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Genetics > Test #5 Review > Flashcards

Test #5 Review Flashcards

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Biology 101 flashcards
1
Q

What is a karyotype?

A

visualization of a full set of chromosomes

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2
Q

What are the types of chromosome mutation?

A

rearrangements, Aneuploidy, polyploidy

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3
Q

Chromosome rearrangements

A

alter the structure of chromosomes

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4
Q

Aneuploidy

A

alters the number of chromosome

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5
Q

polyploidy

A

one or more complete sets of chromosomes are added

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6
Q

What are the types of chromosome arrangements?

A
  • Duplication
  • Deletion
  • Inversion
  • Translocation
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7
Q

What are the problems of chromosome breakage?

A
  • broken gene
  • gene separation from regulatory sequence
  • Gene with new regulatory sequence
  • Chromatin changes
  • fusion genes
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8
Q

Chromosome duplications often result in abnormal phenotypes because….

A
  • developmental processes depend on the relative amounts of proteins encoded by different genes
  • extra copies of the genes within the duplicated region do not pair in meiosis
  • the chromosome is more likely to break when it loops in meiosis
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9
Q

What is deletion

A

loss of chromosomal segment

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10
Q

What are the effects of deletion?

A
  • imbalances in gene product
  • expression of a normally recessive gene (pseudo dominance/ loss of heterozygosity)
  • Haploinsufficiency
  • problems with meiosis (unequal crossover)
  • lost dosage
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11
Q

Types of Inversions

A
  • paracentric inversion (doesn’t include the centromere)
  • pericentric inversion (includes centromere)
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12
Q

Translocations

A

two homologs doing recombination

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13
Q

What are the types of translocations?

A

non reciprocal translation
reciprocal translocation
robertsonian translocation

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14
Q

D: Chromosome rearrangement

A

change in chromosome structure

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15
Q

D: Chromsome duplication

A

Duplication of a chromosome segment

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16
Q

D: Chromsome deletion

A

Deletion of a chromosome segment

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17
Q

D: inversion

A

Chromsome segment inverted 180 degrees

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18
Q

D: Paracentric Inversion

A

Inversion that does not include the centromere in the inverted region

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19
Q

D: Pericentric Inversion

A

Inversion that includes the centromere in the inverted region.

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20
Q

D: Translocation

A

Movement of a chromosome segment to a non homologous chromosome or to another region of the same chromosome.

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21
Q

D: Non reciprocal translation

A

Movement of a chromosome segment to a non-homologous chromosome or to another region of the same chromosome without reciprocal exchange.

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22
Q

Reciprocal Translocation

A

Exchange between segments of non homologous chromosomes or between regions of the same chromosome

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23
Q

Aneuploidy

A

change in number of individual chromosomes

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24
Q

Nullisomy

A

Loss of both members of a homologous pair

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25
Q

Monosomy

A

Loss of one member of a homologous pair

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26
Q

Trisomy

A

Gain of one chromosome, resulting in three homologous chromosomes

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27
Q

Tetrasomy

A

Gain of two homologous chromosomes, resulting in four homologous chromosomes

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28
Q

Polyploidy

A

Addition of entire chromosome sets

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29
Q

Autopolyploidy

A

Polyploidy in which extra chromosome sets are derived from the same species

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30
Q

Allopolyploidy

A

Polyploidy in which extra chromosome sets are derived from two or more species (hybridization)

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31
Q

What negative affects can duplication cause?

A
  • extra dosage
  • meiosis
  • neighborhood effects
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32
Q

Effects of inversion

A
  • Neighborhood effects
  • Meiosis Problems: Dicentric bridge, Chromosome without centromere, passing on fragments of chromosomes
  • Broken gene
  • Gene sep from regulatory seq
  • Gene with new regulatory seq
  • Chromatin change
  • Fusion gene
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33
Q

Effects of translocation

A

non-homologous crossover
neighborhood effects
meiosis (wrong pairing)

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34
Q

What can pericentric inversion cause?

A

inversion loop during pairing in prophase 1 of meiosis

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35
Q

What occurs during robertsonian translocation?

A

The short arm of one acrocentric chromosome is exchanged with the long arm of another, creating a large metacentric chromosome and a fragment that often fails to segregate and is lost.

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36
Q

What are the causes of aneuploidy?

A
  • nondisjunction: chromosomes don’t separate during meiosis 1 or 2
  • robertsonian translocation
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37
Q

What are the types of aneuploidy?

A

nullisomy 2n-2
monosomy 2n-1
trisomy 2n+1
tetrasomy 2n+2

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38
Q

A diploid organism has 2n=36 chromosomes. How many chromosomes will be found in a trisomic member of this species?

A

2n+1=37

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39
Q

Effects of Aneuploidy in Humans

A

Autosomal
- Trisomy 21: Down syndrome
- primary down syndrome: nondisjunction in egg formation
- Familial Down syndrome: robertsonian translocation between chromosomes 14 and 21
- Trisomy 18: Edwards syndrome
- Trisomy 13: Patau syndrome
Sex- chromosome
- Turner syndrom: XO
- Klinefelter syndrome: XXY

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40
Q

Why are sex chromosome aneuploidy more common that autosomal aneuploids?

A

they can be more tolerated due to barr bodies

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41
Q

What can cause autopolyploidy

A

nondisjunction in mitosis or meiosis

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42
Q

What can cause allopolyploids?

A

hybridization between two species followed by chromosome doubling

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43
Q

What is the significance of polyploidy?

A
  • increase in cell size
  • larger plant attributes
  • evolution: may give rise to new species
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44
Q

Species A has 2n=16 chromosomes and species B has 2n=14. How many chromosomes would be found in an allotriploid of these two species?

A

22 or 23

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45
Q

What are discontinuous characteristics?

A

relatively few phenotypes
- just a few option; this or that
- left or right handed

46
Q

What are continuous characteristics?

A

continuous distribution of phenotypes; occurs when genes at many loci interact
- all heights are possible (more than one gene controlling that trait)

47
Q

What are polygenic characteristics?

A

characteristics encoded by genes at many loci.
- lots of genes that control that trait

48
Q

What is pleiotropy?

A

one gene affects multiple characteristics
- ex. cistic fibrosis, lung and kidney problems caused by one gene

49
Q

Quantitative Characteristics

A
  • exhibit complex relationships between genotype and phenotype
  • may be polygenic
  • may have environmental influences
  • phenotypic ranges may overlap
  • cannot use standard methods to analyze
50
Q

What are the types of quantitative characteristics?

A

Meristic and threshold

51
Q

What are Meristic characteristics?

A
  • Determined by multiple genetic and environmental factors
  • animal litter size
52
Q

What are threshold characteristics?

A
  • measured by presence or absence
  • susceptibility to disease
  • everyone is the same until a certain threshold is reached then a new phenotype
53
Q

What are the possible phenotypes with threshold characteristics?

A

The trait is either present or absent but they are quantitative because the underlying susceptibility to the characteristic varies continuously.

54
Q

What is polygenic inheritance (more than one gene)?

A
  • Refers to quantitative characteristics controlled by cumulative effects of many genes
  • each character still follows Mendel’s rules
  • May be influenced by environmental factors.
55
Q

What is an example of polygenic inheritance?

A
  • kernel color in wheat
  • illustrates multiple genes acting to produce continuous range of phenotypes
  • intensity of red pigmentation is determined by three unliked loci.
  • number of phenotypic classes in F2 increases with the number of loci affecting a character.
56
Q

Which experiment demonstrated that kernel color is wheat inherited according to mendelian inheritance?

A

Nilsson-Ehle

57
Q

What is the result of crossing individuals heterozygous for different numbers of loci affecting a characteristic.

A
  • normal distribution
  • involvement of lots of genes
58
Q

What is variance?

A

the variability of a group of measurements

59
Q

what is standard deviation?

A

the square root of variance

60
Q

What is heritability?

A

The proportion of the total phenotypic variation that is due to genetic difference.

61
Q

What are the 5 limitation of heritability?

A
  • Heritability does not indicate the degree to which a characteristic is genetically determined
  • an individual does not have heritability
  • there is no universal heritability for a characteristic
  • Even when heritability is high, environmental factors may influence a characteristic
  • Heritability indicates nothing about the nature of population differences in a characteristic.
62
Q

What is a multifactorial polygenic trait?

A
  • skin color
  • controlled by 3 or 4 genes and environmental factors leading to a wide range of phenotypes
63
Q

What is the additive model of polygenic inheritance?

A

as the number of genes involved increase, the number of phenotypic classes increases

64
Q

What is a polygenic trait?

A

eye color
- five basic eye colors fit a model with two genes, each with two alleles.

65
Q

What causes differences in populations?

A

genetic variation

66
Q

How are genotypic frequencies calculated?

A

The number of individuals possessing the genotype divided by the total number of individuals in sample

67
Q

How are allele frequencies calculated?

A

number of copies of a particular allele present in sample divided by total number of alleles

68
Q

What is the 1st prediction of the hardy weinburg law

A

the allelic frequencies of a population do not change.

69
Q

What is the 2nd prediction of the Hardy - Weinburg law?

A

the genotypic frequencies stabilize

70
Q

What is the Hardy-Weinburg law?

A

describes the effect of reproduction on genotypic and allelic frequencies
= p+q=1
- p2=homozygous dom allele pair freq
- q2= homo rec allele pair frequency
- 2pq=hetero allele freq

71
Q

What conditions must be true for no change in allele frequencies?

A
  • no natural selection
  • no migration
  • no mutation
  • large population
  • random mating
72
Q

What affects the genotypic frequencies of a population?

A

non random mating

73
Q

What is the result of inbreeding?

A

inbreeding depression

74
Q

What is required for statistics and probability to hold up ?

A

large population size

75
Q

What is genetic drift?

A

random changes in allelic frequencies
causes: founder effect , genetic bottleneck

76
Q

Result of genetic drift?

A

changes allele frequencies within populations, leading to a reduction in genetic variation through fixation and genetic divergence among populations.

77
Q

What is the result of natural selection?

A

predicatible, directional selection
overedominance vs under dominance

78
Q

What is evolution?

A

change in allele frequency allele due to natural selection

79
Q

What is artificial selection?

A

selection by promoting the reproduction of organisms with traits perceived as desirable (control of who breeds; human or nature)

80
Q

What is the definition of natural selection?

A

Natural selection occurs when individuals with adaptive traits produce a greater number of offspring than others in the population
i.e. is your phenotype if more fit for the environment you have more babies

81
Q

What is fitness?

A

measurable relative reproduction rate, determined by environment and phenotype interaction

82
Q

What is adaptation?

A

trait shaped by natural selection, individuals cannot choose to adapt

83
Q

What is the short term and long term effect of mutation.

A

Short: change in allelic frequencies
Long: Equilibrium reached between forward and reverse mutations

84
Q

What is the short term and long term effect of migration?

A

short: change in allelic frequencies
Long: Equilibrium reach when allelic frequencies of source and recipient population are equal

85
Q

What is the short and long term effect of genetic drift?

A

short: change in allelic frequencies
long: fixation of one allele

86
Q

What is the short and long term effect of natural selection?

A
  • Short: change in allele frequencies
  • Long: Directional selection: fixation of one allele over dominant selection: equilibrium reached under dominant selection; unstable equilibrium
87
Q

What increases genetic variation within populations?

A
  • mutation
  • migration
  • some types of natural selection
88
Q

What increases genetic variation between population?

A
  • mutation
  • genetic drift
  • some types of natural selection
89
Q

What decreases genetic variation within populations?

A
  • genetic drift
  • some types of natural selection
90
Q

What decreases genetic variation between population?

A
  • migration
  • some types of natural selection
91
Q

What is biological evolution?

A

genetic change in a group of organisms

92
Q

What are the types of evolution?

A
  • Anagenesis: evolution taking place in a single group ( a lineage) with the passage of time ex: humans getting taller
  • Cladogenesis: splitting of one lineage into two; new species arise
93
Q

When does natural selection occur?

A

When individuals with adaptive traits produce a greater number of offspring than other in the population

94
Q

Cladogenesis?

A

the splitting of one lineage into two

95
Q

Anagenesis

A

evolution within a lineage with the passage of time

96
Q

Prezygotic

A

acts before a zygote has formed

97
Q

Ecological

A

differences in a habitat; individuals do not meet

98
Q

Temporal

A

reproduction takes place at different times

99
Q

Mechanical

A

anatomical differences prevent copulation

100
Q

Behavioral

A

differences in mating behavior prevent mating

101
Q

gametic

A

gametes are incomparable or not attracted to each other

102
Q

Postzygotic

A

acts after a zygote has formed

103
Q

hybrid inviability

A

hybrid zygote does not survive to reproduction

104
Q

hybrid sterility

A

hybrid is sterile

105
Q

hybrid breakdown

A

f1 hybrids are viable and fertile, but F2 are inviable or sterile

106
Q

What is an example of post zygotic reproductive isolation?

A

hybrid zygotes between species A and B are spontaneously aborted early in development

107
Q

What is speciation?

A

process by which new species arise

108
Q

What is allopatric speciation?

A

when a geographic barrier splits a population into two or more groups and prevents gene flow between the isolated groups

109
Q

What is sympatric speciation?

A

Arises in the absence of any geographic barrier to gene flow; reproductive isolation mechanisms evolve within a single interbreeding population

110
Q

What is a phylogenetic tree?

A

a graphical representation of the evolutionary representation among a group of organisms

111
Q

What causes normal distribution?

A

It’s a polygenic trait; All dosage amounts are possible, ex; 0-10, range of doses equals range of phenotypes; more doses equals taller,
The most different genotypes that give a middle dosage; middle of range has most genotypes
0 and 10 areas statistically are least likely: 1 genotype for all or no doses

Genetics (14 decks)

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