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biology > Micro-Biology > Flashcards

Micro-Biology Flashcards

1
Q

widespread occurrence

A
  1. Bacteria are found everywhere in the biosphere

2. Fungi are also very widespread.

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2
Q

Monera

A

Bacteria

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3
Q

Prokaryotic

A

have NO membrane bound nucleus and NO membrane bound organelles

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4
Q

Structure and Draw ( bacteria )

A
  • Cell wall: not cellulose
  • Slime capsule: helps in resistance (when present)
  • Flagellum: For movement (when present)
  • Plasmid: ring of DNA; can be exchanged
  • Chromosome: loop of DNA; contains genetic information:no nuclear membrane
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5
Q

Classification ( bacteria )

A

By Shape

(a) Sphere
(b) Rod
(c) Spiral

(ii) Effect of Gram’s Stain: either gram positive (stains) or gram negative (doesn’t stain)

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6
Q

Reproduction ( bacteria )

A 
•	Asexual by Binary Fission not mitosis 
Stages 
1.	Cell elongates
2.	Genetic material replicates
3.	Plasmids replicate
4.	New cell wall forms
5.	Cells separate
•	Mutations occur occasionally and if these are advantageous then the new strain quickly becomes dominant 
•	In adverse conditions thick-walled resistant endospores produced within the cell
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7
Q

Nutrition

A

(i) Autotrophic: make their own food by photosynthesis or chemosynthesis
(ii) Heterotrophic: cannot make their own food so are either
a) Parasitic live in or on living organisms causing them harm e.g. tuberculosis
b) Saprophytic : live on dead material causing decay

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8
Q

Factors Affecting Growth

A

Temperature, pH, O2 concentration, availability of nutrients

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9
Q

Antibiotics

A

Substances made by micro-organisms that kill micro-organisms
Used to control pathogenic bacteria
• Antibiotics do not have any effect on viruses.

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10
Q

• Pathogenic:

A

capable of causing a disease

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11
Q

• Antibiotic Resistant and cause

A

not killed by antibiotics
• Causes:
a) Overuse
b) Failure to complete course e.g. MRSA

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12
Q

Economic Importance of Bacteria: ( beneficial )

A

Beneficial:

a. Produce antibiotics and
b. Make vitamins B and K in the human large intestine
c. Nitrogen-fixing bacteria in root nodules of legumes

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13
Q

Economic Importance of Bacteria: ( harmful )

A

Harmful:

a. Cause tuberculosis
b. Streptococcus causing “Strep Throat”
c. Destroy food

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14
Q

Viruses

Difficult to classify because they

A
  1. Are non-cellular
  2. Consist of either DNA or RNA with an outer protein coat
  3. Are obligate parasites ( can only replicate inside a living host cells )
  4. Have no organelles
  5. Do not respire
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15
Q

Viral Replication Stages ( viruses )

A
  1. Attachment: virus fits onto sites on the cell membrane of host cell
  2. Insertion of viral nucleic acid into the host cell
  3. Uses host structures
  4. Transcription: making copies of DNA or RNA
  5. Translation: produce protein coats
  6. Assembly: joining DNA (RNA) and protein coats
  7. Release new virus particles by lysis (bursting) cell membrane
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16
Q

viruses shapes

A

rod
spherical
complex

17
Q

Economic and Medical Importance of Viruses

harmful and beneficial

A

Many workdays and crops are lost due to viral diseases

Harmful:

a) Foot and Mouth,
b) Tomato (tobacco, potato) mosaic virus,
c) HIV (AIDS), and HPV ( genital wart virus) cause cervical cancer

Beneficial:

(a) Bacteriophages can be used to control pathogenic bacteria
(b) Biological control: e.g. myxomatosis and rabbits
(c) Vector in genetic engineering

18
Q

Protista

A

Amoeba

19
Q

• Eukaryotic

A

have a nucleus and membrane bound organelles

20
Q

• Nucleus

A

control centre of cell

21
Q

• Contractile Vacuole

A

for osmoregulation it is active in fresh water to stop amoeba bursting as water continually moves in due to the contents being hypertonic [more concentrated] to the surrounding water

22
Q

• Pseudopodia

A

(i) for movement

(ii) engulfing prey by phagocytosis

23
Q

• Food Vacuoles

A

digest food mainly bacteria

Undigested food is egested

24
Q

Reproduces ( amoeba )

A

binary fission

25
Q

Growth Curves of Micro-organisms

A
  1. Lag – no reproduction - adapting to a new environment
  2. Log – fast reproduction – no competition – plenty of resources
  3. Stationary – increased competition for nutrients - toxic waste build-up
  4. Decline – death rate increasing – lack of resources – toxic waste build-up
  5. Survival by endospores or death
26
Q
  • Bioprocessing

* Bioreactor

A

use of cells or enzymes to produce useful substances

vessel in which products are made by cells or organisms

27
Q

Batch and Continuous

A

BATCH
• Fixed amount of nutrients added at beginning
• Products removed at end of production
• Vessel cleaned to start again
• E.g. using lactobacillus in cheese making

CONTINUOUS
• Nutrients continuously fed into one end of bioreactor
• Product removed continuously from other end
• Over a long period of time
• e.g. using yeast to make industrial alcohol

28
Q

Yeast ( cycle )

A
  • Unicellular Fungus
  • Yeast reproduces asexually by budding
  • Nucleus divides by mitosis
  • One nucleus moves into the bud
  • Bud is pinched off forming a new cell
29
Q

yeast budding structure

A 
cell wall
cell membrane
bud
cytoplasm
nucleus
vacule
30
Q

amoeba structure

A 
cytosplasm ( ectoplasm / endoplasm )
nucleus
bacteria
pseudopodia
food vacule
contractile vacuole

biology (17 decks)

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