Prokayotic Cells

Question 1

DNA in prokaryotes

Answer 1

• DNA structure is the same as eukaryotes but it is not contained within a nucleus
• usually have one molecule of DNA, a chromosome supercoiled to make it more compact
• the genes on the chromosome are groups into operons, meaning a number of genes are switched on or off at the same time

Question 2

Ribosomes in prokaryotes

Answer 2

• ribosome are smaller than ribosomes in eukaryotes
• eukaryotic ribosome 80S functions to create more complex proteins
• ## prokaryotic ribosome 70S

Question 3

Cell wall in prokaryotes

Answer 3

• they contain a cell wall made of peptidoglycan

- complex polymer formed from amino acids and sugars

Question 4

Flagella in prokaryotes

Answer 4

• a lot thinner than eukaryotes flagella
• does not have 9+2 arrangement
• the energy to rotate the filament that forms flagella comes from chemiosmosis in the molecular motor not from ATP like eukaryotes
• flagellum is attached to bacterium by a basal body via the bacterium’s cell surface membrane

Question 5

Differences between prokaryotes and eukaryotes

Answer 5

P (prokaryotic) E(eukaryotic)

• Nucleus- (P) not present) (E) present)
• DNA- (P) circular) (E) linear)
• DNA organisation- (P) proteins fold and condense DNA) (E) associated with histones)
• Extra Chromosomal DNA- (P) circular plasmids) (E) in chloroplasts and mitochondria)
• Organelles- (P) non membrane bound) (E) both membrane and non membrane)
• cell wall- (P) peptidoglycan) (E) chitin in fungi, cellulose in plants)
• ribosomes- (P) small 70S) (E) large 80S)
• cytoskeleton- (P) present) (E) present more complex
• reproduction- (P) binary fission) (E) asexual and sexual reproduction)
• cell type- (P) unicellular) (E) uni and multicellular
• cell surface membrane (P and E both present