Brainscape's Knowledge GenomeTM

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


See full index

Phase 2 > Microbiology & Infectious Diseases > Flashcards

Microbiology & Infectious Diseases Flashcards

1
Q

What is a virus?
Briefly describe its structure

A

An infectious, obligate intracellular parasite
Comprised of genetic material (DNA OR RNA) surrounded by a protein coat and/or a membrane

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

Big difference between Virus and Bacteria?

A

Virus IS dependent on host cell (bacteria is not)

Bacteria has cell wall, organelles, DNA AND RNA and are alive
Viruses have none of these things and are not alive

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

When virus is outside the cell, what is it called?

A

Virion?

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

How do viruses replicate?
Describe the 6 stages

A
  1. Attachment to specific receptor on host cell
  2. Cell entry - only central viral core (carrying the nucleic acids and some proteins) enters host cell
  3. Interaction with host cells - uses cell materials (e.g. enzymes, amino acids) for their replication
  4. Replication may localise in nucleus, cytoplasm or both
  5. Assembly - occurs in nucleus, cytoplasm or cell membrane
  6. Release - bursting open of cells OR leaking from cell over period of time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do viruses cause disease?
Give examples

A

Damage by :
- direct destruction of host cells e.g. HIV
- modification of host cell structure or function e.g. rotavirus
- over-reactivity of host host as response to infection e.g. hepatitis
- cell proliferation and cell immortalisation e.g. HPV
- evasion of extra AND intracellular host defences

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

What is a pathogen?

A

Organism that causes or is capable of causing disease

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

What is a commensal?

A

Organisms which colonises the host BUT causes no disease in normal circumstances

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

What is an opportunist pathogen?

A

Microbe that only causes disease if host defences are compromised

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

Define virulence / pathogenicity

A

Ability to cause disease once established

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

What is asymptomatic carriage?

A

When a pathogen is carried harmlessly at a tissue site where it causes no disease

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

What do gram negative bacteria have that gram positive don’t?

A

DOUBLE CELL MEMBRANE
2 membranes separated by lipoprotein, periplasmic space and petidoglycan

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

State and describe the types of bacterial toxins

A

ENDOTOXIN - part of outer membrane of bacteria

EXOTOXIN - proteins secreted by gram pos and neg bacteria

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

What does the coagulase test distinguish?

A

Distinguishes S.aureus from other staph
- will be COAGULASE POSITIVE

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

Types of gene mutation

A

Base sub
Deletion
Transfer

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

Types of gene transfer

A

Transformation e.g. plasmid
Transfunction e.g. via phage
Conjugation e.g. via sex pilus

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

Describe how to gram stain

A
  1. Apply primary stain (crystal violet) to heat fixed bacteria
  2. Add IODIDE - binds to crystal violet and fixes it to cell wall
  3. DECOLOURISE with ethanol or acetone
  4. COUNTERSTAIN with safranin (pink)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does gamma haemolysis imply?

A

NO haemolysis

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

Why does alpha haemolysis occur?
How does the agar appear?

A

BC production of hydrogen peroxide oxidising haemoglobin
GREEN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does beta haemolysis occur?

A

Bc lysis of RBCs by haemolysis such as Streptolysin O produced by S. pyogenes

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

What does an oxidase test test for?

A

If micro-organisms contains a cytochrome oxidase
implies organism able to use O2 as terminal e- acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Gram pos bacteria stain what colour?
Give an example

A

PURPLE
Staph. Aureus - coagulase positive

22
Q

What are the groups of Streptococci classification?

A
  1. Haemolysis
  2. Lancefield typing
  3. Biochemical properties
23
Q

What is lancefield grouping?

A

A method of grouping catalyse neg, coagulase neg bacteria
Based on bacterial carbohydrate cell surface antigens

24
Q

How do gram-pos bacteria spread?

A

Aerosols, surface-to-surface, colonisation of prostheses

25
Q

Virulence factors of Gram Neg bacteria?

A
  1. Colonisation factors - adhesins, invasins
  2. Toxins (effectors) - usually secreted proteins - damage, subversion
26
Q

Name the 4 major groups of Gram-Neg bacteria
Describe their shape

A
  1. Proteobacteria - ALL rod-shaped
  2. Bacteroids - rodshaped
  3. Chlamydia - round pleimorphic
  4. Spirochaetes - spiral/helical
27
Q

Why can is be difficult to culture pathogens in the lab?

A

Bc of dependency on host

28
Q

3 Types of Worms

A
  1. Nematodes (roundworms)
  2. Trematodes (flatworms)
  3. Cestodes (tapeworms)
29
Q

What type of nematodes can you get?

A

Intestinal
Larva migrans
Tissue (filaria)

30
Q

What type of trematodes can you get?

A

Blood
Liver
Lung
Intestinal

31
Q

What type of cestodes can you get?

A

Non-invasive
Invasive

32
Q

What is the pre-patent period?

A

Interval between infection and appearance of eggs in the stool

33
Q

What is a protozoa?

A

Single-celled eukaryotic organism with a definitive nucleus

34
Q

Name medically important mycobacteria

A

M. TB
M. leprae - leprosy
M. avium - disseminated infection in AIDS
M.kansasii - chronic lung infection
M.marinum - fish tank granuloma
M.ulcerans - buruli ulcer
Rapidly growing mycobacteria

35
Q

What is a Mycobacteria?

A

Aerobic, non-spore forming, non-motile bacillus

Slow reproduction
Slow response to treatment
Slow growing ∴ hard to culture

36
Q

Describe the cell wall of Mycobacteria

A

Contains high molecular weight lipids
Weakly gram-pos (or colourless)
Survive inside macrophages, even in low pH environments

37
Q

What is acid fast bacilli used for?

A

To identify organisms with wax-like, thick cell walls
E.G. MYCOBACTERIA (which are resistance to gram stain)

38
Q

Name some direct lab methods to diagnose bacterial infections

A

Gram stain
Acid fast stains
Wet film
KOH (fungi)
India ink

39
Q

Name some culture lab methods to diagnose bacterial infections

A

Solid media
Liquid media
Blood culture

40
Q

How do fungi move?

A

By growth or through generation of spores - carried thru air/water

41
Q

Describe fungi

A

Eukaryotic
Chitinous cell wall
Heterotrophic

42
Q

What is a dimorphic fungi?

A

Fungus that exists as both yeast and mould - switches between the 2 when conditions suit

43
Q

What are yeasts?

A

Small single celled organisms that divide by budding

44
Q

What do moulds form?

A

Multicellular hyphae and spores

45
Q

What does selective toxicity in treating fungal disease rely on?

A

Target does not exist in humans
Target is signif different to human analogues
Drug is conc in organism cell (respect to humans)
↑ permeability to compound
Human cells being ‘rescued’ from toxicity by alternative metabolic pathways

46
Q

Why can fungi be hard to treat?

A

Relatively few classes of effective antifungals

47
Q

Why can the total worm burden in a human not increase (unless constant re-exposure)?

A

Bc adult worms can’t reproduce in the body (without a period of development outside) ∴ if worm can’t get out, it will die

Can produce larvae/eggs but once grown, will die

48
Q

Define invasiveness

A

Capacity to penetrate mucosal surfaces to reach normally sterile sites

49
Q

5 Major groups of protozoa

A

Flagellates
Amoebae
Sporozoans
Ciliates
Microsporidia

50
Q
A

Phase 2 (24 decks)

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