Population Genetics

Question 1

What is variation?

Answer 1

Describes the differences in characteristics or phenotypes in organisms of a population

Question 2

What is a phenotype?

Answer 2

An organisms physical appearance, constitution and behavior

Question 3

What is a genotype?

Answer 3

An organisms genetic makeup

Question 4

What is the difference betwen intraspecific and interspecific variation?

Answer 4

Intraspecific variation is variation within a species
Interspecific is variation between different species

Question 5

What are the two factors of variation?

Answer 5

Genetic variation- characteristics that fall into a limited number of distinct forms
Environmental factors- characteristics that that vary only slightly between individuals due to theire environment

Question 6

State three examples of genetic factors that cause variation

Answer 6

Meiosis
Mutations
Random fusion of gametes

Question 7

How can data from genetic variation be represented?

Answer 7

On pie charts, bar charts and histograms

Question 8

Gove examples of environmental factors that cause variation

Answer 8

Diet, disease, climate change

Question 9

How are environmental factors of variation represented? What is a key feature of this?

Answer 9

Frequency curve- shows a normal distribution curve
Mean= mode= median

Question 10

How can gene mutations lead to the production of non-functioning proteins?

Answer 10

A gene mutation alters the base sequence of DNA, which a,ters the base seauence of mRnA after transcription
This can lead to changes in the sequence of amino acids in a protein, hence changing the primary structure
This can change the tertiary structure as hydrogen, ionic and disulphide bonds form in different places
Leads to loss pf function of a protein

Question 11

What are mutagenic agents? Give two examples

Answer 11

Agents that increase the rate of base mutations
X-rays and UV lights

Question 12

State six types of mutations

Answer 12

Addition
Deletion
Substitution
Duplication of bases
Inversion of bases
Translocation of bases

Question 13

What are addition and deletion mutations? What type of mutation do they both cause?

Answer 13

Addition is where an extra base is added to the sequence
Deletion is where a base is removed from the sequence

Both lead to frame shift mutation- they both change all triplet codes, so the whole sequence of amino acids changes

Question 14

What are substitution mutations?

Answer 14

Where one base in the sequence is swapped for another

Question 15

State and explain the three different consequences of substitution mutations

Answer 15

Mis-sense- one amino acid in the polypeptide changes. This can change both primary and tertiary structure

Silent- no difference due to the degenerate nature of the triplet code. The new triplet codes for the same amino acid

Nonsense- base change results in the dormation of a stop codon. Translation stops

Question 16

What is a duplication of bases mutation? What type of mutation does this cause?

Answer 16

Where aone or more bases are repeated. This causes a frame shift mutation to the right

Question 17

What is an inversion of bases mutation?

Answer 17

Where a group of bases are seperated from the sequence and rejoin in the same position of the sequence, but in the inverse order

Question 18

What is a translocation of bases mutation?

Answer 18

A group of bases are separated from the sequence, and are inserted into the same or different chromosome in a different position.

Question 19

What are introns?

Answer 19

Non coding sections of genes

Question 20

What is a population?

Answer 20

All the individuals of one species in the same habitat at any given time, that can interbreed to produce fertile offspring

Question 21

What is the gene pool?

Answer 21

The set number of alleles of all the gene loci in a population at a particular time

Question 22

How do you calculate allele frequencies that show codominance?

Answer 22

Calculate the total number of alleles in the population (population size x2 as there are 2 alleles in every gentoype)
Calculate the frequency of a particular allele (times number of homozygous plants by two and add to number of heterozygous plants)
Divide by total number of alleles

Question 23

What is the hardy weinburg equation used for?

Answer 23

To calculate the proportion of each allele (allele frequency)

Question 24

In the hardy weinburg equatipn, what does each letter represent?

Answer 24

P= frequency of the dominant allele
q= frequency of the recessive allele
p^2= frequency of the homozygous dominant genotype
q^2= frequency of the homozygous recessive genotype
2pq= frequency of the heterpzygous genotype

Question 25

What does the hardy weinburg principle state?

Answer 25

That the frequency of the alleles of a particular gene in a population will stay contstant from generation to generation

Question 26

What conditions does the hardy weinburg principle take place under?

Answer 26

Large population
Mating between indiciduals must be random
No mutations
All genotypes equally likely to reproduce
No immigration or emigration

Question 27

What does it show when the hardy weinburg principle is not correct?

Answer 27

That species are constantly in a state of evelutionary flux

Question 28

What is genetic drift?

Answer 28

The idea that allele frequencies can change simply due to chance

Question 29

In what sozed population is genetic drift most likely to occur?

Answer 29

In small populations, as the changes that pccur due to chance will have a greater influence on allele frequency, as there are less of them to counteract the chanced event

Question 30

What are two examples of genetic drift?

Answer 30

The founder effect

Genetic bottlenecks

Question 31

What is the founder effect in genetic drift?

Answer 31

When a few organisms become isolated from the population, this will decrease the population size so the impact of chance on the allele frequencies would be greater

Question 32

What is genetic bottlenecks in genetic drift?

Answer 32

When the majority of individuals are killed, so the population is reduced to a very small number.
A decreased populatipn size increases the impact of chance on the allele frequencies.