Evolutionary Genetics Flashcards
1
Q
what is population genetics
A
the study of patterns of allelic diversity and their change
in frequency over time.
2
Q
what is genetic drift
A
Genetic drift describes how allele frequencies fluctuate unpredictably from one
generation to the next..
Genetic drift tends to reduce genetic variation through losses of alleles
3
Q
what is the hardy-weinberg equation
A
p2 + 2pq + q2 = 1
where p2 is a frequency of dominant homozygotes (AA),
q2 is a frequency of recessive homozygotes (aa)
4
Q
what the 4 hardy-weinberg assumptions
A
- Absence of environmental factors /outside forces
- A population is infinitely large
- All genotypes at a locus are equally likely to survive and reproduce
- No alleles enter or leave a population
5
Q
what is the bottleneck effect
A
an event in which the number of individuals in a population is reduced drastically.
Even if this dip in numbers is temporary, it can have lasting effects on the genetic variation of a population.
6
Q
what is the founder effect
A
when a small number of individuals start a new population (due to e.g. separation) and genetic variation is lost.
allele frequencies may be very different and diversity may continue to disappear due to drift.
7
Q
what does fitness mean with reference to natural selection
A
the reproductive success of a particular phenotype
8
Q
natural selection increases the frequencies of alleles that…
A
enhance survival and reproduction
9
Q
what is microevolution
A
evolution occurring within populations, including adaptive and neutral changes in allele frequencies from one generation to the next
10
Q
what is macroevolution
A
evolution occurring above the species level, including the origination, diversification, and extinction of species over long periods of evolutionary time.
11
Q
what are three mechanisms that cause allele frequency change
A
- natural selection
- genetic drift
- gene flow
12
Q
what are 6 different techniques to study evolution
A
- radioactive dating and carbon dating - age of fossil
- electron microscopy, histology and imaging - structure of tissues, organs, shells
- Protein electrophoresis
- Sanger sequencing
- PCR
- Human Genome Project
13
Q
what are the 5 major domesticated animals and why
A
- sheep - Fleeces, wool, meat, milk
- goat - meat, milk, fibre, leather, transportation, to clear vegetation
- cow - Meat, milk, leather, in research and in the production of by-products.
- pig - Medicine: Insulin, heart valves
- horse - transport, agriculture
14
Q
what are the 6 characteristics an animal needs to fit to be domesticated
A
- Cannot be picky eaters
- Reach maturity quickly
- Willing to breed in captivity
- Docile by nature
- Cannot have a strong tendency to panic and flee
- Conform to a social hierarchy
15
Q
what are 3 physical characteristics tame animals tend to have
A
- Shorter snout
- Paler fur
- Floppy ear
16
Q
what is hybridization
A
Crossing dissimilar individuals to bring together the best traits of both organisms
17
Q
what is inbreeding
A
Continued breeding of similar individuals.
Increases breed’s susceptibility to disease and deformities
18
Q
what are 5 reproductive technologies associated with selective breeding
A
- Artificial Insemination (AI)
- Embryo transfer in livestock (MOET)
- Sex selection through sperm sorting
- Multiple ovulation and embryo transfer
- Oestrous synchronisation
19
Q
name 5 animals and the characteristics that were improved through selective breeding
A
- cattle - Beef and Milk Production
- pig - Growth Rate and Litter Size
- sheep - Wool Quality and Quantity
- chicken - Growth Rate and Egg Production
- dog - Behaviour, Appearance and Abilities
20
Q
Where does DNA replication begin in prokaryotes?
A
At specific origins of replication, such as OriC in prokaryotes.
21
Q
What is a heterozygous genotype?
A
Two different alleles for a gene.
22
Q
What is the inheritance pattern of cystic fibrosis?
A
Autosomal recessive.
23
Q
What is the F factor?
A
A plasmid responsible for conjugation, first discovered in E. coli.
24
Q
What is a double-strand break (DSB)?
A
Break in both strands of the DNA double helix.
25
How does the environment impact hydrangea colour?
Soil pH affects aluminium uptake, which alters pigment.
26
What type of enzyme is DNA gyrase?
A type II topoisomerase that relieves supercoiling.
27
What is codominance?
Both alleles are fully expressed in the phenotype.
28
What is a consensus sequence?
A common DNA sequence recognized by transcription machinery, e.g., -10 and -35 regions in prokaryotes.
29
What is the role of integrases and transposases?
Enzymes that mediate specific integration or movement of DNA.
30
What is recombination?
Exchange of DNA segments during meiosis.
31
What is the Mega-Plate experiment?
An experiment showing bacterial evolution across a drug gradient.
32
Which parent must carry the X-linked mutation for a son to be affected?
The mother must be at least a carrier.
33
What is a transposon?
A mobile genetic element with transposase and other 'cargo' genes.
34
Why is studying the structure of genes important?
It reveals how replication, transcription, and translation are regulated and how errors drive evolution.
35
What is the difference between trait and character?
Trait: variation of a character; Character: heritable feature.
36
Who is considered the father of genetics?
Gregor Mendel.
37
How do ligands affect transcription factors?
Binding to ligands can activate or inhibit transcription factors, changing gene expression.
38
How do alleles sort when they are close together on the same chromosome?
They are likely inherited together unless separated by recombination.
39
What is a conjugative plasmid?
Has genes for pilus formation and transfer machinery.
40
What is homologous recombination?
Recombination based on sequence similarity, integrating foreign DNA.
41
What does the term 'fidelity' mean in replication?
The accuracy of copying genetic material during replication.
42
What happens to chromosomes during random assortment?
They are randomly distributed during meiosis.
43
How does the genetic basis of blood types demonstrate codominance?
IA and IB are both expressed in AB blood type.
44
What happens if recombination does not occur between two genes?
They are inherited together, leading to linkage.
45
How can a pedigree help determine inheritance patterns?
It shows if a trait is dominant, recessive, or X-linked.
46
What direction does DNA polymerase work in?
In the 5’ to 3’ direction.
47
How do plasmids replicate independently?
Using their own replication origin independent of chromosomal replication.
48
Why doesn’t a high transcription rate always mean high protein levels?
Post-transcriptional regulation and protein degradation also affect protein concentration.
49
What is a non-conservative (missense) mutation?
A mutation that changes an amino acid to a very different one.
50
What does independent assortment apply to?
Genes on different chromosomes.
51
What is the law of dominance?
In a hybrid, only one trait (dominant) appears.
52
How can HGT affect bacterial virulence?
By inserting into or modifying virulence-associated genes.
53
What is transduction?
DNA transfer via bacteriophages that infect bacteria.
54
What are the steps involved in natural transformation?
1. DNA capture via pilus, 2. ssDNA transport into cytoplasm, 3. RecA recombination.
55
What does the law of segregation state about gametes?
Each gamete receives only one allele of a gene.
56
What does selection pressure mean in genetics?
External forces favor one allele over another based on fitness.
57
What is oriT?
The origin site for DNA transfer during conjugation.
58
What is the 'norm of reaction'?
The range of phenotypes produced by a genotype under different conditions.
59
What is the difference between spontaneous and induced mutations?
Spontaneous: replication errors; Induced: from mutagens like UV or chemicals.
60
What is a mutation?
A permanent change in a gene.
61
What is an allele?
An alternative form of a gene at a specific locus.
62
How does Mendel’s work apply to modern genetics?
It showed heritable units (genes) and predicted patterns of inheritance.
63
What is the law of segregation?
Alleles separate so each gamete gets one.
64
What is meant by a ‘cargo gene’?
A gene carried by MGEs that can add new traits to the host.
65
What is the difference between generalised and specialised transduction?
Generalised: random DNA; Specialised: specific DNA regions transferred.
66
What is a plasmid?
Circular, double-stranded DNA separate from chromosomal DNA.
67
How do mobile genetic elements spread antibiotic resistance?
By carrying genes that confer resistance traits.
68
What is the significance of RecA-independent recombination?
Allows mobile elements to integrate without homologous recombination.
69
Why is replication accuracy essential?
Errors can change protein shape/function and impact cellular function.
70
What does DNA primase do?
Synthesizes RNA primers needed to start DNA replication.
71
What is pleiotropy?
One gene affects multiple phenotypic traits.
72
Define heterozygous.
Two different alleles for a gene.
73
Why is replication semi-conservative?
Each new DNA molecule contains one original and one new strand.
74
Why might eukaryotic genomes be larger than prokaryotic ones?
More non-coding DNA, regulatory sequences, and complex control mechanisms.
75
What is epistasis?
One gene’s expression masks or alters the expression of another gene.
76
What is the role of the relaxosome in conjugation?
Nicks DNA at oriT and aids in DNA transfer.
77
What are the three main mechanisms of HGT?
Transduction, transformation, and conjugation.
78
How is horizontal gene transfer different from vertical gene transfer?
HGT occurs between organisms of the same generation, vertical is parent to offspring.
79
What is the function of a sigma factor?
Helps RNA polymerase bind to the promoter.
80
What is Mendel’s law of segregation?
Alleles separate during gamete formation so each gamete gets one allele.
81
What is the central dogma of molecular biology?
DNA → RNA → Protein; it describes genetic information flow.
82
What are examples of cargo genes in transposons?
Antibiotic resistance genes, toxin production genes, or metabolic genes.
83
How does inheritance differ between autosomal dominant and recessive diseases?
Dominant: one parent affected; Recessive: both parents carriers.
84
What is the role of MC1R and TYR in skin colour?
They are genes that contribute to skin pigmentation.
85
What is horizontal gene transfer (HGT)?
Transfer of genetic material between organisms without being parent-to-offspring.
86
What is the difference between haploid and diploid cells?
Haploid has one set of chromosomes; diploid has two.
87
Why might an allele be dominant?
It produces a functioning protein even if another allele is non-functional.
88
Which base pairs are easier to separate and why?
AT base pairs, because they have only 2 hydrogen bonds compared to 3 in GC pairs.
89
How does the Lac Operon get activated?
Presence of lactose binds to the repressor, detaching it from the operator, allowing RNA polymerase access.
90
What happens during replication termination?
Replication forks meet at the dif site; enzymes disassemble and DNA ligase joins final fragments.
91
What is the role of the sliding clamp in DNA replication?
Keeps DNA polymerase attached to the template strand for efficient replication.
92
What is the role of DnaB helicase?
Unwinds DNA strands at the replication fork.
93
What causes dependent assortment?
Genes located close on the same chromosome.
94
What are examples of polygenic traits in humans?
Height, skin colour, weight.
95
What is genetic heterogeneity?
Different mutations in different genes cause the same disease.
96
What are the properties of nucleic acids that aid replication?
Complementary base pairing and antiparallel strand orientation.
97
What is a genotype?
The alleles an individual carries.
98
What is Mendel’s law of independent assortment?
Alleles for different traits segregate independently during gamete formation.
99
What are the steps of bacterial conjugation?
1. Nick at oriT, 2. DNA transfer via T4SS, 3. Circularization and replication.
100
What is DnaA's role in replication?
Binds to OriC and initiates strand separation.
101
What is a homozygous genotype?
Two identical alleles for a gene.
102
What is RecA and what does it do?
A protein that facilitates homologous recombination by searching for DNA homology.
103
What are the three Mendelian laws of inheritance?
Law of dominance, law of segregation, law of independent assortment.
104
What are Okazaki fragments?
Short DNA fragments formed on the lagging strand during replication.
105
How is haemophilia inherited?
X-linked recessive.
106
Why do transposons contribute to genome plasticity?
They enable reshuffling of genetic material within the genome.
107
What is the genotypic ratio in the F2 generation from a hybrid cross?
1/4 homozygous dominant, 2/4 heterozygous, 1/4 homozygous recessive.
108
What is an operon?
A cluster of genes transcribed together, often regulating a specific process (e.g., lac operon).
109
What is a transconjugant?
The recipient cell after receiving DNA via conjugation.
110
How do topoisomerases resolve DNA tension?
By breaking and rejoining DNA strands to relieve torsional stress.
111
What is the law of independent assortment?
Alleles of different genes segregate independently.
112
Who is known as the first geneticist?
Gregor Mendel.
113
How do ICEs integrate and excise?
1. Integrated in genome, 2. Excised, 3. Transferred, 4. Integrated into new host.
114
What are the types of plasmids based on mobility?
Conjugative, mobilizable, and nonmobilizable plasmids.
115
What pattern is seen in X-linked recessive diseases?
More males than females are affected.
116
What is proofreading in DNA replication?
The ability of DNA polymerase to detect and correct mismatched bases.
117
What is a phenotype?
The observable traits of an individual.
118
What does DNA polymerase III do in prokaryotes?
Synthesizes new DNA strands using RNA primers.
119
What does DNA helicase do?
Unwinds the DNA double helix by breaking hydrogen bonds between bases.
