Title: Lecture 11 BIOL L100 Indiana University Southeast David Partin, Instructor
1Lecture 11BIOL L100 Indiana University
SoutheastDavid Partin, Instructor
2Todays Plan
- Announcements/Questions
- Lecture 11 Origins Classification of Life
Microbiology (Ch 19-21) - Video clips
- One Minute paper
- Lab
- Introduce Case Study 5 HIV
3Todays Topics
- Ch19 Origin and History of Life
- Ch20 Classification of Living Things
- Ch21 Viruses/Bacteria/Archaea
4Stanley Miller-1953
Primitive atmosphere containing methane, ammonia,
hydrogen and water vapor
Gases heated, closed system, passed through
electrical spark organic molecules
spontaneously form (amino nucleic acids)
5Millers experiment attempted to start here.
6Fossils provide evidence of prehistoric life.
7Fossils tell a story of the history of life on
Earth. Relative dating- Use rock
layers Absolute dating- Use radioactive
isotopes like carbon-14 and potassium-40, etc.
8Theory of Continental Drift-1920-Alfred
Wegener Evidence for Continental Drift? Plate
tectonics, fossils, geography, magnetism,
etc. Changes in continental positions had a
major effect on evolution of species.
9The Earths crust is divided into plates that
move because of seafloor spreading at ocean
ridges.
10Just for reference. Do not memorize!
11Part IIClassification of Living Things
Think-Pair-Share How would you classify these
organisms into groups?
12Carolus Linnaeus (aka Karl von Linne)
13Biological Classification of Humans
14Phylogenetic tree Phylogeny evolutionary
history of an organism
15Anatomical evidence (fossils, skeletons, etc.) is
sometimes not enough to accurately construct an
organisms phylogenetic tree. These days,
molecular evidence is the final word.
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17More about these coming soon
see attached sheet for better view
Discussed today
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20Part I Viruses
- Viruses are non-cellular
- Viruses are not living organisms
- Require a host for reproduction and maintenance
(obligate intracellular parasites) - All viruses have at least 2 parts a protein
capsid and an inner core of nucleic acid (either
DNA or RNA)
21Part I Viruses
- Viruses are categorized by
- Capsid shape
- Type of nucleic acid
- DNA or RNA
- Single stranded or double stranded
- Presence or absence of a membrane (envelope)
22Part I Viruses
23Part I Viruses
- Viral
- Reproduction I
- Bacteriophages are viruses that infect bacteria.
They reproduce by - Lytic cycle
- Lysogenic cycle
24Part I Viruses
Viral Reproduction II Animal viruses use cell
membranes as camouflage. New viruses are
released by budding.
25Part I Viruses
- Viral infections
- Can lead to cancer
- Papillomaviruses, herpes viruses, hepatitis
viruses, adenoviruses - AIDS is caused by a retrovirus (HIV)
- Antibiotics used to interfere with bacterial
metabolism have no effect on viruses.
26Side Note Viroids Prions
- Viroids are naked strands of RNA that cause
certain crop diseases - Prions are misfolded proteins that cause certain
animal diseases - Creutzfeldt-Jacob Disease humans
- Bovine Spongiform Encephalopathy (Mad Cow
Disease) cattle - Scrapie sheep
27Need a Break?
- Meet back in 10 minutes
- When we return
- Bacteria
- Archaea
28Part II Prokaryotes
- Both Bacteria and Archaea are prokaryotes
- Prokaryotes lack a nucleus and most other
organelles found in eukaryotic cells - Prokaryotes reproduce asexually by binary fission
- Genetic variation occurs mainly by mutations, but
also through conjugation, transformation and
transduction.
29Part II Prokaryotes
- Never seen until 1600s
- Anton von Leeuwenhoek scraped his teeth and
viewed little animals under the microscope - Spontaneous generation was credited until Louis
Pasteurs 1850 experiment
30Part II Prokaryotes
31Part II Prokaryotes
(outside)
Structure
-DNA
-photosynthesis
(inside)
-locomotion
-DNA swapping
(attached to outside)
-locomotion/ stability
32Part II Prokaryotes
? flagella
33Part II Prokaryotes
- Reproduction binary fission (aka cloning, 1
splitting into 2, etc.) - Reproduction can occur as often as every 12
minutes in the right conditions. - Because reproduction is so quick, more genetic
mutations (mistakes) are made. - Haploid (1 copy) so genetic mutations are
subjected to natural selection immediately
34Part II Prokaryotes
Only 1 chromosome Thats NOT the only DNA found
in bacteria. They also have very small pieces of
circular DNA free in the cell, called plasmids.
Genes for antibiotic resistance are usually found
on plasmids.
35Part II Prokaryotes
- Reproduction is asexual, but 3 methods of genetic
recombination exist. - 1. conjugation-one bacterium passes DNA through
sex pilus to a 2nd bacterium - 2. transformation-bacterium picks up free pieces
of DNA from environment - 3. transduction-bacteriophages pass small pieces
of bacterial DNA - Note plasmids can be passed from one bacterium
to another by any of these means.
36Part II Prokaryotes
- Prokaryotes can survive very harsh conditions by
forming spores. - Cell dehydrates, leaving only a small portion of
cytoplasm and the chromosome surrounded by 3
thick layers of spore coat. - Can survive desert heat, arctic ice, boiling
water, and timethousands of years!
37Part II Prokaryotes
- Oxygen requirements
- Most prokaryotes require oxygen to survive
- Obligate aerobes
- Some can live with or without oxygen
- Facultative anaerobes
- Some are poisoned by oxygen
- Obligate anaerobes
38Part II Prokaryotes
- Bacteria are the more common type of prokaryotes
- Groups of bacteria are often differentiated from
one another using the Gram staining technique
that we will use in lab today. - Different types of bacteria stain differently
because of the differences in the structure of
their cell walls. More about this later
39Part II Prokaryotes
- Bacteria are usually discussed concerning
infections, but they serve some very useful
purposes. - Some are photosynthetic, producing oxygen.
- Some are useful for decomposition.
- Some aid in digestion.
- Nitrogen-fixation in plant root nodules.
40Part II Prokaryotes
- Archaea are discussed in terms of their unique
habits. - Methanogens live in anaerobic environments
(swamps, intestinal tracts) and produce methane
gas - Halophiles live in extremely salty environments
- Thermoacidophiles live in extremely hot, acidic
environments (geysers, hot springs, thermal
vents, around volcanoes) - Believe it or not! Archaea are genetically more
similar to eukaryotes than bacteria!
41Bioterrorismpathogens used as weapons
- Anthrax- caused by bacterium Bacillus anthracis
- Easy to acquire grow
- 2 forms inhaled cutaneous
- Flulike symptoms, death within 24-72 hrs from
bacterial toxins - Not contagious
- Treated with strong antibiotics
- Smallpox- caused by variola virus
- Highly contagious, airborne virus
- Fever, headache, aches, rash
- Not likely to be diagnosed until full-blown
- Eliminated??
- Plague- caused by bacterium Yersinia pestis
- Bubonic plague-bite of infected flea
- Pneumonic plague- inhaled (more favored by
terrorists) - Immediate treatment required or death from
respiratory distress - Botulism- caused by toxins of bacterium
Clostridium botulinum - Food-borne
- Difficulty seeing, talking, swallowing within 24
hrs, respiratory failure - Tularemia- caused by bacterium Francisella
tularensis
Possible essay question
42Side Note Diseases in Humansviral vs. bacterial
43Thanks for your attention!
- Take a break if you need one!
- Whats next?
- Video clips
- One-minute paper
- Lab
44Overview of todays lab
- Gram Staining
- Lets read p73-74 together (lab manual)
45Preparation for Lecture 12
- Skim chapters 22 23
- Keep up with your Oncourse quizzes.