BACTERIA, VIRUSES, AND THE

IMMUNE SYSTEM

Biology

Objective 4.03

Assess, describe, & explain adaptations affecting

survival & reproductive success in disease-causing

viruses & microorganisms.

Kingdoms

Archaebacteria

Eubacteria

Cell Type of Bacteria

Prokaryotic

No nucleus or membrane bound organelles

Lots of ribosomes

Thick cell wall

Some have a sticky capsid

outside of cell wall

Circular chromosome (DNA)

Unicellular

Bacteria

Energy Source

Can be autotrophic or heterotrophic

Reproduction: Asexual Reproduction

Called Binary Fission

Makes an exact copy

Happens quickly

Binary Fission

1.Bacteria Grows

2.DNA is copied

3.Cytokinesis Occurs

4.Two identical cells

LABEL

YOUR

NOTES

Movement

Some can move

Cilia = tiny hairs

Flagella = tail

Environment Depends on the Kingdom

Archaebacteria

Harsh environment

High temperatures

High salinity

Acidic

Eubacteria

Normal

Environment

Everywhere else

Bacteria…Good, Bad or Both?

Bacteria is good!

food (yogurt)

medicines

(insulin)

recycles nutrients

decomposer

nitrogen fixation(in plants)

Bacteria is bad!

Decay/rot food

Rot teeth (cavities)

Cause disease/

infections

(strep throat)

Antibiotics

Antibiotics are used to clear up bacterial infections.

Antibiotics put holes into bacterial cell walls causing them to burst and die

Bacteria Growth Patterns

Shapes:

- Coccus = round

- Bacillus = rod

- Spirillum = spiral

Growth:

- Diplo- = in pairs

- Staphylo- = in clusters

- Strepto- = in chains

Guess the Bacteria…

Viruses

Considered to be nonliving because it cannot reproduce on its own and does not use energy

General Structure

Protein coat on the outside

Nucleic acid on the inside (DNA or RNA)

Examples of Viruses

Influenza- the flu

HIV- AIDS

Varicella- chicken pox & shingles

Polio virus- polio

Rubella or measles- measles

Rhinovirus- cold

How Viruses Reproduce

Lytic Cycle

1. Virus DNA enters the host cell

2. Hijacks host to make DNA and

protein

3. Uses cell to puts virus together

4. Cell bursts and releases virus

5. Virus is active: OUTBREAK!

Reproductive Cycles

Lysogenic Cycle

1. Virus DNA is integrated into host cell

2. Every time the cell divides, the virus is in each new

cell

3. Virus is dormant: HIDDEN!

4. Cell eventually enters lytic cycle (bursts and

becomes active)

Examples of Viruses with Lysogenic

Cycles

HIV

Herpes Simplex I = cold sores

Herpes Simplex II = genital warts

Chicken Pox/Shingles

Our Immune System

Responsible for protecting the body from

disease (from bacteria and viruses)

Lines of Defense

1st line: skin and mucus

Skin acts as a barrier

Mucus traps microorganisms

2nd line: cells release chemicals

blood flow to invaded region increases (swelling)

raises body temperature (fever)

3rd line: special white blood cells attack invaders

foreign antigens are detected and Helper T white

blood cells are alerted

Helper T cells “activate” white blood cells called B

cells

B cells multiply and either become plasma cells or

Memory B cells

Plasma cells produce antibodies that attach to the

foreign antigens and “mark” them for destruction

Memory B cells stay in the body in case another

infection arises

Immune Response

Uh Oh!

What if a cell is already infected?!

Helper T cells alert Killer T cells

Killer T cells poke holes in the infected cell to kill it

Types of Immunity

Active Immunity

Exposed to disease

Develop disease and become immune

Longer lasting

Passive Immunity

Injected with antibody that another organism made

Not permanent

Vaccines are an example

Some vaccines have to be received every year (Flu) because it is always mutating (changing) Adapting!!