Meiosis & genetics (other genetic concepts) Part 3 - (Week 8)

Question 1

What is pleiotropy?

Answer 1

Most genes have multiple phenotypic effects, a property called pleiotropy where one gene affects multiple phenotypic characters
E.g pleiotropic alleles are responsible for multiple symptoms of certain hereditary diseases

Question 2

What is linkage?

Answer 2

The close association of genes on the same chromosome - the closer the two genes are to each other on the chromosome, the greater the probability that they will be inherited together

Question 3

What is epistasis?

Answer 3

When a gene at one locus alters the phenotypic expression of a gene at a second locus

Question 4

Give an example of epistasis

Answer 4

One gene may determine the pigment of coat colour and the there gene determines whether the pigment will be expressed or not

Question 5

What is polygenetic inheritance?

Answer 5

• An additive effect of two or more genes on a single phenotype
• Quantitative variation usually indicates polygenetic inheritance

Question 6

What are quantitative characteristics?

Answer 6

Also known as ‘continuous’ characteristics, they are those that vary in the population along a continuum e.g skin colour, height, weight

Question 7

What is the difference between continuous and discontinuous variation?

Answer 7

Continuous - characteristic can vary along a spectrum

Discontinuous - individuals fall into a no. of distinct categories (you either have the characteristic or you don’t)

Question 8

What is meant when describing traits as ‘multifactorial’?

Answer 8

Traits that depend on multiple genes combined with environmental influences

Question 9

Why is variation essential in selection?

Answer 9

• It allows natural selection to increase or decrease the frequency of alleles already in the population
• It enables organisms better adapt to their environment & increase likelihood of survival (if mutation is beneficial)