Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Fundamentals of Microbiology (Y2,S1) > Bacterial Cell Envelope > Flashcards

Bacterial Cell Envelope Flashcards

(48 cards)

Start Studying
1
Q

What are bacterial envelopes

A

Multilayered protective structures which provides protection against hostile external environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do the majority of bacterial envelopes consist of (3)

A
  1. Plasma membrane (lipid bilayer)
  2. Peptidoglycan (cell wall)
  3. Envelope proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Components of the bacterial cell envelope are targets for what

A

Antibiotics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Features of gram pos bacterial envelope

A
  • Thick peptidoglycan layer -> increased turgor pressure
  • Single membrane
  • Lipotechnoic & Technoic acid polymers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Features of gram neg bacterial envelope

A
  • Thin peptidoglycan layer
  • Inner membrane & outer membrane
  • Lipopolysaccharide (endotoxin) surface polymer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Features of mycobacterial bacterial envelope

A
  • Thin peptidoglycan layer
  • Single membrane
  • Mycolic acid layer (hydrophobic)
  • Arabinogalactan links mycolic acids and peptidoglycan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Features of wall-less bacterial envelope

A
  • No peptidoglycan synthesis
  • Must live in osmotically balanced environment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When & by who was the Gram Stain developed

A

In the 1880s by Hans Christian Joachim Gram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Function of Crystal Violet during gram stain

A
  • Pos charged
  • Binds to petidoglycan & neg charged polymers -> Teichoic acids & LPS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Function of Iodine during gram stain

A
  • Complexes w crystal violet
  • “Trapper” reagent -> prevents crystal violet being washed away in further steps
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Function of 95% Ethyl Alcohol during gram stain

A
  • Decolouriser reagent
  • Removes any dyes from lipid membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Function of Safranin during gram stain

A
  • Counterstain
  • Binds to peptidoglycan & associated polymers to give pink colour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Gram Pos gram stain resulting colour

A

Purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Gram neg gram stain resulting colour

A

Pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What feature of Mycobacteria makes gram staining impossible

A

The hydrophobic mycolic acid layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

3 functions of the plasma membrane

A
  1. Permeability barrier - prevents leakage, gateway fro transport of nutrients
  2. Protein anchor - site of proteins that participate in transport, chemotaxis
  3. Energy conservation - site of generation & dissipation of proton motive force
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the plasma membrane completely impermeable for

A

Ions
They require transport proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Components of the hydrophilic region of the phospholipid bilayer of the plasma membrane

A
  • Glycerol
  • Phosphate
  • Ethanolamine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the components of the hydrophobic region of the phosphlipid layer

A

Fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which have the more branched fatty acids chain; bacterial lipids or archaeal lipids

Study These Flashcards
A

Archaeel lipids have more branched chains of fatty acids -> can be more fluid

21
Q

What does peptidoglycan consist of

Study These Flashcards
A
  1. Amino acids (peptido)
  2. Repeating units of carbohydrates (glycan)
22
Q

Cell wall functions (6)

Study These Flashcards
A
  1. Structural strength to cell envelope
  2. Contains the plasma membrane
  3. Captures high concentrations of soluble molecules (nutrients etc) by acting like a sponge
  4. Contains osmotic pressure up to 208kPa
  5. Anchor for surface molecules - proteins & polymers
  6. Target for antibiotics
23
Q

What kind of peptidoglycan do gram pos bacteria have

24
Q

What kind of peptidoglycan do gram neg bacteria have

25
What does petidoglycan consist of
* A repeating disaccharide forming a polysaccharide backbone
26
What does NAM stand for
N-Acetylmuramic acid
27
What does NAG stand for
N-Acetlyglucosamine
28
What gives structural strength to peptidoglycan layers
Crosslinking of amino acids on adjacent polysaccharide strands
29
What are AAs attached to NAM called
The stem peptide
30
What position bond is stem peptide crosslinking in bacteria & archaea
Position 3 to position 4 peptide bond
31
What is the major molecular difference between Gram pos and neg peptidoglycan (GRAM NEG)
* Position 3 on the stem peptide * Gram neg stem peptide linkage is a **direct** linkage between meso-diaminopimelic acid (DAP) to D-alanine
32
What is the major molecular difference between Gram pos and neg peptidoglycan (GRAM POS)
* Position 3 on stem peptide * Gram pos stem peptide linkage is **indirect** between L-lysine and D-alanine, using a pentaglycine bridge
33
Osmosis
The diffusion of water across a membrane
34
Diffusion
The movement of particles from an area of high conc to an area of low conc
35
Active transport
Movement of particles against a concentration gradient
36
What do simple transporters use to facilitate transport of molecules in & out of the cell
They use H+ ions
37
How does an ANTIPORTER work
Transported molecule moves in the opposite direction to H+ to outside the cytoplasm
38
How does a SYMPORTER work
Transported molecule moves in the same direction as the H+ ion, into the cell
39
The phosphotransferase system (PTS system) is an exzmple of what kind of transport
Group translocation
40
What happens in the phosphotransferase system
* Requires multiple enzymes * Transported substances are chemically modified (glucose is phosphorylated, pyruvate is dephosphorylated)
41
The 3 components the ABC transporter system needs
1. Substrate binding protein (in periplasm/extracellular) 2. Transmembrane transporter 3. ATP hydrolysing enzyme (in cytoplasm)
42
What are teichoic acids
Simple polymers of repeating sugar units which decorate gram pos cells
43
What are the 2 types of teichoic acid and where are they found
1. Wall teichoic acid - covalently linked to peptidoglycan 2. Lipteichoic acid - attached to plasma membrane
44
What do the lipopolysaccharides on gram neg outer membrane consist of
1. Lipid A: Hydrophobic domain. Also known as an endotoxin!? 2. Core Oligosaccharide: Hydrophilic non variable (same repeating sugars) core oligosaccharide 3. O-antigen: repeating hydrophilic distal polysaccharide
45
What is the S layer
* Part of the envelope * Protein layer on outer membrane or peptidoglycan
46
WHat is the S layer anchored to and with what bonds
Anchored non covalently through interactions with LPS in gram negs and wall teichoic acids in gram pos
47
What is the capsule
They are gelatinous polysaccharide layers which cover bacterial cells
48
FUnctions of capsule
1. Prevents bacteria cells from desiccating in environment 2. Keeps bacteria hydrated 3. Inhibits phagocytosis during infection

Fundamentals of Microbiology (Y2,S1) (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions