Bacterial Cell Structure and Function

Question 1

major cellular structures of bacteria

Answer 1

pili, capsule, flagellum, nucleoid, and ribosomes

Question 2

capsule is made of

Answer 2

mucoid layer, slime layer, and glycocalyx

-made of some combo of polysaccharide, protein, and/or DNA

Question 3

capsule function

Answer 3

• usually required for pathogenesis

- function = adherence or immune system avoidance

Question 4

Biofilm

Answer 4

• organized multicellular bacterial communities which protect the bacteria until they want to propogate elsewhere
• most bacteria can form them
• forms when bacteria sense the correct density of their cohort: cell-cell communication via pheremones causes matrix synthesis
• once the matrix surrounds the whole community, it is a biofilm
• the microbiota are likely present in biofilms throughout the GI tract

Question 5

biofilm functions

Answer 5

-adherence, controlled release of bacteria from the biofilm, immune system avoidance, alteration of bacterial growth kinetics, alteration of drug pharmacokinetics ***and activation of bacterial stress and defense responses

Question 6

drug strategies to defeat biofilms

Answer 6

• first treat the biofilm with something like a drug that blocks pheremone communication
• then treat the bacterium

Question 7

biofilms can be sites of ______

Answer 7

reinfection

Question 8

name three main bacteria that use biofilms

Answer 8

• cystic fibrosis pneumonia
• urinary catheter infections
• gum disease

Question 9

Biofilm levels decline towards the _______ ______ because of ….

Answer 9

• distal colon
• because IgA may better bind bacteria in the distal colon to inhibit their disposition at that site or may have changes in nutritional status of gut

Question 10

clinical relevance of the flagellum

Answer 10

• flagellum dependent swimming can be required for disease
• the immunological response to flagella can be a diagnostic tool
• flagella can be organelles of attachment

Question 11

flagella have a ____ at the tip which can be replaced with a ______

Answer 11

• cap

- adhesin

Question 12

cell envelope of gram negative bacteria

Answer 12

-inner and outer mb with a thinner layer of peptidoglycan in between

Question 13

gram positive cell envelop

Answer 13

-only an inner mb with a thicker layer of peptidoglycan on the outside

Question 14

inner mb

Answer 14

• site of many biochem reactions and transport

- a separate cellular compartment

Question 15

peptidoglycan

Answer 15

• a series of sheets of sugar residues connected by short protein cross bridges
• determine the cell’s shape
• target for anti-microbials by enzymes of the body as well as in drugs
• can be toxic

Question 16

lipopolysaccharide (LPS)

Answer 16

• on outer leaflet of the mb

- O-specific side chain which is variable (diagnosis), Core, and lipid A toxic which spans the mb (endotoxic shock)

Question 17

multidrug efflux system

Answer 17

• trans-envelope channel and not a porin
• usually associated with a relatively impermeable outer mb
• strongly selected for in hospitals
• gram - bacteria
• can produce a toxin with the spore that is active while the spore is not

Question 18

sporulation

Answer 18

• small piece of cell is used to make the small spore which is then released and has a protective capsule
• spore = dorminant, resistant, and metabolically inactive

Question 19

germination

Answer 19

-capsule comes off spore after it senses that the environment is favorable and then it grows into a full cell that is metabolically active and produces virulence factors

Question 20

c. perfringens

Answer 20

• exudes active toxin with spore

Question 21

c. difficile

Answer 21

-uses spores

Question 22

b. anthracis (anthrax)

Answer 22

-uses the spore to enter the host and produces toxin only upon germination

Question 23

the ______ for sporulation and germination can be imp for disease

Answer 23

-triggers

Question 24

way to target spores with immune system

Answer 24

-immune system activates the spore and then immediately kills it when the capsule is off and it is vulnerable

Question 25

mycoplasma

Answer 25

- lack a proteoglycan so the cells will deform based on the local stresses - can squeese through filters because they are small - lack proteoglycan, so they can't be targeted by anti-microbials in that way - gram +

Question 26

mycobacterial envelope

Answer 26

- gram + - have sugars on the cell surgace that mimic host sugars and engage macrophage receptors that facilitate uptake and sequestration into a safe intracellular compartment, and they can stimulate anti-inflammatory responses - different tools on different mbs