Genetics

Question 0

How does variation occur?

Answer 0

Independent segregation

Crossing over

Question 1

What happens during meiosis?

Answer 1

4 daughter nuclei produced, each with half the number of chromosome as parent cell

Question 2

Who discovered genetic theory?

Answer 2

Gregor Mendel 1822-1884
Studied pea plants.
Discovered laws of inheritance

Question 3

How is the human genome made up?

Answer 3

46 chromosomes
22 pairs ( autosomes)
1 pair sex chromosomes XY- male XX female

Question 4

What is a gene?

Answer 4

Section of DNA that codes for a particular trait or characteristic

Question 5

What is an allele?

Answer 5

A different form of a gene that codes for a different version of a characteristic

Question 6

What does genotype mean?

Answer 6

A description of the pair of alleles present for a characteristic eg. RR

Question 7

What does phenotype mean?

Answer 7

Physical expression of the alleles eg. Brown hair

Question 8

What does homozygous mean?

Answer 8

Pair of alleles that produce a characteristic that are the same eg.HH

Question 9

What does heterozygous mean?

Answer 9

Pair of alleles that produce a characteristic that are different eg. Hh

Question 10

What does dominant mean?

Answer 10

An allele that will always be expressed even when there is only one of these alleles present (represented by capital letter)

Question 11

What does recessive mean?

Answer 11

An allele that will only be expressed when both alleles are of this type
(Represented by lower case letter)

Question 12

What are chromosomes?

Answer 12

Storage units of genes

Question 13

What is the locus on the chromosome?

Answer 13

Position on a chromosome where a particular gene is found

Question 14

What is a mono hybrid cross?

Answer 14

Cross involving a single trait eg. Flower colour

Question 15

How can we calculate probability of a mono hybrid cross

Answer 15

Using a Punnett square

Question 16

What is Mendels law of segregation?

Answer 16

If you have 1 allele for brown eyes(B) and one for blue eyes(b) somatic cells will have Bb and each gamete will carry 1 of B or b chosen randomly.

Question 17

What is autosomal inheritance?

Answer 17

Inherit a recessive gene from each parent eg. Cystic fibrosis. Both parents carry gene so 1/4 chance child will get it.

Question 18

What are the characteristics of autosomal recessive pedigree?

Answer 18

Skip a generation
Unaffected parents can produce affected child
Affected person must be homozygous
Males/females affected evenly

Question 19

What are the characteristics of autosomal dominant inheritance?

Answer 19

Trait in every generation
Every person with the trait must have a parent with the trait
Males/ females affected evenly
Example Huntington’s disease

Question 20

What does co dominance mean?

Answer 20

Some traits 2 alleles can be co dominant - neither allele exerts dominance over the other in the genetic hybrid.
Share dominance
Eg, blood groups and Roan cows

Question 21

What is sex linked inheritance ?

Answer 21

The gene for a certain characteristic are carried on the sex chromosome.
Eg. Colour blindness, haemophilia, tortoiseshell cats( only in females, must have black and ginger allele.

Question 22

What is incomplete dominance?

Answer 22

Both alleles blend their effects,eg snap dragon plants.
RW= pink flower
RR= red flower
WW= white flower