Genetics And Inheritance- Paper 2

Question 1

gene pool definition

Answer 1

All the alleles within an interbreeding population

Question 2

Phenotype

Answer 2

Expression of its genetic constitution and its interaction within the environment

Question 3

allele frequency

Answer 3

The number of times an allele occurs in a gene pool

Question 4

Multiple alleles

Answer 4

More than 2 alleles for the same gene- produces a hierarchy of dominance

Question 5

homozygous

Answer 5

Two copies of the same gene that are the same allele

Question 6

Heterozygous

Answer 6

Two copies of the gene are different alleles

Question 7

Dominant allele

Answer 7

Will always be expressed in the phenotype

Question 8

Recessive allele

Answer 8

Only expressed in the phenotype if the genotype is homozygous

Question 9

Codominant

Answer 9

Equally expressed within a phenotype

Question 10

Mono hybrid ratio

Answer 10

3:1

Question 11

Codominance ratio

Answer 11

1:2:1

Question 12

Dihybrid ratio

Answer 12

9:3:3:1

Question 13

Epsiatus ratio

Answer 13

Adds up to 16 but follows no specific ratio

Question 14

Autosomal linkage ratio

Answer 14

If no crossing over: 3:1
9:3:3:1

Question 15

Hardy Weinberg principle

Answer 15

The alleles frequency will remain constant from 1 generation to the next
Measures the allelic frequency
P + q= 1.0

P2 + 2Pq + q2= 1.0

Question 16

What does HW predict and what are the conditions

Answer 16

The allelic frequency from one generation to the next will remind constant
No migration, mating is random, no gene mutations, no selection for particular gene
Should be a large population, should be random

Question 17

Mono hybrid inheritance

Answer 17

Inheritance of a single gene which determines a single characteristic
Gametes are indicated by drawing a circle around allele
Fusion of gametes is random

Question 18

Dominant characteristic rules for pedigree charts

Answer 18

Affected offspring must have at least one affected parent
Unaffected parents only have one unaffected offspring
If both parents are affected and have unaffected offspring , both parents must be heterozygous
Unaffected parents can face affected offspring if heterozygous.

Question 19

sex linked

Answer 19

Controlled by a gene located on one of the sex chromosomes
A female needs two copies of a recessive allele for it to appear in the phenotype but a male only needs 1

Question 20

Sex linked rules

Answer 20

If a daughter is affected her father is not, it is recessive and not sex linked
If a son is affected and mum is not and it is dominant, then not sex linked

Question 21

Dihybrid inheritance

Answer 21

Two genes either can be on different chromosomes or linked on the same chromosome

Question 22

Autosomal linkage

Answer 22

Non-sex linked genes - not directly involved in determining the sex, genes are on same chromosome

Question 23

What increases the chance of independent segregation occurring?

Answer 23

The further the genes are apart- produces different variations on the chromosome.

Question 24

What is the ratio for autosomal linkage if no crossing over occurs

Answer 24

3:1
All linked genes remain together and end up on the same gamete.

Question 25

What is a linkage group

Answer 25

Set of genes on the same chromosome which tend to be inherited together

Question 26

What is epistatis

Answer 26

Interaction between two genes where one allele influences the expression of another. Can also occur in the expression of genes that control metabolic pathways