Microbiology 1-2 Flashcards

1
Q

What are the three types of bacterial shapes?

A

Cocci (spherical, bacilli (rod-like) and spirilli

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2
Q

What does a gram stain distinguish between?

A

Gram negative and gram positive bacteria depending on whether peptidoglycan in present in the cell wall.

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3
Q

What colour will gram positive bacteria stain?

A

Deep violet due to thick peptidoglycan layer in the cell wall.

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4
Q

What colour will gram negative bacteria stain?

A

Pink as the layer of peptidoglycan is much thinner than in gram positive bacteria.

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5
Q

What is the structure of gram negative bacteria membranes?

A

Two membranes (plasma membrane and an outer membrane) with a periplasm of peptidoglycan in the middle.

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6
Q

What is the exception to gram negative and positive bacteria?

A

Mycobacteria - they have a waxy outer layer instead.

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7
Q

What is flagellum?

A

A highly complex structure made up of several proteins to facilitate proton-notice force needed for movement. It rotates and properly the bacteria to where it is needed.

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8
Q

What is an injectosome?

A

Structure evolutionarily related to flagellum that is involved in bacterial internalisation and actin polymerisation.

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9
Q

How large are bacterial genomes?

A

Big. Between 500 and 4500 proteins.

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10
Q

What percentage of bacterial genes are essential?

A

40%

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11
Q

What causes strains to be different from one another?

A

The 60% accessory genes.

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12
Q

How do bacteria replicate?

A

Binary fission

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13
Q

What is horizontal gene transfer?

A

Acquisition of genetic information by transfer from an organism that is not the parent and it not normally the same species.

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14
Q

What are the three mechanisms for horizontal gene transfer?

A
  • Transformation (DNA uptake and homologous recombination)
  • Conjugation (transmissible plasmid)
  • Transduction (replication of bacteria and packaged into phages)
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15
Q

Examples of viruses that enter via the upper respiratory tract?

A

Influenza
Measles
Pneumonia
MRSA

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16
Q

Example of an extrinsic source of infection in the urogenital tract?

A

Infected catheter

17
Q

What are the ways which infection can enter via broken skin?

A
  • Surgery
  • Any open wound
  • Insect bite
  • Cannula/IV
18
Q

What is pathogenicity?

A

The ability to cause disease.

19
Q

What is the infectious dose?

A

Number of bacteria required to initiate an infection.