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AP Bio- Matter 5: Domains
Transcript of AP Bio- Matter 5: Domains
Before We Begin
Make sure you can
Our understanding of life's diversity is constantly expanding.
This presentation reflects a very brief explanation of some of the relationships among living organisms.
The "branches of the tree" only represent general (though generally accurate, phylogenetically) relationships, not time or abundance or anything else.
Focus on the "Big Picture" questions (the "hows"), instead of the nitty-gritty details (the "whats")
Universal Common Ancestor
A Major dividing line of cellular life.
: "Before the center"
No nucleus or membrane-bound organelles
2 of the 3 major domains of life, 1 of the classic 5 kingdoms.
: "True center"
Have a nucleus & membrane-bound organelles
1 of the 3 major domains of life, 4 of the classic 5 kingdoms
Bacteria live EVERYWHERE!
Bacteria are the foundation of all ecosystems on the planet.
They tolerate vast ranges of environmental conditions.
Prokaryotes have a wide diversity of nutritional modes
The 3 Domains diverged very soon after life's last universal common ancestor
Not sure what it looked like, but we can make some inferences:
DNA as genetic information
prokaryotic, unicellular, various nutritional modes
cell walls made of
Anatomy of a bacterium
Bacteria can be distinguished by the shape of their cells, and the colonies they form.
The bacterial cell wall is made of peptidoglycan.
There are two major ways the cell wall can be arranged.
gram staining: a way to determine the type of cell wall
Some bacteria have a
outside their cell wall
gram positive cocci (purple) & gram negative bacilli (pink)
This can make them more pathogenic (why?)
The bacterial cell membrane is the major organelle used for bacterial metabolism.
Bacteria have evolved all major forms of metabolism
enable bacteria to move
help bacteria adhere
The bacterial flagellum evolved independently of eukaryotic flagella
The bacterial chromosome is a single circular piece of DNA
Bacteria also have small extrachromosomal DNA segments called
: Bacterial reproduction.
The cell copies the chromosome and splits in half.
, and can happen very fast.
1 bacterium can reproduce every 20 minutes
Bacterial ribosomes are smaller than eukaryotic ribosomes.
This makes them a good target for antibiotics (why?)
exchange of genetic information between bacterial cells.
increases and spreads genetic diversity.
of DNA from 2 sources
bacteria take in plasmids from the environment
bacteria exchange DNA through a direct connection
bacteria acquire new DNA from a phage (bacterial virus)
Bacterial Evolution Happens Very Fast
E.coli transformed with green flourescent protein
Griffith's transformation experiment
Data from the long term evolution experiment by Richard Lenski's lab, showing the evolution of
s growth rate over 20,000 generations (~20 years)
Bacterial Ecology: Some Useful Examples
Bacteria as Pathogens:
A very small number of bacterial species can cause disease
, a spirochete that causes lyme disease, endemic to Long Island.
(b) The Deer Tick, the organism that spreads lyme disease.
(c) The characteristic "Bull's Eye" rash that is an early sign of the disease.
Bacterial infections can be treated with antibiotics...
: the original photosynthetic organisms
Can tolerate massive amounts of radiation. Lives in nuclear power plant containment chambers.
lives in marine organisms, providing bioluminescence
discovered the antibiotic penicillin, accidentally in 1928 (Nobel prize in 1945)
mold produces penicillin (why?)
prokaryotic, unicellular, various nutritional modes
live in extreme environments ("
A Domain of weirdos
Discovered in the 1970's
Thought to be bacteria until the 1990's
Have enough unique properties/combinations of the other 2 domains to qualify as their own domain
Yellowstone's hot springs (a), Acidic mining runoff (b), and your water heater (c) are examples of the extreme environments where archea live.
, an acidothermophillic bacterium
Methanogenic archea are able to convert complex hydrocarbons into methane.
A Classic Bacterial Cell
Colorized EMG of Bacteria (
) on the head of a pin (
More on us later...
How can we think about organizing the diversity of life?
What are the major features of organisms that we use to classify them at the domain level?
Determine if a particular organism is eukaryotic or prokaryotic.
Identify the common structures of a prokaryotic cell and explain how each contributes to the overall functioning of the organism
Compare the major modes of prokaryotic genetic recombination.
Compare the biology and ecology of bacteria and archea.
Chlamydomonas: a Protist
Bacteria play very important roles in helping plants absorb soil nutrients
Every day, half of the bacteria in the ocean are killed by phages
Life has diverged into