2.12/2.14 Cystic Fibrosis

Question 1

Describe how insertion during DNA replication cause mutations?

Answer 1

Nucleotide is randomly inserted, this changes the OG amino acid base triplet
This is a frameshift mutation because every triplet base after is affected
This dramatically changes the whole amino acid sequence affecting the polypeptide’s ability to function

Question 2

Describe how deletion during DNA replication cause mutations?

Answer 2

Nucleotide is randomly deleted, this changes the OG amino acid base triplet
This is a frameshift mutation because every triplet base after is affected
This dramatically changes the whole amino acid sequence affecting the polypeptide’s ability to function

Question 3

Describe how substitution during DNA replication cause mutations?

Answer 3

DNA is randomly swapped for another base
Only changes the triplet bases of one amino acid,
No knock-on effect

Question 4

Describe how duplication during DNA replication cause mutations?

Answer 4

A whole gene or a section of gene is duplicated
First copy is intact and unharmed, the second may mutate

Question 5

Describe how inversion during DNA replication cause mutations?

Answer 5

A section of the gene is inverted and backwards
Affects multiple amino acids
Protein is non functional or a different one is created

Question 6

Explain the genetic mutation that causes cystic fibrosis?

Answer 6

It is caused by a recessive allele CFTR that codes for the production of Cl ion channels required for sweat, mucus
Mutation of CFTR causes non function CL ion channels
This reduces the movement of water by osmosis into the secretions

If one parent is homozygous dominant there is a 0% chance of the child having CF

Question 7

Explain how the expression of CFTR mutation impairs the function of the gaseous exchange system

Answer 7

• Thick, sticky mucus cannot be sweeped out of the lungs using cillia
• Microorganisms cannot be readily removed so lung infections are likely
• Mucus blocking airways limiting SA for gas exchange ie breathing difficulties

Question 8

Explain how the expression of CFTR mutation impairs the function of the digestive system

Answer 8

• Tubes of the pancreas are blocked so digestive enzymes can’t enter intestines, this reduces digestion so key nutrients are not available for absorption
• Inestines are lined with thick mucus inhibiting absorptions of nutrients into blood
• Mucus can cause cysts in pancreas which inhibits the production of enzymes for digestion ie less nutrients digested

Question 9

Explain how the expression of CFTR mutation impairs the function of the reproductive system

Answer 9

• Mucus is secreted to prevent infections
• It also processes sperm through the reproductive tract after intercourse
• In men; tubes of the testes are blocked, and sperm cannot reach the penis
• In women; thick cervical mucus prevents sperm reaching the oviduct to fertilise the egg