Lecture 3: A tour of prokaryotic cells

Question 1

What is commensal bacteria?

Answer 1

This is required for good health in the gut as humans cannot produce the vitamin biotin, but bacteria in our gastrointestinal tract produce it for us.

Question 2

Exterior of the prokaryotic cell?

Answer 2

It is rigid and multilayered, the peptidoglycan of the bacterial cell wall defines the cell shape. This layer is a rigid matrix of glycan (sugar) chains crosslinked by short peptides (strings of amino acids).

Question 3

Capsule?

Answer 3

It is a prokaryotic defence mechanism and is the external layer of polysaccharides on outside of cell. This prevents desiccation of the prokaryote and assists in maintaining immunity.

Question 4

Ribosomes in Prokaryotic cells?

Answer 4

Ribosomes perform translation and read mRNA and encoded protein and read mRNA and produce encoded protein.

Question 5

Respiration and photosynthesis in prokaryotic cells?

Answer 5

Prokaryotes do not have mitochondria or chloroplasts. They use their cell membrane as the site of respiration and photosynthesis.

Question 6

What is structure in prokaryotes?

Answer 6

Simple internal structure, including a single naked DNA chromosome, a cell wall, capsule, pili, flagella and ribosomes.