Chapter 5 - Alice Pevyhouse

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Transcript Chapter 5 - Alice Pevyhouse

Thales- Everything stemmed ultimately from
Water. Idea of descent with modification?
Aristotle- Everything has a desire to move from
lower to higher forms.
How did life develop such a
diversity of forms on Earth?
The prevailing perception in the Dark and
Middle Ages in Europe was that all things on
Earth had existed in basically their same
forms since they were created.
Pierre Louis Maupertuis-1750
Small Changes between generations could
accumulate into large changes given enough time.
Example: Trilobite
From 550 Million Years Ago!
Water protects organism for
Bacteria eat soft parts and leave
An organism that is deposited in sediments after
death is covered by additional sediments that
protect it from predation and decay.
Over time, the weight of additional sediments
squeeze out the fluids from the organism and the
sediments that surround it, causing lithification
(sedimentary rock formation).
Charles Lyell
Advocated Uniformitarianism.
Believed in an old Earth.
The time frame given by an old Earth would
allow for Evolution
Voyage of the Beagle
Origin of the Species
• “There is grandeur in this view of life,
with its several powers, having been
originally breathed into a few forms or
into one; and that, whilst this planet has
gone cycling on according to the fixed
law of gravity, from so simple a
beginning endless forms most beautiful
and most wonderful have been, and are
being, evolved.”
Tree of Life
First Law-The amount of energy in the Universe
remains constant
Second Law-The Universe tends towards a
state of disorder.
Basic Metabolic Needs
1. A source of raw materials with which to
build new products.
For a cell- key raw materials are molecules that
provide the cell with carbon and other basic
elements for life
Basic Metabolic Needs
2. A source of energy
This fuels the metabolic processes that
break down old molecules and manufacture
new ones.
Metabolic Classifications
Carbon SourcesHeterotroph- ‘others’ and ‘feed’.
Autotrophes- ‘self’ and ‘feed’
Energy Sourcesphoto- ‘from light’
chemo- from chemicals’
Metabolic Classifications
Photoautotrophs Chemoautotrophs Photoheterotrophs –
Chemoheterotrophs -
Biochemical Processes
Earth Life is Carbon-Based
CARBON- What is the big deal?
Organic Molecules
Silicon-Alternative to Carbon?
Although can
also bond with 4
atoms at a timethe chemical
bonds formed
are weaker than
those for Carbon
Molecular Components of Cells
• Carbohydrates– make important cellular structures
– Store energy
• Lipids– Can form barriers that make it possible for cells to
exist (Cell Membrane!)
– Store energy
Enzymes-serve as catalysts for biochemical reactions.
Evidence for a Common Ancestor
Evidence of Single Common Ancestor:
1. All Life uses the Left Handed Version of
Amino Acids
2. All Life uses only 20 amino acids
3. All Life uses ATP
Nucleic Acids
Amino Acids-building Blocks of Proteins
Tree of Life
The Molecular Basis of Evolution
1. Mistake in Replication
2. Exposure to Radiation
3. Exposure to Carcinogens