Download Notes: Bacteria and Viruses

Bacteria and Viruses Chapter 19
I. Bacteria (Prokaryotes)
A. Characteristics of prokaryotes (bacteria cells)
1. single celled
2. no nucleus
3. smallest and most common organisms
4. microscopic
B. How to identify prokaryotes:
1. Shape
a. bacillus – rod shaped
b. cocci – spherical shaped
c. spirilla – spiral shaped
2. Movement (motility)
a. Structure that allows movement is called a
flagella, a whip-like tail
b. Not all bacteria can move
3. How they get energy (Autotroph, Heterotroph or
both)
4. Type of cell wall
C. Two kingdoms of bacteria (prokaryotes):
1. Kingdom Eubacteria
a. most common type of bacteria
b. live almost everywhere (in side or outside the
body, fresh water, salt water, land, etc)
c. very diverse
d. have special layer in cell wall called
peptidoglycan
e. Sketch: (see Fig. 19-2 p. 472)
Structure  Function
a: cell wall  protection
b: cell membrane  protection
c: ribosomes  make proteins
d: pilli  stick to surface
e: DNA  genetic info
f: flagellum  movement
2. Kingdom Archaebacteria
a. live in harsh environments (ex: hot springs,
oxygen-free environments, or extremely salty areas
(Utah’s Salt Lake)
b. genes are more similar to eukaryotes than
eubacteria
D. Bacteria reproduction:
a. binary fission (asexual)
b. conjugation (sexual)
c. form spores (form a protective layer that allows a
bacteria cell to survive until conditions are more favorable
E. Importance of bacteria - vital to maintaining the living
world!
a. bacteria are decomposers (break down sewage,
dead/decaying organisms
b. bacteria in soil go through nitrogen fixation – the
process of changing nitrogen into NH3, a useable form of
nitrogen for plants
c. human intestines have large numbers of bacteria
and produce vitamins that our body cannot make by
itself (symbiotic relationship)
II. Viruses
A. Characteristics
a. non-living (do not grow, use energy, or respond to
environnment)
b. contain DNA or RNA surrounded by a protein
coat (capsid)
c. cannot reproduce without a host cell (A host cell
is a cell that a virus invades)
d. Sketch (see Fig. 19-9 p. 479)
Structure
A.
B.
C.
D.
Capsid (protein coat)
Tail Sheath
DNA
Tail Fiber
B. Virus infection
a. Lysogenic cycle
step 1: virus enters the cell
step 2: virus DNA replicates with each bacterial
generation
step 3: virus enters lytic cycle
b. Lytic cycle
step 1: virus enters cell
step 2: cells makes copies of virus causing cell to
burst (Lyse)
III. Disease
A. Bacterial Disease
a. Can damage cells and tissues as they are used as
food source
1. ex: M. tuberculosis – destroys lung tissue
2. ex: B. anthrasis – (anthrax) can infect humans
and animals; spore forming; can be deadly
3. see chart on p. 486 for more examples
b. Can produce toxins (poisons)
ex: C. diptheriae – releases toxins into
bloodstream
B. Treatment of bacterial disease
a. antibiotics – block growth and reproduction of
bacteria
b. vaccine – a solution containing dead or weakened
pathogens; when injected into body, it prepares body to
overcome the pathogen if it enters body later
C. Viral disease
a. attack and destroy certain cells and tissues in
body
b. CANNOT be treated with antibiotics
c. can infect all kinds of cells (plant, bacteria, human)
d. vaccines provide protection if taken BEFORE viral
infection (PREVENTION = VACCINATIONS!!)
e. Examples: poliovirus – attack nervous system;
movement problems
smallpox – high fever and disfiguring rash
human papillomavirus (HPV) – warts
D. Prion disease – infectious proteins ex: “mad cow
disease”