1. Inner Nucleic Acid core (DNA/RNA genetic material)
2. Inner Enzymes 
3. Protein Coat (capsid)
4. Outer Membrane Envelope with viral protein spikes
5. Usually smaller than 200 nm!

Identify the parts in the naked virus below?

[image]

1. Core Protein Coat (capside)
2. Nucleic Acid (DNA inside Capsid)
3. Neck
4. Sheath
5. Base Plate
6. Tail Fibers (with protein receptors)

The genetic material in a virus can be single-stranded ___RNA___ or double-standed _DNA____. Viruses containing RNA are called_______RETROVIRUSES____________.

Arrange the following by size:

Bacteria

Fungus Spore

Rain Droplet

Plant Pollen

Virus

Smallest to Largest

1. Virus
2. Bacteria
3. Fungus Sport
4. Plant Pollen
5. Rain Droplet 

Arrange the following from smallest to largest:

1. human hair
2. atom
3. virus
4. wavelength of light
5. grain of sand
6. person

1. Atom (0.1 nm)
2. Virus (20 - 200 nm)
3. Light wave (1000 nm)
4. Red Blood Cell (10 um or 10,000 nm)
5. Human Hair (100 um or 100,000 nm)
6. Sand (1 mm)
7. Person (1 m = 1000 mm)

Order these from smallest to largest :

Bacteria

Animal Cells

Virus

Compare each to the size of a cell:

1. Virus (1000x smaller than cell)
2. Bacteria (10x smaller than cell)
3. Animal Cell

*Virus is 100x smaller than bacteria!

What type of viruses infect each of the following areas:

1. Respiratory Tracks
2. Nerve Cells
3. Tobacco Leaves

1. Influenza Virus
2. Poliomyelitis Virus
3. Tobacco Mosaic Virus

1. CELLS (prokaryotic or eukaryotic)
2. ORGANIZATION 
3. ENERGY (autrophs or heterotrophs)
4. RESPONSIVE TO ENVIRONMENT (light, touch, etc.)
5. GROWTH & DEVELOPMENT 
6. REPRODUCTION (sexual or asexual) 
7. HEREDITY
8. ADAPTATION 

1. CELLS (prokaryotic or eukaryotic) - No
2. ORGANIZATION - YES, minimal 
3. ENERGY (autrophs or heterotrophs) - No in/out energy or matter.
4. RESPONSIVE TO ENVIRONMENT (light, touch, etc.)?
5. GROWTH & DEVELOPMENT - No
6. REPRODUCTION (sexual or asexual) - No, not really, they program a host cell to mass produce themselves like copy software. rather than undero mitosis or meisis.
7. HEREDITY - No, pass their genetic material to the host not to offspring.
8. ADAPTATION - YES mutate and evole

1. Adsorption
2. Entry
3. Replication
4. Viron Assembly
5. Lysis/Exit

Virus enters host cell when either of these match the protein receptors of the host cell:

(1) Naked Virus: part of protein capsid 

(2) Enveloped Virus: some of the protein receptors on envelope 

1. Entry by fusion = virus envelope fuses with host cell mebrane and nucleocapside enters cell
2. Capsid uncoating = Virus capsid is broken down by enzymes
3. Viral DNA/RNA is released into host cell

1. Entry by endocytic vesicle = virus envelope attaches to host membrane at receptors and then host membrane folds in and  pinches off to form new vesicle called "Endocytic vesicle"
2. Capsid uncoating = Virus envelope fuses with membrane of endocytic vesicle, then virus capsid is broken down by enzymes
3. Viral DNA/RNA is released into host cell

What type of enveloped virus entry is shown below.

How do you know?

[image]

Enveloped virus entry via endocytosis.  You should see that the host cell membrane folds inward and surrounds enveloped virus and then pinches off  (called endocytosis) to form endocytic vesicle.  

Next, you should see how the vesicle opens, viral capsid is broken by enzymes.

Next virus DNA/RNA is released.

Left: Virus entry via Endocytic Vesicle (host membrane folds IN (endo) to form membrane around virus envelope - making a endocytic vesicle)

Right: Virus entry via Fusion (virus envelope fuses with host  membrane released capsid virus).  

Stage 3: REPLICATION:

Virus genome (DNA/RNA) programs host cell's machinary (ribosomes, tRNA, nutrients, energy, etc) to make viral enzymes and viral par

Stage 4: ASSEMBLY: 

1. Capsids assemble around viral genome
2. Viral coded proteins + glycoproteins inserted in host cell membrane

1. Virus obtains its envelope from host cell membrane.
2. Virus buds (breaks off) from host cell membrane.

What virual lytic stage is being shown below?

Is this a naked or enveloped virus?

[image]

What differences do you see between the LYTIC CYLE and LYSOGENIC CYCLE shown below?

[image]

In Lytic phase, virus breaks down host DNA and then assembles the now free host nucleotides into

additional copies of virus DNA. Host cell then transcribes and translates new DNA - making virus parts and capsids.  Viruses assemble and escape when cell bursts (lysis)

In Lysogenic cycle, virus doesn't break down host DNA but rathers integrates its DNA/RNA into the host DNA.  The host cell with integated virus DNA can go through many replications and cell divisions.  Somes, the integrated virus DNA will separated...and cell kicks into lytic cycle.

Replication without immediate cell death! (remember, in lysogenic, virus DNA is integrated in host DNA and can undergo many DNA replications and cell divison via mitos without every hurting the host).

 Only when the virus DNA seperates from host DNA does the cell enter the lytic phase - leading to host DNA destruction, transcription/tranlsation of virus DNA, assembly of viruses, and lysis where host cell rupters (lysis) and dies.

1. Injection of broken virus particles
2. Body responds by making particles that recognize virus and kill it - ANTIBODIES
3. White blood cells collect and digest foreign particles covered in antibodies.