Genetics

Question 1

Who was responsible for the laws governing inheritance traits?

Answer 1

Gregor Mandel

Question 2

What are Chromosomes?

Answer 2

Coiled up DNA. We have 23 pairs. One from Mum & one from Dad

Question 3

What is a Gene?

Answer 3

A segment of a chromosome which contains the code of a specific trait. ie eye colour

Question 4

What is an Allele?

Answer 4

Part of the Gene, contained within the Chromosome, that shows the characteristics of the particular trait. ie brown eye colour

Question 5

What does Dominant mean?

Answer 5

Whenever this allele is present its characteristics will always be displayed within the trait.

Question 6

What does Recessive mean?

Answer 6

The characteristic of this trait, unless paired with another recessive allele, will not be expressed.

Question 7

What does Homozygous mean?

Answer 7

Two alleles that are the same i.e. RR (both dominant)

Question 8

What does Heterozygous mean?

Answer 8

Two alleles that are different i.e. Rr (one dominant and one recessive)

Question 9

What is genotype?

Answer 9

The outcome or parents in letter i.e. RR, Rr or rr

Question 10

What is Phenotype?

Answer 10

The displayed characteristics in words i.e Brown Eyes, Blue Eyes

Question 11

What is Monohybrid crosses?

Answer 11

Crosses involving a single trait

Question 12

What are Dihybrid Crosses?

Answer 12

Crosses involving two traits

Question 13

What are the 3 different types of Dominance?

Answer 13

Complete Dominance Incomplete Dominance Co-Dominant

Question 14

What is complete Dominance?

Answer 14

The dominant allele completely masks the effect of the recessive allele in heterozygous pairs.

Question 15

What is Co-Dominance?

Answer 15

Co-dominance occurs when the contributions of both alleles are visible in the phenotype. For example Red and white flower makes a stripy red and white flower.

Question 16

What is Incomplete dominance?

Answer 16

Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes. For example pink flowers.

Question 17

What is an Autosome?

Answer 17

A non sex linked Chromosome. Therefore chromosomes 1 - 22

Question 18

What are Autosomal Disorders?

Answer 18

Disorders that are located on Chromosome 1 - 22

Question 19

What is Autosomal Recessive Disorders?

Answer 19

A disorder that must receive a disorder allele from mum and one from dad to be present. Don’t forget mum & Dad can be carries.

Question 20

What is Autosomal Dominant Disorders?

Answer 20

Only needs to receive the disorder allele from one parent to present with the condition.

Question 21

What is Sex-Linked Inheritance?

Answer 21

Traits that are carried on Chromosome 23.

Question 22

Why are most sex linked traits carried on the X chromosome?

Answer 22

Because the Y chromosome is smaller.

Question 23

What are the quick ways to tell if the condition is recessive of dominant?

Answer 23

The odds of children having the disease i.e 1 in 4 recessive or 1 in 2 dominant. If the disease is present in mum or dad = dominant. If both mum and dad are carriers disease is recessive.

Question 24

When doing blood group squares, how is the genotypes written? What sort of dominance is blood group?

Answer 24

I^A I^A or I^A i = A group

I^B I^B or i = B Group

I^A I^B = AB Group

ii = O Group

Co-Dominant

Question 25

With Dihybrid Crosses what is the ratio for 2nd Generation crosses normally?

Answer 25

9:3:3:1

Question 26

When drawning a Dihybrid punnit square what do you NEED to remember to put in RATHER than parents?

Answer 26

To put in the possibilities from the parents rather than the parents.

i.e RrYy = Possible genotypes RY, Ry, rY, ry - Dont put in RrYy

Question 27

Is huntingtons disease sex linked or not and is is Dominant or recessive?

Answer 27

It is autosomal. You can inherit Huntington’s disorder if one or both of your parents carry the faulty allele, because it is a dominant allele.

Question 28

IS Cystic Fibrosis caused by a recessive or Dominant Trait?

Answer 28

Cystic fibrosis (CF) is caused by a recessive allele and is not sex linked and can by passed by mother or father.

Question 29

Name some Sex linked diseases?

Answer 29

Haemophillia

Colour blindness

Bauldness