Scribe Post for Thursday, 10/13

What we did in class today:

• Sign up with project groups
• Notes: Obj. # 1-3 -viruses (UP p.13)
• Video: FLU (26 minutes)
  

Homework:

• Work on text note sheet
  
• Work on project/script
• Moodle notes
• Review/Study Viruses

What can make us sick?

• Pathogens- Disease-causing microorganisms (many different types)
• Common types:

-Viruses

-Bacteria

-Fungi

-Protists

Above: examples of pathogens

Viruses: Genes in Packages

• Between life & nonlife
• Characteristics of life:
• -Genes
• -Highly organized
• Characteristics of non-life:
• -Non-cellular
• -Cannot reproduce on their own

Virus Structure:

• Nucleic acid enclosed within a protein structure (a protein coat)
• Can only survive by infecting a living cell
• Common Virus parts:
• Head
• Tail
• Tail Fibers
• DNA or RNA
• 

Types of Viral Structures:

Two Types of Phage Reproductive Cycles:

LYTIC:

• DNA injected by virus into host cell immediately highjacks the cell to produce copies of the cell

LYSOGENIC:

• DNA injected by virus into host cell incorporates viral DNA into host cell DNA, passing the DNA to future generations without making copies of the virus
• Sometimes environmental conditions such as weather or stress trigger DNA to switch to Lytic Cycle

Alternative types of Phage Reproductive Cycles: putting it all together

Plant viruses:

• Stunt plant growth and diminish crop yields
• Most have RNA rather than DNA as their genetic material
• To infect, virus needs to get past plant epidermis
• No cure for most plant viruses, but humans have created plant breeds that are resistant to some viruses (EX: TMV + tomatoes, PRSV + papaya)

Above: Tobacco mosaic virus (TMV)

Video: THE FLU

• Holly catches virus from a man who sneezed
• Virus enters nose, originally being blocked by nose hairs but then Holly inhales taking virus in
• Virus on mission to multiply, needs to get to cells in throat
• Reaches throat, burrows through mucus making way to cells
• Spikes on virus impersonate cells and is fooled as a protein
• Virus takes control of cell's machinery making a virus cloning factory
• Single cell: 10,000 viruses made, 1000's of cells being infected
• Killer Cells: patrol body, spray poisons killing some of Holly's good cells, poison not enough to keep virus under control
• Cell debris from dying cells piles in throat
• Debris destroyed by macrophages (eaten) or carried away on cilia to be swallowed and digested
• Immune system destroyed thousands of throat cells in attempt to kill virus, making throat sore and swollen
• Symptoms of flu caused not by virus but by affects of trying to kill virus
• Macrophages release interleukins (smoke-like) sending signals through body for help, this causes pain so that the body is telling Holly to slow down and save energy to fight virus
• Interleukins cause body temp. to increase so that breeding ground for virus is no longer optimal, this causes production of flu virus to slow and immune cells production rate to increase
• Holly feels terrible but immune system will make her suffer until she is healthy
• New virus cells are still being created
• Dendritic cells search for help
• There are a trillion T cells in lymph, 2 of which are designed to kill virus
• Dendritic cells seek cells in lymph trying to make cells recognize the virus
• The correct T cell is found, multiplies into many cells, glands begin to swell as T cells divide
• T cells launch themselves throughout body
• The T cells arrive in in thousands killing virus with great precision
• Holly coughs to try to get the debris from dead cells out
• B cells also recognize virus, releases antibodies who cover viruses, paralyzing them
• B cells and T cells wipe out virus
• New throat cells grow back
• Memory cells: Holly is immune, hopefully cells do not mutate making her not immune
• Last few viruses remain in saliva

Sincerely,

Cici

*next scribe: Regina