Protetin Synthesis And Mechanisms Of Action Of Antibiotics

Question 1

What are the two processes involved in gene expression and what happens during both?

Answer 1

Transcription:
-where DNA is changed to RNA
Translation:
-where RNA is changed to a protein

Question 2

How is RNA different to DNA?

Answer 2

• single-stranded instead of double-stranded
• pentode sugar= ribose instead of deoxyribose
• uracil base instead of thymine

Question 3

What are the different types of RNA?

Answer 3

Ribosomal:
-form basic structure of RNA
-catalyse protein synthesis
Transfer:
-adapters between mRNA and amino acids
Messenger:
-code for proteins

Question 4

What are the steps in protein synthesis?

Answer 4

1. Charging tRNAs with amino acids
2. Initiation of polypeptide synthesis
3. Elongation of the chain via addition of amino acids
4. Termination of polypeptide synthesis

Question 5

What does streptomycin do?

Answer 5

Causes inhibition of initiation and misreading of genetic code

Question 6

What do tetracyclines do?

Answer 6

Causes inhibition of aminoacyl tRNA binding to ribosome

Question 7

What does chloramphenicol do?

Answer 7

Inhibition of peptidyl transferase activity

Question 8

What does erythromycin do?

Answer 8

Inhibits translocation

Question 9

Which two antibiotics target the small ribosomal subunit?

Answer 9

Streptomycin and tetracyclines

Question 10

Which two antibiotics target the large ribosomal subunit?

Answer 10

Chloramphenicol and erythromycin

Question 11

Which antibiotic targets multiple sites in bacteria?

Answer 11

Neomycin

Question 12

What are the limitations of antibiotics acting on protein synthesis?

Answer 12

• can’t be used in viruses as they use the host’s protein synthesis machinery
• resistance via alteration of target sites and destruction of antibiotic
• can also inhibit protein synthesis in mammalian mitochondria due to similar ribosomes as in bacteria