3.2.1.2 - structure of prokaryotic cells and viruses

Question 1

what are the key comparisons between prokaryotic and eukaryotic cells?

Answer 1

prokaryotic have no true nucleus but eukaryotic have a distinct nucleus and nuclear envelope
in prokaryotic cells DNA isn’t associated with proteins but in eukaryotic it is associated with proteins called histones
in prokaryotic cells some DNA may be in the form of circular plasmids but in eukaryotic there are no plasmids and DNA is linear
prokaryotic cells lack membrane-bound organelles however eukaryotic cells have them
prokaryotic don’t have chloroplasts but in eukaryotic there are chloroplasts in plants and algae
prokaryotic have smaller ribosomes (70S) but eukaryotic have 80S
in prokaryotic cells the cell wall is made of murein but in eukaryotic cells if they have a cell wall it is usually cellulose
prokaryotic cells may have a capsule but eukaryotic don’t
prokaryotic cell may have one or ore flagella

Question 2

what is murein (peptidoglycan)?

Answer 2

a glycoprotein found in the cell wall of prokaryotic cells

Question 3

why are plasmids important for bacteria?

Answer 3

they may contain genes making the bacteria resistant to antibiotics

Question 4

what is a slime capsule?

Answer 4

produced by some bacterial cells outside the cell wall which protects the bacteria from phagocytosis by white blood cells

Question 5

what are flagella?

Answer 5

feature of prokaryotic cells which help the move (sperm cells are eukaryotic and have flagella but the structure is different)

Question 6

what are pili?

Answer 6

fine protein strands which bacteria may have on their surface which help them attach to surfaces and other bacteria (for DNA transfer)

Question 7

what do lipid droplets/glycogen granules do in bacteria?

Answer 7

act as nutrient stores for cell

Question 8

what are mesosomes?

Answer 8

infoldings of the cell membrane in prokaryotic cells - scientists believe they are artefacts created when bacterial cells are prepared for electron microscopy

Question 9

how can viruses be described?

Answer 9

as acellular and non-living

Question 10

what are key features of viruses compared to eukaryotic and prokaryotic cells?

Answer 10

they are much smaller (20nm-300nm), they are only able to replicate if they are inside a host cell

Question 11

structure of viruses - genetic material?

Answer 11

can be either DNA or RNA (nucleic acids)

Question 12

structure of viruses - capsid?

Answer 12

this is a protein coat which the genetic material is contained within
in some viruses the capsid is surrounded by a lipid envelope formed from the host cell cell membrane

Question 13

structure of viruses - attachment protein?

Answer 13

found on the surface of the virus, they allow the virus particle to attach to and enter the host cell