Download Bacteria - Lake Travis ISD

Objectives
• To understand the structure of bacteria
– Compared to viruses
• Understand Eubacteria vs. Archaebacteria
• How bacteria classified
– Kingdom, phyla, etc.
• How bacteria reproduce
• Uses and harmful effects of bacteria
• How to prevent bacteria
– Compared to viruses
Chapter 19: Bacteria
How Human are you?
• There are more microbial cells in our bodies
than there are human cells!
• Of the 100 trillion cells that make-up the human
body 90 trillion are bacterial
• Humans are ~90% Bacterial
• Everyone has about 1 kg in weight of bacteria in
their gut.
• Each gram of feces contains 100,000,000,000
(100 billion) microbes.
• Human adults excrete their own weight in fecal
bacteria every year.
Bacteria: Structure
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CELLS (living)
Prokaryotic (No nucleus or MBO’s)
Genetic Material (DNA)
Cell Membranes and Cell Walls
Classifying Prokaryotes
DOMAIN BACTERIA – Kingdom Eubacteria
•Single-celled prokaryote
•Have peptidoglycan cell walls (protein carbohydrate)
•Can form colonies of clumps or filaments.
•Three basic shapes: Cocci (round), bacilli (rod) &
spirilla (spiral)
Strepto – occurs in chains.
Staphylo – occurs in
clusters..
Cell wall – protects the cell &
gives it shape.
Basic Structure
Outer membrane – protects
Ribosome
the cell against some
Cell Membrane antibiotics (only present in
gram-negative)
Cell Wall
Cell membrane – regulates
movement of materials into &
out of the cell; contains
enzymes important to
cellular respiration.
Pilli
Peptidoglycan
Flagella
DNA
(circular =
plasmid)
DNA
(circular =
plasmid)
Plasmid – circular piece of DNA that
contains some genes obtained through
genetic recombination.
Capsule & Slime layer – protect the cell
& assist in attaching the cell to other
surfaces.
Classifying Prokaryotes
DOMAIN ARCHAEA – Kingdom Archaebacteria
•Genes that resemble eukaryotic genes & some that
resemble prokaryotes.
•Have unusual lipids in their cell membranes
•Found in EXTREME environments!
•Cell walls lack peptidoglycan
•Have introns in their DNA
•Single-celled prokaryote
Archaebacteria
Methanogens
•Convert H2 & CO2 into methane CH4
•Anaerobic bacteria (no oxygen… early Earth)
•Found in bottoms of swamps, sewage & intestinal
tracts of animals.
Extreme Halophiles
•Salt loving
•Found in Great Salt Lake & Dead Sea
Thermoacidophiles
•Live in extreme acidic & hot environment
Archaebacteria vs Eubacteria
• Type of
environment:
EXTREME
• Cell Wall
composition:
LACKS
PEPTIDOGLYCAN
• Type of
environment:
COMMON
• Cell Wall
composition:
PEPTIDOGLYCAN
Prokaryote Evolution
•Fossil Evidence indicates bacteria existed about 3.5
billion years ago.
•Eukaryotes existed about 2.5 billion years ago (Theory of
symbiosis)
•Bacteria evolved to adapt to almost any environment,
from ocean trenches to thermal vents.
Identifying Prokaryotes
Prokaryotes are identified by characteristics such as:
•the way they obtain energy
•shape
•type of cell wall
•the way they move
V. Ways Bacteria are Identified
I. Shapes of Bacteria:
a. Bacilli - rod-shaped
b. Cocci - round shaped
Staphylococcus - cocci in
clusters
Streptococcus - cocci in chains
Diplococcus - cocci in pairs
c.
Spirilla - spiral shaped
Ex: Treptonema pallidum
How do bacteria obtain and use
energy?
BACTERIA ARE EITHER
AUTOTROPHIC OR HETEROTROPHIC
Chemoheterotrophs – organisms that must take in organic
molecules for both energy and a supply of carbon.
Photoheterotrophs – organisms that are photosynthetic, but
still need to take in organic compounds as a carbon source.
Chemoautotrophs – make organic carbon molecules from
carbon dioxide and other inorganic compounds using
energy from chemical reactions.
Photoautotrophs – use energy from sunlight to convert
carbon dioxide and water to carbon compounds.
Releasing Energy
Obligate aerobes – organisms that require a constant
supply of oxygen in order to live. EX: Mycobacterium
tuberculosis, the bacterium that causes tuberculosis.
Obligate anaerobes – do not require oxygen; some may be
killed by O2! EX: Clostridium botulinum, found in soil and
can grown in canned food causing fatal food poisoning.
Facultative anaerobes – can survive with or without O2.
EX: E. coli, can live in the large intestines contaminated
water.
Growth & Reproduction
Binary Fission – bacterium doubles in size, it replicates
its DNA and divides in half. ASEXUAL
Growth & Reproduction
Conjugation – the process by which two living bacteria
bind together and one bacterium transfers genetic
information to the other.
Sex pili
Conjugation
• http://highered.mcgrawhill.com/sites/0072556781/student_view0/
chapter13/animation_quiz_3.html
Growth & Reproduction
Endospore – adaptation that protects the cell against
harsh environmental conditions, such as heat and
drought. May allow the bacterium to survive for
thousands of years.
How do Bacteria benefit humans and
ecosystems?
1. Decomposers – recycle nutrients: break down the
nutrients in dead matter & atmosphere.
2. Nitrogen – Fixing Bacteria (Nitrogen fixation)
•Live freely & symbiotically with plants
•Rhizobium; converts N2 into a form of nitrogen plants
can use.
•Found in legumes (bean type plants)
3. Aid in digestion – live symbiotically within our GI tracts
and help us extract nutrients
Bacteria and the Nitrogen Cycle
Importance of Bacteria
Phylum Cyanobacteria
•Photosynthetic
Eutrophication or Population Bloom – the sudden
increase in the number of cyanobacteria due to a high
availability of nutrients.
•Leads to anoxic environment (dead zone)
Human Uses of Bacteria
•Food – baking & beverages
•Clean up oil spills, rivers & streams
•Pharmaceuticals
•Aide in digestion (symbiotic relationship with bacteria
in our guts)
Bacteria & Disease
Pathogen – any disease-causing agent
Only
1% of bacteria are pathogenic!
Exotoxins – toxic proteins secreted by
bacterial cells, includes some of the most
potent poisons known.
Clostridium botulinum – one gram of the
exotoxin
that causes botulism could kill
1,000,000 people!
MRSA
Staphylococcus aureus – harmless, found on
skin; if it enters the body through a wound it
can cause layers of skin to slough off,
vomiting, severe diarrhea & deadly toxic
shock syndrome.
MRSA = methicillin resistant Staphylococcus
aureus
Evolutionary Arms Race
• http://vitals.nbcnews.com/_news/2013/03/
05/17195353-more-bad-news-aboutnightmare-bacteria-cdc-says?lite
Antibiotics: how we TREAT bacterial
infections
Antibiotics are drugs that combat bacteria by interfering
with various cellular functions
Some bacteria are antibiotic-resistant and destroy
antibiotics, or prevent entry of the antibiotic into the
cytoplasm.
Antibiotics
Bacteria can be tested
for their sensitivity to
antibiotics by growing
them in a petri dish with
paper disks containing
different antibiotics.
As the antibiotics diffuse
into the agar, the
bacteria’s growth will be
inherited by the
antibiotics if the
bacteria are sensitive to
that antibiotic.
Bacteria & Disease
Endotoxins – are NOT secretions; but components of cell
walls in bacteria: glycolipids, which are large molecular
complexes of polysaccharides & lipids.
All endotoxins induce the same general symptoms: fever,
aches and sometimes a dangerous drop in blood
pressure (shock).
Salmonella – produces endotoxins that cause food
poisoning & typhoid fever.
Bacteria & Disease
Lyme Disease
•Most widespread pest carried disease in U.S.
•Caused by Borrelia burgdorferi, a bacterium carried by
ticks that live on deer & field mice.
•Antibiotics can cure the disease if administered within a
month of exposure.
•If untreated, it can lead to arthritis,
heart disease & nervous disorders.
Bacteria & Disease
Yersinia pestis – the bacterium that causes bubonic
plague throughout Europe.
Infected rodents  fleas  humans.
Bacteria & Disease
Bacillus anthracis
Bacteria & Disease