Transcript Chapter 19 - Cloudfront.net

Daily Questions
1. What is the difference between binary
fission and conjugation?
2. What are obligate anaerobes?
3. Archaebacteria belong to the domain
_________________.
Daily Questions
1. What is a virus?
2. Name the three ways bacteria can
reproduce.
3. Most bacteria are
(heterotrophs/autotrophs).
Daily Questions
1. What is a phylum?
2. List Linnaeus’ 7 taxons in order from
largest to smallest.
3. Name the three domains.
Daily Questions
1. What are the 4 ways bacteria
can move?
2. What are chemoautotrophs?
3. What are photoheterotrophs?
Daily Questions
1. What is the difference between
Archaebacteria and Eubacteria?
2. Your doctor says you have
pneumonococcus. What shape of bacteria
is this?
3. Your doctor says you have a “staph”
infection. What do you know about this
bacteria?
Chapter 19
Bacteria and
Viruses
I. Prokaryotes
A. Prokaryotes: single-celled organisms that
lack a nucleus
1. Eubacteria – walls contain
peptidoglycan (a carbohydrate)
2. Archaebacteria – lack peptidoglycan,
DNA similar to eukaryotes, have
different cell membrane lipids
Prokaryotic Body Plan
pilus
bacterial flagellum
capsule
cell wall
plasma
membrane
ribosomes in
cytoplasm
B. Identifying Prokaryotes
1. Shapes
a. Bacilli (rod shaped)
b. Cocci (spherical)
c. Spirilla (spiral)
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
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. Facultative 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
(such as anthrax)
Prokaryotic Fission
The bacterial chromosome is
attached to the plasma membrane
before DNA replication
The two DNA molecules are moved
apart by membrane growth
between the two attachment sites
Replication starts and proceeds in
two direction from some point in
the bacterial chromosome
The DNA copy is attached at a
membrane site near the attachment
site of the parent DNA molecule
New membrane and new wall
material are added transversely,
through the cell’s midsection
The ongoing, orderly deposition of
membrane and wall material at the
midsection cuts the cell in two
Conjugation
Conjugation tube forms
between a donor and recipient.
An enzyme nicks the plasmid
Plasmid DNA replication
starts. The free DNA strand
starts moving through tube
In the recipient cell,
replication starts on the
transferred DNA
The cells move apart and the
plasmid in each forms a
circle
nicked plasmid
in donor cell
conjugation tube
to recipient cell
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
2. 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 prevented with
vaccines, 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
III. Viruses
A. Viruses: particles of nucleic acid and
protein
1. Nucleic acid = DNA or RNA that
contains instructions for making new
copies of the virus
2. Capsid: outer protein coat
DNA and RNA
DNA – deoxyribonucleic acid
chemical compound (a nucleic acid,
which contains hydrogen, oxygen,
nitrogen, carbon, and phosphorus) with
instructions for coding proteins that
determines your genetic makeup
RNA – ribonucleic acid
nucleic acid that contains the sugar
ribose
B.Viral Infection
1. Infect cells and replicate 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 DNA of host and is
replicated with host cell’s DNA
C. Viruses and Disease
1. Many viruses can be prevented
through the use of vaccines (polio,
measles, influenza)
2. Oncogenic viruses cause cancer
3. Retroviruses contain RNA
4. Prions contain no DNA or RNA, only
protein
The Prophage
Prophage = viral DNA that is inserted into
a cell
The prophage can have the cell make
copies of the virus right away or may wait
several generations (a latent infection) and
then begins making copies at a later time