Genetics Lecture 5: Inheritance and Genetic Disease.

Question 1

Genotype

Answer 1

The genetic constitution (make up) of an organism.

i.e. the sum total of all it’s genetic info (e.g. DNA, RNA, Proteins)

Question 2

Phenotype

Answer 2

The observable characteristics of an organism.

Question 3

Haploid

Answer 3

An organism or cell having only one complete set of chromosomes or genome.

(Gametes are usually in this state)

Question 4

Diploid

Answer 4

An organism or cell having 2 complete sets of chromosomes/genomes.

(Somatic cells are usually in this state.)

Question 5

Dominance

Answer 5

One member of an allelic pair is manifested to the exclusion of another.

Question 6

Recessive

Answer 6

One member of an allelic pair lacking the ability to manifest itself when the other dominant is present.

Question 7

Autosomal

Answer 7

Describes a gene or trait which is not carried on the X or Y Chromosome.

Question 8

Sex-Linked

Answer 8

Describes a gene or trait that is carried on the X or Y Chromosome.

Question 9

How do genes work?

Answer 9

They operate in pairs (paternal and maternal)

Question 10

What are Allelles?

Answer 10

Alleles are different form of the same gene.

Question 11

What determines your Phenotype?

Answer 11

Your Phenotype is determined by the interplay of the allelic products.

Question 12

What is a Family Pedigree?

Answer 12

It’s one of those sill Mind-Map things that use varying symbols to represent Male or Female, Affected, Carrier of Clean and X linked or Deceased.

They can be used to trace a mutated gene from children to parents. The results are shown on Family Pedigrees.

Question 13

Dominant Autosomal

Answer 13

Only need 1 bad gene, to be affected

Question 14

Recessive Autosomal

Answer 14

Need two bad genes, to be affected

Question 15

Recessive X Linked

Answer 15

Boy can get it as they only have one X Chromosome. Girls can carry it, however need 2 bad copies of the genes to be affected.

Question 16

Dominant X Linked

Answer 16

Boy and Girls are equally likely to be affected.

Question 17

What sort of Genetic Disease if Cystic Fibrosis?

Answer 17

Autosomal Recessive.

Question 18

What goes wrong in the Karyotype for Cystic Fibrosis to occur?

Answer 18

Mutation in the CFTR gene on Chromosome 7.

Question 19

Explain what happens in Cystic Fibrosis?

Answer 19

Defective secretions by epithelial cells, salt gathers on surface of lung, leads to bacteria growing there, creating problems with the lungs, digestive system and reproducing.

1 in 2000 live births - causes death at 20 - 40.

Question 20

What sort of Genetic Disease if Marfan’s Syndrome?

Answer 20

Autosomal Dominant

Question 21

What goes wrong in the Karyotype for Marfan’s Syndrome to occur?

Answer 21

Mutation in fibrillin gene on chromosome 15.

Question 22

What if the outcome of Marfan’s Syndrome?

Answer 22

Connective Tissue Abnormalities. It also leads to Spinal Deformity, Scoliosis, Arachnodactyly.

1 in 10 000 live births - Life Expectancy Reduced by 30%.

Question 23

What sort of Genetic Disease if Duchenne Muscular Dystrophy?

Answer 23

X linked Recessive.

Question 24

What goes wrong in the Karyotype for Duchenne Muscular Dystrophy to occur?

Answer 24

Mutations in the Dystrophin gene Chromosome X.

Question 25

Explain what happens in Duchenne Muscular Dystrophy?

Answer 25

Sever progressive muscle weakness before age 6, mental impairment and cardiac disease.

Very strong darwinian selection as the boys who have the dieases pass away before they’re given the opportunity to reproduce.

Question 26

What is the prognosis of Duchenne Muscular Dystrophy?

Answer 26

1 in 3500 boys - They’re Chair bound by 12 - Death at 20.