1D Genes And Protiens In Health And Disease

Question 1

What are proteins held together with?

Answer 1

They are held in a 3D shape by peptide bonds, hydrogen bonds and interactions between individual amino acids.

Question 2

What shape do most proteins fold into?

Answer 2

Polypeptide chains fold to form the 3D shape of the protein.

Question 3

What is a mutation?

Answer 3

An alteration to the original DNA sequence.

Question 4

What happens if a mutation occurs?

Answer 4

A faulty protein or no protein is made.

Question 5

Are mutations common?

Answer 5

No. They are random, rare and spontaneous.

Question 6

Name three mutagenic agents.

Answer 6

Mustard gas, UV-Rays, UV Light and Gamma Rays.

Question 7

Mutations occurring because of mutagens are said to be what?

Answer 7

An induced mutation.

Question 8

How do single gene mutations arise?

Answer 8

By substitution, insertion or deletion.

Question 9

What is a substitution gene mutation?

Answer 9

A nucleotide is substituted for another one.

Question 10

What is the effect of a substitution gene mutation?

Answer 10

The amino acid coded for could be a missence mutation or a nonsense mutation. An incorrect protein will be made.

Question 11

What is a missense mutation?

Answer 11

The mutation still codes for an amino acid but not the correct amino acid.

Question 12

What is a nonsense mutation?

Answer 12

This mutation causes the codon to now code for a stop codon. This results in a shortened protein/faulty protein being made.

Question 13

What is an insertion gene mutation?

Answer 13

A nucleotide is inserted into the DNA sequence.

Question 14

What is the effect of an insertion gene mutation?

Answer 14

Frameshift mutation. All the codons after the point of mutation are altered and a faulty protein is made.

Question 15

What is a deletion a gene mutation?

Answer 15

A nucleotide is deleted from DNA sequence.

Question 16

What is the effect of a deletion gene mutation?

Answer 16

Frameshift mutation. All the codons after point of mutation are altered and a faulty protein is made.

Question 17

What is a splice-site mutation?

Answer 17

Splicing is controlled by specific nucleotide sequences at splice sites on those parts of the introns that or next to the exons. If a mutation occurs at one of these splice-sites, codon for an intron-exon splice may be affected send an intron may to be retained in error.

Question 18

What is the effect of a splice-site mutation?

Answer 18

Faulty protein is made.

Question 19

What is a nucleotide sequence repeat expansion?

Answer 19

The insertion of a large number of copies of a nucleotide sequence (e.g. Several hundred repeats)

Question 20

What is the effect of a nucleotide repeat expansion?

Answer 20

A faulty protein is made.

Question 21

Diseases which are caused by a substitution mutation.

Answer 21

Phenylketonuria (PKU). It is an inborn error of metabolism.

Question 22

What metabolic conversion does not take place in a person who has phenylketonuria (PKU)?

Answer 22

They cannot convert the amino acid Phenylalanine to Tyrosine.

Question 23

What is the effect of a buildup of phenylalanine?

Answer 23

It is converted into toxins. The poisonous metabolites inhibit one or more of the enzymes that control the metabolic pathways of the brain. The brain fails to develop properly causing severe mental impairment.

Question 24

What can be done to detect phenylketonuria (PKU)?

Answer 24

Post-natal screening.

Question 25

Babies are diagnosed with phenylketonuria, what are they prescribed?

Answer 25

A diet low in phenylalanine. They are not albinos as they still have tyrosine in their diets.

Question 26

Name three types of chromosomal mutations.

Answer 26

Deletion, duplication and translocation.

Question 27

Describe a deletion mutation.

Answer 27

I deletion mutation occurs when a chromosome breaks in two places and the segment becomes detached. The two ends join together giving a shorter chromosome.

Question 28

Describe duplication mutation.

Answer 28

A segment of genes becomes attached to one end of the first chromosome or becomes inserted somewhere along its length.

Question 29

Describe a translocation mutation.

Answer 29

A section of one chromosome breaking off and becoming attached to another chromosome that is not its (homologous) matching partner.

Question 30

What is the effect of any substantial chromosomal mutation?

Answer 30

The effect is often lethal (death).