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Life Sciences 2 > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

Types of microbes

A
  • Bacteria
  • Viruses
  • Fungi
  • Protozoa
  • Helminths
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2
Q

Two types of microorganisms

A

Prokaryotes:
- Have a relatively simple
morphology and lack a true
membrane-bound nucleus (e.g.
bacteria)

Eukaryotes:
- Are morphologically complex
and have a true, membranebound nucleus (e.g. algae,
fungi, protozoa)

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3
Q

Characteristic of bacteria

A
  1. They are prokaryotic.
  2. They are unicellular.
  3. They have DNA and ribosomes
  4. Exist almost every where on earth
  5. Cells that do not have a nucleus
  6. Contains a rigid cell wall, cytoplasm and ribosomes.
  7. Bacteria like a warm, dark, and moist environment
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4
Q

Basic structure of bacteria

A
  • Cell wall
  • Cell membrane
  • Ribosomes
  • Flagella
    ➢ a whip-like tail that some bacteria have for locomotion
  • DNA
  • Pilli
    ➢ hollow hair-like structures made of protein
    ➢allows bacteria to attach to other cells.
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5
Q

What is microbiology?

A

Microbiology is the study of very small living organisms, called microorganisms or microbes, including bacteria, algae, protozoa, fungi, viruses, and helminths.

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6
Q

Bacteria Classification

A
  1. By shape
  2. Cell wall by gram stain
    - Gram positive = thicker cell wall
    - Gram negative = thinner cell wall
  3. Dependence on oxygen
    - Anaerobes = grown and survive with no oxygen.
    - Aerobes = dependence of oxygen
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7
Q

Shapes of bacteria

A
  1. Spiral (spirilla)
  2. Rod-shaped (Bacilli)
  3. Round (cocci)
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8
Q

Cell wall

A
  • In addition to conferring rigidity upon bacteria, the ell wall protects against osmotic damage
  • Chemically, the rigid part of the cell wall is
    peptidoglycan
  • Gram’s stain differentiates all bacteria into two distinct groups:
  • a. Gram-positive organisms (blue)
  • b. Gram-negative organisms (red)
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9
Q

Gram Staining Technique

A

A procedure to classify bacteria by the
ability of the cell wall to absorb a crystal
violet dye followed by a red safranin
counter stain.

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10
Q

Bacteria with deficient cell walls

A
  • Mycoplasma = a genus of naturally occuring bacteria which lack cell walls.
  • L-forms = cell-wall deficient forms of bacteria, usually produced in the body of the patient treated with penicillin.
  • Spheroplasts = derived from gram-negative, produced artificially by lysozyme or by growth with penicillin or any other agent capable of breaking down the peptidoglycan layer.
  • Protoplasts = derived from gram-positive bacteria and totally lacking cell walls. Produced artificially by lysozyme and hypertonic medium
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11
Q

Endospores

A

A thick wall that develops around the genome and a small amount of cytoplasm when exposed to environmental stress
* Resistant to heat, chemicals, radiation
*Dormant, non-dividing state
* Can germinate and return to normal division once stress has passed

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12
Q

Sporulation

A
  • Sporangium divides to produce the mother cell and forespore.
  • Mother cell engulfs forespore and double-membrane forespore is formed.
  • Coat assembly begins.
  • Peptidoglycan cortex is assembled.
  • Mother cell lyses to release mature spore
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13
Q

How do pathogenic bacteria work?

A
  • Bacteria produce disease in one of two ways:
  • Using cells for food: The bacteria break down healthy cells for food,
    destroying tissues
  • Releasing toxins: The bacteria produce a toxin (poisonous protein) that
    is released into the bloodstream where it can travel throughout the
    body, disrupting normal activity and damaging tissues
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14
Q

Spread

A
  • Airborne/droplet
  • Contact
  • Vectors
  • Ingested
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15
Q

Viruses

A
  • Not independently living cellular organisms, but are defined as a piece of nucleic acid encased in protein.
  • Must infect a cell to reproduce
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16
Q

Morphology of viruses

A
  • Do not possess cellular organization
  • Contain one type of nucleic acid
    either RNA or DNA
  • Lack enzymes necessary for protein and nucleic acid synthesis machinery of host cells
  • They are unaffected by antibiotics.
  • They are sensitive to interferon.
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17
Q

Structure of Viruses

A
  • Either DNA or RNA which contain between 1 and 100+ genes and a protein coat called a capsid.
  • Capsid allows viruses to attach to other cells and inject them with RNA or DNA
  • Envelope
  • Enzyme
18
Q

Bacteriophage

A

Virus that infects bacteria

19
Q

Virus Replication

A

Viruses can infect only a certain type of host cell
* Each type of virus has a limited host range
* Inside a host, the virus may only infect certain tissues - tissue tropism

Goal of virus is to make more copies of itself
* Viruses lack their own tools, energy and building blocks for protein and nucleic acid
synthesis
* Virus hijacks the host’s machinery and nutrients to express its genome
* End result is assembly and release of viruses
* Cell with a virus is often damaged by infection

20
Q

Viral Reproduction types

A
  1. Lytic Infection - a virus enters a cell, makes copies of itself and cause the cell to burst.
  2. Lygosenic Infection- a virus integrates its DNA into the DNA of the host cell.
21
Q

Protozoa

A
  • Single-celled eukaryotes
  • Live freely in water some in animals
  • Asexual (most) and sexual reproduction
  • Some free living and some are parasites
  • Often fecal/oral route through contaminated food or water.
22
Q

Helminths

A
  • Worms
  • Multicellular
  • Often eggs enter GI tract
  • In others, may piece skin
  • Long term infection may cause blood loss/absorption failure.
23
Q

Fungi

A

-Eukaryotic
- Possess cell walls
- Composed of = molds (multicellular) and yeasts (unicellular)
- Reproduces from spores
- Have to obtain food and water from other sources

24
Q

Body defences

A
  1. Physical barriers (skin, nosehair, mucous in airways)
  2. Chemical barriers (saliva, stomach acid, tears)
  3. Inflammatory response
  4. Phagocytosis (non specific immune responses)
  5. Specific immune responses: Antibodies are specific for specific
    antigens and are produced by B cell lymphocytes
25
Q

Which is bigger, virus, bacteria, protozoa?

A

Protozoa

26
Q

Name three differences of a prokaryotic cell to that of a eukaryotic cell

A
  • Unicellular
  • Lack a membrane bound nucleus.
  • Smaller then eukaryotic cells
27
Q

Name three ways by which bacteria are classified?

A
  1. By shape
  2. Gram strain
    - Positive = thicker cell wall = purple/blue.
    - Negative = thinner cell wall = red/pink
  3. Dependence on oxygen
    - Aerobes = Depends on oxygen
    - Anaerobes = grow and survive in environment where there is no oxygen.
28
Q

Name two ways by which bacteria cause disease

A
  1. Using cells for food:
    - Bacteria breakdown healthy cells for food, destroying tissues.
  2. Releasing toxins:
    - The bacteria produce a toxin that is released into the bloodstream where it can travel throughout the body, disrupting normal activity and damaging tissues.
29
Q

A protein spike is a feature of which type of organism?

A

Virus

30
Q

Name three differences between viruses and bacteria

A
  1. Bacteria are larger then viruses.
  2. Viruses cannot be eliminated by antibiotics.
  3. Viruses need to infect a cell to reproduce.
31
Q

Give an example of a fungi, protozoa, and helminth

A

Fungi: candida, molds, yeast, mushrooms.

Protozoa: Plasmodium

Helminth: Roundworms, hook worms, tape worms

32
Q

Which helminth enters through walking on infected soil?

A

Hookworm

33
Q

What is Gram staining?

A

Procedure to classify bacteria by the ability of the cell wall to absorb a crystal violet dye followed by a red safranin counter stain.

34
Q

What colour are Gram-negative bacteria?

A

Pink/red because they do not retain the crystal violet dye

35
Q

What advantage does spore formation offer bacteria?

A
  • To ensure survival in harsh environment
  • Highly resistant to heat, chemicals and radiation.
36
Q

What are the basic shape classifications of bacteria?

A

Spiral: Spirilla
Rod shaped: Bacilli
Round: Cocci

37
Q

What type of nucleic acid do viruses have?

A

DNA or RNA

38
Q

Define a viral capsid and describe its main function

A

A protein coat surrounding and protecting genetic material

39
Q

What is a disadvantage of having a viral envelope?

A

More sensitive to acid, heat and detergents

40
Q

How do viruses cause cell death?

A

Taking over the cellular mechanism and therefore the cells can no longer perform their functions, and by the accumulation of viral particles within the cell leading to lysis.

41
Q

Are antibiotics used to treat viral infections?

A

No

42
Q

What makes fungi different from other plants?

A
  • Reproduce from spores, unlike plants from a seed.
  • Do not produce their own food and have to obtain both food and water from other sources.

Life Sciences 2 (9 decks)

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