2.2- prokaryotes

Question 1

Structures in bacteria

Answer 1

Mesosomes
Membrane
70s ribosomes
Cell wall
Plasmids
Nucleoid
Flagellum
Capsule or slime layer

Question 2

Why are bacteria referred to as hypertonic

Answer 2

• bacteria cell walls are hypertonic to the medium around them
• means water tends to move in by osmosis

Question 3

What is peptidoglycan

Answer 3

• found in bacteria cell walls
  -made up of many parallel polysaccharide chains

Question 4

What does the slime layer do

Answer 4

• protects the bacteria from phagocytosis by white blood cells

Question 5

What is a nucleoid

Answer 5

Found in bacteria
- where DNA tangle is found

Question 6

Gram pos bacteria

Answer 6

Thick layer of peptidoglycan
-contains teichoic acid
-stained purple by iodine

Question 7

Gram negative bacteria

Answer 7

Thin layer of peptidoglycan
-appears red due to safranin stain

Question 9

What do antibiotics usually target

Answer 9

-features of bacteria cells that differ from eukaryotic cells
-include cell walls and peptidoglycan
- some effect production of peptidoglycan and therefore more effective for gram pos

Question 10

What are spherical bacteria called

Answer 10

Cocci

Question 11

What are rod shaped Bactwria called

Answer 11

Bacilli

Question 12

What are obligate aerobes

Answer 12

Organisms that need oxygen for respiration

Question 13

What are facultive anaerobes

Answer 13

Organisms that use oxygen if available but can respite and survive without

Question 14

What are obligate anaerobes

Answer 14

Organisms that can only respire in absence of oxygen and killed by it

Question 15

Virus protein coat

Answer 15

Known as capsid
Made up of repeating protein units called capsomeres

Question 16

DNA viruses

Answer 16

• genetic material is DNA
  -viral dna acts as template for new dna
  -e.g. smallpox, and lambda

Question 17

RNA viruses

Answer 17

-more likely to mutate than DNA viruses
- most contain just a single RNA strand
E.g. influenza and Ebola

Question 18

RNA retroviruses

Answer 18

-special type of RNA virus
—protein capsid and lipid envelope
-strand of rna synthesises reverse transcriptase
-this goes on to make dna corresponding to viral genome
- this DNA is then incorporated into host cell dna and used as template for new viral proteins
-e.g. HIV

Question 19

Lysogenic pathway

Answer 19

-non virulent on entry
- insert dna into host dna so it replicates every time cell divides
-this is called provirus
-virus does not make host I’ll at this stage
- lysogeny period- when virus part of reproducing host cells it is said to be latent

Question 20

Lytic pathway

Answer 20

• viral genetic material replicated independently of host dna upon entry
• mature viruses made and eventually host cell burts releasinf large number of viruses to invade other cells
  -virus said to virulent(disease causing )
  -when host is damaged lysogenic state scafivted