EXAM 2 P4

Question 1

cell envelope

Answer 1

refers to everything surrounding the cell, including the membranes, wall, s-layer, capsule

Question 2

cell wall

Answer 2

refers to the structural element defining the cell shape; the strength element preventing the cell from popping, aka peptidoglycan layer
it is ONE PART of the cell envelope

Question 3

gram positive cells

Answer 3

has an ester linked cytoplasmic membrane with a thick peptidoglycan cell wall outside. NO OUTER MEMBRANE

Question 4

gram negative cells

Answer 4

has an ester linked cytoplasmic membrane with a thin peptidoglycan cell wall. has an outer membrane

Question 5

periplasm

Answer 5

the space between 2 membranes

peptidoglycan wall is within this space

Question 6

components of the cell wall

Answer 6

also known as murein or peptidoglycan
peptide is attached to sugars. short in length so they are not proteins.
diamino acid has 2 amino groups. the amino groups are needed to make peptide bonds

Question 7

structure of cell walls

Answer 7

glycan are long strands
peptides on the outside
peptide side chains link glycan strands together to form crosslinks
these are polymerized into one single molecule

Question 8

transglycosylase

Answer 8

makes the glycan strand by polymerization

Question 9

transpeptidase

Answer 9

make the peptide strands into crosslinks.

as new units are added, they’re cleaving off a terminal D and using this energy to form more chains

Question 10

bactoprenol

Answer 10

lipid carrier for precursor transport

Question 11

autolysins

Answer 11

means self-lysing, causing the cell to burst

cleave peptidoglycan bonds to allow expansion and insertion of new material

Question 12

PBPs

Answer 12

penicillin binding proteins that catalyze both the glycosyltransferase and transpeptidase activities

Question 13

degradation of bacterial cell walls

Answer 13

antibiotics, like penicillin, prevent crosslinking and cause the cell to burst
lysozymes cleave glyosidic bonds between NAG and NAM

Question 14

prokaryotes that can live without cell walls

Answer 14

very few
mycoplasma (bacteria)
thermoplasma (archaea)
only within an isotonic environment

Question 15

teichoic acid

Answer 15

found in gram positive cell walls
a polymer containing ribitol and sugar with phosphates attached. they are attached to the lipids and peptidoglycan
phosphates provide a negative charge to the cell surface

Question 16

lipid A

Answer 16

found in gram negative cells

makes up the outer membrane outer leaflet

Question 17

lipopolysaccharide (LPS)

Answer 17

attached to lipid A

Question 18

porin proteins

Answer 18

nonselective pores that let a lot of small molecules cross the outer membrane

Question 19

lipoprotein

Answer 19

attaches the outer membrane to the peptidoglycan

Question 20

periplasm

Answer 20

space between the membranes. the peptidoglycan is submerged here, as well as the site for PMF since protons accumulate here

Question 21

structure of gram negative outer membrane

Answer 21

lipid A has long fatty acid chains with sugar. frequently called endotoxin
core polysaccharide
o specific polysaccharide

Question 22

archaeal cell walls

Answer 22

have an ether linked cytoplasmic membrane
NO peptidoglycan
NO outer membrane
SOME contain pseudomurein
beta 1,3 bonds instead of 1,4
not lysozyme sensitive
no D amino acids
not penicillin sensitive
contain N-acetyl talosaminuromic acid

Question 23

s layers

Answer 23

paracrystalline surface layer
protein or glycoprotein can self assemble. covers the entire cell surface
common in archaea functioning like a cell wall, resisting osmotic pressure

Question 24

capsule/slime layer/extracellular polysaccharide

Answer 24

used for attachment to surfaces
EPS used in biofilm formation. this holds cells together and keeps them stuck to a surface, working as millions instead of one
provide protection from phagocytosis by immune cells

Question 25

fimbriae

Answer 25

``` filament made of proteins relatively short abundant with thousands per cell easily fixed, stay and don't change important in surface adherence sticky and can bind ```

Question 26

pili

Answer 26

``` filament made of proteins long fewer with 1-20 per cell retractable, extending in and out as needed do not rotate or swing ```

Question 27

functions of pili

Answer 27

adherence, retraction allows the cell to pull itself closer to things exchange of DNA through the process of conjugation motility

Question 28

twitching motility

Answer 28

utilizes type 4 pili needs ability of attachment and retraction important in pathogenesis

Question 29

flagella and swimming motility

Answer 29

rotary filaments that spin the cell forward

Question 30

polar flagella

Answer 30

only produced at the tips of the cell

Question 31

amphitrichous flagella

Answer 31

found on both poles

Question 32

lophotrichous flagella

Answer 32

only at one pole

Question 33

peritrichous flagella

Answer 33

produced all over the cell

Question 34

tumble

Answer 34

the cell rotates to a new random direction

Question 35

unidirectional flagella

Answer 35

tumble one way, stop, and spin off in another direction by random chance like a box

Question 36

reversible flagella

Answer 36

tumble one way, stop, and go back the way they came | runs are straight lines back and forth

Question 37

motor

Answer 37

made primarily of the basal body driving force is in the cytoplasmic membrane a rod extends through it, forming a flexible hook at the end where the filament is attached filament is made of protein flagellum turning driven by PMF

Question 38

chemotaxis

Answer 38

can swim up or down gradients is a biased random walk can't tell which way they're going, but can sense concentrations of attraction they swim in response to chemicals

Question 39

capillary assay

Answer 39

bacteria is placed in a media like buffer. a capillary with a control, attractant, or repellent is place in it as well. the bacteria will react to this presence, swimming to or from it

Question 40

phototaxis

Answer 40

bacteria swim to places containing more light, preferably with more pigment for better absorption

Question 41

aerotaxis

Answer 41

swim towards high or low oxygen concentrations

Question 42

gas vesicles

Answer 42

produced by aquatic phototrophs | little membrane sacs that accumulate gas that is trapped, giving buoyancy to keep suspension at high points in the water