Test #5 Review Flashcards
(111 cards)
1
Q
What is a karyotype?
A
visualization of a full set of chromosomes
2
Q
What are the types of chromosome mutation?
A
rearrangements, Aneuploidy, polyploidy
3
Q
Chromosome rearrangements
A
alter the structure of chromosomes
4
Q
Aneuploidy
A
alters the number of chromosome
5
Q
polyploidy
A
one or more complete sets of chromosomes are added
6
Q
What are the types of chromosome arrangements?
A
- Duplication
- Deletion
- Inversion
- Translocation
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
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
9
Q
What is deletion
A
loss of chromosomal segment
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
11
Q
Types of Inversions
A
- paracentric inversion (doesn’t include the centromere)
- pericentric inversion (includes centromere)
12
Q
Translocations
A
two homologs doing recombination
13
Q
What are the types of translocations?
A
non reciprocal translation
reciprocal translocation
robertsonian translocation
14
Q
D: Chromosome rearrangement
A
change in chromosome structure
15
Q
D: Chromsome duplication
A
Duplication of a chromosome segment
16
Q
D: Chromsome deletion
A
Deletion of a chromosome segment
17
Q
D: inversion
A
Chromsome segment inverted 180 degrees
18
Q
D: Paracentric Inversion
A
Inversion that does not include the centromere in the inverted region
19
Q
D: Pericentric Inversion
A
Inversion that includes the centromere in the inverted region.
20
Q
D: Translocation
A
Movement of a chromosome segment to a non homologous chromosome or to another region of the same chromosome.
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.
22
Q
Reciprocal Translocation
A
Exchange between segments of non homologous chromosomes or between regions of the same chromosome
23
Q
Aneuploidy
A
change in number of individual chromosomes
24
Q
Nullisomy
A
Loss of both members of a homologous pair
25
Monosomy
Loss of one member of a homologous pair
26
Trisomy
Gain of one chromosome, resulting in three homologous chromosomes
27
Tetrasomy
Gain of two homologous chromosomes, resulting in four homologous chromosomes
28
Polyploidy
Addition of entire chromosome sets
29
Autopolyploidy
Polyploidy in which extra chromosome sets are derived from the same species
30
Allopolyploidy
Polyploidy in which extra chromosome sets are derived from two or more species (hybridization)
31
What negative affects can duplication cause?
- extra dosage
- meiosis
- neighborhood effects
32
Effects of inversion
- 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
33
Effects of translocation
non-homologous crossover
neighborhood effects
meiosis (wrong pairing)
34
What can pericentric inversion cause?
inversion loop during pairing in prophase 1 of meiosis
35
What occurs during robertsonian translocation?
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.
36
What are the causes of aneuploidy?
- nondisjunction: chromosomes don’t separate during meiosis 1 or 2
- robertsonian translocation
37
What are the types of aneuploidy?
nullisomy 2n-2
monosomy 2n-1
trisomy 2n+1
tetrasomy 2n+2
38
A diploid organism has 2n=36 chromosomes. How many chromosomes will be found in a trisomic member of this species?
2n+1=37
39
Effects of Aneuploidy in Humans
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
40
Why are sex chromosome aneuploidy more common that autosomal aneuploids?
they can be more tolerated due to barr bodies
41
What can cause autopolyploidy
nondisjunction in mitosis or meiosis
42
What can cause allopolyploids?
hybridization between two species followed by chromosome doubling
43
What is the significance of polyploidy?
- increase in cell size
- larger plant attributes
- evolution: may give rise to new species
44
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?
22 or 23
45
What are discontinuous characteristics?
relatively few phenotypes
- just a few option; this or that
- left or right handed
46
What are continuous characteristics?
continuous distribution of phenotypes; occurs when genes at many loci interact
- all heights are possible (more than one gene controlling that trait)
47
What are polygenic characteristics?
characteristics encoded by genes at many loci.
- lots of genes that control that trait
48
What is pleiotropy?
one gene affects multiple characteristics
- ex. cistic fibrosis, lung and kidney problems caused by one gene
49
Quantitative Characteristics
- 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
What are the types of quantitative characteristics?
Meristic and threshold
51
What are Meristic characteristics?
- Determined by multiple genetic and environmental factors
- animal litter size
52
What are threshold characteristics?
- measured by presence or absence
- susceptibility to disease
- everyone is the same until a certain threshold is reached then a new phenotype
53
What are the possible phenotypes with threshold characteristics?
The trait is either present or absent but they are quantitative because the underlying susceptibility to the characteristic varies continuously.
54
What is polygenic inheritance (more than one gene)?
- 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
What is an example of polygenic inheritance?
- 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
Which experiment demonstrated that kernel color is wheat inherited according to mendelian inheritance?
Nilsson-Ehle
57
What is the result of crossing individuals heterozygous for different numbers of loci affecting a characteristic.
- normal distribution
- involvement of lots of genes
58
What is variance?
the variability of a group of measurements
59
what is standard deviation?
the square root of variance
60
What is heritability?
The proportion of the total phenotypic variation that is due to genetic difference.
61
What are the 5 limitation of heritability?
- 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
What is a multifactorial polygenic trait?
- skin color
- controlled by 3 or 4 genes and environmental factors leading to a wide range of phenotypes
63
What is the additive model of polygenic inheritance?
as the number of genes involved increase, the number of phenotypic classes increases
64
What is a polygenic trait?
eye color
- five basic eye colors fit a model with two genes, each with two alleles.
65
What causes differences in populations?
genetic variation
66
How are genotypic frequencies calculated?
The number of individuals possessing the genotype divided by the total number of individuals in sample
67
How are allele frequencies calculated?
number of copies of a particular allele present in sample divided by total number of alleles
68
What is the 1st prediction of the hardy weinburg law
the allelic frequencies of a population do not change.
69
What is the 2nd prediction of the Hardy - Weinburg law?
the genotypic frequencies stabilize
70
What is the Hardy-Weinburg law?
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
What conditions must be true for no change in allele frequencies?
- no natural selection
- no migration
- no mutation
- large population
- random mating
72
What affects the genotypic frequencies of a population?
non random mating
73
What is the result of inbreeding?
inbreeding depression
74
What is required for statistics and probability to hold up ?
large population size
75
What is genetic drift?
random changes in allelic frequencies
causes: founder effect , genetic bottleneck
76
Result of genetic drift?
changes allele frequencies within populations, leading to a reduction in genetic variation through fixation and genetic divergence among populations.
77
What is the result of natural selection?
predicatible, directional selection
overedominance vs under dominance
78
What is evolution?
change in allele frequency allele due to natural selection
79
What is artificial selection?
selection by promoting the reproduction of organisms with traits perceived as desirable (control of who breeds; human or nature)
80
What is the definition of natural selection?
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
What is fitness?
measurable relative reproduction rate, determined by environment and phenotype interaction
82
What is adaptation?
trait shaped by natural selection, individuals cannot choose to adapt
83
What is the short term and long term effect of mutation.
Short: change in allelic frequencies
Long: Equilibrium reached between forward and reverse mutations
84
What is the short term and long term effect of migration?
short: change in allelic frequencies
Long: Equilibrium reach when allelic frequencies of source and recipient population are equal
85
What is the short and long term effect of genetic drift?
short: change in allelic frequencies
long: fixation of one allele
86
What is the short and long term effect of natural selection?
- Short: change in allele frequencies
- Long: Directional selection: fixation of one allele over dominant selection: equilibrium reached under dominant selection; unstable equilibrium
87
What increases genetic variation within populations?
- mutation
- migration
- some types of natural selection
88
What increases genetic variation between population?
- mutation
- genetic drift
- some types of natural selection
89
What decreases genetic variation within populations?
- genetic drift
- some types of natural selection
90
What decreases genetic variation between population?
- migration
- some types of natural selection
91
What is biological evolution?
genetic change in a group of organisms
92
What are the types of evolution?
- 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
When does natural selection occur?
When individuals with adaptive traits produce a greater number of offspring than other in the population
94
Cladogenesis?
the splitting of one lineage into two
95
Anagenesis
evolution within a lineage with the passage of time
96
Prezygotic
acts before a zygote has formed
97
Ecological
differences in a habitat; individuals do not meet
98
Temporal
reproduction takes place at different times
99
Mechanical
anatomical differences prevent copulation
100
Behavioral
differences in mating behavior prevent mating
101
gametic
gametes are incomparable or not attracted to each other
102
Postzygotic
acts after a zygote has formed
103
hybrid inviability
hybrid zygote does not survive to reproduction
104
hybrid sterility
hybrid is sterile
105
hybrid breakdown
f1 hybrids are viable and fertile, but F2 are inviable or sterile
106
What is an example of post zygotic reproductive isolation?
hybrid zygotes between species A and B are spontaneously aborted early in development
107
What is speciation?
process by which new species arise
108
What is allopatric speciation?
when a geographic barrier splits a population into two or more groups and prevents gene flow between the isolated groups
109
What is sympatric speciation?
Arises in the absence of any geographic barrier to gene flow; reproductive isolation mechanisms evolve within a single interbreeding population
110
What is a phylogenetic tree?
a graphical representation of the evolutionary representation among a group of organisms
111
What causes normal distribution?
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
