Anatomy and Physiology SHC151 > Microbiology > Flashcards

Microbiology Flashcards

(57 cards)

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1
Q

What system classifies organisms? What is the exception?

A

Taxonomic ranking system
Except viruses

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2
Q

What is the binomial system of classification?

A

The two-part latin naming method

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3
Q

Which living organisms reproduce through spores?

A

Bacteria/fungi/both

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4
Q

What are spores?

A

single-celled units of reproduction

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5
Q

How are spores transported?

A

In air or liquid

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6
Q

What is germination?

A

The process by which an organism grows from a spore/seed.

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7
Q

What is metabolism?

A

Chemical reactions which occur within an organism

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8
Q

What is reproduction?

A

The process of producing new individuals

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9
Q

What is the ‘equation’ for growth?

A

Metabolism + Reproduction

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10
Q

What are the two types of bacterial growth?

A

Budding and fission

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11
Q

What is budding?

A

An outward growth which eventually detaches

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12
Q

What is fission?

A

Parent cells divide to produce two daughter cells

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13
Q

Fungi growth

A

Tend to grow as filaments called hyphae

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14
Q

What is an open growth system?

A

Nutrients for growth are constantly replenished and so population will not stop.

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15
Q

What is a closed growth system?

A

Nutrients for growth (+space etc) become limited and growth will eventually cease.

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16
Q

Unicellular organisms in a closed system growing in a liquid culture go through what 4 key growth phases?

A

Lag. log, stationary, death

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17
Q

Example question: For bacteria in a closed system with all of the nutrients required, describe how the growth process will proceed.

A

.

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18
Q

Example question: The stage where growth increases exponentially is called what?

A

The log phase

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19
Q

Describe the lag phase

A
  • No growth
  • Cells adapting to environment
  • Duration dependent on conditions
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20
Q

Describe the log phase

A
  • Depending on the exact conditions; the population doubles within certain times 20 mins +.
  • This is generation time
  • AKA exponential growth phase
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21
Q

Describe the stationary phase

A
  • Growth levels off as a result of nutrient depletion, space availability, toxic by-product formation etc
  • Limiting condition(s) prevent cells metabolising and growth ceases.
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22
Q

Describe the death phase

A

Cells begin to die due to limiting factors.
Population decrease = exponential

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23
Q

Ways of measuring growth

Study These Flashcards
A
  • Colony counts
  • Microscopy
  • Spectrophotometric absorbance
24
Q

Why is the lack of cellular growth not a fail-safe indicator of cell death?

Study These Flashcards
A
  • Certain species enter a dormancy phase where they remain alive but do not reproduce.
  • Some pathogenic species remain infective
25
What is a pathogen?
Cause of infection
26
Bacteria are;
- Microscopic - Single-celled (unicellular)
27
All bacteria contain plasmids...
Usually: circular DNA Also: Linear + RNA forms
27
Bacteria are prokaryotic. Therefore key features of bacteria:
- No; nucleus nor organelles - They do have cell walls - The are sensitive to antibiotics
27
Describe the genetic material in bacteria
- DNA - Single, circular bacterial chromosome
28
Two ways of classifying bacteria
- Shape - Gram staining
29
Describe cocci bacteria
- Spherical - Single/pairs/groups e.g. streptococci
30
Describe Bacilli bacteria
- Rod-shaped - Can have flagella e.g. TB
31
Describe Spirilla bacteria
- Never straight, appear twisted e.g. campylobacter
32
Summarise gram staining stages in 5 words/phrases
Fixation Crystal Violet Gram's iodine Decolouriser Safranin
33
First stage of gram staining and colour observations
Fix cells on slide and treat with crystal violet stain. Both positive and negative bacteria stain purple
34
Second stage of gram staining and colour observations
Treat with Gram's iodine solution to fix stain to cell Both positive and negative bacteria stain purple
35
Third stage of gram staining and colour observations
Treat with decolouriser e.g. ethanol Positive bacteria retain the purple colour Negative bacteria lose the purple colour
36
Fourth stage of gram staining and colour observations
Treat with safranin counterstain Positive bacteria remain purple Negative bacteria stain red
37
Describe gram +ve
Retain crystal violet Thick, layered wall Mainly exotoxins High resistance to physical damage and drying - due to thicker peptidoglycan cell wall layer Susceptible to antibiotics incl. penicilin
38
Describe gram -ve
Lose CV, counterstain safranin Thin, single layered Mainly endotoxins Low resistance to physical damage and drying out due to thinner peptidoglycan cell wall Susceptible to antibiotics incl. tetracycline
39
Describe the cell membrane
Phospholipid bilayer Controls movement in and out Allows cells to selectively interact with the environment
40
Describe the flagellum
Composed of the protein flagellin Originate at cell membrane and protrude through cell wall Present at either/both ends Sometimes on the whole surface Beat rhythmically for mobility: - seek nutrition - avoid unfavourable situations e.g. toxins - In photosynthetic bacteria to move towards the light.
41
Describe the cell wall
- Peptidoglycan - Gives the cell shape - Provides protection from the environment - Support for fimbirae and flagella - Allows resistance (to an extent) to changes in osmotic pressure
42
Describe the capsule
Polysaccharide covering Not all bacteria Roles: prevent drying out, protection from physical damage, protection from phagocytosis
43
Describe the DNA (in bacteria)
Typically single, circular bacterial chromosome Continuous strand Found localised in the nucleoid Contains genetic instructions for binary fission
44
Describe the fimbria(fimbriae)
AKA pilus(pili) Made of the protein fimbrilin Originate at the cell membrane and protrude through the cell wall Present in; most gram -ve and a dew gram +ve Help bacteria to attach to other cells and surfaces Important in pathogens to attach to the host
45
Describe the plasmid
Found in the cytoplasm of all baceria Seperate from chromosomal DNA Usually circular, linear + RNA also exist Genetic advantages: antibiotic resistance, provision of virulence factors in pathogenic bacteria.
46
Are viruses eukaryotes or prokaryotes?
Neither - No nucleus - No organelles
47
Infectious particles ->
- Utilise host cell to reproduce (only way to reproduce) - Not considered living = Obligate intracellular parasites
48
Some viruses possess:
An external membrane envelope
49
Virus structure
Made up of DNA or RNA genome contained within protein-rich coat = Capsid
50
Why is it difficult to make immunisations/ vaccines?
They contain surface proteins which can change
51
Shape/structure of a virus?
Exist in a variety shapes/structures
52
Life cycle of a virus
1) Entry into host 2) Spread in host to target cells 3) Viral replication in host cell 4) Spread to other cells and host organisms
53
How do viruses enter the host?
a) Respiratory tract b) Gastrointestinal tract c) Broken skin/mucous membranes d) Placenta
54
How do viruses spread to target cells?
a) Blood b) Lymph c) Nerves
55
Bacteria vs viruses
Bacteria: - Replicate outside the host cell - Genetic material DNA contain DNA and RNA - Are sensitive to antibiotics Viruses: - Replicate inside host cells - DNA or RNA - Are not sensitive to antibiotics
Anatomy and Physiology SHC151
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