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Lecture 3

Biology 1001A Lecture Notes - Lecture 3: Ribozyme, Transfer Rna, Homochirality

Course Code
BIOL 1001A
Beth Mac Dougall- Shackleton

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Biology Lecture 3: Origins
Independent STUDY Outcomes
1. What are the characteristics shared by all life (7 of them)?
I. Display Orde r - all forms of life are arranged in a highly ordered manner, with the cell
being the fundamental unit of life.
II. Harness and Utilize Energy - all forms of life acquire energy from the environment
and use it to maintain their highly ordered state.
III. Reproduce - all organisms have the ability to make more of their own kind.
IV. Respond to Stimuli - organisms can make adjustments to their structure, function, and
behaviour in response to changes to the external environment (A plant can adjust the size of its
pores (its stomata) on the surface of its leaves to regulate gas exchange).
V. Exhibit Homeostasis - organisms are able to regulate their internal environment such
that conditions remain relatively constant (Sweating is on way in which the human body attempts
to remove heat and thereby maintain a constant temperature).
VI. Growth and Development - All organisms increase their size by increasing the size
and/or number of cells. Many organisms also change over time.
VII. Evolve - populations of living organisms change over the course of generations to become
better adapted to their environment.
2. In what way are properties of life considered “emergent”?
- Properties, like the 7 characteristics of life, are considered emergent because they come about
or emerge from many simpler interactions that, in themselves, do not have the properties found at
the higher levels.
- An emerged ability is one that emerges from many interactions that are at a lower level
3. The characteristics of the “habitable zone” of a solar system.
- region around star where water would exist in a liquid state
- water would thus be conductive to the development of life
- distance from the star where the occurs varies upon energy output of the star
4. The conditions of a primitive Earth.
- atmosphere of Earth 4 billion years ago was very different (primordial atmosphere)
- primordial atmosphere contained an abundance of water vapour
- large quantities of H2, CO2, NH3 (ammonia), CH4 (methane)
- it was proposed that organic molecules could have formed in the atmosphere of primordial
- the early atmosphere was considered to be a reducing atmosphere because of the presence
of large concentrations of molecules such as hydrogen, methane and ammonia
- these molecules contain lot of e- and and many reactions would of taken place which
would have led to the creation of more complex organic molecules
- no ozone O3
- complete absence of O2
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