lec 3

Question 1

cell shapes of prokaryotes

Answer 1

1) coccus: basically a sphere
2) rods
3) spirillium: twisted rods
4) spirochete: very good at swimming through liquid and drill into tissues
5) stalk: more complex, their membranes are capable of elongating and creating motile daughter cells. mostly water bond and capable of attaching to water molecules
6) filamentous: forms a very long filaments and the cells that does detach from each other

Question 2

functions of the cell wall of bacteria

Answer 2

• allows the bacteria to withstand the intracellular osmotic pressure
• shape and rigidity
• on top of the cytoplasmic membrane

Question 3

gram stain

Answer 3

a procedure to stain cells in order to view them under the microscope

Question 4

cells are divided into gram stains based on their:

Answer 4

cell wall composition

Question 5

how to make a gram stain

Answer 5

1) prepare a thin later of bacteria o na slide
2) mix with crystal violet for 1 min –> purple
3) add iodine for 1 min –> purple
4) decolonize with alcohol for 20 sec –> gram +: purple, gram - : color less
5) counterstain with safranin fro 1-2 min –> gram +: purple, gram -: pink to red

Question 6

gram positive vs gram negative

Answer 6

gram negative has an outer membrane on top of the peptidoglycan

Question 7

structure of peptidoglycan

Answer 7

• the backbone is basically similar among most
• 2 sugars: N-acetylglucosamine and N-acetylmuramic acid
• side chain attached to the sugars: peptide chain –> D amino acids
• mammals destroys these bacteria by producing lysozyme and breaking the beta 1-4 linkages

Question 8

gram — is more sensitive to lysozyme, why?

Answer 8

positive, its peptidoglycan is exposed

Question 9

transpeptidation

Answer 9

polymerization of the sugar backbones that provides rigidity in only one direction

Question 10

transpeptidation in gram neg

Answer 10

direct cross linkage (covalently)

Question 11

transpeptidation in gram positive

Answer 11

inter bridge cross linkage, by adding more AAs between the 2 sugars, so then you make it thicker

Question 12

how does penicillin destroy bacterial infections

Answer 12

inhibits binding the 2 peptide chains together by inhibition transpeptidase enzymes

Question 13

upto —- % of the cell wall is peptidoglycan

Answer 13

90

Question 14

proteins attached to the peptidoglycan layer:

Answer 14

1) teichoic acid. *variable can be either or

2) lipoteichoic acid

Question 15

how does TA and LTA impact the overall charge of the cell

Answer 15

net negative, because they are negative

Question 16

what happen if LTA is bound to the peptidoglycan

Answer 16

• it binds deeper with it and ends with a glycerol phospholipid
• anchored inside the cytoplasmic memebtan
• makes peptidoglycan fully attached to the cytoplasmic membrane

Question 17

how are proteins attached to the peptidoglycan layer

Answer 17

enzyme: sortase

Question 18

(T/F) eukaryotes doen have sortase

Answer 18

true

Question 19

structure of the outer membrane of gram neg

Answer 19

• porins
• outer membrane proteins
• inside layer: phospholipids
• outer layer: LPS + phospholipids

Question 20

periplasm space:

it is covered by:

Answer 20

where the peptidoglycan is located

- outer membrane and cytoplasmic membrane

Question 21

function of LPS

Answer 21

protects the bacteria against antibiotics and host defence system

Question 22

structure of LPS

Answer 22

a family of complex sugar polymers attached to lipid A

• lipid A contains 6 lipid tails embedded in the membrane
• KDO links lipid A to the polysaccharide chain:
• connected to core polysaccharides (don’t change much)
• and O specific polysaccharides or O antigens:repeating sequences of 2-4 monosaccharides (very variable)

Question 23

consequences of lipid A

Answer 23

septic shock

Question 24

pseudomuerin in archaea vs. peptidoglycan

Answer 24

• lack D AAs, instead has L AAs
  contains N-acetylalsaminuronic aid instead of NAM
• linkage is insensitive to lysozyme, due to its beta 1–> 3 linkage

Question 25

the great majority of archaea have --- and/ or ---- on their cell walls. some can be composed of ----

Answer 25

protein, glycoproteins, heteropolyasachchrides

Question 26

S layer

Answer 26

the cyrtslaline appearance of the cell walls of archaea it may also be found in bacteria gram + : on top of the peptidoglycan gram -: on top of the outer membrane - esp when the archaea is composed of any of: protein, glycoprotein, sugar

Question 27

the capsule or slime layer are composed of --- for majority and ---- in some gram positive

Answer 27

heteropolyasachcrides | homopolysaccharides

Question 28

how is the capsule attached to the cell

Answer 28

it is covalently bound to either the outer membrane or the peptidoglycan layer

Question 29

fxn of capsule

Answer 29

doesn't confer sig strength | - due to its glue like texture, external matter stick to it therefore, protection against the host defence system

Question 30

flagella and fimbriae are ---- than the size of the bacteria

Answer 30

larger

Question 31

function of fimbriae

Answer 31

used for attachments and anchor the cell to something. these are short filaments o the surface of the bacteria

Question 32

monotrichous vs. peritirichous vs. lophotrichous

Answer 32

diagrams

Question 33

structure of flagella

Answer 33

diagrams

Question 34

fimbriae is found primarily on gram --- bacteria

Answer 34

negative

Question 35

movement in peritrichous

Answer 35

forward + change direction

Question 36

movement in mono and lopho

Answer 36

forward and reverse

Question 37

how is fimbriae attached to gram positive

Answer 37

via sortase on the peptidoglycan

Question 38

assembly of fimbriae for both gram neg and pos

Answer 38

diagram

Question 39

taxis

Answer 39

directed movement toward or away from a gradient of chemical or physical agents - when there is an attractant, the bacteria keeps moving in the right direction. so it spends more time in the direction that is favoured

Question 40

name the surface appendages of bacteria and archaea

Answer 40

flagella, fimbriae

Question 41

what is an endospore

Answer 41

highly differentiated cells that are extremely resistant to harsh environments - safety vessel for the genome of a species

Question 42

2 bacterias that are well known for producing endospore

Answer 42

clostridium, bacillus

Question 43

structure of and endospore (outer most layer to the inner most)

Answer 43

1) exosporium 2) spore coat 3) core wall 4) cortex 5) DNA

Question 44

exosporium

Answer 44

a coat of protein on top of the spore

Question 45

spore coat

Answer 45

layers of protein that are only found in the spores of the species (spore specific protein)

Question 46

core wall

Answer 46

contains some protein and genome of the species of interest

Question 47

cortex

Answer 47

on top of the core wall, thick layer of peptidoglycan

Question 48

in the core of an endospore, besides the genome and proteins you also have:

Answer 48

1) SASPS | 2) Dipicolnic acid (DPA) + Ca2+

Question 49

SASPS

Answer 49

bind to the DNA an =d protect it from bad things ,esp UV light

Question 50

DPA + Ca2+

Answer 50

they dehydrate the core in order to stop enzymatic activity therefore, keep the spore fresh

Question 51

vegetative cycle

Answer 51

where the bacteria is actively growing and dividing

Question 52

sporulation

Answer 52

when the env becomes harsh a spore is formed

Question 53

during germination ----- is increased, resulting in ----

Answer 53

water uptake, outgrowth

Question 54

cell inclusions

Answer 54

in bacteria and archaea, nrg reserves and building blocks are sometimes stored in granules or inclusions

Question 55

cell inclusions are often enclosed by

Answer 55

a single layer of phospholipid, protein, glycoprotein

Question 56

what nutrients are stored in cell inclusions

Answer 56

P,S,C

Question 57

How are some bacteria able to respond to earth's magnetic field

Answer 57

their cell inclusions store magnetites, and allows the cells to respond to magnetic fields - meganotaxis

Question 58

how do cell inclusions confer buoyancy

Answer 58

when they store gas, the cell can float on the water and be closer to areas with a higher level of O2