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

Lecture Exam 3 Flashcards

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
Uncoating
The separation of viral nucleic acid from its protein coat
26
Synthesis in the host cell
Virus creates proteins that are necessary for viral replication. (Must have mRNA to carry it's code to the ribosome). ----- ▻ 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
What does a virus need to do | to make new viruses?
▻ Copy its genome (DNA or RNA) ▻ Make new viral protein coats ▻ Make new spike proteins ▻ Get an envelope if it needs one
28
Release of Viruses
➣ Enveloped viruses are released through budding. | ➣ Naked viruses are released by exocytosis or lysis of the host cell.
29
Latent Viruses
Remains in host without producing an infection --------- ➣ Different forms ➣ Some viruses remain dormant inside host cell ➣ Others incorporate genetic material into chromosome of host cell
30
How does a virus like Influenza escape the immune system?
Antigenic drift. | Influenza develops a series of mutations that allow it to escape recognition.
31
Antigenic drift
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
Host Range
Most viruses are limited to a few hosts. | ➣ With the exception of rabies
33
Persistent Viruses
Viruses that can reactivate periodically. ➣ Typically seen in enveloped viruses that exit the host cell by budding. ➣ Infected cells do deteriorate over time!!! ---- ➣ Varicella-zoster virus, measles virus, HIV-1, and human cytomegalovirus are examples of viruses that cause typical persistent infections.
34
Cytopathic effect (CPE)
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
Teratogenic
Viruses that can cause birth defects in pregnant women. ------- Acronym TORCH: TO: Toxoplasma (protozoa) R: Rubella virus C: Cytomegalovirus H: Herpes virus Other: Hepatitis B, Varicellovirus
36
Oncogenic
Viruses that can cause cells to become cancerous. ex: Epstein Barr virus - Burkitt's lymphoma, Papilloma virus, Hepatitis B, Retroviridae
37
Acute Infections
Acute infections are of relatively short duration with rapid recovery.
38
Immunity
Resistance to an infection by microorganisms
39
Adaptive Immunity (specific)
Immunity against a particular microorganism after having been exposed to it.
40
Innate Immunity (non-specific)
Immunity against any invader, born with it.
41
Non-specific Mechanisms
➣ Anatomical barriers ➣ Secretory Chemicals ➣ Cellular Mechanisms
42
Anatomical Barriers
➣ 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
Cells
``` ⓵ Neutrophils ⓶ Monocytes (prophage) ⓷ NK Cells ⓸ Basophils ⓹ Eosinophils ```
44
Neutrophils (PMNs)
GOAL: To become a macrophage ------------- ➣ 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
Monocytes
GOAL: To become macrophages ------------ ➣ Nuclei in the shape of a horseshoe
46
Phagocytosis Steps
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
Macrophage
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
Basophils
Not as abundant in the body. • Release Histamine - Causes inflammation. - Dilate blood vessels, capillaries more permeable, recruit WBCs to infected site. • Stain purple
49
Eosinophils
``` Destroy helminths (parasitic worms). • Aid in allergic response • Stain red/orange ```
50
NK Cell
Destroy any abnormal cell in the body. | • Punch membranes (perforins). "Surprise motherfker!"
51
Interferons
Proteins made when a virus infects a cell. | • Binds to adjacent cells, protects other cells from viral replication.
52
Complement
Series of proteins in the plasma. a. Increase inflammation b. opsonization c. MAC (membrane-attack-complex): Punch holes in microbe, kill it.
53
Classical pathway
Complement is activated through the binding of a specific antigen to an antibody
54
Alternate pathway
Complement is activated through surface proteins of the invading microorganism.
55
Inflammation
``` 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
Inflammation Mediators
* 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
Inflammation Steps
1) Vasodilation 2) Chemotaxis 3) Tissue Repair
58
Fever
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
Specific Immunity Mechanisms
a. Humoral: (Antibody-mediated) - For bacteria, and viruses outside of cells. b. Cell-mediated: (T-lymphocytes) - For viruses, cancers, fungi, worms, and transplants.
60
Antigen
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
Antibody
Made in response to antigen (activated B-lymphocyte) | - Antibody attaches to antigen so it can be phagocytized
62
Adaptive immunity characteristics
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
B-cells
Make up 15% of lymphocytes. - Become plasma cells when stimulated. - Secrete antibodies
64
T-cells
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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