Microorganisms (Viruses, Bacteria & Immune System)

Pathogens

Pathogens

A virus, bacteria, or other microorganism that causes disease

Viruses

A pathogen that reproduces inside the cells of living hosts and causes disease

Are viruses living or nonliving?

Nonliving

Nucleic acid

DNA or RNA (genetic code for virus)

Capsid

Protein coat surrounding the nucleic acid

Envelope

Membrane that surrounds capsid ("cloak" that allows virus to enter host cell undetected)

Can viruses reproduce on their own?

No, they must hijack a living cell and reproduce through that cell.

What 2 elements do viruses ALWAYS have?

nucleic acid and capsid

What 1 element do viruses SOMETIMES have?

Envelope; so they can "unlock" the cell membrane of a target host eukaryotic cell

Immune system

The _____ is made up of many types of "white blood cells"

it's created inside the bone marrow and located in blood vessels and lymph vessels

Antigens

Substances that activate an immune response because white blood cells recognize them as foreign; located on the surface of a pathogen

White Blood Cells

These cells produce antibodies; proteins that fit together with specific antigens and "tag" the pathogen for destruction.

Allergy

An immune response is triggered by a normally harmless antigen in the environment.

Why are fevers good (within reason)?

The heat generated destroys pathogens (denatures their proteins)

Vaccine

A dose of weakened virus (or pathogen pieces) that trains the immune system to produce the right antibodies & recognize the virus if it appears.

Prokaryotic Cells

no nucleus or other organelles; unicellular

Cell Walls

Made of peptidoglycan; in bacteria

Flagella

Used for movement; spins to propel bacteria cell

Capsules

Outer coating of carbohydrates; prevents the cell from drying out; immune to WBC

Pili

Small hair-like projections & allow bacteria to attach to surfaces or transfer DNA

DNA in Bacteria

Circular chromosomes floating around in cytoplasm

Plasmid

Small circular segment of DNA that carries genetic advantage like antibiotic resistance

Binary Fission

Bacteria's process of reproduction; asexual--> identical daughter cells

How do bacteria achieve genetic diversity?

Random mutations in the DNA

Two ways bacteria cause disease

1. Produce toxin

2. Consumes host tissue

Antibiotics

A chemical used to treat bacterial infections. Goal is to destroy the cell wall to spill out the DNA.

Antibiotic resistance

Results in some bacteria with a resistance to survive and continue to multiply, causing more harm.

Benefits of Bacteria

Sewage treatment plants, producing & processing foods, digestive system