Bacterial Physiology

Question 1

what is a nucleoid?

Answer 1

one chromosome with no nuclear membrane

Question 2

what are the components of the cell envelope?

Answer 2

cytoplasmic membrane, cell wall, capsule or slime layer and cell structures

Question 3

what is the cytoplasmic membrane?

Answer 3

an arrangement of a bilayer of lipids and proteins that is selectively permeable

Question 4

where does cell respiration occur?

Answer 4

in the cytoplasmic membrane

Question 5

how is the prokaryotic membrane and eukaryotic membrane similar?

Answer 5

both have integral, surface and transmembrane proteins and receptors

Question 6

what is the purpose of the cell wall?

Answer 6

to give the cell rigidity and shape and protect against attacks

Question 7

what do cell walls consist of?

Answer 7

peptidoglycan

Question 8

what 2 chemicals does peptidoglycan consist of?

Answer 8

N- acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM)

Question 9

how are NAG and NAM arranged?

Answer 9

in alternating chains that are cross linked via peptide bonds

Question 10

what colour do gram positive cells appear after staining?

Answer 10

purple

Question 11

what kind of cell wall do gram positive cells have?

Answer 11

thick cell wall

Question 12

what are the 2 major components of a gram positive cell?

Answer 12

trichroic acid and peptidoglycan

Question 13

what effect does penicillin have on bacteria?

Answer 13

acts on the cell wall of gram positives and prevents the organism developing new cell walls

Question 14

what do gram positive cells not have that gram negative cells do?

Answer 14

an outer membrane

Question 15

what colour do gram negatives turn after staining?

Answer 15

pink

Question 16

how does a gram negative cell differ from a gram positive?

Answer 16

thinner cell wall yet more complex, no teichoic acid, has lipopolysaccharides

Question 17

what do lipopolysaccharides do?

Answer 17

assists in pathogenicity as when recognised by phagocytic cells, they are not engulfed

Question 18

what do lipoproteins do in gram negative cells?

Answer 18

attach the peptidoglycan to the outermembrane

Question 19

what is a capsule or slime layer?

Answer 19

a sugar coat surrounding the prokaryote

Question 20

what is the difference between a capsule and a slime layer?

Answer 20

the capsule is attached to the cell yet a slime layer is not

Question 21

what are examples of cells with a capsule?

Answer 21

strep pneumo and haemophilus

Question 22

what are examples of cells with a slime layer?

Answer 22

staphs

Question 23

what are fimbriae? what do they do?

Answer 23

thin, straight protein appendages that are involved in pathogenesis by sticking to surfaces

Question 24

what are pili and what do they do?

Answer 24

they are specialised fimbriae that are involved in the transfer of genetic material

Question 25

what are the types of flagella?

Answer 25

peritrichous, polar and lophotrichous

Question 26

what do peritrichous flagella look like?

Answer 26

project from all areas of the cell

Question 27

what do lophotrichous flagella look like?

Answer 27

multiple flagella that project from one point

Question 28

what are the key features of endospores?

Answer 28

thick walls, contain little water and resistant to heat, desiccation, disinfectants and irridation

Question 29

what is the cell called when it contains no spore?

Answer 29

a vegetating cell

Question 30

what is a cell called when a spore is beginning to form?

Answer 30

a sporulating cell

Question 31

what are the layers of a spore?

Answer 31

spore coat, cortex, exosporium and the core wall

Question 32

what is the structure called in which the forespore develops?

Answer 32

a sporangium

Question 33

why might a cell produce spores?

Answer 33

resistant to heat, UV, chemicals and freezing