Chapter 26 Part 2

Front 1

What is required for an antibiotic?

Back 1

- Toxic to target
- Specific for target (minimize side effects)

Front 2

What is a good target for antibiotics?

Back 2

- Biochemical/metabolic Target (usually a protein)

- Translation Machinery: Bacterial ribosomes are significantly different than ours
- Cell wall production

Front 3

What are GI tract Ulcers?

Back 3

- Prior to the early 80s: Ulcers believed to be caused by overproduction of stomach acid
- Early 80s: Helicobacter Pylori(ulcers) was suspected to be the case/trigger

Front 4

What did Dr. Barry Marshall & Robin Warren become famous for?

Back 4

- Studied patients with GI tract ulcers

- Marshall inoculated himself, and found antibody to cure himself

Front 5

What are common side effects of antibiotics?

Back 5

- They kill beneficial bacteria of the gut or vagina
-- Consume probiotics (Yogurt)

Front 6

What are common problems with Antibiotic therapy?

Back 6

- Allergic reactions to antibiotics (some are fatal)

- Killing off 'good' bacteria long with 'bad' ; may allow overgrowth of certain harmful bacteria or yeast
- Increasing incidences of antibiotic resistance

Front 7

What is Antibiotic Resistance?

Back 7

- Killing of susceptible bacteria = selecting for non-susceptible
- Bacteria can mutate = antibiotic no longer works; 99% killed - 1% can mutate

- Bacteria can transfer drug-resistance genes to another bacteria; this leads to MDR

Front 8

What makes bacteria resistant?

Back 8

Genetic change; change in bacterial DNA = change conformation of target (protein)

Front 9

What are the 4 aspects of genetic change?

Back 9

- Mutation = change in DNA
- Conjugation = exchange of genetic material (sex pilus)
- Transformation = bacteria take up DNA from environment (Exampe:E.coli with shigella toxin)
- Transduction = virus introduces genetic material into bacteria

Front 10

Are viruses living or nonliving?

Back 10

Nonliving because they don't have a metabolism

Front 11

What are the 3 MAIN structures of a virus?

Back 11

- Capsid

- Nucleic Acid

- Envelope

Front 12

What is a capsid in a virus?

Back 12

- Protein coat made of many subunits
-- Containment and physical interaction
-- Molecular recognition
-- Redirects host cell activity

Front 13

What is nucleic acid in a virus?

Back 13

- DNA or RNA, but not a mix of both

- Can be single-stranded or double-stranded

- Instructions for making more virions/particles

-- possibly causes host cell death which release new virions (~100)

Front 14

What is the envelope in a virus do?

Back 14

- Not all viruses have one

- Virus exits cell without killing it

Front 15

What are the 6 stages of the virus infection cycle?

Back 15

1) Recognition/Binding

2) Entry
3) Un-coating
4) Replication
5) Assembly
6) Exit

Front 16

What is recognition/binding in the virus infection cycle?

Back 16

Viral Spike protein binds host cell surface protein (lock & key)

Front 17

What is the entry in the virus infection cycle?

Back 17

- Endocytosis

- Nucleic acid injection (protein coat remains outside)

Front 18

What is Un-coating in the virus infection cycle?

Back 18

Viral coat proteins separate (often due to cytoplasmic pH disrupting weak bonds)

Front 19

What is replication in the virus infection cycle?

Back 19

- Replication of viral nucleic acids & proteins

- They go through transcription, and translation

Front 20

What is the assembly in the virus infection cycle?

Back 20

Get proteins constructed around nucleic acid

Front 21

What is the exit in the virus infection cycle?

Back 21

- Viral enzymes ruptures cell membrane -lytic exit

- Exocytosis = little at time; cell lives

Front 22

What is the Lytic Cycle?

Back 22

- Virus infection cycle

- Proceeds stages 1-6 of the virus infection cycle without stopping

Front 23

What is the lysogenic cycle?

Back 23

- Done by temperature viruses

- has latent stage between un-coating(3) and replication(4)

- Viral DNA integrates into host cell DNA; Integrase = open hot cell DNA; allow the virus DNA to incorporate in that
- Bacteria may replicate with integrated viral DNA

- Change in bacterial environment = stimulates viral progression into stage 4 = and onward

Front 24

What is transduction in bacteria ?

Back 24

- Bacteria gets nucleic acid from a virus

- Movement of DNA from one bacterial cell to another via virus
- Virus behaves as vector = doesn't cause disease, but transmits the agent that causes disease; the gene is being carried by the virus

Front 25

What is popping out?

Back 25

Integrated viral DNA plus piece of host/bacterial DNA = transmit to new bacterial cell

Front 26

What is ancient viral DNA?

Back 26

- Incorporated into human DNA 100,000s years ago

- 8-50% of human DNA once viral

Front 27

What is sequencing?

Back 27

- Similar sequencing, viral genome got into human genome

- They can be activated

Front 28

What is the RNA virus production problem?

Back 28

Complementary RNA (-RNA) cannot be used as mRNA

Front 29

What is RNA-dependent RNA polymerase?

Back 29

- Brought in by a virus (released during un-coating)

- Transcribes complementary RNAs from RNA template; AUG is start codon

Front 30

What is reverse transcriptase?

Back 30

- Used by retroviruses
- Transcribes complementary ssDNA from ssRNA template

- Bringing in its RNA, complementing copy there several rounds then reverse transcriptase

Front 31

What is a retrovirus?

Back 31

- Single stranded RNA virus

- Using reverse transcription enzyme to make nucleic copy

Front 32

What is CD4?

Back 32

It's a major protein to help with the attachment of the virus

Front 33

What are the 2 parts of un-coating?

Back 33

- Reverse transcriptase

- Integrase = cuts into host DNA

Front 34

What is HIV?

Back 34

- Human Immunodeficiency Virus
- Variable, but with treatment a person can live 10+ years after diagnosis

Front 35

How many different types of herpes viruses are there?

Back 35

- 8

- Latent for much of the time

Front 36

What does latent mean?

Back 36

Usual symptoms are not yet manifested

Front 37

What is Herpes simplex virus type 1 (HSV-1)?

Back 37

- Oral Herpes

- Cold sores; fever blisters

- Estimated 70-90% adults infected

- Dormant in nerves; flares when body is stressed

Front 38

What is Herpes simplex virus type 2 (HSV-2)?

Back 38

- Genital Herpes

- Painful Blisters

- Estimated 20-25% of US population infected

Front 39

What is Varicella-zoster virus?

Back 39

- Chickenpox

- Pus-filled blisters that itch, break, and crust
- After symptom pass = symptom free for years

- Virus latent in nerve cells

- Re-emergence later in life as painful shingles

Front 40

What are shingles?

Back 40

- Painful nerve condition

-- Vaccine available

Front 41

What is Epstein-Barr virus?

Back 41

- Infectious mononucleious (mono)

- Fever, fatigue for ~ 1 month
- Virus latent thru life, re-emergence during stress
- CDC estimates 95% of U.S adults 35-45 years old infected; many non-symptomatic

Front 42

How do you classify influenza/flu/cold viruses?

Back 42

- H# = Hemagglutinin (Viral surface protein; used to enter the host cell)
- N# = Neuraminidase (Viral surface protein; used to exit from host cell)

Front 43

What is H3N2?

Back 43

Seasonal flu

Front 44

What is H1N1?

Back 44

Swine flu

Front 45

What is H5N1?

Back 45

- Avian flu
- High mortality; so far not transmitted to people well (but it could be if virus mutates)

Front 46

What are antivirals?

Back 46

- Not as successful as antibiotics (target bacteria not viruses) against bacteria
- Must target virus but not eukaryotic cells

Front 47

What is a target of a virus? What could be target?

Back 47

- Polymerases
-- Depends, got to target viral ones
--- Target verse transcriptase

Front 48

What are potential Targets for a virus?

Back 48

- Integrase
- Protease (viral)

- Reverse Transcriptase
- Hemagglutinin
- Neuraminidase

Front 49

What are RTIs?

Back 49

- Reverse Transcription inhibitors

- Stop reverse transcription

Front 50

What is AZT?

Back 50

- Azidothymidine = stops replication of nucleic acid
- Thymidine nucleotide analog

- Incorporated as 'T' during DNA replication
- Inhibits reverse transcriptase because lack 3'-OH group
*** Puts AZT instead of T in the polymerase
- By adding AZT, it causes polymerization to stop right there

Front 51

What is Acyclovir?

Back 51

- Used for genital herpes

- Guanosine analog

- Inhibits viral polymerase

Front 52

How many HIV drugs are on the market?

Back 52

~20

Front 53

What is a 3 drugs cocktail?

Back 53

Combination of 3 individual drugs

Front 54

What are viroids?

Back 54

- Naked vial RNA, about 1/10th zie of normal viral RNA

- Not code for proteins on its own

- Infects plants; not known to affect humans

Front 55

What are prions?

Back 55

- Separate from viruses

- Proteins that abnormally fold, then induse other proteins to abnormally fold

- Destroy nerve cells

-*Breaks from convention that DNA or RNA is required for infection

Front 56

Where are Prions located & what do they do?

Back 56

- They exist in brain cells

- Misfolded a certain way, causes a chain reaction of misfolded cells

- Clumps of proteins that happen

- If it happens to neurons it kills CNS

-- Sheep = scrapie;Cows = mad cow disease; Humans = Crutzfeld-Jacob disease

Front 57

How do you get prions?

Back 57

It is an infectious agent which you can get either genetically (Curtzfeld-Jacob) or through ingestion of prions such as eating a cow with Mad cow Disease