BIO304 > Genetics Exam Two > Flashcards

Genetics Exam Two Flashcards

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1
Q

segregation

A

alleles at the same locus on two homologous chromosomes separate in meiosis

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2
Q

independent assortment

A

alleles at one locus act independently of alleles at another locus due to recombination

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3
Q

independent assortment recomination is __________

A

interchromosomal

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4
Q

linked genes

A

genes close enough to one another on the same chromosome that crossover reshuffles them <50% of the time

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5
Q

crossover generates _______ variation

A

intrachromosomal

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6
Q

the closer two genes are on a chromosome, the _______ crossover occurs between them

A

less often

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7
Q

coupling

A

dominant allels reside on one chromosome and recessives on the other

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8
Q

repulsion

A

each chromosome carries one dominant and one recessive allele

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9
Q

what is the two-point testcross?

A

double heterozygous x homozygous recessive

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10
Q

the farther apart two genes are, the more likely we are to _____________ between them and underestimate their genetic distance as a result

A

miss double crossovers

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11
Q

recombination frequency

A

(# single recombinants + double recombinants) /( total offspring ) x 100

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12
Q

chromosomal rearrangements are due to

A

incorrect repair of double-strand breaks (each person has up to about 1000)

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13
Q

duplication

A

doubling of base pair sequence

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14
Q

tandem duplication

A

go right next to the original loci (this can cause unequal crossing over when similar genes are next to each other)

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15
Q

reverse duplication

A

duplication in reverse orientation but ends up right next to the original loci

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16
Q

displaced duplication

A

duplicated region ends up elsewhere in the genome

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17
Q

segmental duplication

A

> 1000 base pairs in length and can belong to any category (tandem, reverse, or displaced)

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18
Q

deletion

A

segment of gene is gone (can be very harmful)

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19
Q

inversion

A

can break up genes and/or change their expression due to position effect

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20
Q

paracentric inversion

A

does NOT involve a centromere
-crossover in inverted region leads to acentric and dicentric chromosomes

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21
Q

acentric chromosomes

A

no centromere, get lost

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22
Q

dicentric chromosome

A

two centromeres instead of one, usually break

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23
Q

pericentric inversion

A

-involves a centromere
-crossover in the inverted region leads to chromosomes with incorrect sets/numbers of genes

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24
Q

translocation

A

part of a gene moved elsewhere

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24
25
Robertsonium translocation
long arms of two nonhomologous acrocentric chromosomes join together ; short arms join together but are lost --> this is the cause of FAMILIAL DOWN SYNDROME
26
aneuploidy
changes the number of a particular chromosome
27
causes of aneuploidy
1. centromere deletion 2. Robertsonian Translocation 3. nondisjunction 4. in mother's gametes, tends to increase frequency with maternal age
28
nondisjunction
failure of homologous chromosomes to separate in mitosis/meiosis
29
nullisomy
loss of both copies of a homologous pair of chromosomes
30
monosomy
loss of one copy of a homologous pair of chromosomes
31
trisomy
gain of one copy of a homologous pair of chromosomes
32
tetrasomy
gain of two homologous chromosomes
33
for smaller chromosomes, aneuploidy is _____ likely to be lethal
less
34
polyploidy
an increase in the number of all chromosomes
35
autopolyploidy
results from accidents in mitosis/meiosis
36
allopolyploidy
happes when two similar species hybridize
37
characteristics of bacteria
-no nucleus or membrane-bound organelles -genome = one small circular chromosome -gene density higher in eukaryotes -plasmids may be present -no histones
38
16s sequencing
-best way to illustrate evolutionary relationships -this has slow evolving regions so we can compare regions among distantly related species
39
binary fission
mechanism of reproduction that produces clonal offspring
40
horizontal gene transfer
allows bacterial cells to transfer DNA with one another
41
conjugation
allows one bacterial cell to transfer DNA to another through a pilus - does not usually last long enough for an entire bacterial chromosome to be transferred - does not necessarily start at the same point on every bacterial chromosome - the closer two genes are together, the more liley they are to be cotransferred into a recipient cell by conjugation
42
transformation
allows bacteria to take up DNA from the environment -efficiency is impacted by chemicals, temperature, etc -if a bacterial chromosome is fragmented and transformed into recipient cells, the closer two genes were on the fragmented chromosome, the more likely they are to be co-transformed
43
transduction
when phages move DNA from one bacterial cell to another
44
lysogenic cycle
phage genome integrates into bacterial chromosome, allowing bacteria to divide as usual and copying the phage genome in the process
45
lytic cycle
phage may cut up host genome, phage may replicate, and the bacterial cell may burst, releaseing phage progeny
46
temperate phages
undergo lysogenic and lytic cycles
47
virulent phages
only lytic cycle
48
if lytic cycle...
phage progeny may end up carrying a fragment of bacterial DNA to new bacterial hosts
49
the closer two bacterial genes are to each other...
the more likely they are to be cotransduced
50
phages can undergo ______ with one another
recombination
51
nucleotide
1. phosphate 2. sugar 3. nitrogenous base
52
purines
two rings - adenine and guanine
53
pyrimidines
one ring - thymine, uracil, and cytosine
54
A and T form __ bonds
2
55
C and G form ___ bonds
3
56
phosphodiester bonds
strong covalent bonds that link the 5' phosphate of one nucleotide to the 3' hydroxyl of another (backbone of the strand)
57
single-stranded nucleic acid can form _____
stem-loop
58
methylation
-adding CH3 to DNA -protects bacterial DNA from antiviral restriction enzymes -eukaryotes: correlated with low transcription of genes
59
Griffith experiment
two strains of streptococcus pneumonia IIR : rough, nonvirulent IIIS: smooth, virulent - the live IIR does not kill mice and neither does the heat-killed IIIS -the live IIIS kills mice -the heat-killed IIIS and live IIR kills mice (live IIIS recovered from dead mice) -demonstrates TRANSFORMING principle
60
Avery, MacCleod and Maclyn experiment
-DNase destroys Griffith's transforming principles (but not RNase or protease)
61
Hershey-Chase
1. phosphorous is in DNA, and sulfur is in protien - they grew bacteria in culture with 32P or 35S -they then infected them with a phage -transferred phage to unlabeled bacteria -new bacteria: 32P was found INSIDE cells, 35S remained in the old phage protein coats -proved DNA is genetic material
62
The Central Dogma
DNA is replicated --> genes in DNA are transcribed to RNA --> RNA is translated to a protein
63
what are the exeptions to the Central Dogma?
-some RNA viruses have their genome reverse transcribed to DNA -some RNA viruses undergo RNA replication
64
incomplete dominance
heterozygous phenotype is intermediate between homozygous phenotypes (phenotypic and genotypic ratios are the same) -this happens when one dominant allele is not enough to produce full homozygous dominant phenotype
65
codominance
-heterozygous phenotype is intermediate between homozygous phenotypes -phenotypic and genotypic ratios are the same -happens when two different alleles are simultaneously expressed in the heterozygote
66
incomplete penetrance
not everyone with a particular genotype has the predicted phenotype
67
variable expressivity
the degree of a particular phenotype varies among individuals with the genotype
68
lethal alleles
homozygosity for dominant allele may be lethal, causing a 2:1 ratio in offspring instead of the expected 3:1
69
allelic series
>2 alleles are a particular gene may be present in a population - # of possible genotypes: [n*(n+1)/2]
70
epistasis
causes unusual phenotypic ratios in AaBb x AaBb dihybrid cross
71
recessive epistasis
-3 phenotypic classes (instead of 4) -9:3:4 phenotypic ratio in offspring -homozygous recessive genotype for one gene masks effect of the other gene -ex: coat color in labs
72
dominant epistasis
-3 phenotypic classes -12::1 phenotypic ratio in offspring -dominant allele for one gene massks effect of the other gene -ex: fruit color in squash
73
duplicate recessive epistasis
-2 phenotypic classes -9:7 phenotypic ratio in offspring -being homozygous recessive for either gene masks effect of the other gene -ex: shell color in snails
74
sex-influenced characteristics
autosomal which allele is dominant depends on sex
75
sex-limited characteristics
-autosomal -males and females have two alleles, but one of the two phenotypes only shows up in one sex
76
cytoplasmic inheritance
-mitochondrial and chloroplast DNA -always from biological mom -any cell can have multiple mitochondria/chloroplasts with multiple copies of organellar genome
77
genetic maternal effect
mom's genotype determines offspring's phenotype
78
genomic imprinting
-mom and dad's copies of a gene are expressed differentially, particularly during development
79
heritability is _____ when most phenotypic variation comes from environmental variation
higher
80
polygenic
trait influenced by multiple genes
81
quantitative characteristics have a ____________ distribution of phenotypes and are often based on genes + environment
continuous
82
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