Dna mutation

Question 1

DNA mutation

Answer 1

-DNA mutation is a change in the base sequence of DNA

Question 2

How do DNA mutations occur

Answer 2

-DNA mutations can occur spontaneously during DNA mutation
-DNA mutations can also be the result of mutagens such as UV, radiation, chemicals etc

Question 3

Substitution

Answer 3

-Substitution is when a base in the base sequence is replaced with another base
This can lead to:
-A different amino acid being produced
-No effect, as genetic code is degenerate, so the codon may still produce the same amino acid
-May introduce a stop codon, which can make the protein too short to be able to carry out it’s function

Question 4

Insertion

Answer 4

-Insertion is when an extra base is added to the DNA sequence
-This causes a frameshift, and all codons downstream may change

Question 5

Deletion

Answer 5

-Deletion is when a base is removed from the base sequence
-This can also cause a frameshift, and all codons downstream may change

Question 6

How does DNA mutation cause problems

Answer 6

1. DNA mutation can change the codon in mRNA during transcription
2. This can change the amino acid in a peptide
3. This can change the primary structure of the protein
4. The primary structure determines the folding and bonding of the protein
5. The final shape of the protein affects its function, therefore the protein may be unable to carry out it’s function

Question 7

How DNA mutations can lead to cystic fibrosis

Answer 7

-Cystic fibrosis is a disorder caused by a mutation to the CFTR gene, which codes for a channel protein
-The normal CFTR gene transports chloride ions out of the cell, and water follows via osmosis
-This keeps mucus thin and easy to move
-In cystic fibrosis, the CFTR protein does not function problem, and chloride ions cannot leave the cell, meaning water remains in the cells as well
-This results in thick and sticky mucus building up on surfaces like the lungs, the digestive system and the respiratory system

Question 8

Effects of cystic fibrosis on various systems

Answer 8

-In the lungs, thick mucus traps pathogens, and cilia cannot move it, leading to frequent respiratory infections and breathing problems
-In the digestive system, the pancreatic tract becomes blocked with sticky mucus, meaning enzymes cannot reach the small intestine
-This results in poor absorption and digestion, potentially causing malnutrition
-In the respiratory system, the sperm duct can be blocked, causing male infertility