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IPM > Bacteria Lectures 1-3 > Flashcards

Bacteria Lectures 1-3 Flashcards

Understand this Shiz

1
Q

Key distinguishing features of Prokaryotes from Eukaryotes?I

A

Prokaryotes:
- not compartmentalised (no ER, Mitochondria, lysosome)

  • ATP made in plasma membrane via oxidative phosp.

70s ribosomal unit as opposed to the 80s in eukaryotes

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2
Q

Steps of how to Do the Gram Stain

A

1: Crystal Violet is the primary stain
2: Iodine Solution/ Gram’s Iodine (fixes Violet in cell wall)
3: Decolouriser is applied e.g ethanol
4: Safranin (Counter stain)

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3
Q

How does Gram Stain work??

A

Gram +ve have thicker peptidoglycan layer (and lower lipid content) and can retain the crystal Violet stain

Gram -ve lose the crystal Violet stain and are instead stained by safranin

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4
Q

How does the Decolouriser work in Gram negative staining

A

It dissolves the lipid layer from the Gram -ve cells. The removal of lipid layer enhances the leaching of the primary strain from the cells into the surrounding solvent

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5
Q

How does the Decolouriser work on Gram +ve staining

A

The Decolouriser closes the pores as the cell wall shrinks during dehydration. As a result the diffusion of the violet-iodine complex out of cell is blocked + bacteria remains stained

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6
Q

What does prolonged exposure to Decolourising agent cause?

A

it will remove stains from both types of bacteria

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7
Q

Bacteria that lose the stain easily appear to be a mixture of gram +ve and gram -ve. This is known as

A

Gram Variable

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8
Q

what shape do Cocci appear as

A

Spherical

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9
Q

what shape do bacilli appear as

A

Rod shape

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10
Q

What shape do Spirillium appear as

A

Spiral

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11
Q

what shape do Vibric appear as?

A

curved rod shaped

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12
Q

What additional function do Prokaryotic cells have on their plasma membrane to Eukaryotes

A

Electron Transport and the Phosphorylation of ADP

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13
Q

3 Key features of the bacteria cytoplasmic matrix

A

1: Nucleoid - consists of supercoiled
2: Plasmid - Extra Chromosomal DNA often coding for antibiotic chromosome
3: Inclusion bodies - granules of organic/inorganic and may be bound by protein or lipid membranes

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14
Q

Features of a bacterial gram +ve envelope

A

Cell wall consists of many layers of peptigoglycan formed by alternating units of NAG and NAM cross-linked by short peptides.

NAG and NAM arrangements gives a strong and rigid but semi-permeable structure

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15
Q

State the 3 different Symbiotic Relationships with Microbes and Humans. State examples

A

Mutualism - e.g Lactobacillus acidophilus

Commensialism - e.g Escherichia Coli

Parasitism - e.g Helicobacter Pylori

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16
Q

What does NAG and NAM stand for

A

NAG = N-acetylglucosamine and NAM = N-acetylmuramic acid

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17
Q

Features of a bacterial gram -ve envelope

A

The most inner layer is composed of a phospholipid layer. Outer membrane is made up of lipopolysaccharide (LPS).

In between membrane = periplasmic space

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18
Q

On a gram -ve envelope, what does the periplasmic space consist of

A

Peptidoglycan layer and Periphrastic proteins

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19
Q

Tell me more about Lipopolysaccharide

A

Makes up the outer membrane of gram -ve bacteria and is an endotoxin. On destruction of the cell, it is released into the environment. This can be toxic to humans.

20
Q

What is Acid Fastness?

A

A physical property that relates to their resistance to decolourisation by acids in the staining procedure

21
Q

Give an example of an acid fast bacteria. What happens to it in acid-fast testing?

A

mycobacterium tuberculosis - It is stained red after the decolourisation step during the acid fast staining procedure

22
Q

Characteristics of a acid-fast bacterium

A

cell walls contain large amounts of lipid substance (mycolic acid) resulting in a very hydrophobic cell wall. This allows for survival within Macrophages and intrinsic resistance to antimicrobials

23
Q

External Components of all Bacterium

A

All bacterium secrete a form of glycocalyx. Having this layer aids adhesion to environment, and allows host to form a colony or bio-film formation. This helps inhibit opsonisation

24
Q

If glycocalyx is tighly bound to the cell, the bacterium is referred to as..

A

A Capsule

25
Q

If glycocalyx is loosely bound to the bacterium, it is referred to as…

A

The Slime layer

26
Q

What is Opsonisation

A

Identification and subsequent destruction by a phagocyte

27
Q

Describe the bacterial flagella

A

Long protein filament extending from cell envelope. The molecular motor is driven by Proton Motive Force.

28
Q

Describe the Pilli and state its role on a bacterium

A

Hair-like projections from the bacterium. Involved in conjugation & Plasmid transfer. Also involved in attachment to host epithelium.

29
Q

What can happen under environmental stress from bacteria, that allows them to resist destruction?

A
  • Formation of endospores (most commonly by genera of bacillus clostridium) They are highly resistant dehydrated structures containing bacterial genome.
  • Resistant to high temp, UV, Chemical and Enzymatic damage.
30
Q

What are Nitrogens used for biologically and give examples of nitrogen containing compounds

A

e.g NH4+ and NO3-. Nitrogen is a constituent of amino acids, nucleotide, phospholipids, cell wall component etc.

31
Q

What is Sulphur used for biologically and give examples of Sulphur containing compounds

A

e.g SH. Required for disulfide brdges, cysteine + Methionine + B Vitamins

32
Q

What is Carbon used for biologically and give examples of Carbon containing compounds

A

e.g CO2, CHO’s, Oil, Plastics. Carbon is the backbone for all functional biological molecules, sources.

33
Q

I know it’s simple but whats oxygen for

A

required for synthesis of organic molecules and as a terminal electron acceptor of electron transport in anaerobes

34
Q

Define Commensalism

A

Bacterium uses larger organism as its physical environment, acquiring nutrients, but not directly from host organism

35
Q

Define Mutualism and give a practical example where this occurs

A

Bacterium and larger organism have a mutually beneficial relationship e.g Normal gut flora digesting complex carbohydrates

36
Q

Define Parasitism

A

Bacterium lives at the expense of the larger organism

37
Q

An Anaerobe that is completely dependent on oxygen for growth is called… and an example is..?

A

Obligate Aerobe, e.g Mycobacterium Tuberculosis, lives in the lungs

38
Q

A Bacterium that does not require oxygen for growth but grows better in its presence is called.. e.g..?

A

Facultative Anaerobe e.g Escherichia Coli

39
Q

A Bacterium that grows equally well in the presence & Absence of oxygen is called… e.g?

A

Aerotolerant e.g Streptococcus Pyogenes

40
Q

A Bacterium that dies in the presence of oxygen is called.. eg?

A

Obligate Anaerobe e.g Clostridium Spp - These produce spores that can exist outside the body. Faecal Oral contact allows spores to enter GI then germinate

41
Q

A Bacterium that requires 2-10% of oxygen and is damaged by atmospheric oxygen is called.. eg?

A

Microaerophile e.g Treponema Pallidum

42
Q

What is a primary metabolite and provide examples

A

Primary metabolites are produced during the log phase of growth. It is essential for cells growth, e.g Amino Acids, Lipids, etc

43
Q

What is a secondary metabolite and provide examples

A

Secondary metabolites are produced at the onset of the stationary phase or as a result of quorum sensing; e.g Alkaloids, Antibioitics, Toxins, Pheromones etc.

44
Q

Reasons for high bacterial abundance

A
  • divide rapidly
  • diverse set of species physiology
  • aerobic or anaerobic bacteria exist
45
Q

what is sterilisation of microbes?

A

The complete removal of microbes or damaging microbes such that all our killed. It does not use antimicrobial agents. e,g

  • Heat
  • Ionising
  • Filter sterilisation

IPM (15 decks)

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