3.1 genes

Question 1

define gene

Answer 1

a section of DNA that codes for a particular characteristic (via the production of a specific protein)

Question 2

define locus

Answer 2

the specific location of a gene on a particular chromosome

Question 3

define allele

Answer 3

an alternate form of a gene

Question 4

define genome

Answer 4

the totality of genes in a cell, organism or organelle

Question 5

list 3 potential applications of the completed human genome project

Answer 5

-screening for known genetic conditions
-discovering new drug treatments and medications
-establishing ancestral lineages

Question 6

identify 3 types of mutagens

Answer 6

physical ex: radiation
chemical ex: tobacco
biological ex: certain viruses

Question 7

distinguish between somatic and germline mutations

Answer 7

somatic mutations affect body cells and cannot be inherited by offspring (mutation restricted to affected tissue)

germline mutations affect sex cells and will be passed on to offspring (will affect all cells in offspring)

Question 8

explain the consequences of a base substitution mutation in the development of sickle cell anemia

Answer 8

-mutations change GAG to GUG on the mRna transcript
(this is a change of CTC to CAC on the antisense strand)

-mutation affects the 6th codon of the haemoglobin beta chain gene

-the mutation change the amino acid from Glutamic acid to Valine (Glu to Val)

• this causes the haemoglobin to form insoluble strands (and clump together)

-the red blood cells adopt a characteristic sickle cell shape

-the sickle cells break down, leading to anaemia and reduced oxygen transport

-the sickle cell mutation demonstrates co-dominance

-the trait shows heterozygous advantage (resistance to malaria)