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Lecture 4

Astronomy 2232F/G Lecture 4: 2232 Lecture 4-The Search for LifePremium

3 pages64 viewsSpring 2018

Department
Astronomy
Course Code
Astronomy 2232F/G
Professor
Els Peeters
Lecture
4

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Lecture 5
Page 1
- 3 questions driving what is defined as astrobiology:
o Where do we come from?
o Are we alone?
o Where are we going?
Page 2
- What is alive and what is dead?
o Needs energy to function, can move at carrying speeds and turn corners,
expel waste… but animals are alive and vehicles are not?
What separates a car/rock from a living organism?
Page 3&4
- 6 Key properties of life:
1. Materials in living organisms exhibit some kind of ORDER. Books and rock
crystals have order but are not alive. It is a necessary condition for life, but alone
does not work
2. Living organisms REPRODUCE and are products of REPRODUCTION. Mules are
alive but cannot reproduce, and are products of reproduction. Viruses cannot
reproduce alone because they need a host. Alive or not? (not dont need energy
or have a metabolism)
3. Living organisms GROW and DEVELOP at some point in their life; heredity
4. Living organisms USE ENERGY to create and maintain order within cells,
reproduce and to grow. A fridge utilizes energy… life needs a long-term
continual energy source
5. All living organisms interact with their surroundings and RESPOND TO
CHANGES IN THE ENVIRONMENT. Sweating, panting, BF to maintain
temperature … thermostat also does this
6. Life EVOLVES over (geologic) time new organisms evolve better suited to
environments new species form
Page 5
- Fire conforms to 4 of 5 properties of life BUT is not alive
Page 6
- The most general definition of what is life is adopted by NASA in : life is a self-
sustained chemical system capable of undergoing Darwinian evolution.
- Alternatively, life is defined by what it does not what it is made of much less
restrictive than other ideas (non-biological life aka artificial intelligence)
Page 7
- All earth life is carbon based
- Finding carbon-based life is the assumption which drives our current exploration of
the solar system
- Carbon forms the backbone for polymeric chemistry essential for life: nucleic acid
polymers of DNA and RNA, amino acids and polymers of proteins
- Circle image is periodic table of what life on earth need
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