Patterns of Inheritance

Question 1

What did Mendel’s model stated and what is the issue with those statements

Answer 1

Stated that:

• traits are controlled by a single gene
• there is only 2 alleles for a given gene
• there is clear dominant-recessive relationship between alleles

Problem: most genes don’t fit these criteria

Question 2

What is polygenic inheritance

Answer 2

When many traits are controlled by multiple genes and their alleles; a characteristic is determined by alleles of 2 or more genes)

Question 3

What role can environmental factors play in gene interaction

Answer 3

The expression of some genes can be influenced by the environment

Question 4

What characterizes traits in polygenic inheritance ( give examples) ?

Answer 4

They are traits that show continuous variation and that are referred to as quantitative traits

Example: skin colour and height

Question 5

What is pleiotropy ?

Answer 5

When a gene affects more then one trait

Question 6

How are called alleles that have more then one affect on phenotype and explain their relation to dominance

Answer 6

Pleiotropic alleles
- a pleiotropic allele can be dominant with respect to a certain phenotype and recessive to another

Question 7

What is Epistasis ?

Answer 7

When a gene at a certain locus alters the phenotype of a different gene at a second locus

Question 8

What is degree of dominance ? ( Give the 2 kinds)

Answer 8

Situations where neither alleles a completely dominant

• incomplete dominance
• Co-dominance

Question 9

What is incomplete dominance ?

Answer 9

When the dominant allele does not fully mask the recessive one; creating sort of an intermidiate phenotype

Question 10

What is co-dominance

Answer 10

When two alleles are equally expressed in the phenotype and in distinguishable ways.

Example: co-dominance of blood type A and B

Question 11

What are antigens

Answer 11

Substances that stimulates the body to make antibodies

Examples: ABO are antigens contained in red blood cells.

Question 12

What are antibodies

Answer 12

Substances made up by the body after the stimulation of antigens; they are the substances that react with antigens

Question 13

What is multiple allele hierarchal dominance ?

Answer 13

A is dominant to B that is dominant to C

Question 14

What is Circular Dominance

Answer 14

A is dominant to B that is dominant to C that is dominant to A