match unlinked expected ratio
- then the genes are linked
49
double heterozygote back crossed with homozygous recessive
- 1 dom/dom - 1 dom/red - 1 rec/dom - 1 rec/rec
50
which are the recombinants?
- the dom/rec and the rec/dom