Inheritance

Question 1

Di-hybrid cross

Answer 1

Inheritance of two different characteristics controlled by two different genes

Question 2

Co-dominance

Answer 2

Both alleles in a heterozygous organisms are expressed in the phenotype

Question 3

Define an allele

Answer 3

One of the different forms of a gene

Question 4

Dominant

Answer 4

The allele of a heterozygous organism that is expressed in the phenotype
Only one copy needed

Question 5

Recessive

Answer 5

In a heterozygous state the allele is NOT expressed, only expressed if homozygous recessive.

Question 6

Define a gene

Answer 6

A base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA molecule

Question 7

Define phenotype

Answer 7

The expression of an organism’s genetic constitution and its interaction with the environment.

Question 8

Autosomal linkage

Answer 8

Two Genes carried on the same autosome- non-sex chromosome

Question 9

What is the effect of genes being closer together on the same autosome?

Answer 9

The closer together the more closely linked they are
Less likely to be split up in meiosis, crossing over
Therefore higher proportion of gametes and offspring will have parents geno/phenotypes

Question 10

Epistasis

Answer 10

The interaction of non-linked genes when one affects/ masks the expression of another

Question 11

What is a Chi-squared test?

Answer 11

Statistical test used to find out wether there is a significant difference between observed and expected results.

Or difference is due to chance- sampling effects

Used on categoric data, frequencies

Null hypothesis, alternative hypothesis
Is Chi value > critical value at p=0.05
Then Reject Ho

Question 12

Sex linkage

Answer 12

Genes which have a locus on a sex chromosome

Most often x linked

Question 13

Males

Answer 13

XY

So recessive X-linked genes will expressed even if only one copy present

Question 14

Females

Answer 14

XX

So recessive X-linked genes will only be expressed if the organism is homozygous recessive

Question 15

Multiple alleles

Answer 15

More than two alleles (versions) of the same gene

Question 16

Why are observed results not similar to predicted?

Answer 16

Small sample size- high influence of chance
Fertilisation of gametes is a random process
Lethal genotypes
linked genes

Question 17

Why is a chi-squared test used?

Answer 17

To determine the probability; [Accept: Likelihood]

Of the results being due to chance; [Accept: Coincidence]

Question 18

Effect of autosomal linkage

Answer 18

They will stay together during independent segregation
Assume no crossing over
All linked genes will stay together during meiosis
So linked genes are passed onto gametes and the offspring together
Higher proportion of offspring will have parents
Geno/phenotype

Question 19

Evidence of autosomal linkage

Answer 19

when a di-hydrid cross results in production of offspring/ gametes which are predominately 2 genotypes

identify which alleles are linked- which are the 2 most common gametes?

production of most gametes- therefore most offspring produced like to have the geno/pheno types of parents- inherited together

Question 20

What dose the Hardy-Weinberg Principle predict?

Answer 20

predicts allele frequencies will not change in a population from one generation to the next

Question 21

Conditions for the Hardy-Weinberg Principle

Answer 21

mating is random
no death 
no immigration 
large population
no natural selection

Question 22

Hardy equation to predict allele frequencies

Answer 22

p+q=1

where p is freq of domination, q is freq of recessive

Question 23

Hardy equation to predict geno and phone type frequencies

Answer 23

p^2 +2pq+ q^2=1

p^2 homozygous dominat

q^2 homozygous ressecive

2pq hetrozygous