Bio Exam 3 (Dr. Chordas - 1114 osu)

Viruses

Non-cellular infectious agents. Not in any domain or kingdom. Can infect almost any living thing. Alive or not alive is unknown.

2 basic components that construct viruses

DNA or RNA as a genetic core. A tough protein coat or capsule.

3 DNA viruses

Pox viruses, Herpes viruses, Hepadnaviruses. PHH

Pox viruses

Small pox and cow pox

Herpes viruses

Herpes and varicella (chicken pox)

Hepadnaviruses

Hepatitis B (liver disease)

3 RNA viruses

Togaviruses, Filoviruses, retroviruses. TFR

Togaviruses

Rubella (German measles), Chikungunya fever.

Filoviruses

Ebola and Marburg (hemorrhagic fevers)

Retroviruses

HIV (AIDS)

Viral infection process

Infect living cell to reproduce (cannot replicate themselves), infected cell does all the work to manufacture new viruses.

Viral attachment (step 1)

Virus attaches to a host cell. Specific receptor on the host cell.

For HIV, what is the name of the glycoprotein spikes that attatch to CD4 receptors on certain white blood cells

GP120

Question

a. HIV

Where to warts infect, they have little spikes that fit nicely into what tissue?

Skin - A

Influenza has many little spikes that come out and go into what tissue?

Lungs - C

Herpes has many little spikes that come out and go into what tissue?

Nerves - B (this is why its permanent!) - immune system does not kill nerve cells

Why is Herpes (a relative of Chicken Pox) a permanent viral infection in humans?   It is because …..

 

A).  The virus invades skin tissue of the sex organs, your immune system does not attack tissue of the sex organs.

B). The virus invades the nerve cell body, once in nerve cells it is permanent - hidden from your immune system

C). Herpes viruses reproduce so rapidly that it is impossible for your immune system to kill 100% of them and some remain forever in your body.

D).  Herpes is a virus, all viruses result in permanent infections . . . . Hello !!!

E).  None of these

B). The virus invades the nerve cell body, once in nerve cells it is permanent - hidden from your immune system

Viral penetration (step 2)

The genetic material of the virus enters the host cell. For HIV, RNA molecules enter

DNA formation (step 3)

Viral genetic material is made into DNA. For HIV, RNA molecules are converted to DNA by the enzyme reverse transcriptase. For DNA viruses this step is skipped.

Viral DNA incorporation (step 4)

Viral DNA is incorporated into host cell DNA. Infection can be permanent after step 4 because 1 infected cell remains alive.

Component construction (step 5)

Host cell makes all necessary parts to form new viruses

Assembly and release (step 6)

Viral assembly and release: host cell assembles pieces into new viruses. New viruses released and can potentially infect another host cell.

2 basic release pathways for new viruses

Budding and lysis

Budding (virus release pathways)

Single or few viruses released

Lysis (virus release pathways)

Large number of viruses released

West Nile virus

enter, but don't go into nucleus, also affects nerve cell, typically birds to mosquitos, rests in mosquito salivary glands, in horses- 40% deadly, humans slightly deadly

 

Influenza

• The pathogen that causes influenza is an RNA virus.

• This RNA virus is commonly referred to as influenza virus.

• There are three major types of influenza viruses that infect humans: Influenza A, Influenza B, and Influenza C.

What tissue does influenza effect in humans

Lungs

How many influenza deaths per year in the U.S.?

• 100

• 2000

• 13500

• 14000

• 20000

20,000! (F)

Natural reservoir of the influenza virus?

The natural reservoir that holds the flu is a naturally occurring organism: birds!

What is a natural resovoir?

The population of organisms or the specific environment in which an infectious pathogen naturally lives, persists, and reproduces, or upon which the pathogen primarily depends.

Spanish flu - 1918:

50 million deaths (warned the public first to keep them safe and sent out public service announcements so it claimed it started there). Dodge brothers got it.

Why was the Spanish flu so lethal?

lethal because the actual virus itself had totally different configuration so no one had mutation to resist it. The shape it was blocked the airways even higher up than before. 

Asian flu - 1957:

1-4 million deaths (stated in Asian continent)

Hong Kong Flu - 1968:

1-4 million deaths (actually started in Kansas on military base but WW 1 was going on so U.S. didn’t want people to know that their troops were getting sick)

Antigenic drift

Small change in virus’s surface protein shape cause by a small mutation that happens when the virus copies its RNA without error-checking. This creates a slightly new version of the flu (influenza viral shift).

Antigenic shift

If a person has multiple strains of the virus (like A and B), it can mis them up and blend them together to create a new strain (virus AB).

Viral re-assortment

Swine’s lungs receive both the human and non-human version of the virus and will re-sort them creating a merge of them so that humans can get the virus.

Why do we get a flu shot every year?

Antigens on the virus change. Antigenic drift/mutation. Your body doesn’t recognize new antigens. New antigens = new infection. Flu shots = many antigens.

What do H and N stand for with influenza virus subtypes

H = hemagglutinin. Molecule that hangs off the side, known distinct shape for each H1, H2, H3, H4, H5

N = Neuraminidase. Enzyme that hangs off the side, known distinct shape for N1, N2

Different combinations of these = different sub-types

How does soap work (any why is important to use when washing hands to stop spread of influenza)

Soap is spheres of hydrogen (like a lipid) has a polar (hydrophilic) and non-polar (hydrophobic) end. Soap will coat the dirt so the only thing that sticks out is the polar end with is water soluble and the water will attach so it is washed away. Influenza virus acts as dirt and is comparatively easy to inactivate.

Pathogen

Microorganism —such as a virus, bacterium, fungus, or parasite— that causes disease or illness in a host organism.

How many viruses are there?

200+

What is a cold?

Virus in the nasal membrane

Why do we get less colds as we age and at what age do we get the most?

As you age, you get less and less colds. This is because you build immunity and many viruses are pretty stable. We get the most at our age right now.

Why aren’t we immune to colds?

We can’t get immune to colds because there are 200+ viruses, you would become almost immune at age 100 if you got two colds a year. You can get immune to the most common ones after you get them.

Two myths about colds

Wet hair and no coat means you are more likely to get the virus. Don’t drink milk because it increases your nasal production making it more likely for you to develop the virus.

Sneeze speed and particle travel

Particles can travel 2-3 meters! Can reach speeds of 150 km/hour (94 miles/hour)! This makes it a very effective way for the cold virus to spread because the droplets contain the virus. Make sure to cover mouth with ELBOW. B/c hands touch door nobs.

John Stanley Griffith

proposed there’s a mechanism that things that have no genetic material are capable of reproducing. Everyone disagreed. He mathematically showed it could happen.

Stanley B. Prusiner

Named it prion. disease comes from a misfolded shape, not a different sequence. He demonstrated that the misfolded (“rogue”) protein can convert normal proteins into the same harmful shape, allowing prions to replicate without genetic material. This work confirmed John Stanley Griffith’s earlier hypothesis and earned Prusiner the Nobel Prize.

Spongiform Encephalopathies and examples of it

Causes nerve tissue to become spongey and cause loss of motor functions. Prions puncture holes in the nervous system and causes the brain to become spongey. Irreversible and permanent. Can’t do any type of task. Typically fatal.

Examples: mad cow disease in cows. Scrapie in sheep, Chronic wasting disease (Deer/Elk). CJD (in humans)

Mad cow disease

all beef needs to be recalled because it has prions and is irreversible. It can cause the humans to get infected.

Scrapie in sheep

Called this because it makes them very itchy, they will start ripping their skin off until they kill themselves. Once one sheep in the herd has it they have to kill all of them.

Chronic wasting disease (deer/elk)

Makes them feel so full that they can’t eat, they will starve themselves to death and they die. 100% deadly. Don’t know if it can be transferred to humans. Ohio as a state will test deer for free for hunters. Spread by contaminated body fluids, consumption of infested items.

Normal disinfection methods do not work on prions! What temperature do you need to cook the meat to kill the prions?

E. No temperature can make it safe for consumption. Even if you cook it until ash and it will still have it. (Tested by Stanley prusiner on mice)

What cells are prions spread by? They clump together in her into where? What are two ways they are spread by deer?

Spread in the lymph cells, prions clump together and get into the brain. Spread to others through saliva and feces. Prions are very resistant in the environment and can be absorbed by plants

What part of the brain stem has the most concentration of prions if present?

The Obex

Kingdom vs. domain Prior to 1970 - 2 kingdoms

Plantae and animalia

Kingdom vs. domain Post 1970 - 5 kingdoms

Monera, protista, plantae, fungi, animalia

Kingdom vs. domain Recent - 3 domains

Bacteria, archaea, eukarya

Bacteria cause approximately ___% of human illnesses?

B.) 50%

One gram of the exotoxin from botulism “clostridium botulinum” is potent enough to kill ____ people?

F.) 1,000,000

What does Botox do ? (How does it work?)

A).  Muscle Toxin, destroys muscle fibers

B).  Nerve Toxin, kills whole nerves

C).  Shrinks skin cells = reduces wrinkles

D). Shrinks connective tissue = reduces wrinkles

E).  NeuroToxin, destroys a part of a nerve

F).  Botox does nothing, it is a scam

E).  NeuroToxin, destroys a part of a nerve

Under idea conditions : a bacterium can reproduce every 20 minutes

At this rate a single bacterium can produce how many offspring in 10 hours ?

2^30 =1,073,741,824

How often does Botox need to get redone?

Every 6 months

Number one side affect of Botox

Spontaneous death

The only cell type that does not develop cancer?

Mature Red Blood cellS

~22%/ 5 year survival rate

22 percent of the patients diagnosed today will still be alive in five years

How long have prokaryotes existed and how long were they the only living organisms?

3.5 billion years, 1.5 billion years

Prokaryote with oxygen and without oxygen is called what?

Obligate aerobic → must have O₂

Obligate anaerobic → O₂ is toxic

Facultative anaerobic → with or without O₂; prefer O₂

What does obligate vs. Facultative mean?

Obligate: must, Facultative: can but doesn’t have to

Where are prokaryotes found?

Upper atmosphere to ocean depths and miles below the surface of the earth

Are prokaryotes harmful?

A few cause disease or harm, but most are completely harmless, some are beneficial

Three domains of living organisms

Eukarya, bacteria, and archaea

How do bacteria and Achaea differ?

Lack membrane bound organelles, mostly have circular DNA, reproduce asexually by budding, binary fission. Different composition of cell walls, structure of plasma membranes, ribosomes, RNA polymerase, flagella, etc.

Bacteria vs. archaea: Histones associated with DNA

Yes archaea, no bacteria

Bacteria vs. archaea: Histones associated with DNA

Yes archaea, no bacteria

Bacteria vs. archaea: First amino acid incorporated during translation

Bacteria: formylmethionine, archaea: methionine. (Remember because a before b and b adds the formyl)

Bacteria vs. archaea: RNA polymerase

Bacteria: just one type (consists of five subunits). Archaea: just one type (consists of 13 subunits; similar to RNA polymerase II in eukaryotes)

What are Histones (archaea also have them)

Histones are positively charged proteins that DNA wraps around to stay organized, compact, and regulated inside the nucleus.

• Our DNA is linear so the double helix is a long linear strand, wrapped around a “spool” like a garden hose

• Histones are protein blocks that help act as a “spooler” to wrap up the DNA. Histones are blocked together to stay organized. Coil of blocks gets coiled again and then put into a chromosome.

• To read DNA, must uncoil it twice and then take the DNA off of the coil and then open it and transcribe it.

• Histones keeps the DNA nice and organized.

Why are archaea called “extremophiles”?

live in extreme environments like methane or high salt or high temp areas. Because nearly all have anaerobic respiration

• Methanogens, halophiles, thermoacidophiles (bacillus infernos - live in volcanoes)

• Colorful thermophilic archaebacteria (heat loving bacteria) - anaerobic archaea

3 types of extremophiles

Methanogens → strict anaerobes that produce methane.

Halophiles → require extremely salty environments.

Thermoacidophiles → thrive in hot, acidic conditions.

5 characteristics of bacteria

1. All prokaryotic cells (domain bacteria)

2. Reproduce by binary fission

3. Peptidoglycan (archaea don’t have) - why antibiotics won’t hurt humans because they target this

   1. Many have plasmids (genetic engineering)

   2. Additional DNA = extra characteristics

4. Widest diversity of metabolic activity

   1. Because of the genetic diversity and the plasmids, bacteria have one of the largest metabolic activity making them occur everywhere.

What is genetic engineering?

Humans take the code and splice it into the chromosome by the same mechanism the bacteria were doing. = genetic engineering

Gram stain

Gram negative: stains red

Gram positive: stains purple (positive is purple (both p’s))

Certain antibiotics work well on each kind but not the other

3 most common cell shapes

• Coccus = (berries) round bacteria

• Bacillus = (staff) rod shaped bacteria

• Spiral = various spiral shaped bacteria

Shape of the cell shape (2 types)

• Staphylo = cluster

• Strepo= twisted chain

Two types of bacteria toxins

Endotoxin (part of bacteria cell walls) and exotoxin (secreted by bacteria cell)

Endotoxins

a substance that is part of the bacteria cell (the cell wall)

Within, a substance that is part of a bacterial cell wall, cell wall is toxin, bacterial cell has to be present

Exotoxins:

a substance secreted by the bacteria cells

Outside, substance secreted by bacteria cells, effective b/c of secretion, clostridium tetani - tetanus, exotoxin affects any of muscles and causes them to contract

Potent!: one gram of exotoxin from botulism “clostridium botulinum” is potent enough to kill 1 MILLION people. One millionth of a gram is lethal does for human, secretion.

Botulism

type of food poisoning relevant all over the world (and Ohio), anaerobic, one one millionth can kill, Botox is botulism

Clostridium tetani

can also cause gastrointestinal problems (a spore-forming bacterium and the cause of tetanus)

What does Botox do?

Neurotoxin, destroys part of a nerve. (is destroys the terminal point of axon, destroyed connection between two neurons, it can repair b/c only junction broken, so grows a new junction, blocked in synaptic cleft, axon can fire to next neuron again after repair - takes about 6 months)

Destroyed nerve that attached to axon bulb in face to make the muscles non-functioning

• 1 1 millionth of a gram will kill us but it is safe to inject

• Number one side affect: spontaneous death Foodborne botulism can happen by eating foods that have been contaminated with botulinum toxin

Endospores

Endospores are a specialized bacterial cell structure which are dormant, highly resistant bacterial structures that allow survival through extreme heat, cold, chemicals, radiation, dehydration, and nutrient loss. They can persist for centuries and germinate into active bacteria when conditions improve.

Peptidoglycan

bacterial protein, Vital component of bacterial cell wall (Plant and animal cells do not have this)

Many antibiotics inhibit peptidoglycan (Some for gram + and some for gram -)

• Penicillin: for example, Stops bacterial growth

Why Protists are not a monophyletic group

Protists are a paraphyletic group of early eukaryotes that can be unicellular, colonial, or weakly multicellular. They show complex cell structures and life cycles, and include the ancestors of plants (green algae), animals, and fungi (flagellates). Because they do not form a true evolutionary clade, Protista is not considered a monophyletic kingdom.

Nitrogen fixation

Nitrogen is a major component in the air we breathe and abundantly available, It’s in the form of N2. Not biologically available so you don’t process any of it. Doesn’t contribute to functions in your body that use nitrogen

So it has to become biologically available and does that through bacteria. Bacteria are able to form ammonia from N2, Reduces N2 to NH3, N fixation is anaerobic. Nitrogen‑fixing bacteria — including cyanobacteria (“blue‑green algae”) — convert N₂ into ammonia (NH₃), making nitrogen biologically available.

Nitrogen fixing bacteria make all of the following compounds possible:

DNA, Amino acids, Proteins

What causes health threats - bacteria or archaea?

Only bacteria