Inheritance

Question 1

What is a gene?

Answer 1

A sequence of bases that code for a protein

Question 2

What is an allele?

Answer 2

Variation/ form of a gene

Question 3

What is the genome?

Answer 3

All the genes in an organism

Question 4

What is the proteome?

Answer 4

All the expressed proteins in an organism

Question 5

What is the phenotype?

Answer 5

Observable characteristics

Question 6

What is the phenotype due to?

Answer 6

Combination of genetics and environmental factors

Question 7

What is a dominant allele?

Answer 7

Always expressed in the phenotype

Question 8

What is a recessive allele?

Answer 8

Need to have both alleles to express the trait in the phenotype

Question 9

What is heterozygous?

Answer 9

2 different alleles

Question 10

What is homozygous?

Answer 10

2 same alleles

Question 11

How do you label a heterozygous cross?

Answer 11

One side says mother genotype/gametes/alleles
One side says father genotype, etc.
The results have offspring genotypes written next to it

Question 12

What is the cause of variation/ why are the probabilities not the same as the actual visible offspring/ why is the observed different from the expected?

Answer 12

Due to independent assortment and random fertilisation

Question 13

What is a test cross?

Answer 13

Taking an unknown possibly heterozygous parent and mating with a homozygous recessive parent

Question 14

What is codominance?

Answer 14

When both alleles are expressed in the phenotype
(red + white flowers = pink offspring)

Question 15

What do monohybrid genes usually code for?

Answer 15

An enzyme
(recessive may be producing a dysfunctional enzyme)

Question 16

What do codominance genes usually code for?

Answer 16

A protein
(e.g. pigment)

Question 17

What are there usually for most genes?

Answer 17

More than 2 alleles

Question 18

What is there usually for a trait?

Answer 18

Multiple genes

Question 19

What are the 3 alleles for blood types?

Answer 19

Io (not expressing an antigen)
IA (A antigen on RBC’s)
IB (B antigen on RBC’s)

Question 20

What is a sex-linked disease?

Answer 20

Diseases where the mutation is only found on the x chromosome

Question 21

Who are sex linked diseases more prevalent in and why?

Answer 21

Male humans as they only need to inherit one mutated copy of an allele to have the condition

Question 22

How do you disprove a sex-linked dominant disease from a diagram?

Answer 22

Evidence against = girl without condition but dad with (she must get affected X from her dad)

Question 23

What is the ratio for a double heterozygous cross?

Answer 23

9:3:3:1

Question 24

What is the ratio for a double heterozygous x double homozygous cross?

Answer 24

1:1:1:1

Question 25

What is the ratio for a double homo for one, hetero for the other?

Answer 25

1:1:1:1

Question 26

What is epistasis?

Answer 26

When one gene controls the expression of another gene (e.g. if you have the gene for widow's peak, you won't be able to tell if you're bald)

Question 27

What is the ratio for a double heterozygous cross, when epistasis plays a role?

Answer 27

9:4:3

Question 28

When does autosomal linkage occur?

Answer 28

If 2 or more genes are located on the same autosome

Question 29

What does autosomal linkage result in and why?

Answer 29

The alleles of the linked genes being inherited together - the 2 genes are less likely to be separated during crossing over

Question 30

When is the likelihood of crossing over increased?

Answer 30

If the genes are further apart

Question 31

What are the gametes known as when there is a crossing over in autosomal linkage?

Answer 31

Recombinant gametes

Question 32

What are the assumptions for hardy Weinberg?

Answer 32

- No migration/outside breeding - Random mating/no natural selection - No new mutations - Large population

Question 33

What is the first hardy Weinberg equation?

Answer 33

p + q = 1 p = frequency of the dominant allele q = frequency of the recessive allele

Question 34

What is the second hardy Weinberg equation?

Answer 34

p^2 + 2pq + q^2 = 1 p^2 = individuals that are homozygous dominant 2pq = individuals that are heterozygous q^2 = individuals that are homozygous recessive (all values are as a fraction of 1)

Question 35

What is a gene pool?

Answer 35

All the alleles in a population