bacterial morphology and growth

Question 1

pleomorphic

Answer 1

no defined shape

Question 2

most common bacterial shapes

Answer 2

• coccus
• bacillus

Question 3

a cell that divides in one plane gives rise to short or long chains described as?

Answer 3

• diplo-:pair
• strepto-:chain

Question 4

staphylo-:

Answer 4

grapelike cluster

• cell divided in two or more planes

Question 5

sarcina

Answer 5

• packet of 8 cells
• cell divided in two or more planes

Question 6

most bacterial cell membranes do not contain what compound?

Answer 6

sterols

Question 7

a bacterial cell wall is found in what relation to cell membrane?

Answer 7

outside of cell membrane

Question 8

virtually all bacterial cell walls contain what structure?

Answer 8

Peptidoglycan

Question 9

what is Peptidoglycan

Answer 9

• repeating disaccharides (NAG and NAM) cross-linked by tetrapeptides

Question 10

in Peptidoglycan, tetrapeptide linkage is between what

Answer 10

NAMs

Question 11

function of Peptidoglycan

Answer 11

important for bacterial cell support

Question 12

organisms can kill bacterial cells by interfering with the synthesis/structure of peptidoglycan. Name two ways

Answer 12

1. secretion of various antimicrobial compounds
2. secretion of lysozyme

Question 13

cell wall inhibitors only affect cells in what stage?

Answer 13

cells that are actively growing, as these cells are synthesizing peptidoglycan

Question 14

effect of lysozyme of peptidoglycan

Answer 14

degrades the glycan backbone of peptidoglycan

• lysozyme is found in tears, saliva, and mucus

Question 15

gram negative bacteria have what peptidoglycan layer

Answer 15

a thin peptidoglycan layer

Question 16

gram positive bacteria have what peptidoglycan layer

Answer 16

thick peptidoglycan layer

Question 17

describe the staining technique to differentiate between gram positive and gram negative bacteria

Answer 17

• stain with primary stain: crystal violet
  
  • bacteria will stain purple
• stain with counterstain: safranin
  
  • gram negative bacteria will turn red
  • gram positive bacteria will remain purple

Question 18

what group of bacteria can not be classified with gram staining

Answer 18

• acid fast bacteria
  
  • cell wall contains peptidoglycan
  • unique cell wall structure
  • do not stain using gram stains

Question 19

what are the three main types of cell walls found in bacteria?

Answer 19

• gram negative
• gram positive
• acid-fast

Question 20

gram negative cell wall contain 1-2 layers of peptidoglycan plus the following structures?

Answer 20

• outer membrane
• periplasmic space

Question 21

outer membrane is bi-layer. Inner layer is identical to cell membrane, outer later of the outer membrane is composed primarily of what?

Answer 21

lipopolysaccharide (LPS)

Question 22

lipopolysaccharide (LPS) contains what three parts?

Answer 22

1. O antigen
2. core polysaccharide
3. Lipid A

Question 23

function of O antigen part of lipopolysaccharide (LPS) in gram negative bacteria

Answer 23

• outer portion of LPS
• serves as attachment site
• highly variable and immunogenic: used to identify bacterial stains

Question 24

function of core polysaccharide part of lipopolysaccharide (LPS) in gram negative bacteria

Answer 24

• connects lipid A to O antigen

Question 25

function of Lipid A part of lipopolysaccharide (LPS) in gram negative bacteria

Answer 25

• has toxin activity

Question 26

which structure of LPS is responsible for bacterial sepsis?

Answer 26

Lipid A

Question 27

function of porins in gram negative cells

Answer 27

• trimeric outer membrane protein channel
• non-specific channels allowing water and small molecules across the outer membrane

Question 28

what is the most abundant protein of gram negative cells? Function?

Answer 28

lipoprotein

• stabilizes the outer membrane and anchors the outer membrane to the peptidoglycan layer

Question 29

location of periplasmic space in gram negative cell walls

Answer 29

• between outer membrane and cell membrane
• houses thin peptidoglycan layer