Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology and Genetic Toxicology > Microbiology > Flashcards

Microbiology Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is the major cause of infectious disease in humans?

A

Bacteria

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

What do bacteria do?

A

Encounter and gain access to host

Evade defence mechanisms

Colonise and maintain colony

Result in host toxicity or damage

Potential for spread of infection (but not always the case)

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

What are the key features of a Prokaryote cell?

A

Smaller and simpler in size than eukaryotic cells

No membrane-bound organelles (no nucleus, mitochondria, Golgi etc.)

Single DNA genome

Plasmid DNA free in cytoplasm

Enzymes and ribosomes free in cytoplasm

Rigid, complex wall with appendages

Extreme adaptation to environment (pH, enzymes, viscosity etc.)

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

What is Flagella, Fimbriae and pili used for?

A

Flagella used for motility and also as a sensory organelle (detect chemicals in the environment, the temperature of the environment etc).

Fimbriae and pili used for cell adhesion

Sex pili important for movement of DNA between cells by conjugation

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

What do capsules do?

A

Surrounds certain Gram –ve and Gram +ve bacteria

Aids cells adherence by the slime layer

Protect from neutrophils (impermeable to lysosome contents)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Purpose of cell wall?

A

To give structure to the cell

To maintain positive internal osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does Peptidoglycan contain?

A

Contains N-acetylglucosamine (NAG) and N-acetylmuramic (NAM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Difference in structure between Gram -ve and Gram +ve

A

Go to lecture slide

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

What is Peptidoglycan?

A

A substance forming the cell walls of many bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain Gram +ve Peptidoglycan?

A

Contains a Carbohydrate backbone at the top – just NAM and NAG connected together

Contains an amino acid cross bridge – five glycine

Contains amino acid side chain – different amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain Gram -ve Peptidoglycan?

A

Has the same structure as +ve but no amino acid cross bridge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain Gram +ve cell wall?

A

You have a phospholipid bilayer (cytoplasmic membrane) and protein channels going through.

Then you have the peptidoglycan layer, consisting of NAM and NAG residues, peptide bonds. Then you have cell wall (surface) proteins attached; and you have teichoic acid and lipoteichoic acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain Gram -ve cell wall?

A

You have the cytoplasmic membrane.

The peptidoglycan is very thin and this is called periplasm.

The entire cell wall consist of the peptidoglycan layer and an outer membrane. On the outer membrane you have LPS – O polysaccharide.

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

Where are Periplasm found?

A

Only found in Gram -ve cell walls.

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

What is contained in the aqueous gel-like region between the two membranes of Gram –ve bacteria?

A

Contains enzymes associated with nutrient acquisition and transport

Also contains defence enzymes used to resist antibiotics

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

Which cell wall has an outside membrane?

A

Gram -ve cell walls.

17
Q

What is on the outside cell wall of Gram -ve?

A
  • Porins that allow passive diffusion of molecules into periplasmic space
  • Braun’s lipoprotein that anchors outer membrane
  • Llipopolysaccharides
18
Q

Explain how both Grams are differentiated?

Explain the test carried out?

A
  • Heat with crystal violet
  • Add iodine solution
  • Decolourise with alcohol
  • Stain with safranin

They both take in dye:
- Insoluble crystals are formed

  • Crystals escape Gram –ve
  • Red stain seen in Gram –ve
19
Q

What are the three types of active transport in bacteria?

A

PMF-driven transport

ABC transport (ATP-Binding Cassette)

Group translocation eg. Glucose 6-P

20
Q

Explain the structure of Nucleoid in Prokaryotic DNA?

A

Circular, supercoiled, double stranded

Not associated with histone proteins

Generally only one chromosome

21
Q

Explain the structure of Plasmids in Prokaryotic DNA? And functions?
(not essential for survival)

A

Small loops of extrachromosomal DNA

May contain genes that are expressed in response to certain situations

May be used to transfer genes between cells

Cell be incorporated into the chromosome

Single DNA stand transferred between cells by conjugation using ‘rolling circle’ replication

22
Q

Explain Ribosome and Translation?

A

There are:
Small 30S subunit binds in mRNA – bind to the messenger RNA

Large 50S subunit binds, completes 70S ribosome

– binds to and completes the 70s ribosome

23
Q

Explain Streptococcus Pneumoniae ?

A

Gram +ve

Encapsulated coccus

Causes respiratory infections

SEM x3750

24
Q

Explain Escherichia Coli?

A

Gram –ve

Flagella and fimbriae

Enteric, urinary and nosocomial infections

SEM x3515

25
Q

Explain Escherichia Coli 0157:H7 – anaerobic form of E.Coli?

A

Gram –ve rods

Anaerobic

Causal agent of haemorragic disease due to toxic secretion

SEM x9335

26
Q

Explain Clostridium difficile?

A

Gram +ve rods

Anaerobic

Forms part of normal gut microflora

Causes inflammation (colitis) and abdominal disease

SEM x1200

27
Q

Explain Helicobacter Pyori?

A

Gram –ve spirals

Moves using flagella

Associated with chronic superficial gastritis

SEM x2200

28
Q

Explain Mycobacterium tuberculosis?

A

Gram +ve rods

Moves using flagella

Able to reside inside tissue due to hydrophobic cell wall

SEM x3000

29
Q

Explain Staphylococcus aureus?

A

Gram +ve cocci

MRSA

Causes a variety of infections and disease

SEM x13335

30
Q

Explain how Antibacterial Chemotherapy works?

A

Treats a bacterial disease and causes minimal toxicity to host.

It does this by exploiting biochemical differences between the infectious organism and the host organism .

31
Q

What are the two types of antibiotics?

A

Bactericidal and bacteriostatic

Bactericidal = kills bacteria

Bacteriostatic = stops bacteria growing (it can also kill bacteria in patients, it’s just a matter of time and exposure)

32
Q

What is Minimum Bactericidal Concentration (MBC)?

A

The lowest concentration of antibacterial agent, that reduces the viability of a bacterial inoculum by more or equal to 99.9%

33
Q

What is Minimum Inhibitory Concentration (MIC)?

A

The lowest concentration of a chemical, which prevents visible growth of a bacterium.

34
Q

When is a drug considered bactericidal?

A

A drug is considered bactericidal if:

MBC is no more than four times the MIC.

35
Q

Explain the Antibiotic Susceptibility Test to determine MIC?

A

Strips impregnated with a gradient of antibiotic, are placed on a lawn of bacteria and are incubated.

MIC is determined at the point where the zone of inhibition intersects the scale.

36
Q

What are the Two strategies for Antibacterial Chemotherapy?

A

Targeting reactions and Targeting structures.

37
Q

Explain class 1 reaction for Anabolic cell metabolism?

A

Carbon sources used to produce simple compounds

Similar mechanism in prokaryotes and eukaryotes

Bacteria can utilise alternative carbon sources

38
Q

Explain class II reaction for Anabolic cell metabolism?

A

Use Class I products to make small molecules

Different pathways exist in prokaryotes and eukaryotes

Sam pathway may have differing sensitivity

39
Q

Watch video

A

Watch video

Microbiology and Genetic Toxicology (2 decks)

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