Changes in genetic makeup of a population

Question 1

Allele

Answer 1

Variation of a gene

Question 2

gene pool

Answer 2

should be called allelle pool. Complete set of alleles present in a population.

Question 3

polyploidy

Answer 3

Condition in which an organism has more than two matched sets of chromosomes.
eg: triploids, tetraploid, etc.

Question 4

Allopolyploid

Answer 4

When the additional chromosome sets in a polyploid comes from antoher speices.

Question 5

Autopolyploid

Answer 5

Additional chromosomes sets in a polyploid are from its own speices.

Question 6

Aneuploidy

Answer 6

When an organism has a chromosome number that differes by a small number from the standard chromosome number for its speices.
typically +/- 1 or 2.

Question 7

Point mutations

Answer 7

Affect a single base in DNA, either by substitution, insertion, or deletion.

Question 8

Base substitutions

Answer 8

mutations can be can be silent, nonsense, or missense

Question 9

Silent mutations

Answer 9

The substitution does not change the polypeptide produced. One amino acid may be coded for by a variety of codons.
Can only be identified when DNA is examined.

Question 10

Nonsense Mutations

Answer 10

-sub may result in STOP codon, therefore shorten polypeptide chain.
this would result in missing amino acids, and therefore different protein folding
more detremental than missense (just diff folding)

Question 11

Missense Mutations: conservative mutations

Answer 11

-conservative: sub still enables mutation to be tolerated. EG: the diff amino acid may have similar 
chemical properties (eg both hydrophobic)

Question 12

Missense Mutations: non-conservative mutations

Answer 12

-non-conservative: sub results in sub of amino acid with diff chem properties, that connot be tolerated.

Question 13

Point Mutations: Frameshift mutations

Answer 13

insertions or deletions that cause the remaining bases to SHIFT (to the left/right.).

Question 14

Missense vs Nonsense

Answer 14

mis= replacement of amino acid, nonsense= stop codon

Question 15

Points for natural selection to occur:

Answer 15

1. There is a variation in population
2. a selection presuure means that some organisms have a better chance of reproducing than others.
3. the organism that reproduce are likely to pass on favourable characteristics (alelles) to the next generation
4. greater (allele) frequency of favoured characteristic is present in population.

Question 16

natural selection

Question 17

gene flow

Answer 17

movement of alleles between populations by migration/emigration of individuals carrying them.
-there MUST be sexual reproduction for new alleles to be introduced into the population. This introduction is the “gene flow’

Question 18

genetic drift

Answer 18

• changes in allele frequencies that occur by chance
• bottleneck, founders effect
• not driven by selection pressure

Question 19

Genetic drift: bottleneck

Answer 19

• allele frequencies of survivors are unrepresentative of the original population. (the population must start again)
• 12 blue:8 red. a fire comes along. now it’s a 1 blue: 6 red ratio.

Question 20

genetic drift: founders effect

Answer 20

• allele frequencies of founders have different allele frequencies than the original population. (involves moving and starting a new population)
• og pop has 12 blue: 8 red. dude comes along and takes a sample, the sample has a 1 blue: 6 red ratio.

Question 21

how can allele frequencies be cha nged?

Answer 21

selection, gene flow, genetic drift

Question 22

How do new alleles appear?

Answer 22

gene flow, mutation

Question 23

HOw is a subspecies formed?

Answer 23

One of the population becomes serveral seperate population, and each undergoes changes in isolation from the other populations.
they are considered to be part of the same species if they’re still able to produce viable, fertile offspring when the both do the diddly doo.

Question 24

allopatric speciation

Answer 24

speciation caused by geogrphical isolation.

Question 25

isolating mechanisms: behavioural

Answer 25

-diff reproductive behaviours (eg: mating calls) would mean that they would not recognise each other for mating purposes.

Question 26

isolating mechanisms: mechanical

Answer 26

-eg diff genitalia structure

Question 27

isolating mehanisms: reprodutive isolation

Answer 27

-eg: some lizards recognise that cheeky red necl, while the others dont.

Question 28

Hybrid sterility

Answer 28

mating b/w two species produces infertile offspring. (horse and donkey= mule) note, the mule is a diff species.

Question 29

speciation

Answer 29

• a group of genes become isolated from another to begin a seperate evolutionary history
• the isolation can be occur two ways: allopatric or sympatric isolation.

Question 30

sympatric speciation

Answer 30

-genetic isolation caused by behaviour, chromosome differences, season behaviour (reproductive, mechanical. behavioural isolation=isolating mechanisms).