Week 2 Lecture 2

Front 1

what are the general composition of bacterial cell wall?

Back 1

peptidoglycan

Front 2

what two microbes have no cell walls?

Back 2

mycoplasma and chlamydias

Front 3

What composes the monomer of peptidoglycan?

Back 3

NAG and NAM

Front 4

describe the bonding involved in peptidoglycan

Back 4

Glycosidic bonds between NAM and NAG
Tetrapeptide bond between NAM and polysaccharide chains

Front 5

What is the function of peptidoglycan?

Back 5

prevents lysis

Front 6

why does peptidoglycan must allow breakage and insertion?

Back 6

to allow cells to divide

Front 7

what enzymes allow to do breakage and insertion of peptidoglycan?

Back 7

autolysins and transpeptidase

Front 8

what is the principle behind antibiotics?

Back 8

inhibits normal synthesis of peptidogyclan by bacteria

Front 9

how does penicilin work?

Back 9

binds to transpeptidases hence tetrapeptide cross-links are not made

Front 10

how does Vancomycin work?

Back 10

Vancomycins bind to peptide monomers and block transpeptidases from forming
peptide cross-links

Front 11

What are the three groups of bacteria based on colour staining?

Back 11

Gram positive
Gram negative
Acid fast

Front 12

What are the colours of Gram Stains? what about acid fast?

Back 12

Purple for gram positive
Pink for gram negative

neither

Front 13

What are the steps in gram staining?

Back 13

1. Primary stain: crystal violet. Colours all cells
2. Add mordant: iodine
3. Decolourising : alcoholacetone. Decolourises
some cells but not others.
4. Counterstain: safranin
or carbolfuchsin

Front 14

Describe the gram positive cell wall

Back 14

broad, dense and very thick 20-80nm

numerous interconnecting layers of peptidoglycan

90% of cell wall is peptidoglycan

contain teichoic acids which are interwoven

Front 15

what are teichoic acids?

Back 15

extend beyond the cell wall
help make the cell wall stronger
stimulate the human body's defence systems

Front 16

what is so special about teichoic acid in human defense system?

Back 16

cause fever

Front 17

Describe features of the gram negative cell wall

Back 17

multilayered (inner, outer and periplasm)

inner layer: 2-3 layers of peptidoglycans (2-3nm thick)

outer layer: lipid bilayer with phospholipids, lipoproteins, lipopolysaccharides (LPS) and protein

Front 18

why have fever?

Back 18

increase body temperature
white blood cells and enzymes become more active
bacteria don't like high temperature

Front 19

What are the functions of LPS in Gram negative cell wall?

Back 19

add strength to the outer membrane
stimulate the human body's defence system
activates complement proteins
can be harmful endotoxyn

Front 20

what is periplasm?

Back 20

gelatinous material between the outer membrane, the peptidoglycan, and the cytoplasmic membrane

contain enzymes for nutrient break down and binding proteins for transfer of nutrients across the cytoplasmic membrane

Front 21

describe acid fast cell wall

Back 21

has small amount of peptidoglycan
has large amount of glycolipid
has waxy glycolipid calle dmycolic acid which make up 60% and make wall impermeable

Front 22

what is the name of the waxy glycolipid in acid fast cell wall?

Back 22

mycolic acid

Front 23

what function does mycolic acid serve in acid fast cell wall?

Back 23

impede the entry of chemicals causing the organisms to grow slowly and be more resistnat to chemical agents and lysosomal components of phagocytes

Front 24

describe the prokaryotic cell cytoplasm

Back 24

80% water
contain DNA, RNA, enzymes and amino acids, carbohydraes, lipids, inorganic ions

Front 25

what is the liquid component of cytoplasm called?

Back 25

cytosol

Front 26

what are the functions of cytoplassm?

Back 26

site of most metabolism
site of chemical reactions
contain helical actin like protein that contribute to shape
inclusion bodies carry out specialised cellular function

Front 27

State what colour Gram-positive bacteria stain after the Gram stain procedure and
briefly describe why.

Back 27

purple
the crystal violet stain enters thru the cell wall but because the cell wall is so thick, the crystals are not washed away with alcohol

Front 28

Describe the composition of a Gram-positive cell wall indicating the possible or
known functions of peptidoglycan, teichoic acids, and surface proteins.

Back 28

broad, dense wall 20-80 nm thick,
The peptidoglycan in the gram-positive cell wall prevents osmotic lysis. The
teichoic acids probably help make the cell wall stronger.
The Peptidoglycan and teichoic acids function to stimulate the human body’s
defence systems:

Front 29

Describe what a peptidoglycan monomer consists of and state the function of
peptidoglycan in bacteria.

Back 29

NAG and NAM with gloycosidic linkage and tetrapeptide bondds

function:Peptidoglycan prevents osmotic lysis.

Front 30

Briefly describe how bacteria synthesize peptidoglycan, indicating the roles of
autolysins and transpeptidases.

Back 30

autolysin break the polymer chain
NAM-NAG-peptide complex is attached to the polymer chain
transpeptidase enzymes join the peptide of one monomer to another

Front 31

State the structural component that makes peptidoglycan so strong.

Back 31

glycosidic linkage between NAM-NAG monomers
NAM-NAG complex is vertically attached to polysaccharide chain via tetrapeptide bond

Front 32

State what colour gram-positive bacteria stain after gram staining and briefly describe why

Back 32

purple

the crystal violet stain is trapped beneath the cell wall because it is so thick

Front 33

State what colour gram-negative bacteria stain after gram staining

Back 33

pink

Front 34

State what colour acid-fast bacteria stain after acid-fast staining

Back 34

red

Front 35

Describe the composition of a gram-negative cell wall indicating the possible
functions of peptidoglycan, lipopolysaccharide, porins, and surface proteins.

Back 35

inner wall
outer wall
periplasm

peptidoglycan: resist lysis
lipopolysaccharide:add
strength to the outer membrane, stimulate the human body’s defence system
porins: allows small molecules to pass through walls
surface proteins:functioning as enzymes, adhesins, invasins, and aiding certain bacteria in resisting phagocytic destruction.

Front 36

Define periplasm.

Back 36

gelatinous material between the outer membrane, the
peptidoglycan, and the cytoplasmic membrane. It contains enzymes for nutrient
breakdown as well as binding proteins to facilitate the transfer of nutrients across the
cytoplasmic membrane.

Front 37

State what colour acid-fast bacteria stain after the acid-fast stain procedure and briefly
describe why.

Back 37

resist decolorization with an acid-alcohol mixture
during the acid-fast stain procedure and retain the initial dye carbol fuchsin and appear red.

Front 38

Define the following: a. exoenzymes, b. endoenzymes. c. cytosol

Back 38

exo-enzyme: hydrolyze macromolecules for transportation across cytoplasmic membrane

endoenzyme: controls chemical reactions within the bacterium

cytosol: liquid component of cytoplasm

Front 39

State the primary function of the bacterial cytoplasm

Back 39

cytoplasm is the site of most bacterial metabolism.