Genetic Changes

Question 1

Allele

Answer 1

variation of a gene at a particular gene locus

Question 2

Gene

Answer 2

a section of DNA that codes for a protein

Question 3

Gene locus

Answer 3

location of a gene on a chromosome

Question 4

Mutation

Answer 4

A change in the DNA sequence

Question 5

Phenotype

Answer 5

Physical, behavioural or physiological characteristics of an organism which are a result of the combination of the genotype and the environment.

Question 6

Point mutation

Answer 6

Mutation where a single nucleotide has changed

Question 7

Types of point mutations

Answer 7

Substitution: change of one base for another
Insertion: inclusion of an extra base
Deletion: removal of a base

Question 8

Silent mutation (outcome)

Answer 8

code for same amino acid as the DNA code is degenerate. This will lead to a functional protein.

Question 9

Missense mutation (outcome)

Answer 9

change the amino acid sequence and so will affect the function of the protein.

Question 10

Nonsense mutation

Answer 10

changes the sequence of amino acids to an early STOP codon, so will affect the function of the protein.

Question 11

Frameshift mutation (outcome)

Answer 11

The reading frame of the codons/triplets has changed from the mutation onwards, causing a change in the amino acid sequence produced from the mutation onwards.

Question 12

Block mutations

Answer 12

Chromosome mutations (two or more bases)

Question 13

Types of block mutations involving one chromosome

Answer 13

Deletion
Duplication
Inversion

Question 14

Type of block mutation involving two chromosomes

Answer 14

Translocation

Question 15

Translocation

Answer 15

portion of one chromosome (or whole chromosome ) is transferred to another chromosome

Question 16

Aneuploidy

Answer 16

a diploid cell with too many or too few chromosomes e.g. 2n = 46 +1

Question 17

Polyploidy

Answer 17

a cell with more than one paired set of chromosomes e.g. 3n (this only occurs in plants).

Question 18

VAST SEINE

Answer 18

There is variation in the phenotypes in the ________ population due to random mutations as _________
All organisms face a daily struggle to survive and reproduce. The _________ struggle because _________, which is the selection pressure
The _________ have a selective advantage as ___________
The organisms that have a selective advantage (___________), survive, reproduce and their offspring inherit the alleles for the trait of _______________
Evolution occurs by natural selection and there is a change in allele frequency over time and the __________ population becomes better suited to its environment.

Question 19

Species

Answer 19

A group of organisms that interbreed to produce fertile and viable offspring.

Question 20

Population

Answer 20

A population is a group of individuals of the same species in the same defined geographical area.

Question 21

What is the cause of variation?

Answer 21

Mutations

Question 22

Evolution

Answer 22

There is a change in allele frequency over time.

Question 23

Gene pool

Answer 23

The complete set of alleles present in a population.

Question 24

Allele frequency

Answer 24

the proportion of one allele in a gene pool.

Question 25

Biological fitness

Answer 25

The ability to survive, reproduce and pass on alleles to the next generation

Question 26

Selection pressure

Answer 26

factors in an organism’s environment that removes unsuited individuals from a population.

Question 27

Gene flow

Answer 27

the movement of individuals into or out of a population changing the allele frequency.

Question 28

Immigration

Answer 28

Gene flow into a population (Immigration- Into)

Question 29

Emigration

Answer 29

Gene flow out of a population (Emigration = exit)

Question 30

Genetic diversity

Answer 30

the variation in a genetic makeup or alleles within a population

Question 31

Impact of immigration on genetic diversity

Answer 31

When individuals enter a population via immigration- their alleles are added to the gene pool of that particular location That means the genetic diversity of the population increases

Question 32

Impact of emigration on genetic diversity

Answer 32

When individuals exit a population via emigration- their alleles are removed from the gene pool of that particular location That means the genetic diversity decreases

Question 33

Advantage of high genetic diversity

Answer 33

a population with a greater variation in alleles has a higher chance of possessing a favourable allele that will help them survive if a new selection pressure arises.

Question 34

Consequence of low genetic diversity

Answer 34

Populations with low genetic diversity are often at risk of extinction due to their inability to adapt to changing environmental selection pressures.

Question 35

Population size more liklely to have low genetic diversity

Answer 35

Small populations Inbreeding (sexual reproduction between two related individuals) is also more common in populations with low genetic diversity, which can lead to a harmful alleles staying in a gene pool

Question 36

Genetic drift

Answer 36

the random change in allele frequencies in a population by chance which causes a decrease in genetic diversity.

Question 37

Types of genetic drift

Answer 37

Bottleneck effect and founder effect

Question 38

Founder effect

Answer 38

A group of individuals whose allele frequency is unrepresentative of the normal population break away and found a new population (no gene flow between the populations). OPTIONAL IF SPECIATION OCCURS: Populations will be subject to different selective pressure and so allele frequencies change. Eventually the two populations can become so different they cannot interbreed to produce fertile and viable offspring.

Question 39

Example of the founder effect

Answer 39

Galapagos island finches

Question 40

Bottleneck effect

Answer 40

A severe reduction in genetic diversity due to a catastrophe that may change allele frequency.

Question 41

Extinction

Answer 41

no members of a particular species exist.

Question 42

Effect of bottleneck effect and founder effect on genetic diversity

Answer 42

Reduces genetic diversity through the removal of alleles due to random events (e.g. natural disaster) Reduces genetic diversity through the establishment of a new population with a small unrepresentative sample of the original population

Question 43

Selective breeding/artificial selection

Answer 43

humans choosing which organisms will breed, and pass on their alleles, based on desired traits.

Question 44

Selective breeding scaffold

Answer 44

Select organisms based on desired traits/based on phenotype. Breed selected male and female individuals together Repeat over many generations

Question 45

What changes the allele frequency more rapidly: natural selection or selective breeding?

Answer 45

Selective breeding

Question 46

Natural selection vs selective breeding / artificial selection differences

Answer 46

In artificial selection, humans select for or against phenotypes, choosing who will reproduce whereas…… In natural selection a selection pressure/agent removes the unsuited individuals and individuals and the organisms with a phenotype that has a selective advantage are more likely to survive and reproduce. (so survival of the fittest).

Question 47

Natural selection vs selective breeding / artificial selection similarity

Answer 47

Both lead to evolution and a change in allele frequency over time.

Question 48

Impact of selective breeding on genetic diversity

Answer 48

Decreases genetic diversity