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Bacteria Flashcards

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1
Q

Bacteria(kingdom - Monera)

A
  • Monera are single celled organisms
  • Monera are prokaryotic
  • A pathogen is a micro-organism that causes disease
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2
Q

Structural features

A
  • Cell Wall: Made from sugars and proteins, protects the cell from bursting as they are in a less concentrated solution
  • Capsule: protects the bacteria from other micro-organisms
  • Flagellum: allows bacteria to move
  • Plasmids: contain genes in DNA loop (these are responsible for antibiotic resistance) and are used as a vector in genetic engineering)
  • Cytoplasm: contains ribosomes, storage granules( used for food and waste)
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3
Q

Bacterial groups

A
  1. Round shaped bacteria(Pneumonia, food poisoning)
  2. Rod shaped bacteria(Tuberculosis, tetanus)
  3. Spiral shaped bacteria(Syphilis, cholera)
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4
Q

How do bacteria reproduce?

A
  • Bacteria reproduce by binary fission(asexual)
    1. DNA replicates(there are two identical strands of DNA)
    2. The cell elongates
    3. DNA strand goes to each end
    4. The cell splits into two similar cells
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5
Q

How often can bacteria reproduce

A

Bacteria can reproduce every 20 mins which increases their chances of becoming antibiotic resistant as positive mutations are more likely to occur.

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6
Q

How do some bacteria survive in harsh conditions

A

Bacteria can withstand harsh conditions(lack of food, high temperature) by producing an endospore

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7
Q

How does an endospore form

A
  • During asexual reproduction(binary fission), a tough walled endospore encloses the new strand of DNA
  • The endospore can remain dormant for a long period of time until conditions become suitable again
  • When conditions do become suitable the endospore absorbs water. The tough wall breaks down and the bacteria can continue to reproduce again
    Note: Endospores are difficult to kill and survive without food or water for hundreds of years
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8
Q

Mutations in bacterial cells

A
  • A mutation is the change in the amount or structure of DNA
  • Bacteria can evolve very fast due to the speed at which new mutations can spread increasing their chances of becoming antibiotic resistant
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9
Q

Antibiotics

A
  • An antibiotic are chemicals produced by micro-organisms that are used to kill other micro-organisms.
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10
Q

Who discovered the first antibiotic

A

Sir Alexander Fleming

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11
Q

What is meant by antibiotic resistance

A

It occurs when bacteria are no longer killed or inhibited by the antibiotics

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12
Q

How does bacteria become antibiotic resistant

A

Bacteria become resistant to antibiotics by developing mutations(can happen quickly as they reproduce fast)

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13
Q

What encourages bacteria to become antibiotic resistant

A

MISUSE(Taking antibiotics too often and failure to finish a course of antibiotics)

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14
Q

How do bacteria get food

A
  • Bacteria get their food by being autotrophic or heterotrophic
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15
Q

What are autotrophic bacteria

A
  • They make their own food
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16
Q

Two types of autotrophic bacteria

A
  1. Photosynthetic bacteria: have chlorophyll to absorb light to make food(purple sulfur bacteria)
  2. Chemosynthetic bacteria: make their own food from chemical reactions(nitrifying bacteria)
17
Q

What are heterotrophic bacteria

A

Organisms that take in food from other organisms

18
Q

Two types of Heterotrophic bacteria

A
  1. Saprophyte: organisms that take in food from a dead host
    Role in nature: act as decomposers(allow recycling of materials (bacteria of decay)
  2. Parasites: organisms that take in food from a live host and causes them harm
    Role in nature: control other population numbers (tetanus)
19
Q

Five stages of bacterial growth

A
  1. Lag phase
  2. Log phase
  3. Stationary phase
  4. Decline phase
  5. Death/survival phase
20
Q

What stages do endospores form

A

Endospores can form in the stationary, decline and death/survival stages

21
Q

Lag phase

A
  • Population of bacteria remains low(no increase in bacterial numbers)
  • They are adapting to their new environment
22
Q

Log phase (exponential phase)

A
  • Bacteria numbers are increasing rapidly
  • Conditions are ideal (plenty of oxygen, food, space, moisture)
23
Q

Stationary phase

A

Bacteria numbers remain steady (no longer increasing)

24
Q

Why is the bacteria numbers not increasing

A
  • Lack of food, moisture, space, oxygen
  • Build up of toxic wastes
25
Q

Decline phase

A

Due to unsuitable conditions, the bacteria numbers decrease

26
Q

Why does bacteria population decrease

A
  • Lack of food, moisture, space, oxygen
  • Build up of toxic wastes
27
Q

Death or survival phase

A
  • All bacteria can die or a small number may survive by producing spores

Biology (8 decks)

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