Origin of Genetic Variation Flashcards Preview

Mechanisms of Evolution > Origin of Genetic Variation > Flashcards

Flashcards in Origin of Genetic Variation Deck (31)
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1
Q

Why is variation critical to evolution?

A

Evolution can only happen with variation in characteristics, natural selection needs variation to be able to select individuals

2
Q

What are silent/synonymous mutations?

A

Mutations that don’t change the amino acid encoded

3
Q

What are non-synonymous mutations?

A

Mutations that change the amino acid encoded

4
Q

What are gene mutations?

A

Alterations of genes or chromosomes

5
Q

What are point mutations?

A

Alteration of a single base pair

6
Q

What are base pair substitutions?

A

One base replaced by another, either transition or transversion

7
Q

What are frameshifts?

A

Alteration in the reading frame which changes a bunch of amino acids downstream of the mutation. Caused by indels

8
Q

What is intragenic recombination?

A

Difference in two or more base pairs in a gene, which generates a new sequence within the gene

9
Q

What is gene conversion?

A

A damaged DNA strand on one chromosome is repaired based on an undamaged homologous chromosome

10
Q

What causes unequal crossing over and what is the result?

A

Imperfect alignment between homologous chromosomes during bivalent formation. Results in an unequal exchange of genetic information and one chromosome with a duplication and the other with a deletion

11
Q

How does the mutation rate compare to the size of the genome of the organism?

A

Mutation rates are generally pretty low, but tends to increase as the genome gets larger. The exception are viruses, which have high mutation rates to evade host defences

12
Q

What are somatic mutations?

A

Mutations that occur in somatic cells and can’t be passed on to the next generation. They don’t matter for evolution

13
Q

What are germline mutations?

A

Mutations in the reproductive cells that can be passed on and do matter for evolution because that change can be acquired by the next generation

14
Q

What are homeotic mutations?

A

Mutations that can alter developmental processes and can cause an anatomical structure in the wrong place

15
Q

Why are mutations limited for what can be changed in an evolutionary sense?

A

Mutations can only modify whats already there, and can’t alter developmental foundations

16
Q

What is aneuploidy?

A

The loss or gain of a whole chromosome or a major part of it

17
Q

What causes polyploidy?

A

Failure of the reductional division of meiosis

18
Q

Which group organisms is polyploidy seen in more often?

A

Plants

19
Q

Where did the multiple chromosome sets originate from in autopolyploids?

A

Within one species

20
Q

Where did the multiple chromosome sets originate from in allopolyploids?

A

Two or more species

21
Q

Why are polyploid organisms advantageous commercially?

A

They are larger than their diploid counterparts

22
Q

How can polyploidy occur in animals?

A

Parthenogenic animals, hybrids, some frogs and toads are polyploid

23
Q

What is parthenogenesis?

A

A form of asexual reproduction that allows a female to create offspring without fertilization

24
Q

What causes chromosome structural alteration?

A

Breaking and resealing of a chromosome

25
Q

What is a deletion?

A

A segment of the chromosome is lost

26
Q

What is a duplication?

A

A segment gets replicated and is in the chromosome twice

27
Q

What is an inversion?

A

A segment has its orientation reversed

28
Q

What is a translocation?

A

A segment gets moved to another chromosome

29
Q

How common are chromosomal abnormalities in human sexual reproduction?

A

Surprisingly common. 15% of conceptions abort spontaneously, and 50% of those are due to chromosomal abnormalities

30
Q

Why are chromosomal abnormalities so common in human sexual reproduction?

A

Cellular processes are error prone

31
Q

What caused two closely related species of Muntjac deer to have such different chromosome numbers, with one having 2N = 46 and the other with 2N = 8?

A

Fusion of chromosomes in the 2N = 8 species. The size of the genome hasn’t really changed but the chromosomes have fused into fewer large chromosomes