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Bacteria(Complete) Flashcards

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1
Q

What are the general characteristics of kingdom monera?

A 
Unicellular
Prokaryotic
Carry out respiration
Have ribosomes
Varied nutrition
Normally reproduce asexually
Play a major role in the decomposition of dead organisms causing mineral recycling
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2
Q

What is a prokaryotic organism?

A

No nucleus and no membrane-bound organelles such as mitochondria or chloroplasts.

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3
Q

How do you classify bacteria?

A

By shape

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4
Q

Classify bacteria according to their shape.

A

Coccus
Rod
Spiral

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5
Q

Give an example of coccus bacteria.

A

Streptococcus which causes septic throat.

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6
Q

Give an example of rod bacteria.

A

E. Coli in the colon, others cause tetanus.

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7
Q

Give an example of spiral bacteria.

A

Causes cholera and syphilis

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8
Q

Describe two benefits of bacteria.

E.G- Economic importance of bacteria

A

Beneficial bacteria:
Lactobacillus sp. Produce yoghurt and cheese.
Genetically modified bacteria produce insulin

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9
Q

Describe two drawbacks of bacteria.

E.G- Economic importance of bacteria.

A

Harmful bacteria:
Bacteria causes food decay,e.g lactobacillus causes milk to turn sour.
Can cause human, plant and animal diseases:
Strep throat, food poisoning, tetanus, cholera, leaf spot disease, bovine mastitis.

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10
Q

What is the structure of the bacterial cell wall?

A

It is composed of protein and carbohydrates.

It is fully permeable- allows all substances through.

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11
Q

What is the function of the bacterial cell wall?

A

Prevents the cell from bursting due to the entry of water by osmosis.

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12
Q

What is the structure of the bacterial cell membrane?

A

It is composed of a lipid bilayer.

It has infoldings where aerobic respiration occurs.

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13
Q

What is the function of the bacterial cell membrane?

A

It is selectively permeable meaning that it does not allow all substances to pass through.

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14
Q

What is the structure of the bacterial cytoplasm?

A

Jelly like liquid that surrounds the single chromosome.

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15
Q

What is the function of the bacterial cytoplasm?

A

It suspends the ribosomes and storage granules.

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16
Q

What is the structure of the bacterial plasmid?

A

It is a self-replicating loop of DNA.

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17
Q

What are the functions of the bacterial plasmid?

A

It contains cloning vectors for genetic engineering.

It has genes responsible for bacterial resistance to antibiotics.

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18
Q

What is the structure of the bacterial capsule?

A

A semi-solid slime layer.

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19
Q

What are the functions of the bacterial capsule?

A

It prevents the bacterial cell from drying out.

It hosts the immune system.

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20
Q

What are the functions of the bacterial flagellum?

A

It is responsible for the movement of the bacterial cell in order to find food and good growing conditions.

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21
Q

What is the name of the asexual reproduction in bacteria?

A

Binary fission.

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22
Q

Describe the process of binary fission.

A

The cell grows bigger in size.
DNA replicates, there are now two chromosomes present.
The cell elongates, the 2 chromosomes are now further apart.
The cell membrane and cell wall infold and create two genetically identical cells called clones.

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23
Q

How often does binary fission occur?

A

Every 20 minutes.

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24
Q

What are the consequences of binary fission?

A

Infection can produce symptoms rapidly.
Due to the short life-cycle( binary fission occurring every 20 mins), mutations become significant. e.g, antibiotic-resistant bacteria can suddenly appear in large numbers, ie, MRSA.
Bacteria produce efficient returns of product in the industry.

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25
Q

What is an endospore?

A

A unicellular resistant structure produced during harsh conditions like freezing.

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26
Q

When are endospores formed?

A

During harsh conditions like freezing.

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27
Q

Describe how endospore formation occurs.

A

DNA replicates.
The cell cytoplasm shrinks and becomes more rounded.
A thick wall forms internally and encloses the cytoplasm and one chromosome.
The parent cell breaks down and the endospore remains dormant.
When suitable conditions return:
The endospore absorbs water.
The spore wall softens and ruptures.
A new bacterial cell emerges, enlarges and reproduces every 20 minutes by binary fission.

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28
Q

How do you kill an endospore?

A

By autoclaving at 120C for 20 minutes.

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29
Q

What is nutrition?

A

How a living organism obtains its food.

Can be autotrophic or heterotrophic.

30
Q

Why is food needed?

A

To grow, live and reproduce.

31
Q

What does autotrophic bacteria mean?

A

Produces their own food by means of simple chemicals and an energy input.

32
Q

What does heterotrophic bacteria mean?

A

Cannot produce their own food and therefore take in food made by other organisms.

33
Q

What are the types of autotrophic nutrition in bacteria?

A

Photosynthetic Bacteria- produces its own food using sunlight energy.
Example: Purple sulphur bacteria.

Chemosynthetic Bacteria- produces its own food using energy from chemical reactions.
Example: Nitrifying bacteria.

34
Q

What are the types of heterotrophic nutrition in bacteria?

A

Parasitic Bacteria- live in or on a living organism causing harm.
Example: Streptococcus.

Saprophytic Bacteria- feed on dead or decaying organisms causing decay and therefore mineral recycling.
Example: Decay bacteria in soil.

35
Q

What are the factors that affect bacterial growth?

A 
Temperature
pH
External solute concentration
Oxygen Concentration
Pressure
36
Q

How does temperature affect bacterial growth?

A

Low temperatures slow down the rate of bacterial growth.
Optimum temperature is 20-30C.
High temperatures denature bacterial enzymes.

37
Q

How does pH affect bacterial growth?

A

Unsuitable pHs denature bacterial enzymes.
Optimum pH is 7.
Helicobacter in the stomach grows at pH 2 and is linked to stomach ulcers.

38
Q

How does oxygen concentration affect bacterial growth?

A

Most bacteria respire aerobically and therefore require oxygen to respire.
Example: Streptococcus.
As a result, low levels of oxygen would inhibit their growth.

Some bacteria respire anaerobically and therefore do not need oxygen to respire.
Obligate anaerobes: Respire only in the absence of oxygen, e.g tetanus.
Facultative anaerobes: Respire in the presence and absence of oxygen but do not use it, e.g E-coli.

39
Q

How does external solute concentration affect bacterial growth?

A 
Bacteria is placed in salty water.
It loses water by osmosis.
Bacterial enzymes become denatured.
Stops and inhibits the growth of bacteria.
Forming the basis of food preservation.
40
Q

How does pressure affect bacterial growth?

A

Bacterial cell walls cannot withstand high pressure.
High pressure inhibits bacterial growth.
Pressure tolerant bacteria is genetically modified for bioreactors.
Bacteria present in deep-sea vents can withstand high pressure.

41
Q

What are antibiotics?

A

Chemicals produced by fungi and bacteria to kill other micro-organisms but do not have an effect on viruses.

42
Q

What is the purpose of an antibiotic?

A

To treat bacterial or fungal infections.

43
Q

What is antibiotic resistance?

A

When bacteria or fungi are not killed by an antibiotic as they are immune to it, e.g MRSA.

44
Q

How does antibiotic resistance develop/ arise?

A

When a person treats a viral infection with antibiotics.

Failure to complete the full course of antibiotics when ill.

45
Q

How does bacteria become resistant to antibiotics?

A

When a colony of bacteria is exposed to an antibiotic, the most sensitive die.
Due to mutations in their genes, some bacteria become antibiotic-resistant.
As there are no competitors and they reproduce quickly every 20 minutes, the antibiotic-resistant population grows.
These bacteria can pass on their antibiotic-resistant gene to pathogenic bacteria which can lead to infections as antibiotics cannot kill them.
MRSA is a bacterial strain resistant to antibiotics and is commonly found in hospitals.

46
Q

Doctors are reluctant to prescribe antibiotics to patients with common-cold like symptoms. Suggest a biological reason for this statement.

A

The common cold may be a viral infection.

Viruses are not affected by antibiotics.

47
Q

Write notes on antibiotic resistance in bacteria.

A

Antibiotic resistance is when bacteria or fungi are not killed by the antibiotic as they are immune to it.
Antibiotic resistance is caused by:
Failure to complete the full course of antibiotics when ill.
Treating viral infections with antibiotics.
Bacteria can pass on their gene to pathogenic bacteria causing infection.
The plasmid contains genes responsible for bacterial resistance to antibiotics.
MRSA is a bacterial strain resistant to antibiotics.

48
Q

How do scientists construct a growth curve?

A

They measure the increase in the number of live cells at fixed time intervals.
A log scale is used to show a large number of bacteria on the graph.

49
Q

What are the stages of bacterial growth, in order?

A 
Lag phase.
Log phase.
Stationary phase.
Decline phase.
Survival phase.
50
Q

Describe the bacterial numbers in the lag phase.

A

Little or no increase in bacterial numbers.

51
Q

Describe the bacterial numbers in the log phase.

A

Bacterial numbers are doubling every 20 minutes due to binary fission.

52
Q

Describe the bacterial numbers in the stationary phase.

A

No overall increase in bacterial numbers as for every new bacteria, one dies.

53
Q

Describe the bacterial numbers in the decline phase.

A

Large decrease in bacterial numbers.

54
Q

Describe the bacterial numbers in the survival phase.

A

Bacterial population stabilises.

55
Q

What are the reasons for the change in bacterial numbers in the lag phase?

A

The bacteria are adapting to their new environment.
Low reproductive rate.
Bacterial enzymes are being produced.

56
Q

What are the reasons for the change in bacterial numbers in the log phase?

A

High reproductive rate.

Optimum conditions are present- good temperature, a lot of space and food.

57
Q

What are the reasons for the change in bacterial numbers in the stationary phase?

A

Slowed reproductive rate.
Competition for resources like food.
Toxins appearing and lack of space

58
Q

What are the reasons for the change in bacterial numbers in the decline phase?

A

Little/ no reproduction.
Extreme lack of resources like food and space.
High levels of toxins.

59
Q

What are the reasons for the change in bacterial numbers in the survival phase?

A

Bacteria form resistant endospores.

60
Q

What is food processing?

A

Using living organisms, their organelles or enzymes to produce commercially valuable products like yoghurt.

61
Q

What is a bioreactor?

A

A vessel in which living organisms, their organelles or enzymes are used to produce commercially valuable products.

62
Q

Highlight the differences between batch food processing and continuous food processing.

A

Batch Food Processing:
Uses a closed bioreactor.
A fixed amount of sterile nutrients are placed in the beginning.
Microorganisms undergo all stages of bacterial growth, usually stopped at decline.
Products made for a short time.
At the end of production, the bioreactor is emptied and sterilised.

Continuous Flow Food Processing:
Uses an open bioreactor.
Nutrients are continuously added.
Microorganisms undergo the upper log phase to maximise yield.
Nutrients are continuously removed.
the bioreactor is only emptied once every 6 months due to contamination.

63
Q

What are the advantages of batch food processing?

A

Easy to run as no close monitoring is required.

Useful when a small amount of product is needed at a specific time, e.g penicillin.

64
Q

What are the disadvantages of batch food processing?

A

Product cannot be made on short notice.

Cleaning and sterilising bioreactor after every use is very time-consuming.

65
Q

What are the advantages of continuous flow food processing?

A

Constant production of product, e.g Quorn.

Does not have to be cleaned and sterilised often which doesn’t take up a lot of time.

66
Q

What are the disadvantages of continuous flow food processing?

A

Heavy monitoring and people with great experience is required and therefore it may be expensive.

67
Q

State how parasitic bacteria can survive for long periods outside the host’s body.

A

They form an endospore.

68
Q

State the role of parasitic bacteria in the overall scheme of nature.

A

Population control.

Natural selection.

69
Q

What is asepsis?

A

To exclude as many microorganisms as possible.

70
Q

What is sterility?

A

Free from all microorganisms.

Biology (36 decks)

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