Mendels genetics 2

Question 1

How many chromosomes does a body cell have?

Answer 1

46

Question 2

How many chromosomes does a sex cell have?

Answer 2

23

Question 3

Sex-linked

Answer 3

A trait that is carried on a gene on a sex chromosome

Question 4

What is genetic sex determined by?

Answer 4

The presence or absence of the Sry gene on the Y chromosome

Question 5

Hemizygous

Answer 5

Only having 1 copy of each gene e.g XY

Question 6

Lyonization

Answer 6

One of two female X chromosomes is switched off

Question 7

Dosage compensation

Answer 7

ensuring that the same level of hormones are expressed in both males and females

Question 8

Barr Body

Answer 8

The inactive X chromosome in females

Question 9

Mosaicism

Answer 9

When a person has 2 or more genetically identical different sets of cells in their body

Question 10

Loss of function

Answer 10

Inactivation mutations (gene product reduced or lost)

Question 11

Gain of function

Answer 11

activating mutations (increasing activity of an allele)

Question 12

Heterosis

Answer 12

also known as Hybrid vigour, individuals that are heterozygous at many gene loci

Question 13

Overdominance

Answer 13

The heterozygote produces a more dominant phenotype than the homozygote that is also superior

Question 14

Polygenic inheritance

Answer 14

Two or more genes effect a single phenotype, e.g skin colour

Question 15

Penetrance

Answer 15

The proportion of individuals in a group with a given genotype that express the corresponding phenotype

Question 16

What is SRY?

Answer 16

the sex-determining region of the Y chromosome contains TDF

Question 17

What is an example of overdominance?

Answer 17

sickle-cell anaemia

Question 18

What is a mutation?

Answer 18

New alleles that can lead to a loss or gain in function

Question 19

What is Genetic Drift?

Answer 19

Change in allele frequency based on random sampling effects

Question 20

What is Gene Flow?

Answer 20

Due to Physical barriers, the population either side begins to differ, can be introduction of alleles on either side through immigration

Question 21

What is an example of lyonization?

Answer 21

Tortoiseshell cats