Transcript Prokaryotes and Metabolic Diversity

Microbilogy
viruses
protozoa
bacteria
bacteriophage
algae
cyanobacteria
spirochaetes
fungi
Microbiology
study of organisms too small to
be seen by the naked eye
What are microbes?
Single-celled organisms and some
non-cellular parasites
• Microorganisms (mo’s) are able to carry out life
processes of growth, energy generation, and
reproduction in a single cell.
• Mo’s are unicellular, small and reproduced by
fission (asexually)
• 99% of the mo’s cannot be cultured in the lab
• Specifically, they have the ability to:
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grow on different substances
withstand variation in temperature
withstand variation in barometric pressure
withstand osmotic pressure
withstand changes in pH
Microbial ubiquity…
• MO’s exist everywhere! They are in the soil,
water, your skin and hair, your gastrointestinal
tract, and even on or in your food.
• Yet we are barely aware that they exist. We
become aware when we become sick, see spoiled
food or damaged goods.
• However, the sheer minority (much less than
1%) cause disease. Most are beneficial to man
and the biosphere of the earth.
They’re (almost) everywhere!
An overview of prokaryotic life
• Prokaryotes were the earliest organisms on Earth
(>3.5 bya) and evolved alone for 1.5 billion years.
• Today, prokaryotes still dominate the biosphere.
• Their collective biomass outweighs all eukaryotes
combined by at least tenfold.
• More prokaryotes inhabit a handful of fertile soil
or the mouth or skin of a human than the total
number of people who have ever lived.
Microbes exist in huge
numbers!
• For example, for bacteria
– 10 times as many microbial cells as human cells
on/in body
– 109/gram of soil; 103-104 different populations
– 1011/ gram in intestinal tract
– 105/ml in groundwater
– 104/ml in ocean
Amazing But True
More bacteria in our bodies
than human cells!
More different types of
bacterial genes in our body
then there are human genes!
“The second human genome
project” (David Relman)
What Microbiologists Do ???
• Work in almost every industry - from food, agriculture and
pollution control to biotechnology, pharmaceuticals and health,
government agencies and labs, in education as teachers and
researchers.
• No one microbiologist can study everything! That's why people
who become microbiologists usually focus on a particular microbe
or research area.
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Bacteriologists focus on bacteria.
Virologists specialize in viruses.
Mycologists study fungi.
Epidemiologists track down outbreaks of disease
Immunologists study how the body defends itself against
microbial invaders?
Fields of Microbiology
Characteristics of Cells
Eucaryotic cells: animals, plants, fungi, and protists
– contain double-membrane bound nucleus with DNA
chromosomes
– contain membrane-bound organelles that
compartmentalize the cytoplasm and perform specific
functions
Procaryotic cells: bacteria and archaea
– no nucleus or other membrane-bound organelles
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The size and cell type of microbes
Microbe Approximate range of
sizes
Cell type
Viruses
0.01-0.25µm
Acellular
Bacteria
0.1-10µm
Prokaryote
Fungi
2µm->1m
Eukaryote
Protozoa
2-1000µm
Eukaryote
Algae
1µm-several meters
Eukaryote
Size of Microbes
Microbes vary in size ranging
from 10 nm (nanometers) to
100 mu (micrometers) to the
macroscopic.
Viruses in nm = 10-9 m (meter)
Bacteria in um = 10-6 m
Helminths in mm = 10-3 m
Relative sizes of microbes
The power of microbe lies in its speedy
growth
Imagine the weight of biomass of E.coli after 24 hrs under optimal growth?
Bacteria
Reproduction
Asexual, through binary fission
No true sexual reproduction, since neither
mitosis nor meiosis exist in
prokaryotes
Horizontal transfer of genetic material
Transformation
Transduction
Direct transfer of genetic
Conjugation
material from one
prokaryote to another
Binary fission
E. coli
DNA
cell wall
Conjugation in E. coli
Sex pilus connects cells and
draws them together
Conjugation tube then forms
Sex pilus
Kinds of microbes
Non-cellular, parasitic molecules
Viruses
Viroids
Prions
Prokaryotes
Domain Bacteria
Domain Archaea
Eukaryotes
Several Kingdoms in Domain Eukarya
Classification of Microbes
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Based primarily on
genetic sequence data;
e.g., small subunit ribosomal
RNA – present in all
organisms
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NOTE: “Microbes” and
“Prokaryotes” are not taxonomic
categories
Bacteria
Prokaryotes
Peptidoglycan cell walls
Binary fission
Ex: Escherichia coli
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Cyanobacteria
Archaea
Prokaryotes
Lack peptidoglycan
Live in extreme environments
(extremophiles)
Include:
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Methanogens
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Extreme halophiles
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Extreme thermophiles
Archaebacteria
Algae
Eukaryotes
Cellulose cell walls
Photosynthetic
Produce molecular oxygen
and organic compounds
Part of food chain
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Fungi
Eukaryotes
Chitin cell walls
Molds and mushrooms
are multicellular
Yeasts are unicellular
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Protozoa
Eukaryotes
Mostly saprobes and
commensals
May be motile by means
of pseudopod, cilia or
flagella
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Viruses
Acellular
Obligate intracellular parasites
Genome consist of DNA or
RNA called Core
Core surrounded by protein
coat called Capsid
Virion may be enclosed in lipid
envelope
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Nonliving parasitic molecules
Viruses
Single or double stranded RNA or DNA
with a protein coat
Common cold, Ebola, HIV
HIV
Nonliving parasitic molecules
Viruses
Single or double stranded RNA or DNA
with a protein coat
Common cold, Ebola, HIV
Viroids
Short, single strand of RNA w/o protein coat
Primarily infect plants
Prions
Protein particles w/o genetic material
Kuru, mad cow, chronic wasting disease
Differences between
bacteria and viruses
• Viruses
– Obligate intracellular
parasites
– No ribosomes
– DNA or RNA, not both
– seen by EM
– 10-100s of genes
– Tangled phylogeny
• Bacteria
– Usually free-living, but
can be parasites
– Ribosomes
– DNA and RNA
– seen by LM
– 100s-1000s of genes
– Natural phylogeny
Nutritional Patterns