Biology (Miller and Levine) Chapter 20

virus

a non-living particle made up of proteins, nucleic acids, and sometimes lipids.

the reproduction of viruses

viruses cannot reproduce alone, so they fail to meet the criteria for life.

Viral Structure

capsid - protein coat on outside of virus

membrane envelope - not all viruses have this

genes - may have RNA or DNA - number of genes varies

bacteriophages

viruses that infect bacteria

- also known as "bacteria killers"

Lytic Infection

- virus enters bacterial cell

- forces cell to make copies of virus

- causes cell to burst

(i.e. t4 bacteriophage)

Lysogenic Infection

- host cell not immediately taken over

- viral DNA inserted into host DNA and copied as host reproduces

- the embedded viral DNA is called prophage

- a virus eventually leaves the lysogenic cycle and enter the lytic cycle.

prophage

embedded viral DNA

Retro Viruses

- common cold

- HIV

about 70% of viruses contain RNA not DNA

prokaryotes are in which domains

archea and bacteria

obligate aerobe

requires oxygen to make ATPs

obligate anaerobe

- only carries out fermentation

- will die in presence of oxygen

facultative anaerobe

- can survive without oxygen when necessary

- can carry out cellular respiration when oxygen is present

endospore

forms when conditions for growth become unfavorable

- a thick wall encloses DNA and cytoplasm, protecting the prokaryote until the environmental conditions change

conjugation

the exchange of genetic material between prokaryotes

- plasmids (independent DNA) are transferred

nitrogen fixers

convert atmospheric nitrogen into forms plants can use

- produce foods like yogurt

- make drugs and chemicals

pathogeon

organism that causes disease

Bacteria prevention and treatment

- prevent bacterial diseases by vaccination

- treat bacterial diseases with antibiotics

Viral Diseases

- viruses attack and destroy cells in the body

- some viruses attack cellular processes

- viral diseases can be prevented by vaccination

- antibiotics do not treat viruses

Emerging Diseases

an emerging disease is one that appears in a population for the first time OR when a well-known disease suddenly becomes harder to control

- the short time between successive generations of pathogens allows them to evolve quickly

- changes in lifestyle, like commerce and travel, make emerging diseases more of a threat

- are threatening to humans because we have no resistance to them and treatment methods have yet to be developed

"Super bugs"

antibiotic-resistant forms of bacterial diseases

- the use of antibiotics has acted as a type of natural selection

Prions

clumps of tiny proteins that are improperly folded

- damage nervous system tissue

bacili

Rod-shaped bacteria

cocci

Spherical bacteria.

spirilla

spiral shaped bacteria

capsule

Covers the cell wall in prokaryotes.

pili

Appendages that allow bacteria to attach to each other and to transfer DNA

Binary Fission

A form of asexual reproduction in which one cell divides to form two identical cells.