Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Principles of Biology-August 26,2013 Lecture 1


Molecular Prerequisites of Life
In class lecture:
Scientific Method
Hypothesis:
An educated guess
-Suggested explanation for an observable phenomenon
Theory:
An educated guess and data from an experiment
Well-substantiated, unified, working explanation, for a hypothesis or hypotheses
N
...

Observations lead to hypothesis which lead to predications
Then, you do many tests/experiments and if they are not inconsistent they lead to a
theory
Themes:
Evolution: is the dominant theme of biology
Structure and function: are correlated at all levels of biological organization-from
molecules to entire organisms
Organisms: interact with environment and other organisms(abiotic/biotic
interactions)
Continuity of Life: based on heritable information
Cells: the basic unit of life and metabolism and energy transfer
-the ‘unity in diversity’ of organisms
-the suitability of an organism or adaptation to a particular environment
We’ll carry this theme throughout this course- from molecules to organisms to
biosphere
What is Biology?
-The Study of Life
What is life?
-ability to reproduce -the ability to adapt -homeostasis -the characteristics of
having a community and population -metabolism -transfer of energy -growth and
development -where structure meets function -evolution - cellular respiration
(“Life is a contained, organized, regulated, responsive genetic unit capable of
metabolism, growth and development, reproduction, and evolution”)-Modified from
purves et
...
2004



Where does the story of life begin?
Molecular prerequisites of life:

-Once a molecules(or set of molecules) can successfully replicate itself and harvest
energy from its surroundings, it can break free from the shackles of the second law
of thermodynamics
-Life originated from the aggregation of complex chemicals in the process of
chemical evolution
...

This chemical viewpoint neatly matches everything else
...
Read More about this*
Likely early earth atmosphere
-Heavy water vapor, with volcanic eruption debris
-Nitrogen compounds, carbon dioxide, methane, est
...
The RNA molecules whose
sequence is best suited to the surrounding environment and has the greatest ability
to replicate itself will leave the most descendant of molecules
...
Similar
selection events may have occurred on early Earth
...


Out of Class Notes:
-The sweeping changes in life on Earth as revealed by fossils illustrate
macroevolution, the broad pattern of evolution above the species level
...

-By the force of natural selection; simple cells could have been produced through a
sequence of four main stages:
1
...
) The joining of these small molecules into macromolecules, such as proteins and
nucleic acids
3
...
) The origin of self-replicating molecules that eventually made inheritance
possible
...
I
...
B
...
Haldane
independently hypothesized that Earth’s early atmosphere was a reducing(electron-

adding) environment, in which organic compounds could have formed from simpler
molecules
...
His apparatus yielded a variety of amino acids found in organisms today,
along with other organic compounds
...
In addition, it is likely that small pockets of the early
atmosphere-perhaps near the openings of volcanoes-were reducing
...

-A 2009 study demonstrated that one key step, the abiotic synthesis of RNA
monomers, can occur spontaneously from simple precursor molecules
...

-The necessary conditions may have been met in vesicles, fluid-filled compartments
bounded by a membrane-like structure
...

-Finally, experiments have shown that some vesicles have a selectively permeable
bilayer and can perform metabolic reactions using an external source of reagentsanother important prerequisite for life
...

Thomas Cech called RNA that carry out enzyme-like catalytic functions, ribozymes
...

-RNA could have provided the template on which DNA nucleotide were assembled
...
DNA also can be replicated more accurately
...




---