Brainscape's Knowledge GenomeTM

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


See full index

MD2001 > Microbial Structure > Flashcards

Microbial Structure Flashcards

1
Q

What is the difference in the genetic material of eukaryotes vs prokaryotes concerning nuclei?

A

Eukaryotes:
- has true nucleus; bound by double membrane

Prokaryotes:
- no nucleus; has a nucleoid; no physical boundary

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

What is the difference in the genetic material of eukaryotes vs prokaryotes concerning DNA?

A

Eukaryotes:

  • linear DNA
  • organised into chromosomes; complexes with proteins

Prokaryotes:

  • circular DNA
  • DNA “naked”; plasmids present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the difference in the genetic material of eukaryotes vs prokaryotes concerning ribosomes?

A

Eukaryotes:
- large complex ribosomes with many types of rRNA & proteins

Prokaryotes:
-70S ribosomes

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

What is the difference in structure between eukaryotes and prokaryotes concerning membrane bound organelles?

A

Eukaryotes:
+ Cytoplasm filled with large complex collection of membrane bound organelles

Prokaryotes:
+ No membrane bound organelles independent of plasma membrane

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

Which type of cells have mitochondria and what are they?

A

Eukaryotes - mitochondria with cristae are “energy centres”

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

Which type of cells have mesomes and what are they?

A

Prokaryotes - mesomes are used in aerobic respiration, cell division, DNA replication

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

What are the structural components of bacteria?

A 
\+ Capsule
\+ Pili (fimbriae)
\+ Flagellae
\+ Spores
\+ Slime
\+ Cell wall
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are features/properties of the bacteria capsule?

A

+ Loose polysaccharide structure
+ Protects cell from phagocytosis
+ Protects cells from dessication

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

What are features/properties of pili?

A

+ Singular = pilus “hair”

+ Composed of oligomeric pilin proteins

+ Appendage used for bacterial conjugation

+ Forms tube/bridge to enable transfer of plasmids between bacteria

+ Highly antigenic

+ Plays role in attachment

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

What are the features/properties of fimbriae?

A

+ Singular = fimbria “thread”

+ Not on all bacteria

+ May contain lectins which recognise oligosaccharide units on host cells

+ Facilitates bacterial attachment to host surfaces

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

What are the features/properties of flagellae?

A

+ Singular = flagellum “whip”

+ Organs of locomotion

+ Single/multiple

+ Composed of flagellin protein

+ 20nm-thick helical hollow tube

+ Driven by rotary engine at anchor point on inner cell membrane

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

What are the features/properties of spores?

A

+ Metabolically inert form triggered by adverse environmental conditions

+ Adapted for long-term survival allowing regrowth under suitable conditions

+ Hard, multi-layered coats making spore difficult to kill

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

What are some common diseases caused by sporing bacteria?

A 
\+ Botulism 
\+ Gas gangrene
\+ Tetanus
\+ Food poisoning
\+ Anthrax
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What sporing bacteria causes botulism?

A

Clostridium botulinum

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

What sporing bacteria causes gas gangrene?

A

Clostridium perfringens

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

What sporing bacteria causes tetanus?

A

Clostridium tetani

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What sporing bacteria causes food poisoning?

A

Clostridium perfringens

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

What sporing bacteria causes anthrax?

A

Bacillus anthracis

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

What are the features/properties of slime?

A

+ Polysaccharide material

+ Secreted by some growing bacteria in biofilms

+ Protects against immune attack

+ Protects against eradications by antibiotics

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

What is Gram staining?

A

+ Based on chemical and physical properties of the cell walls

+ Differentiates bacterial species into 2 groups:

  • Gram positive (+)
  • Gram negative (-)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the 4 steps involved in Gram staining?

A
  1. Primary stain
  2. Trapping agent
  3. Decolourisation
  4. Counterstain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is involved in step 1: Primary stain?

A

Cresyl violet dye stains all the bacterial cells purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is involved in step 2: Trapping agent?

A

+ Gram’s iodine is used

+ Forms CVI complexes in cell wall (larger than CV so not to be easily washed out of the PGN layer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is involved in step 3: Decolourisation?

A

+ Alcohol/acetone is utilised

+ Interacts with lipids in cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens during decolourisation if the bacterial is Gram negative?

A

+ Loses outer LPS layer
+ Exposes thin inner PGN layer
+ Coloured complexes mainly wash away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens during decolourisation if the bacteria is Gram positive?

A

+ Becomes dehydrated and traps the complexes in thicker PGN layer of cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is involved in step 4: Counterstain?

A

The dye safranin is used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What colour is the cell if it is Gram negative?

A

Pink/reddish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What colour is the cell is it is Gram positive?

A

Purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does PGN stand for?

A

Peptidoglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What does LPS stand for?

A

Lipopolysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What does LTA stand for?

A

Lipoteichoic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the cellular differences in Gram positive and Gram negative regarding layers of the cell?

A

Gram positive:
+ 2 layers
- thick PGN layer
- cytoplasmic membrane

Gram negative:
\+ 3 layers
- outer membrane
- thin PGN layer (inside periplasmic space)
- cytoplasmic membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the differences in cell wall components between Gram positive and Gram negative?

A

Gram positive: LTA

Gram negative: LPS

35
Q

What are the different cell wall components?

A

+ Peptidoglycan (PGN; murein)
+ Lipoteichoic Acid (LTA)
+ Lipopolysaccharide (LPS)
+ Outer Membrane Proteins (OMPs)

36
Q

What are the features of peptidoglycans?

A

+ Comprised from polymers of sugars and amino acids
+ Forms mesh-like layer outside plasma membrane
+ Sugar component = alternating residues of N-acetylglucosamine + N-acetylmuramic acid

37
Q

What are the features of lipoteichoic acids?

A

+ Complex of lipoteichoic acid and lipids
+ Provides cell rigidity
+ Recognised by host immune cells

38
Q

What are the features of lipopolysaccharides (Gram -ve)?

A

+ Essential for function of outer membrane
+ Elicits potent immune and inflammatory host responses
+ Produces endotoxins

39
Q

What are the features of outer membrane proteins?

A

+ Consist of lipoproteins & porins

+ Not endotoxins but do contribute to virulence

40
Q

Features of bacterial replication of genome

A

+ Reproduce by binary fission (asexual)
- 1 cell reproduces to give 2 daughter cells

+ Genetic information found in circular DNA
- distributed equally between each daughter cell

+ DNA is a self-replicating molecule
- can make an exact copy of itself before cell division

+ Circular DNA; replication starts at ‘origin’

  • replicates in 2 directions (bi-directional replications)
  • 2 replication forks split off from origin and meet at bottom
41
Q

What are features of the bacterial growth cycle?

A

+ During active growth, the number of cells continuously doubles at specific time intervals

+ Each binary fission takes a specific duration of time (depends on bacterium)

+ 1=21 =22=23 =24 =25 =26 …2n n = number of generations

42
Q

What are the 4 bacterial growth phases?

A

+ Lag
+ Log/exponential
+ Stationary
+ Death

43
Q

What happens in the Lag Phase (1)?

A

+ Represents the period of active growth (i.e in size, not number)

+ Bacteria prepare for reproduction i.e synthesising DNA and enzymes for cell division

44
Q

What happens in the Log/Exponential Phase (2)?

A

+ Cells divide at maximum rate
+ Uniform cell replication
+ Graph line is almost straight (vertical)

45
Q

What happens during the Stationary Phase (3)?

A

+ Cessation of growth
+ Exhaustion of nutrients
+ Accumulation of inhibitory end products of metabolism or oxygen availability
+ Number of cells dying balances the number of new cells so the population stabilises

46
Q

What happens during the Death Phase (4)?

A

+ Number of dying cells starts to exceed the number of newly born cells so the number of viable cells starts to deline

47
Q

Due to what characteristics are bacteria classified/identified?

A

+ Gram stain: positive/negative
+ Cell shape: cocci; bacilli; helical/spiral
+ Atmosphere preference: aerobic; anaerobic; michroaerophilic
+ Key enzymes
+ Fastidiousness

48
Q

What shape are ‘cocci’ bacteria?

A

Spherical

49
Q

What shape are ‘bacilli’ bacteria?

A

Rod-shaped

50
Q

What shape are ‘spiral’ bacteria?

A

Helical rod

51
Q

Which bacteria are Gram positive?

A

+ Staphylococcus aureus

+ Listeria monocytogenes

52
Q

What are the structural components of viruses?

A

+ Nucleic acid
+ Capsid
+ Envelope
+ Spikes

53
Q

What types of nucleic acid might be involved as a structural component of viruses?

A

+ ds DNA
+ ss DNA
+ ds RNA
+ ss RNA

54
Q

What are the features of Capsids?

A

+ Protein coat/shell

+ Composed of protein subunits (capsomeres)

+ Capsomeres consist of aggregated protomeres

+ Various shapes of caspids

  • rod-like
  • polyhedral
  • complex
55
Q

What are the features of an envelope?

A

+ Amorphous structure surrounding some viruses

+ Composed of lipid, protein & carbohydrate

56
Q

What are the features of spikes?

A

+ Glycoprotein projections arising from envelope

+ Highly antigenic

+ May have enzymatic, adsorption or haemagglutin activity

57
Q

What are features of viruses?

A

+ Intracellular obligate parasites

+ Uses host’s cellular machinery to replicate

+ Produces many progeny which leave host to infect other cells in the organism

+ May infect any type of cell

  • animal
  • plant
  • bacterial
58
Q

What are the 6 steps in viral replication?

A
  1. Adsorption
  2. Penetration
  3. Replication
  4. Assembly
  5. Maturation
  6. Release
59
Q

Step 1 - Adsorption:

A

+ Virus binds to host cell

+ Highly specific

60
Q

Step 2 - Penetration:

A

+ Virus injects its genome into host cell

+ Occurs by:

  • fusion
  • binding
  • ingestion
61
Q

Step 3 - Replication:

A

+ Capsid digested by proteolytic enzymes

+ Viral genome replicates using host’s cellular machinery

62
Q

Step 4 - Assembly:

A

+ Viral components and enzymes are produced and begin to assemble

63
Q

Step 5 - Maturation:

A

+ Virus fully develops

64
Q

Step 6 - Release of Naked Viruses

A

+ Occurs at site of nucleic acid replication

+ Viral enzymes break down bacterial cell wall

+ RNA viruses released as they are produced

+ DNA viruses expelled from host cell:

  • as cells autolyse
  • in inclusion bodies
65
Q

Step 6 - Release of Enveloped Viruses

A

+ Viruses migrate to either plasma membrane or nuclear membrane

+ Envelopes formed around nucleocapsids by “budding” of cell membrane

+ Slow continuous release of mature viral particles

+ No inclusion bodies

66
Q

What are protozoa?

A

Single celled eukaryotes

67
Q

What are the different classifications of protozoa?

A

+ Sporozoa: intracellular parasites

+ Flagellates: possess tail-like structures for motility

+ Amoeba: use temporary cell-body projections (pseudopods)

+ Ciliates: move by beating multiple hair-like structures (cilia)

68
Q

Name some common protozoal infections:

A

+ Malaria
+ Giardiasis
+ Toxoplasmosis
+ Cryptosporidiosis

69
Q

What protozoa causes Malaria?

A

Plasmodium falciparum

70
Q

What protozoa causes Giardiasis?

A

Giardia lamblia

71
Q

What protozoa causes Toxoplasmosis?

A

Toxoplasma gondii

72
Q

What protozoa causes Cryptosporidiosis?

A

Cryptosporidium parvum

73
Q

What are features of fungi?

A

+ Eukaryotic
+ Multinucleate or multicellular organisms
+ Yeasts are single-celled
+ Thick carbohydrate wall containing chitin and glucans
+ usually grow as thread-like filaments (hyphae)
+ Reproduce asexually by budding, and occasionally by binary fission
+ Part of normal macrobiota as well as being pathogens
+ Fungal infections = “mycoses”

74
Q

What are some common fungal infections?

A

+ Candidiasis
+ Cryptococcosis
+ Aspergillosis
+ Ringworm

75
Q

What causes Candidiasis?

A

Candida Albicans (yeast)

76
Q

What are features of Cryptococcosis?

A

+ Cryptococcus neoformans

+ Encapsulated yeast

+ Lab diagnosis by India Ink

+ Mainly treated with amphotericin B

+ Affects lungs or meninges

77
Q

What are features of Aspergillosis?

A

+ Aspergillus flavus (yeast)

+ Production of aflatoxins

+ Spores inhaled

+ Immune response and hypersensitivity pneumonitis results

78
Q

What are features of ringworm?

A

+ Tinea corporis (tinea pedis is athlete’s foot)

+ Skin infection

+ Affects scalp, skin, fingernails, toenails, feet

79
Q

What are features of helminths?

A

+ 3 main groups important in humans

+ Infections most common in tropical/sub-tropical climates

+ Usually intestinal species

80
Q

What are the 3 main groups of helminths?

A

+ Cestoda: tapeworms

+ Trematoda: flukes

+ Nematoda: roundworms

81
Q

What are the transmission pathways of helminths?

A

+ Via intermediate host
+ Faeco-oral route
+ Active skin penetration
+ Injection by blood-sucking insect

82
Q

What are features of the helminth: Schistosomiasis (bilharzia)?

A

+ Fluke (trematode)
+ Schisosoma haematobium, schistosoma mansoni, schistosoma japonica
+ Larval development in aquatic snails
+ Urinary & intestinal infections

83
Q

What are features of the helminth: Trichiuriasis?

A

+ Nematode (roundworm)
+ Trichuris trichiuria
+ Human whipworm
+ Intestinal infection

84
Q

What are features of the helminth: Tapeworm?

A 
\+ Taenia solium
\+ Acquired from ingesting worms or eggs in undercooked pork
\+ Reside in large intestine
\+ Can grow up to 7m long
\+ Scolex (sucker/hooks) for attachment

MD2001 (52 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions