3.1

Question 1

Alleles definition

Answer 1

are alternative forms of a gene that code for different variations of a specific trait

Question 2

What is a gene mutation?

Answer 2

is a change in the structure of a gene, caused by a change in nucleotide sequence of a section of DNA coding for a specific trait

Question 3

how can gene mutations be beneficial?

Answer 3

change the gene sequence(missense mutations) to create new variations of a trait

Question 4

how can gene mutations be detrimental?

Answer 4

truncate the gene sequence (nonsense mutations) to abrogate normal function of a trait

Question 5

how can gene mutations be neutral?

Answer 5

have no effect on the functioning of the specific feature (silent mutations)

Question 6

What is the max amount of alleles you can have for a gene?

Answer 6

2

Question 7

What characteristic of the sickle cells cause problems?

Answer 7

the shape

-the haemoglobin fibres are stretched out inside

Question 8

What are sickling events triggered by?

Answer 8

low oxygen levels, dehydration, infection & sudden exposure to sudden temp changes

Question 9

Name the amino acid that is normally replaced in the beta subunit of hemoglobin in a sickle cell anemia patient.

Answer 9

Valine replaces Glutamic acid as the 6th amino acid in the haemoglobin polypeptide

Question 10

What is a gene?

Answer 10

a heritable factor of DNA that consists of a length of DNA & influences a specific trait

Question 11

What is a locus?

Answer 11

the place on the chromosome where the gene is located

Question 12

What does it mean if an organism is a homozygote?

Answer 12

if the organism has 2 alleles for a specific gene which are the same

Question 13

What are single nucleotide polymorphisms caused by?

Answer 13

caused by point mutations that give rise to different alleles containing alternative bases at a given nucleotide position within a locus

Question 14

What is the genome?

Answer 14

all the genetic information of an organism

Question 15

Missense mutations

Answer 15

beneficial mutations, change gene sequence to create new variations of a trait

Question 16

Nonsense mutations

Answer 16

detrimental mutations truncate gene sequence to abrogate normal functions of a trait

Question 17

Silent mutations

Answer 17

neutral mutations that have no affect on the functioning of a specific feature

Question 18

Sickle Cell anaemia

Answer 18

• occurs in HBB gene of chromosome 11
• diseased allele arose frombase substitutionmutation

Change to the 6th codon for the beta chain of haemoglobin

• DNA: DNA sequence changes from GAG to GTG on the non-transcribed strand
• mRNA:mRNA sequence changes from GAG to GUG at the 6th codon position
• Polypeptide: 6th amino acid changed from glutamic acid to valine (Glu to Val)

This change alters the structure of haemoglobin, causing it to forminsoluble fibrous strands

• cannot carry oxygen as effectively, causing the individual to feel constantly tired
• formation of strands changes the shape of the red blood cell to asickle shape
• sickle cells may form clots within the capillaries, blocking blood supply to vital organs and causing a myriad of health issues
• sickle cells destroyed more rapidly than normal cell —> low red blood cell count (anaemia)