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Introductory Microbiology (BIOL 2117) > Lecture Exam 3 > Flashcards

Lecture Exam 3 Flashcards

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1
Q

Why are viruses non-living?

A

Viruses are not made out of cells, they can’t keep themselves in a stable state, they don’t grow, and they can’t make their own energy.

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2
Q

Obligate intracellular parasites

A

Require a living host to multiply

Ex: Viruses

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3
Q

What is the basic structure of a virus?

A
  • Protein coat- capsid
  • Nucleic acid (DNA or RNA)
  • Enveloped/Naked
  • Noncellular
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4
Q

Virus size range

A

10-400 nm on average.

Range from 20-1000 nm.

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5
Q

Host specificity

A

Virus particles are commonly very specific about what organisms they attack.

  • Lock and Key mechanism (protein spikes)
    Ex. Bacteriophage will only attack bacteria.
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6
Q

3 major virus characteristics

A

a. DNA or RNA
b. Single or double stranded
c. Single molecule or segmented

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7
Q

Virus Particle Structure

A

a. Isometric: Sides of a triangle
b. Helical: Rod shaped
c. Pleomorphic: Irregular

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8
Q

Presence of Absence of an Envelope

A

a. Non-enveloped
b. Enveloped
- Advantage: Protection against host’s immune
system (Phagocytosis).
- Disadvantage: Does not survive on objects.

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9
Q

Capsid

A

Protein coat surrounding a virus. Determines the shape of the virus, made up of capsomeres.
➣ Capsomeres = Subunit of viral protein units.

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10
Q

Genome (virus)

A

Either RNA or DNA.

➣ Can be single or double stranded, enzymes may be packaged with it.

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11
Q

Nucleocapsid

A

The capsid together with the nucleic acid.

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12
Q

Virion

A

A complete virus particle that has not yet attached to a host cell.

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13
Q

Viroid

A

A virus that infects plant cells.

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14
Q

Helical capsid

A

Consists of a ribbonlike protein that forms a spiral around the nucleic acid.
- Appears as a rod

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15
Q

Isometric capsid

A
  • Capsomeres arrange a shell around nucleic acid.

- Each side of the shell is an equilateral triangle.

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16
Q

Protein Spikes

A

Projections of the envelope or capsid

  • Use glycoproteins to attach to cell
  • Illicit immune responses in the host.
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17
Q

Bacteriophages replication

A

➣ Lytic Replication - Bacterial cell is destroyed through release of the virus.

➣ Lysogeny - Bacterial cell is not destroyed. Incorporation into the bacterial DNA.

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18
Q

Lytic Replication Steps

A
  1. Attachment/penetration
  2. Synthesis
  3. Maturation
  4. Release of new phage
    by lysis of host cell
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19
Q

Lysogenic Replication Steps

A
  1. Attachment/penetration
  2. Incorporation of phage DNA
    into DNA of bacterial host
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20
Q

Prophages

A

Inactive phages

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21
Q

Provirus

A

Viral DNA that inserts into a host genome.
▻ Causes latency in human host.
▻ Retrovirus: A retrovirus is a type of virus that
inserts a copy of its RNA genome into
the DNA of a host cell that it invades,
thus changing the genome of that cell.

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22
Q

Viruses that produce latent infections in humans

A

▻ Herpes simplex virus

▻ Varicellovirus

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23
Q

Attachment to host cell

A

Virus:
▻ The virus must have protein spikes.
——————————————————
Host:
▻ Needs receptors that bind with the Viral spikes.
▻ Specific

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24
Q

Penetrating the host cell

A

▻ Direct Penetration (RARE) - Naked virions inject their genomes into a cell.
▻ Endocytosis - Naked or enveloped virus is engulfed by the host cell.
▻ Membrane Fusion - The viral envelope becomes one with the host’s cell membrane.

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25
Q

Uncoating

A

The separation of viral nucleic acid from its protein coat

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26
Q

Synthesis in the host cell

A 
 ▻ ds DNA Virus: Viral dsDNA ➙ RNA ➙ Protein
 ▻ ss DNA Virus: Creates the complement of viral 
                              ssDNA and combines them to 
                              create dsDNA. dsDNA is then used 
                              to make mRNA, and then translated 
                              into a protein. ----- ▻ (+) sense ssRNA Virus: Acts directly as mRNA ▻ (-) sense ssRNA Virus: Must convert (-) sense to a complement (+) sense in order to be used as mRNA.
27
Q

What does a virus need to do

to make new viruses?

A

▻ Copy its genome (DNA or RNA)

▻ Make new viral protein coats

▻ Make new spike proteins

▻ Get an envelope if it needs one

28
Q

Release of Viruses

A

➣ Enveloped viruses are released through budding.

➣ Naked viruses are released by exocytosis or lysis of the host cell.

29
Q

Latent Viruses

A

➣ Different forms
➣ Some viruses remain dormant inside host
cell
➣ Others incorporate genetic material into
chromosome of host cell

30
Q

How does a virus like Influenza escape the immune system?

A

Antigenic drift.

Influenza develops a series of mutations that allow it to escape recognition.

31
Q

Antigenic drift

A

A kind of genetic variation in viruses, arising by the accumulation of mutations in the virus genes that code for virus-surface proteins that host antibodies recognize.

32
Q

Host Range

A

Most viruses are limited to a few hosts.

➣ With the exception of rabies

33
Q

Persistent Viruses

A

Viruses that can reactivate periodically.

➣ Typically seen in enveloped viruses that exit
the host cell by budding.

➣ Varicella-zoster virus, measles virus, HIV-1, and human cytomegalovirus are examples of viruses that cause typical persistent infections.

34
Q

Cytopathic effect (CPE)

A

Structural changes in host cells that are caused by viral invasion.
➣ Can be used to determine type of viral infection.
ex: Virus may cause cell to swell or burst. This may be unique to the
virus.

More examples:
➣ Rabies: Negri Bodies (clusters of virus) within the cells.
➣ Respiratory Syncytial Virus (RSV): Syncytia (cause cells to merge)

35
Q

Teratogenic

A

Acronym TORCH:

   TO: Toxoplasma (protozoa)
         R: Rubella virus
             C: Cytomegalovirus
                 H: Herpes virus

Other: Hepatitis B, Varicellovirus

36
Q

Oncogenic

A

Viruses that can cause cells to become cancerous.
ex: Epstein Barr virus - Burkitt’s lymphoma, Papilloma virus, Hepatitis B,
Retroviridae

37
Q

Acute Infections

A

Acute infections are of relatively short duration with rapid recovery.

38
Q

Immunity

A

Resistance to an infection by microorganisms

39
Q

Adaptive Immunity (specific)

A

Immunity against a particular microorganism after having been exposed to it.

40
Q

Innate Immunity (non-specific)

A

Immunity against any invader, born with it.

41
Q

Non-specific Mechanisms

A

➣ Anatomical barriers
➣ Secretory Chemicals
➣ Cellular Mechanisms

42
Q

Anatomical Barriers

A

➣ Skin (Epithelium) - Layers of protection.
• Two layers: Epidermis, and Dermis
• KERATIN protects Dermis
- Keeps moisture out, create salty
environment on skin
➣ Mucus Membranes - Contain antibodies (Iga)
• Ciliary Escalator: Traps particles
➣ Lacrimal Apparatus - Glands that produce tears
• Dilute particles that get into the eyes.
• Natural antibiotic: Lysozymes (protects from
gram +)
➣ Cerumen - EARWAX!
• Fatty acid composition. (acidic)
• Lysozyme: Break down Gram positive cell
walls

43
Q

Cells

A 
⓵ Neutrophils
⓶ Monocytes (prophage)
⓷ NK Cells
⓸ Basophils
⓹ Eosinophils
44
Q

Neutrophils (PMNs)

A

➣ Nuclei contain 2 or 5 lobes.
➣ Highly phagocytic
➣ Active during the 1st phase of infection
➣ Exit through the blood to enter infected tissue, destroy microbes.

FIRST RESPONDERS

45
Q

Monocytes

A

➣ Nuclei in the shape of a horseshoe

46
Q

Phagocytosis Steps

A

⓵ Chemotaxis:
• Recruitment of phagocytes to an infected area
⓶ Attachment:
• Microbe is tagged to inform WBCs that it must be phagocytosed (Opsonization).
• Opsonins: Antibodies and Compliment proteins
⓷ Injestion:
• Macrophage morphs membrane into a psuedopod (False Feet), begins to engulf the microbe. Traps microbe in a phagosome.
⓸ Digestion:
• Phagosomes are fused with lysozomes (Phagolysozomes).
• RESULT: Microbe is murdered eheheheh >:D
• Secrete parts of microbe through exocytosis

47
Q

Macrophage

A

Destroys microbes in the body.
• Once microbe is destroyed the Macrophage signals to the white blood cells what it encountered.
- Display the antigen on it’s surface, “Y’all kill this thang”

48
Q

Basophils

A

Not as abundant in the body.
• Release Histamine - Causes inflammation.
- Dilate blood vessels, capillaries more permeable, recruit WBCs to infected site.
• Stain purple

49
Q

Eosinophils

A 
Destroy helminths (parasitic worms).
• Aid in allergic response
• Stain red/orange
50
Q

NK Cell

A

Destroy any abnormal cell in the body.

• Punch membranes (perforins). “Surprise motherfker!”

51
Q

Interferons

A

Proteins made when a virus infects a cell.

• Binds to adjacent cells, protects other cells from viral replication.

52
Q

Complement

A

Series of proteins in the plasma.

a. Increase inflammation
b. opsonization
c. MAC (membrane-attack-complex): Punch holes in microbe, kill it.

53
Q

Classical pathway

A

Complement is activated through the binding of a specific antigen to an antibody

54
Q

Alternate pathway

A

Complement is activated through surface proteins of the invading microorganism.

55
Q

Inflammation

A 
Body's response to an infection, caused by an increase in histamines.
------------
Four Cardinal Signs (Increase bloodflow)
1) Redness (Erythema)
2) Heat
3) Swelling (edema)
4) PAIN (That's what this class is fr)
OTHER SIGNS:
- Pus: dead bacteria
- Abscess: Pus accumulation 
- Granuloma: Chronic inflammation
56
Q

Inflammation Mediators

A
  • Histamines - Cause vasodilation (edema)
  • Kinins - Cause vasodilation, and chemotaxis
  • Prostaglandins - Intensify histamine and kinin response ( Aspirin and Ibuprofen )
  • Leukotrienes - increased permeability of the blood vessels
57
Q

Inflammation Steps

A

1) Vasodilation
2) Chemotaxis
3) Tissue Repair

58
Q

Fever

A

Caused by PYROGENS ( fever causing chemicals).

  • Cytokines are released by macrophages
  • Body’s way of getting rid of microbes by increasing temperature.
  • Increased phagocyte activity and metabolism.
59
Q

Specific Immunity Mechanisms

A

a. Humoral: (Antibody-mediated)
- For bacteria, and viruses outside of cells.
b. Cell-mediated: (T-lymphocytes)
- For viruses, cancers, fungi, worms, and transplants.

60
Q

Antigen

A

A protein that produce immune responses.

  • Epitope: Part where antibody will bind
    1. Exogenous antigen - on surface (flagella, walls, etc.)
    2. Endogenous antigen - antigens within the body cell.
61
Q

Antibody

A

Made in response to antigen (activated B-lymphocyte)

- Antibody attaches to antigen so it can be phagocytized

62
Q

Adaptive immunity characteristics

A
  1. Recognize self/non-self
  2. Antigen specific
  3. Diversity: recognize antigens but only respond to 1
  4. Rapid production of cells that react to an antigen
  5. Memory
63
Q

B-cells

A

Make up 15% of lymphocytes.

- Become plasma cells when stimulated. 
- Secrete antibodies
64
Q

T-cells

A

Classified into subgroups CD (cluster differentiation)

- T-Helper Cells (CD4): Humoral and cellular responses.
- T-Cytotoxic Cells (CD8): Cellular response.

Introductory Microbiology (BIOL 2117) (8 decks)

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