Cell structure - prokaryotic cells + virus

Question 1

description of prokaryotic cells?

Answer 1

• no membrane bound organelles + no nucleus
  -circular DNA not associated with proteins
  -small ribosomes (70s)
• binary fission - always asexual reproduction
  -murien cell walls
  -capsule,sometimes plasmid + cytoskeleton

Question 2

State the role of plasmids in prokaryotes?

Answer 2

small ring of DNA which carries non-essential genes.
can be exchanged between bacterial cells via conjugation
they are antibiotic resistant
not always present in prokaryotes

Question 3

state the role of flagella in prokaryotes?

Answer 3

Long hair like structure that rotates to make the prokaryotic cell move. not all prokaryotes have a flagellum.

Question 4

state the role of the capsule in prokaryotes?

Answer 4

polysaccharide layer:

-prevents desiccation
-acts as food reserve
-provides mechanical protection against phagocytosis and external chemicals
-sticks cells together

Question 5

compare eukaryotic and prokaryotic cell.

Answer 5

both have:
cell membrane
cytoplasm
ribosomes

Question 6

Why are viruses referred to as ‘particles’ instead of cells?

Answer 6

Acellular + non-living : no cytoplasm, cannot self reproduce , no metabolism

Question 7

describe the structure of a viral particle?

Answer 7

Linear genetic material -either DNA or RNA
viral enzymes
surrounded by capsid- protein coat around the core
no cytoplasm

Question 8

describe the structure of a enveloped virus?

Answer 8

simple virus surrounded by matrix protein
matrix protein surrounded by envelope derived from cell membrane of host cell
attachment protein on surface.

Question 9

state the role of a capsid on a viral particle?

Answer 9

protects nucleic acid (dna or rna)

Question 10

state the role of attachement proteins on viral particles?

Answer 10

enables viral particle to bind to complementary sites on host cell.