2.1.1 K) Similarities and Differences in Structure and Ultrastructure of Prokaryotic and Eukaryotic Cells

Question 1

Prokaryotic cell diagram:

Answer 1

Question 2

Plasmids:

Answer 2

• small loops of DNA found in cytoplasm separate from main circular DNA molecule
• plasmids containgenesthat can be passed between prokaryotes (e.g. genes forantibiotic resistance)
• not present in all eukaryotes

Question 2

Nucleoide:

Answer 2

area in cytoplasm where free loop of DNA is found

Question 3

Capsule aka slime capsule:

Answer 3

• helps protect bacteria from drying out and from attack by immune system cells of host organism
• not present in all prokaryotes

Question 4

Pili:

Answer 4

• adhesion to surfaces
• directional movement
• aid in transfer of plasmids

Question 5

Flagellum:

Answer 5

• long tail-like structure that rotates allowing prokaryotes to move (propelling motion)
• some prokaryotes have more than flagellum

Question 6

Differences between prokaryotes and eukaryotes:

Answer 6

• size - prok. (radius = 5 - 50nm) are much smaller than euk. (radius = up to 100nm) (10x to 100x smaller)
• DNA - prok. DNA is circular with no proteins in the cytoplasm whereas euk. DNA is linear and associated with histones (proteins) formed into chromosomes
• cell wall - prok. cell wall made of a peptidoglycan (polysaccharide and amino acids) and murein whereas in euk. there is no cell wall in animals, cellulose cell wall in plant cells and chitin cell wall in fungi
• cell division - prok. cell division occurs by binary fission with no spindle involved whereas in euk. cell division occurs by mitosis or meiosis ad involves a spindle to separate chromosomes
• ribosomes - prok. have 70S ribosomes whereas euk. have 80S ribosomes but also contain 70S in chloroplasts in mitochondria
• euk. have a more developed cytoskeleton than prok.
• nucleus - in prok. have no nucleus instead have a single loop of DNA found in the cytoplasm whereas in euk. the genetic information is enclosed in the nucleus
• prok. have fewer organelles and no membrane bound organelles (e.g. mitochondria) whereas euk. have many organelles and contain membrane bound organelles
• prok. have small ribosomes (20nm or less) whereas euk. have larger ribosomes (over 20nm)

Question 7

Similarities between prokaryotes and eukaryotes:

Answer 7

• both have a plasma membrane
• both have a cytoplasm
• both have ribosomes for protein synthesis
• both have DNA and RNA