Lecture 28 Flashcards
(16 cards)
1
Q
what is the nucleoid?
A
like nucleus, circular chromosomes
2
Q
what is the glycocalyx for?
A
extracellular cell protection
3
Q
what are flagella for?
A
cell movement, like a propeller
4
Q
what are the 3 shapes of prokaryotic cells?
A
rod, cocci, spiral
5
Q
what are plasmids?
A
Other small circular self-replicating DNA
molecules can be found in the cytosol of bacteria
6
Q
what is peptidoglycan + purpose?
A
- cell wall of bacteria
- mesh like structure
- functions are:
1. Rigid macromolecular layer that provides strength to cell
2. Protect cells from osmotic lysis and confers cell shape
7
Q
what are prokaryotes without cell walls called?
A
mycoplasmas
8
Q
what is the peptidoglycan structure?
A
- carb backbone (NAG-NAM)
- has peptide cross bridges, attach carbs together
- uses enzyme transpeptidase to cross-link
9
Q
how is a gram stain done?
A
- add crystal violet
- add iodine
- alcohol wash
- add safranin
10
Q
what makes a bacteria gram positive?
A
- has thick peptidoglycan layer
- traps crystal violet, masks safranin dye
11
Q
what makes a bacteria gram negative?
A
- thin peptidoglycan layer
- has inner and out membrane (peptidoglycan sandwich)
- crystal violet easily washed off
12
Q
what are fimbriae?
A
- adhesive, causes bacteria to stick
- inherited trait
- not for movement
- hair-like
13
Q
What are pili?
A
- attachment to other bacteria
- transfer genetic info from one bacteria to another
- transfer = conjugation = horizontal gene transfer
14
Q
what are glycocalyx?
A
- A gelatinous polysaccharide and /or polypeptide outer
covering. - 2 types
- slime layer = disorganized + loose
- capsule = organized into a
defined structure attached
firmly to cell wall
15
Q
what are the functions of a capsule on a bacteria?
A
- protects bacteria from phagocytosis
- prevents dessication
16
Q
what are bacterial endospores?
A
- only in gram positive bacteria
- formed during unfavourable growth conditions and germinate under favourable
conditions - protects cell from stress
- may be due to starvation or high cell density/competition
- dormant
- resistant
