Chapter 2.6 - Prokaryotic & Eukaryotic Cells

Question 1

When did Prokaryotic cells appear

Answer 1

Among earliest forms of life on Earth

Appeared 3.5 billion years ago

Question 2

Conditions of earth that prokaryotic cells adapted to

Answer 2

Surface of earth was very hostile environment

Extremes of salinity, pH and temperature

Question 3

Name of early prokaryotic cells

Answer 3

Extremophiles

Question 4

Domain of extremophiles

Answer 4

Archaea

Question 5

Where are extremophiles found

Answer 5

Soil and human digestive system

Question 6

DNA

Answer 6

Packaged differently to eukaryotic cells
One molecule of DNA, chromosome, supercoiled so very compact
Genes on chromosome are grouped into operons (number of genes turned on and off at one time)

Question 7

Ribosomes

Answer 7

Smaller than eukaryotic
Relative size determined by rate at which they settle, form a sediment, in solution
70s (whilst eukaryotic cells at 80s form more complex proteins)

Question 8

Cell wall

Answer 8

Cell wall made from peptidoglycan aka murein

Complex polymer formed from amino acids and sugars

Question 9

Flagella

Answer 9

Thinner than eukaryotes
Does not have 9+2 arrangement
Energy to rotate supplies from chemiosmosis
Attached to cell membrane of bacterium by basal body
Rotated by molecular motor - causes hook to rotate giving filament whip like movement that propels cell

Question 10

Comparison with eukaryotic

Answer 10

• older
• DNA in eukaryotic packed in complex chromatin
• no membrane bound organelles