2.6 prokaryotic + eukaryotic cells

Question 1

DNA in prokaryotic cells

Answer 1

Generally one molecule of DNA, a chromosome, which is super coiled to make it more compact. The genes on the chromosome are often grouped into persons, meaning a number of genes are switched on or off at the same time.

Question 2

Ribosomes in prokaryotic cells

Answer 2

Smaller than in eukaryotic cells. Relative size is determined by the rate at which they settle in solution. Larger eukaryotic = 80S, smaller prokaryotic = 70S.

Question 3

Cell walls in prokaryotic cells

Answer 3

Made of peptidoglycan, also known as murein. A complex polymer formed from amino acids and sugars.

Question 4

Flagella in prokaryotic cells

Answer 4

Thinner and does not have 9+2 arrangement. The energy to rotate the filament that forms the flagellum is supplied from chemiosmosis (not from ATP).

Question 5

Structure of flagella

Answer 5

The flagellum is attached to the cell membrane of a bacterium by a basal body and rotated by a molecular motor. The basal body attaches the filament comprising the flagellum to the cell-surface membrane of a bacterium.

Question 6

How do flagella work?

Answer 6

A molecular motor causes the hook to rotate giving the filament a whip like movement, which propels the cell.