Intro to Bacteria Flashcards

1
Q

Structure of a bacterium

A
  • Capsule
  • Cell wall
  • Plasma membrane
  • Cytoplasms, ribosomes
  • Single chromosome, no nucleus
  • Flagellum
  • Fimbriae - attachment
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2
Q

Describe Gram positive cell wall

A
  • Plasma membrane
  • Periplasmic space
  • Peptidoglycan
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3
Q

Describe Gram negative cell wall

A
  • Plasma membrane
  • Periplasmic space
  • Petidoglycan
  • Another Peri. space
  • Lipopolysaccharide nd protein outer membrane
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4
Q

Difference between cell wall of gram pos. and neg.

A

Negative has enter Periplasmic space and outer membrane of lipopolysaccharide

-Pos. has thick peptidoglycan wall with techoic acid and neg. has thin

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5
Q

What is the gram stain appearance of Gram positive?

A

Purple due to thick peptidoglycan wall

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6
Q

What is the gram stain appearance of Gram negative?

A

Pink

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7
Q

What is the shape of cocci?

A

Spepherical

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8
Q

What is the shape of bacilli?

A

Rod shaped

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9
Q

What do penicillin binding proteins do and name examples

A

Cross link peptidoglycan chains to form rigid cell walls

  • Transpeptidases
  • Carboxypeptidases
  • Endopeptidases
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10
Q

What is peptidoglycan?

A

Strong carbohydrate polymers cross linked with 3/5 amino acids

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11
Q

Function of the capsule

A

Helps bacteria to survive in host system and prevents it being phagocytosed

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12
Q

Describe the different types of Flagellum

A
  • Montrichous - 1
  • Lophotrichous - all at one point
  • Amphitichous - both sides
  • Peritrichous - all over
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13
Q

Give examples of bacteria with flagellum

A

Eacherichia coli and salmonella enterica

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14
Q

Function of fimbriae

A

Allow adhesion and cause infection

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15
Q

Use of spores by bacterium

A

Ensures survival of bacterium during environmental stress

-Resistant to UV, gamma rays, desiccation, temp, starvation and chemical disinfectants

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16
Q

Function of Periplasmic space

A

Contains enzymes important for digestion of materials, transporting material and detecting chemical gradients in environment

17
Q

What are plasmids?

A
  • Small, circular, double stranded DNA

- Can replicate independently

18
Q

Bacterial conjugation steps

A
  1. Donor cell (F+) produces pilus
  2. Pilus attaches to recipient cell (F-)
  3. Single strand of DNA from plasmid transferred to F-
  4. Both cells synthesise complementary strand
19
Q

How to bacterium replicate?

A

Binary fission (asexually)

20
Q

How is variation introduced?

A

Spontaneous mutation (random) and transfer of DNA - dead cells present containing DNA and if it’s advantageous then it is taken up

21
Q

Describe process of binary fission

A
  1. Cell replicates DNA
  2. Cell elongates, separating DNA molecules
  3. Division of bacterium - cytokinesis
  4. Two new daughter cells (genetically identical)
22
Q

What is a bacteriophage?

A

A virus which attacks bacteria and lyses them

23
Q

Describe detection and culture of bacteria

A
  • Individual bacteria can only be seen with microscope and gram staining
  • Colonies of individual bacteria cultured on solid medium (agar and then can be seen by eye
24
Q

Bacterial nomenclature

A
  • First part (i.e. staphylococcus) is genus

- Second part (i.e. aureus) is the species

25
Q

What technique is used to identify strained of a species?

A

DNA typing

-Strains of species have similar characteristics