Download Let`s Review the last few “Big” Concepts!

Let’s Review the last few “Big”
Concepts! 
Spontaneous generation vs. Biogenesis
• 1. Redi
• 2. Spallenzani
• 3. Pasteur
History of Life
• http://www.youtube.com/watch?v=YXSEyttblM
I
Theories
• Earth formed about 4.6 billion years ago.
• Scientists use radiometric dating to determine
age of specific artifacts.
• 1st prokaryotic cell- 2.5 bya
• 1st eukaryotic cell- 1.5 bya
• 1. Haldane and Oparine
▫ Atmosphere contained different gases that
sparked the formation of 1st organic molecules
able to sustain life.
▫ Primordial Soup Model
• 2. Miller and Urey made an apparatus to test this
theory.
3. Bubble Model
• Louis Lerman in 1986 proposed a different
hypothesis for the beginning of life.
• The model summarized 5 steps of events
1) Gases trapped in bubbles in the oceans
2) Reactions in bubbles began formation of amino acids
3) Bubbles rose to surface releasing contents into the
atmosphere
4) Sun and energy from lightning caused further
chemical reactions of bubble contents with nitrogen
and hydrogen gas in the atmosphere.
5) Molecules fell back into the ocean
Bubble Model
• Remember the PBS Video: RNA
• In the 1980’s, Cech (U. of Colorado) & Altman
(Yale U.) found that certain RNA molecules can
simulate enzymes (proteins).
• Experiments have shown that RNA can form
spontaneously in water but not DNA or proteins.
• Hypothesis: RNA was the first self-replicating
molecule capable of storing information!
Evolution of Eukaryotes
• Eukaryotes appeared 1.5 billion years ago.
• Complex cell structures with a nucleus
containing DNA.
• Theory of endosymbiosis (Margulis, 1966)
suggest that mitochondria (cellular respiration)
and chloroplasts (photosynthesis) were
prokaryotic cells that lived within another cell.
EVOLUTION and NATURAL
SELECTION
• Natural Selection is the
process by which individuals are
better suited to survive in their
environment.
4 main parts of
darwin’s reasoning
1. Overproduction: more offspring can be produced than
can survive to maturity.
2. Genetic Variation: Within a population, individuals have
different traits.
3. Struggle to Survive: Individuals must compete. Darwin
called it ”struggle for existence”. Some variations give
individuals an advantage called :Adaptations.
4. Differential Reproduction: Those with the best
adaptations are most likely to survive and reproduce.
“Survival of the Fittest”.
• Darwin also referred to the measure of of an
individual’s hereditary contribution to the next
generation as: FITNESS.
• It refers to one’s ability to reproduce
successfully to pass on the genetic trait that
makes it successful.
Evidence of evolution
•
•
•
•
1. Age of Fossils
2. Distribution of Fossils
3. Transitional Species
4. Biogeography
 Ex. Australia has animals that resemble wolves, cats, mice, moles or
anteaters, but in Australia they are marsupials (pouch to carry young).
Possible explanation- isolation of Australian continent.
• 5. Anatomy and Embryology
•
• HOMOLOGOUS STRUCTURES as anatomical structures that
occur in different species but have different functions.
• ANALOGOUS STRUCTURES have similar function, but often
come from different structures.
• VESTIGIAL STRUCTURES: structures that seem to serve NO
function, but resemble structures with functional roles in related
organisms.
• Ex. Human coccyx (tailbone)- made up of 4 fused
vertebrae resemble animal tail.
• Ex. Appendix
• Ex. Pelvic bones of whales
Primate and Human Origins
Primate Characteristics
• 1. Large brain parts capable of complex skills. i.e. using hands, interpret
visual data, interact socially, caring for offspring.
• 2. Acute color vision. 3-D vision
• 3. Generalist teeth: permitting herbivorous and omnivorous diets
• 4. Communication: facial and vocal expression.
• 5. Infant care: infants require prolonged care. Reduced litter size permits
greater mobility and attention to each of the young.
• 6. Manual Dexterity: Opposable thumbs. Fingers that can grip or manipulate
objects, prehensile appendages.
• 7. Social organization: many primates live in social groups w complex
behaviors.
• 8. Characteristic skeletal structures.
The First Humans:
● Australopithecus africanus:
▫ walked upright; humanlike teeth and hands
▫ brain was about 1/3 size of modern humans
▫ 4 million years ago; existed for 3 million yrs.
Chimpanzee Australopithecus africanus Homo sapien
● Australopithecus afarensis (“Lucy”)
▫ upright posture
▫ evidence of coexistence with A. africanus for about
1 million years
● hominids walked upright for two million years
without a substantial increase in brain size!
● this posture may have freed the hands for
other things such as gathering food or caring
for infants
Homo habilis
● enlargement of brain is evident
in fossils dating back to about
2.5 m.y.a. (650 cc vs. 500 cc)
● simple stone tools found with
larger-brained fossils
● coexisted with A. africanus for
almost 1 million years
 (A. africanus was an
evolutionary “dead end”)
adult cranial capacity
(range in cm3)
•Chimpanzees
300-500
•Australopithecines
400-530
•early transitional
humans 500-750
•modern humans
900-2300
DEAD
END!
Homo
erectus
Homo
habilis
A. africanus
“Lucy”
A. afarensis
Homo erectus & descendants
● taller and larger brain than H. habilis (1200
cc)
● first hominid to migrate out of Africa
● 1.8 m.y.a. to 250,000 years ago
● H. erectus remains have
been found on other
continents
● diet shifted to include a
larger portion of meat
● intelligence allowed them
to survive in colder
climates (lived in huts or
caves, built fire, wore
clothing, designed more
refined tools)
**best known
descendants of H.
erectus are
Neanderthals!
-lived in Europe,
Middle East, & Asia
-130,000 to 35,000
years ago
Bipedalism
Brain
Size
Jaw Size
Tools
Australopithecus
Africanus
500 cc
Small
None
canine teeth
None
Australopithecus
afarensis
500 cc
Enlarged
cheek,
teeth, jaws
None
Homo habilis
650 cc
More
Simple tools
vertical face
w/o snout
None
Homo erectus
1000 cc
Small jaws
and cheek
teeth
Sophisticated
tools for
hunting
None
Homo
Neandethal
1200 cc
protruding
jaw and
receding
forehead
Continued
tool making
None
Homo sapien
1400 cc
Small face
tucked below
brain case w
rounded
cranium
Continued
sophisticate
d tools
None
Language