Topic 5 - Mutations and Genetic Variation Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What must occur if there is to be some form of evolution occurring (genetic basis)?

A
  • the traits must be heritable to some genetic basis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the challenges with genetic and environmental variation? two examples of this?

A
  • genetic and environmental changes can look very similar
  • Snow Goose (genetic variation)
  • Willow Ptarmigan (environmental variation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain what drives the variation of the snow goose and willow ptarmigan.

A
  • these are not examples of genetic differences, rather a genetic difference driven by changing environmental conditions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are two examples which could resemble Lamarck’s idea, what is his idea again?

A
  • the idea of inheritance of acquired traits
    1. Peach Aphid: effect of the physical environment determines if it has wings or not
    2. Desert locus: epigentic inheritances (based on the maternal genotype) - crowded vs isolated conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What would explain evolution occurring but no phenotypic traits appearing?

A
  • there may be substantial amounts of unexpressed genetic variation occurring -these differences could evolve
  • this genetic variation is not always observed through the phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the three explanations for observing phenotypic variation?

A
  1. genetic difference
  2. environmental difference
  3. combination of genetic and environmental interactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain how genetic differences can explain when phenotypic variation occurs?

A
  • there could be one or many gene variations occurring

- this could be a result of epigenetic effects (expression of a gene varied by parental origin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain what effect environmental differences can have for phenotypic variation, and what is this typically called?

A

the result of the same genotype presenting different phenotypes in changing environments

  • aka phenotypic plasticity
  • changes through environmental stimuli and conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do genetoype and environmental interactions affect phenotypic variation?

A
  • the environmental affect varies with the genotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Individuals in populations will show high levels of genetic variation, how is this variation maintained?

A
  • this maintenance of variation is driven by Natural Selection selecting for the best genotype in the populations
  • if the environmental factor is continuously changing, then these variants would not have been eliminated yet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the origin of genetic variation, and give two examples of it.

A
  • mutations is the basis for evolutionary change (essential in changing genetic material)
    1. Point mutations (base substitutions)
    2. Structural mutations (deletions, insertions, or chromosomal rearrangement)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Review: what two components do organismal genomes include?

A
  • genes (functional DNA which transcribe and translate for a structural product)
  • noncoding DNA (which do not contribute to final gene products and do not appear to have a function yet)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Of the two origins of genetic variation, explain point mutations.

A
  • aka single base-pair substitutions where one nucleotide base replaces another
  • they may occur in coding regions where they affect amino acid sequences
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Of the two origins of genetic variation, explain structural mutations, and as a result of them occurring what further mutation may occur?

A
  • these include indels: gains or losses of nucleotide bases
  • these may be short or long
  • result in frameshift where the entire coding region of a whole gene is affected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define microstatellites and their function.

A
  • short (few bases) of repeating DNA sequences

- abundant in eukaryotes, highly variable and may lead to chromosomes to getting longer when the DNA sequences align.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What occurred between microsatellites and the fairy-wren?

A
  • mutation changes (in terms of the number of repeats) occurred between the parents and their offspring
17
Q

How do structural mutations occur? DNA rearrangement (3)

A
  • through recombination during meiosis (intragenic recombination)
  • when something goes wrong during the crossing-over which leads to new alleles of a gene region
  • or their could be UNEQUAL crossing-over during recombination (of meiosis) which leads to either INSERTIONS or DELETIONS
18
Q

What is meant by the statement: structural mutations can be both small scale and large scale?

A
  • these mutations are a consequence of unequal crossing-over during meiosis
  • mispairings when chromosomes swap leads to whole gains or loses of a whole gene
19
Q

How would one observe a mutation? in the old days compared to the present? what effect does this phenotypic mutations have?

A
  • before molecular methods, to detect mutations one would have to observe it phenotypically
  • challenge is though some phenotypic mutations maybe minimally invasive
  • phenotypic mutations occur they can affect fitness, however most are neutral
20
Q

What occurs when a mutation affects the fitness of an organism?

A
  • this may be deleterious
21
Q

What are some limitations of these mutations? new traits?

A
  • mutations occur as RANDOM events
  • organisms cannot produce advantageous mutations in response to an environment
  • for a new trait to evolve, a mutation must first produce it
22
Q

What occurred in the Joshua and Esther Lederberg experiment?

A
  • this was a replicate plate experiment which showed how a mutation in an E. coli from a T1 phage was present prior to any exposure to a virus - an advantageous mutation occurred without exposure to an environment where this mutation would be advantageous
23
Q

Define chromosomal mutations, and give two examples of what could occur.

A
  • Aneuploidy: a gain or loss of ONE chromosome
  • Polyploidy: gain of entire chromosome sets - causing a rearrangement
  • these result in eukaryotic organisms: where there is a GAIN, LOSS or REARRANGEMENT of entire chromsomes
24
Q

Explain where polyploidy would occur for eukaryotes?

A
  • polyploidy (common in plants) would occur during either mitosis or meiosis, specifically if the division of the cytoplasm is out of sync with the replication of DNA
25
Q

What can polyploidy result from?

A
  • the production of unreduced (diploid) games during meiosis

- failure of cytoplasmic division during mitosis

26
Q

Explain how a triploid may result from abnormal chromosome behaviour at meiosis.

A
  • when a trios of homologous chromosomes undergo synapsis and unequal numbers separate
  • leading to aneuplod gametes
27
Q

What affect do chromosomal mutations have on the order of genes?

A
  • may change the order or number of genes on a chromosome
28
Q

Explain how an Autotetraploid may result from abnormal chromosome behaviour at meiosis.

A
  • when a quartet of chromosomes undergo synapsis but DO NOT separate as two and two, rater three and one
  • leading to aneuplod gametes
  • will have reduced fertility
29
Q

Explain how an Allotetraploid may result from abnormal chromosome behaviour at meiosis.

A
  • each chromosome pairs with a single homologue from some parental species, with normal segregation
  • normal fertility results with viable gametes
30
Q

What are three types of chromosomal rearrangements that can occur?

A
  • inversion, translocations, and fissions/fusions
  • this occurs when chromosomes break and rejoin in new configurations, but this may change gene order and chromosome structure itself
31
Q

What consequences arise from chromosome inversions?

A
  • this occurs when a normal and inverted gene leads to gene duplication and losses
  • hybrid progeny will not form viable gametes, fertility is reduced being a reproductive barrier
32
Q

What consequences arise from reciprocal translocations?

A
  • this occurs when 2 non homologous chromosomes give rise to a translocation heterozygote, where this heterozygote undergoes meiosis and he products having incomplete gene complements
33
Q

Explain what is so different between the two species of muntjac deer.

A
  • is the case of related species differing in karyotype (visual number of chromosomes)
  • they are genetically different but phenotypically different
  • this means that chromosomal evolution occurred NOT gene evolution
34
Q

What is non genetic inheritance?

A
  • epigenetic inheritance is heritable but is NOT caused by changes in DNA sequence
35
Q

How are epigenetic inheritance mediated? do paternal genotype affect inheritance in this case?

A
  • through mechanisms such as DNA methylation - preventing expression of a gene being expressed
  • maternal effect results where the parents genotype rather than the genotype of the affected individual on which genes were expressed
36
Q

What is an example where the maternal genotype effects the inheritance of the progeny

A
  • the snails coiling direction of the shell is dependent on the individuals mother.