Lecture 4- bacterial cell structure

Question 1

bacteria do not have

BUT

Answer 1

membrane bound organelles (like golgi, er, etc)

BUT they perform all the fxns of a eukaryotic cell without compartmentalization

Question 2

bacterial cell walls prevents ___ ___

Answer 2

osmotic lysis

Question 3

name the 2 types of bacterial cell walls

Answer 3

1. gram positive

2. gram negative

Question 4

gram positive cell walls have a thick layer of ____ which is _______

Answer 4

peptidoglycan = structural polysaccharide (polymer of the sugars MAG and NAM)

Question 5

gram negative cell walls have a thin layer of ____ and an outer ____

Answer 5

peptidoglycan

membrane

Question 6

describe the outer membrane of a gram neg cell wall

Answer 6

the outer membrane is made up of an LPS (lipopolysaccharide) layer and a phospholipid inner leaf. The LPS layer is not a major permeability barrier
- the sugars of LPS are neg charged, therefore repulsion occurs

Question 7

how does a bacterial flagellum allow for movement?

Answer 7

it rotates like a corkscrew (H+ moving through forces rotation)

Question 8

In a bacterial flagellum:

• what does the basal apparatus do?
• what does the hook do?
• where does energy for rotation come from?

Answer 8

• basal apparatus= anchors filament into cell wall/ membrane. Contains a gear system that drives rotation
• hook= rotation about the hook allows movement
• energy comes from a proton gradient

Question 9

antibiotics kill a bacterial pathogen by targeting which two structures?

Answer 9

1. bacterial ribosomes

2. bacterial cell wall

Question 10

penicillin works by disrupting transpeptidation step of _______ ___
Therefore it works best on GROWING gram ____ cells because _____

Answer 10

peptidoglycan synthesis

positive b/c they have more PG

Question 11

list and dscribe 2 other forms of attachment in prokaryotes

Answer 11

1. fimbriae: hair like structures in bacteria that allow attachment to surfaces (common in pathogens)
2. biofilm: a mucus secreted by some bacteria that surrounds the cell; protects cell from desiccation and allows attachment

Question 12

microbiome=

Answer 12

the collection of organisms normally found on our body

Question 13

colonization =

Answer 13

establishment of microbial growth in host tissue

- begins at birth

Question 14

2 sources of colonizing bacteria from birth are:

Answer 14

1. birth canal

2. milk digestion

Question 15

competitive exclusion: good bacteria produce inhibitory compounds like ___ ___ and ___that prevent growth of potential ___

Answer 15

organic acids and toxins

pathogens

Question 16

The ____ hypothesis states that exposure to microbes helps maintain a healthy immune system
- lack of expose to healthy microbes leads to a ____ immune system

Answer 16

hygiene

hyperactive (eg allergies)