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Microbiology > Lecture 3 - Structure and function of bacteria > Flashcards

Lecture 3 - Structure and function of bacteria Flashcards

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Biology 101 flashcards
1
Q

What is the capsule composed of and how can it be protected

A

Polysaccharides or polypeptide (called slime layer or glycocalix) which is a sticky layer of goo on outside.

It can prevent desiccation and prevent phagocytosis as the slime capsule can hide the bacteria from the immune system a bit more

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2
Q

What does plaque (e.g.streptococcus mutans) stick to teeth

A

The sticky capsule

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3
Q

Describe a biofilm

A

Community of microorganisms stuck together in a goo so they stick to a surface. They function as a unit.

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4
Q

Describe issues with bio films

A

Hard to control, more resistant to cleaning and antibiotics.

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5
Q

Name and describe the 4 types of flagella

A

Monotrichous - single polar flagellum
Lophotrichous - two or more at one/both ends
Amphitrichous - single polar flagellum at each end
Peritrichous- disturbed over entire cell

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6
Q

Describe a typical prokaryotic cell

A

Cytoplasm, nucleoid, ribosomes, cytoplasmic membrane, cell wall, capsule, flagella

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7
Q

In gram negative or gram positive bacteria does the flagellum spin anti-clockwise to move forward?

A

Gram negative

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8
Q

What are the 3 rings called in the flagellum that penetrate the cell wall (from lipid layer to inner membrane)

A

L (lipid)
P (peptidoglycan)
M (membrane -inner)

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9
Q

Which way would gram negative bacteria spin their flagellum to move backwards

A

Clockwise

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10
Q

What is the process called of a bacterial cell undergoing motility and describe the process

A

Run and tumble.
Run - moving forward towards with bundled flagella
Tumble - flagella pushed apart from clockwise rotation until aware of direction to travel
Run again in direction

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11
Q

What are the two types of Chemotaxis and describe the

A

Positive Chemotaxis - movement towards a molecule

Negative - movement away from a molecule

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12
Q

What is the difference between fimbrae and pili

A

Fimbrae - early attachment structure, have hooks so organisms moved through the body with food use fimbrae to grapple on side of gut

Pili- join 2 cells together. Bacteria can undergo a form of sexual recombination of genome through pilus (whereas normally clone) give to DNA to another cell

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13
Q

How many fimbrae are there compared to pili

A

Fimbrae many fibres whereas pili one to two per cell

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14
Q

What protein is pili made of

A

Pillin

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15
Q

List two functions of the cell wall in gram negative and positive bacteria

A

Prevent osmotic rupture and contributes to disease mechanisms

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16
Q

What are the repeating subunits that form peptidoglycan

A

NAG - N-acetylglucosamine

NAM - N-acetylmuramic acid

17
Q

What does the outer membrane of the gram negative bacteria have

A

Lipopolysaccharide sticking up - endotoxins which trigger the immune system to give certain presentations of gram negatives infection. Also has a porin protein

18
Q

What is the LPS made of

A

LIPID A and O polysaccharide

19
Q

How much of bacterial cells are water

A

70%

20
Q

What is the internal matrix of the cell (cytoplasm) composed of and what other things are contained within the cytoplasm

A

80% H2O
Proteins, COH, lipids

Other things - inclusion bodies (store things), DNA, ribosomes

21
Q

How is the genome split in bacteria

A

Chromosomes and plasmid (replicate independently of genome) which is transferable.

22
Q

What is conjugation?

A

Pilus is link where copied plasmid can go through so both cells have plasmid

23
Q

What is transformation?

A

Transfer genetic info without the bacterial cell being in the environment. When cells die they tend to lyse - bacterial cells take up DNA when naked DNA bind to cell wall and taken up by bacteria.

24
Q

What is transduction

A

VIRUSES Take DNA from one cell and put it in another.

25
Q

What is horizontal gene transfer

A

Bacterial genome influenced by environment leads to changes e,g. Plasmid and genetic lineage taken up by surrounding cells e.g. Lecturer give us info

26
Q

What is vertical Lineage

A

Bacterial cells give info to offspring e,g, lecturer give info to his children

27
Q

What is the total S for the ribosomes in prokaryotes and eukaryotes

A

70s prokaryotes

80s eukaryotes

28
Q

What antibiotics target ribosomes

A

Streptomycin
Neomycin
Tetracyclines

29
Q

Name the inclusion body that stores phosphates if there is a loss of them

A

Volutin

30
Q

On what type of bacteria do endospores occur and give examples

A

Gram positive

Clostridium and bacillus

31
Q

At what 4 positions can the endospore form

A

Terminally (at one end)
Sub terminally (near one end)
Centrally
Size (same size as cell so doesn’t make it swell)

32
Q

Is sporulation a replicative process

A

No the cell undergoes sporulation to protect the cell from a harsh environment
1 cell = 1 endospore

33
Q

Describe the process of sporulation

A

1- Take a big bit of genome and move it to one Side of cell
2- begin to grow membrane around it so forms a forespore
3- start to protect it layer it in coats of peptidoglycan so if environment gets harsh then it is protected.
4- when environment gets better the cell starts to grow out and it’s called germination.
5- water gets into cell so spore swims away

34
Q

Describe the process of germination

A 
1- germination 
2- swelling
3- shedding of spore wall
4- outgrowth of vegetative cell 
5- cell division
35
Q

Compare exotoxins and endotoxins

A

Exotoxins - gram + bacteria, produced inside bacteria as part of growth and released from cell

Endotoxins - part of gram - cell wall.

36
Q

Describe the structure of exotoxins and their features

A

Protein molecules - have active (a group) subunit and binding (b group) subunit so SPECIFIC

MAINLY GRAM +

  • soluble in blood
  • rapid transmission
  • rapid onset of symptoms
37
Q

Give two examples of exotoxin producers

A

Clostridium botulinum - inhibits release of acetylcholine (toxin bind to other side, muscle flaccid and paralysis)

Clostridium tetani - inhibits removal of acetylcholine (spasmic paralysis, tetanus toxin blocks other side, fits and spasms and die)

38
Q

Describe the structure of endotoxins and their features

A

Outer cell wall of gram -.
Lipid portion of LPS - lipid A
Released on cell lysis

Symptoms, same regardless of species
- severity can vary
- fever, weakness, general aches, shock.
Cause immune system to go into panic

General

Microbiology (5 decks)

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