Transcript Planet Detection - University of Washington

Astronomy190 - Topics in Astronomy
Astronomy and Astrobiology
Lecture 7 : Biology I
Ty Robinson
Questions of the Day
• What does it mean for something to be alive?
• What is the ‘Central Dogma’ of biology?
• How has evolution led to the incredible biodiversity
we see on Earth today?
The result of 4 billion years of evolution:
Life’s tremendous biodiversity
How to define life?
Order
Reproduction
Energy utilization
Response to the
environment
Growth and development
Evolutionary
adaptation
What is life made of?
Oxygen
C arbon
Hydrogen
Nitrogen
C alcium, Phosphorus, Potassium, Sulfur,
Sodium, C hlorine, Magnesium
Chemical composition of
the human body
(by weight)
Trace elements (B, C r, C o, C u, F, I, Fe,
Mn, Mo, Se, Si, Sn, V, Zn)
DNA: the information molecule
Gene: a discrete unit of
information represented
in a DNA sequence
RNA:
the
multitasking
molecule
Proteins: the workhorse
of the cell
• structure
hemoglobin (blood)
• catalysts (enzymes)
• signaling
• delivery of nutrients
• transportation
• etc.
p53 (spellchecker)
keratin (hair, nails)
Central Dogma of Biology
D
NA
transcription
RNA
translation
protein
Transcription: DNA to RNA
Translation: RNA to
protein
DNA as a “language:”
4 letter alphabet in 3
letter words
National Institutes of Health
AUG CGA AGU GGG UGA
Met - Arg - Ser - Gly - Stop
The
Genetic
Code
Mutation: a change in the base sequence of
the DNA
Example:
ATA GTC TGA CTG
ATG
Sickle cell anemia
Tyr - Gln - Thr - Asp - Tyr
ATA GTC AGA CTG
ATG
Tyr - Gln - Ser - Asp - Tyr
Darwin’s Big Idea:
Evolution
HMS Beagle
Charles Darwin
Darwin’s Big Idea
Four Postulates:
1. Individuals within populations are variable.
2. Variation is inherited from your parents.
3. Some individuals are more successful at
surviving and reproducing than others.
4. Individuals with the most favorable variations
are naturally selected.
Fitness: the capability of an individual to reproduce
and pass on genes to the next generation
Evolution is not goal-oriented
Natural selection in action
The peppered moth and the Industrial Revolution
Evolution operates by
means of changes in
trait frequencies in
populations, as well
as through speciation
events
American Museum of Natural History
Evolution is not goal-oriented: something may ultimately be useful, but
that may not be WHY it was selected at the time.
Archaeopteryx
Feathers: originally selected for thermoregulation or sexual selection
Unexpected results in evolution
Birds of paradise: sexual selection rules
Questions of the Day
• What does it mean for something to be alive?
• What is the ‘Central Dogma’ of biology?
• How has evolution led to the incredible biodiversity
we see on Earth today?
Biology, viewed through an astrobiological lens:
1. The blueprints for making every aspect of life is contained within
its informational molecule. On Earth, this is DNA.
2. Life on Earth is carbon-based.
3. Life diversifies into its tremendous biodiversity through the
process of evolution.
4. Evolution is not goal-oriented!
The chirality of life
Some molecules are chiral: they are non-superposable with
their mirror image.
On Earth, all of life’s amino acids are left-handed, and its
sugars are right-handed!
Central Dogma of Biology
“master copy”
DNA
transcription
RN
A
“working copy”
translation
pro
tein