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Bacteria Flashcards

(60 cards)

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1
Q

Why should we study bacteria?

A
  • Evolutionary purposes
  • Microbiome (bacteria within the body)
  • Infections
  • Antibiotics
  • Bioremediation (using bacteria to break down waste products)
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2
Q

What are the differences between prokaryotes and eukaryotes?

A 
Prokaryote
- No membrane bound organelles 
- No nucleus 
- 70S ribosomes 
- Circular DNA 
- Cell walls = peptidoglycan 
Eukaryote
- Membrane bound organelles 
- No flagellum 
- 80S ribosomes
- Chromosomal DNA
- Cell walls = cellulose
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3
Q

What are archaea?

A

Single-celled organisms that live in the most extreme conditions

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4
Q

What are the levels of the classification system?

A 
Domain (archaea, bacteria, eukarya) 
Kingdom 
Phylum 
Class 
Order
Family 
Genus 
Species
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5
Q

What is contained in bacterial cytoplasms?

A

80% water
Molecules required for life and reproduction
DNA
Ribosomes

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6
Q

What does the cell membrane of bacteria consist of?

A

Phospholipid bilayer with selective carrier proteins = regulate the uptake of nutrients

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7
Q

What does the cell wall of bacteria contain?

A

Peptidoglycan which provides strength

Toxic molecules

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8
Q

Where in a bacterial cell is the common site for antibiotic action?

A

Cell wall

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9
Q

What is the composition of a gram negative cell wall?

A

Thin layer of peptidoglycan

Outer membrane which is external to the cell wall

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10
Q

What compounds are found on the outer membrane of gram negative cell walls?

A 
Lipopolysaccharides 
Endotoxins 
Proteins 
Lipoproteins 
- Protect bacteria from harmful substances in the environment
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11
Q

Do gram negative cell walls retain crystal violet dye?

A

No

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12
Q

Do gram negative cell walls retain counterstain?

A

Yes - they appear pink

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13
Q

What is the composition of a gram positive cell wall?

A

Thick layers of peptidoglycan

Chains of teichoic acids extend off the plasma membrane and through the cell wall

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14
Q

What are teichoic acids?

A

Sugar containing polymers

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15
Q

What is the function of teichoic acids?

A

Assist in maintaining cell shape

Help bacteria infect cells and cause disease

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16
Q

Do gram positive cell walls retain crystal violet dye?

A

Yes - retained in thick layers peptidoglycan making it appear purple

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17
Q

How might bacteria excrete extracellular materials?

A

In capsules

In slime layers

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18
Q

What are capsules and how are they attached to bacteria?

A

Polymers of simple sugars which are firmly attached to bacteria

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19
Q

What is the function of capsules?

A

To protect bacteria from ingestion and destruction by white blood cells

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20
Q

Are capsules hydrophilic or hydrophobic?

A

Hydrophilic - prevent water loss

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21
Q

What is the slime layer composed of and how is it attached to the bacteria cell?

A

Glycocalyx = carbohydrate enriched coating which provides a protective coat from the host factors
Loosely attached with bacteria so can be easily washed off

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22
Q

What can capsules and slime layers both form?

A

Biofilms

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23
Q

What are flagella?

A

Long whip like structures required for motility

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24
Q

What are the three components of flagella?

A

Long spiral filament
Hook
Motor

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25
What are long spiral filaments composed of a what is their function?
Composed of protein flagellin which is attached to a hook | Act as a propeller
26
What is the function of the hook?
Transmit torque = a twisting force that causes rotation | Attached to the basal body
27
What is the function of motors?
Drive rotation
28
What are pili and what are their function?
Hair like appendages that are short but stronger than flagella Involved in forming biofilms and attachment of cells to each other
29
What are endospores?
Dormant forms of bacterium which are resistant to extreme conditions
30
What are the functions of endospores?
Ensures survival of bacteria through periods of environmental stress
31
How do bacteria grow?
Exponentially by binary fission = asexual production | - Genetic material is duplicated and the cell divides in two
32
What is generation time?
The time in which it takes one bacteria cell to become two
33
What is bacteria growth limited by?
Space Nutrient availability (carbon, nitrogen, phosphate) Competitors Temperatures
34
What are the four phases of growth?
Lag Exponential Stationary Death
35
What occurs during the lag phase of growth?
Bacteria express genes Bacteria adapts to the surrounding conditions Chemical composition required for growth is established
36
What occurs during the exponential phase of growth?
Bacteria grow as quickly as possible
37
What occurs during the stationary phase of growth?
Growth = death Population is stable Overall growth stops due to something limiting growth
38
What are the methods of measuring growth directly?
Counting bacterial cells - Microscopes - Flow cytometer - Plate counts
39
What are the methods of measuring growth indirectly?
Estimating number based on indirect measure of growth - Optical density - Measuring respiration
40
How is bacterial growth measured using a flow cytometer?
Counting cells that pass through a light detector
41
How is bacterial growth measured using plate counts?
Cultivation = grow bacteria and count individual colonies
42
How is bacterial growth measured by optical density?
The higher the number of bacteria cells the greater the turbidity (cloudiness) Using a spectrophotometer
43
How is bacterial growth determined by measuring respiration?
Using a dye
44
What are the pros and cons of measuring bacterial growth with a microscope?
``` Pro = relatively quick and easy Con = Human error and you cannot distinguish between dead and alive bacteria ```
45
What are the pros and cons of measuring bacterial growth by cultivation?
``` Pro = you can ensure bacteria is alive Con = human error, time consuming, not all bacteria can be cultured, optimum conditions may be hard to replicate ```
46
What are the pros and cons of measuring bacterial growth by optical density?
``` Pro = relatively quick and cheap Con = cannot distinguish between dead and alive bacteria ```
47
What are the pros and cons of determining bacterial growth by measuring respiration?
``` Pro = you can ensure all bacteria are alive Con = just because bacteria is respiring does not mean it is growing and dividing ```
48
How can bacteria be viewed?
Light field microscopy Dark field microscopy Fluorescence microscopy
49
What are the three mediums in which bacteria can be grown?
In broth = liquid In agar = solid In sloppy agar = semi-solid
50
What are the pros and cons for growing bacteria in a broth?
``` Pro = liquid mediums are good for enriching number of bacteria Con = unable to know exactly what is in the broth ```
51
What are the pros for growing bacteria in agar?
Pro = good for bacterial identification, able to observe colonial morphology, able to assess the purity of a culture
52
What are the pros for growing bacteria in sloppy agar?
Pro = good for demonstrating motility, good for preserving bacteria
53
What features of bacteria enable them to be identified?
``` Colour Shape Size Smell Effect on the medium growth it is in ```
54
Diseases caused by what type of bacteria are hard to diagnose?
Non-culturable bacteria
55
Name five different shapes of bacterial cells.
``` Coccobacillus Cocci Comma shaped Rod Diplococci ```
56
Name four different ways in which bacterial cells grow.
Bunch of grapes Chains Diplobacillus Palisades
57
Name four staining methods used to identify bacteria.
Simple stain Negative stain Fluorescent stain Gran stain
58
Describe the process of gram staining.
1. Fixation 2. Crystal violet added (retained by gram positive) 3. Lugol's iodine 4. Decolourizatiom 5. Safranin
59
What biochemical tests may be used to identify bacteria?
Analysis of sugar fermentation products Ability to utilise specific sugars Analysis of enzymes Growth under aerobic and anaerobic conditions
60
What molecular techniques may be used to identify bacteria?
PCR QPCR RT-PCR Next generation sequencing

Microbiology (18 decks)

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