Overview of Bacterial cells

Question 1

3 types of surface appendages

Answer 1

1. Capsule
2. Flagella
3. Pili

Question 2

Extracellular components

Answer 2

Toxins, enzymes, acids etc.

Question 3

Gram stain: Gram negative

Answer 3

Due to the thin cell wall and outer membrane, crystal violet/iodine complex is washed out during decolourization

Pink dyed stain due to counterstain with safranin

Question 4

Gram stain: gram positive

Answer 4

Thick cell wall traps crystal violet/iodine complex during decolourization, resulting in a purple stain

Question 5

Capsule: composition

Answer 5

Slime layer or glycocalyx

Made of carbohydrates
-except for the capsule of Bacillus anthracis which is a polypeptide

Not all bacteria will make them

Question 6

Capsule: 6 functions

Answer 6

1. Mediate adherence
2. Constitute biofilm matrix
3. Protect from phagocytosis
4. Refractory to antibiotics
5. Resist drying
6. Nutrient reservoir

Question 7

Flagella

Answer 7

Also called H antigen

Long threadlike proteinaceous structures

Question 8

3 parts of the flagellum

Answer 8

Basal body, hook, filament

Question 9

Monotrichous

Answer 9

Single flagellum at one end

Question 10

Lophotrichous

Answer 10

Cluster of multiple flagella at one end

Question 11

Amphitrichous

Answer 11

Single or multiple flagella at both ends

Question 12

Peritichous

Answer 12

covered with flagella

Question 13

Pili/Fimbriae

Answer 13

Fine hair like structures composed of proteins

Some can be receptors for bacteriophages

Question 14

Somatic pili role

Answer 14

Mediate adherence and biofilm formation

Question 15

Sex/F pili role

Answer 15

Mediate conjugation

Question 16

Cell Wall: function

Answer 16

1. Provide rigidity

2. Act as a physical barrier to hazardous agents

Question 17

Gram pos. cell wall

Answer 17

single, uniform, and thick (15-80 nm) layer of peptidoglycan

-highly crosslinked polymer of NAG and NAM

Question 18

Gram neg. cell wall

Answer 18

Thin peptidoglycan layer and an outer membrane

-periplasm is the space between the two

Question 19

Mycobacteria cell wall

Answer 19

Contains a layer of mycolic acids and arabinogalactan in addition to peptidoglycan

*mycobacteria are technically G+

Makes mycobacteria resistant to most conventional antibiotics

Question 20

Mycoplasma lack ___?

Answer 20

A cell wall

Question 21

Peptidoglycan composition

Answer 21

Consists of repeating units
of a N-acetylglucosamine (NAG) & a N-acetylmuramic acid (NAM) forming the glycan chains

Chains are cross-linked by short peptides

Question 22

Teichoic acids and lipoteichoic acids : composition

Answer 22

Unique to gram + bacteria

Linear polymers of glycerol or ribotol with phosphates

TA covalently linked to peptidoglycan

LTA contain FA chains, allowing molecules to anchor to cell membrane

Question 23

TA and LTA: function

Answer 23

Provide negative charges and hydrophobic sites for adherence

Act as a bacterial surface antigenic determinants
-recognized by immune cells

Question 24

Lipopolysaccharides (LPS): location

Answer 24

Unique to gram negative bacteria
-on outer leaflet of the outer membrane

also referred to as endotoxin

Question 25

Lipopolysaccharides (LPS): Composition

Answer 25

has 3 parts - lipid A - core plysaccharide - o-antigen (polysacchatide)

Question 26

Lipopolysaccharides (LPS): function

Answer 26

Responsible for a broad spectrum of pathophysiological effect such as inflammation and shock

Question 27

Porins

Answer 27

Located in the outer membrane of gram - bacteria and allow small hydrophilic molecules the enter the cell -ie. AA and antibiotics

Question 28

Cytoplasmic inner membrane: composition

Answer 28

Phospholipid bilayer with integral and peripheral proteins

Question 29

Cytoplasmic inner membrane: functions

Answer 29

1. Nutrient uptake 2. Ultimate barrier to hostile agents 3. Site of electron transport chain

Question 30

Cytoplasmic contents

Answer 30

DNA, ribosomes, proteins, ions Inclusion bodies Endospores Membrane invaginations (like photosynthetic structures) Gas vacuoles

Question 31

Inclusion bodies

Answer 31

Very useful to humans | -can be used in an industrial setting to decompose plastic bags (as an example)

Question 32

Endospores

Answer 32

harmless until they germinate, endospores are involved in a number of diseases in humans, such as tetanus (lockjaw) and gas gangrene.

Question 33

5 examples of extracellular products

Answer 33

Toxins, enzymes, acids, solvents, antibiotics