3.2.1.2 (prokaryotic + viral cell structure)

Question 1

Describe prokaryotic cells

Answer 1

Prokaryote= before nucleus
Average cell diameter 0.1-10μm - smaller than eukaryotic cells
Binary fission- no mitosis/meiosis
DNA is circular, also found in plasmids, not associated with proteins
Cell wall always present- muerin/peptidoglycan (not cellulose!)
No membrane bound organelles
Ribosomes present but smaller than eukaryotes (70s)

Question 2

Name the 8 bacterial cell structures and describe them

Answer 2

Nucleoid - DNA not bound by a membrane- in loop free in cytoplasm
Cell wall- made of peptidoglycan called muerin
Plasmid- small ring of DNA in cytoplas, useful in genetic engineering
Ribosomes- smaller than eukaryotic cells
Mesosomes- infoldings of cell membrane, site of respiration
Flagella- motility
Pilli - Hollow hair like structures made of protein, allow bacteria to attach to other cells
Capsule- slime layer (often a polysaccharide) for protection

Question 3

Describe the structure of a virus

Answer 3

Acellular, non living
50 times smaller than a bacterial cell
Acellular so don’t have a cell structure like other living organisms
Can only replicate when inside another cell

Question 4

Name the 6 components of a viral cell

Answer 4

Genetic material (RNA)
Reverse transcriptase enzyme
Capsid
Matrix
Lipid envelope
Attachment protein