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Flashcards in Genetics & Evolution Deck (53)
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1

When did the big bang occur?

13.7 bya

2

How old is the earth?

4.5 billion years

3

What is the Panspermia hypothesis?

Life arrived from another planet. (E.g. Fossil bacteria from Mars).

4

What is the 'seeded' hypothesis?

Life was 'seeded' on earth by other, advanced civilisations.

5

What would be needed for life to evolve on earth?

1) Simple monomeric compounds 2)Assembly of them into longer molecules 3) Replication of nucleic acids 4) Restriction of interacting molecules into compartments 5) Production of increasing variety of proteins/polypeptides.

6

What is a monomeric compound?

Nucleotide bases, amino acids - monomers

7

What was the Miller-Urey experiment?

Simulation of early earth - ammonia, methane, water. This yielded amino acids, purines and pyrimidines.

8

What is a ribozyme?

An RNA molecule capable of acting as an enzyme.

9

How did proteins become involved in an RNA world?

Amino acids may have been added as cofactors and aided RNA ribozymes in replication, leading to greater RNA production. Amino acids found in meteorites in 1969.

10

What is a species?

Smallest evolutionary unit that is independent (barriers to gene flow).

11

Biological species concept?

Independent = reproductive isolation. Members of populations that actually or potentially interbreed in nature, not according to similarity of appearance.

12

Phylogenetic species concept?

Independent = evolved separate traits. Shared evolutionary history.

13

Morphospecies concept

Based on anatomical appearance.

14

What did Darwin conclude?

1) Factors causing variability are passed from parents to offspring. 2) Some individuals are more successful (fit). 3) This success is linked to variation and selection. 4) Fitness is relative to the rest of the population.

15

What did Peter & Rosemary Grant do?

Studied Geospiza fortis on the galapagos island. Bigger beaks better at eating bigger seeds. 1977 drought - more big beaks in later generations.

16

What is directional selection?

Individuals at one end of phenotypic range survive or reproduce more successfully than at mean.

17

What is stabilizing selection?

Mean phenotype favoured.

18

What is disruptive selection?

Both extremes favoured, mean selected against.

19

What causes sexual selection?

Differences in reproductive success in obtaining mates. E.g. Grey treefrog - Females prefer males with long calls = directional selection on call length in males.

20

What is the neutral theory?

Mutations have little impact on evolution - genetic drift has more impact.

21

What is a synonymous substitution?

Silent - not influenced by mutation, occur by drift. More common.

22

What is a non synonymous substitution?

Replacement - occur at lower rate as deleterious so eliminated.

23

What is kin selection?

Natural selection that favors altruistic behavior by enhancing indirect fitness.

24

What is indirect fitness?

Reproduction of relatives.

25

Why should parents look after young altruistically?

Ensuring survival of 2 young = genetically equivalent to surviving yourself.

26

What is batesian mimicry?

Mimic species evolves to look like model species, which has defence mechanisms.

27

What is aposematism?

Warning colouration.

28

What are the outcomes of Hardy-Weinberg?

Frequencies of alleles in a population expected to be in equillibrium between generations. Allows prediction of genotype frequencies from allele frequencies in the population.

29

The conditions of Hardy-Weinberg equillibrium

1) No natural selection 2) No mutation 3) No migration (isolated pop.) 4) No genetic drift 5) Random-mating

30

What does selection do?

Remove mutations by deleting them.