Transcript Cell

Bacteria
I. Prokaryotes
A. Prokaryotes: single-celled organisms that
lack a nucleus
1. Eubacteria – common bacteria
2. Archaebacteria – lives in extreme
harsh environments
B. Identifying Prokaryotes
1. Shapes
a. Bacilli (rod shaped)
b. Cocci (spherical/circle)
c. Spirilla (spiral)
Gram Staining: Helps to determine what type of antibiotic to use
To treat the bacterial infection
Peptidoglycan is a sugar
2. Cell Walls
a. Gram-positive (w/peptidoglycan)
– purple
b. Gram-negative (w/o peptidoglycan
– red
3. Arrangement
a. Staphyl: Clumps or clusters
b. Strepto: long chains
c. Diplo: pairs
4. Movement
a. Propelled by tail-like structure called
flagella
b. Glide along a slime secretion
c. Move along like snakes
d. Some don’t move
C. Obtaining Energy
1. Autotrophs
a. Photoautotrophs: obtain energy
from photosynthesis
b. Chemoautotrophs: obtain energy
from inorganic molecules
2. Heterotrophs
a. Can cause food poisoning
b. Photoheterotrophs: photosynthetic,
but also need organic compounds
for nutrition
D. Releasing Energy
1. Obligate aerobes: require oxygen
2. Obligate anaerobes: cannot live in
presence of oxygen
3. Faciltative anaerobes: do not need
oxygen, but can live in the presence
of it
E. Growth and Reproduction
1. Binary fission: cell divides, asexual
2. Conjugation: transfer of genetic
information from one cell to another,
sexual
3. In unfavorable conditions, many
bacteria can form endospores – can
remain dormant for months or years
II. Bacteria in Nature
A. Decomposers
1. Help recycle nutrients – break down
dead organisms
2. Used in sewage treatment
B. Nitrogen Fixers
1. Nitrogen fixation: converting nitrogen
into a form plants can use
(EX: Rhizobium grow on roots of
soybeans and other legumes –
converts nitrogen to ammonia for
the plant)
C. Bacteria and Disease
1. Pathogen: disease-causing agents
2. 2 ways bacteria cause disease
a. Break down tissues for food
b. Release toxins
3. Many can be treated with
antibiotics
D. Human Uses of Bacteria
1. Food – cheese, yogurt, buttermilk,
sour cream, pickles, sauerkraut
2. Industry – cleaning up oil spills,
mining minerals, synthesizing drugs
3. Bacteria live in our digestive tract to help
in digestion (called normal flora)
E. Controlling Bacteria
1. Sterilization: destroy bacteria by
subjecting them to great heat or
chemicals
a. Boiling, frying, steaming can all
kill bacteria
b. Disinfectant chemical solutions
can be used in homes and
hospitals
2. Refrigeration – bacteria grow slowly
at low temperatures
Antibiotics
•Fighting Bacteria Bacterial disease can be
fought with soap, chemicals, and antibiotics.
•Antibiotic-Resistant Bacteria Mutations that
confer resistance to antibiotics are strongly
favored in bacterial populations being treated
with an antibiotic.
Viruses
A virus is an infectious agent made up of
nucleic acid (DNA or RNA) wrapped in a
protein coat called a capsid.
Viruses have no nucleus, no organelles, no
cytoplasm or cell membrane—Non-cellular
This is why it does NOT belong to any
kingdom.
vs
Virus Parts
Viruses with RNA that transcribe
into DNA are called retroviruses.
Viruses are parasites—an
organism that depends
entirely upon another living
organism (a host) for its
existence in such a way that it
harms that organism.
HIV Infected
Cell
(This is the reason why HIV is so
incurable.)
A flea is a parasite to a dog and is
harmful to the dog.
Certain viruses can only attack certain
cell types. They are said to be specific.
Example: The rabies virus only attacks brain or
nervous cells.
Surface
Markers
Viru
s
Receptor
Sites
It’s like the pieces of a puzzle.
The ends have to match up so
only certain pieces fit.
Cell
A virus recognizes cells it can infect by matching
its surface marker with a receptor site on a cell.
Virus
Surface
Markers
Receptor
Sites
Cell
Viral Infection
1. Infect cells and replicates
inside host cell
2. Bacteriophage: viruses that
infect bacteria
3. 2 types of viral infections
a. Lytic infection: virus enters
cell, make copies of itself and
causes the cell to burst
b. Lysogenic infection: virus
embeds its DNA into the DNA of
host and is replicated with host
cell’s DNA
Lytic Cycle
Lysogenic Cycle
C. Viruses and Disease
1. Many viruses can be prevented
through the use of vaccines (polio,
measles, influenza)
Vaccines are parts of a virus that are injected into you
so that your body can recognize the parts and build antibodies to
fight against the virus – not a cure
2. Oncogenic viruses cause cancer
3. Prions contain no DNA or RNA, only
protein
Importance:
*Harmful
Causes disease—pathogenic
Disease producing agent—pathogen
Human Diseases: Warts, common cold,
Influenza (flu), Smallpox, Ebola, Herpes,
AIDS, Chicken pox, Rabies
Viruses disrupt the body’s normal
equilibrium/balance
Viruses can be prevented with
vaccines, but NOT treated with
antibiotics.
(antibiotics treat bacteria)
Beneficial:
Genetic Engineering—harmless virus
carries good genes into cells.
Structure
Reproduction
Genetic Material
Growth and
Developmen
t
Obtain and
Use Energy
Response to
Environment
Change over time
RNA or DNA core (center),
protein coat (capsid)
Copies itself only inside
host cell--REPLICATION
DNA or RNA
Cell membrane, cytoplasm,
genetic material, organelles
Asexual or Sexual
DNA and RNA
NO
YES—Multicellular Organisms
NO
YES
NO
YES
NO
YES