Genetic Variation - The Basic Definitions!

Question 1

What is a gene?

Answer 1

A general area of DNA that codes for a particular characteristic

Question 2

What is an allele?

Answer 2

The alternate forms of a gene. Basically the different base sequences that a particular gene could have or has. e.g. eye colour (the gene) has an allele (b) that codes for green eyes and another allele (B) that codes for brown eyes.

Question 3

What is a mutation?

Answer 3

The permanent change in the base sequence of a gene. e.g. if a sequence went from ATCTCA to AGCTCA

Question 4

What is a gene pool?

Answer 4

Complete set of unique alleles within a breeding population at any one time

Question 5

What is an allele frequency?

Answer 5

It is the number of a particular allele within a population.

Question 6

What is genetic variation?

Answer 6

When there are different allele frequencies within a population

i.e. different genotypes (alleles) and therefore phenotypes

Question 7

What is the effect of a mutation on variation?

Answer 7

It is the only mechanism that can produce a completely new allele (i.e. one that did not exist before) into a population

Question 8

Are mutations good or bad?

Answer 8

Both. Mutated alleles can have positive, negative or neutral phenotypes.

Question 9

Are all mutations passed onto the next generation? Why or why not?

Answer 9

No; for two reasons:

• if it is a somatic cell it will not be passed on
• the randomness of fertilization means the mutated allele might not be passed on.

Question 10

What is a somatic cell?

Answer 10

A somatic cell is a non-sex cell. An example of a somatic cell is a brain cell. Because it is not used in fertilization, mutations in this cell are not passed onto the next generation.

Question 11

What is a gametic cell?

Answer 11

A gametic cell is a sex cell. An example of this is a sperm or egg cell. Because it is used in fertilization, mutations in the cell are passed onto the next generation.