Powerpoint

download report

Transcript Powerpoint

Semester projects!
❖
Miraculin paper based!
❖
Find a partner with same TA (needn’t be same section)
❖
You will
❖
Be supplied with suspicious red tablets!
❖
Be expected to support/refute a claim from the paper
❖
Read & reference >= 1 reference from the Miraculin paper
as well as the paper itself
❖
Be awarded 3 point bonus for improving on the Dr.
Pepper!!!
1
Midterm musings
❖
How are bases & amino acids suited to their tasks?
❖
How does hemoglobin function as a machine?
❖
pH triggers
❖
DPG--how & why; fetal changes
❖
Cooperativity
❖
Periodic table: clues & progress
❖
siRNA: send a thief to catch a thief
❖
tamiflu: tracing lineages through mutations
❖
Blue eyes & milk drinking: single vs. multiple origins (hemo?)
2
3
Does milk make you
gassy?
Why/why not?
What’s normal? What’s the discover?
*According to dictionary.com: the necessary changes have been made
Key concept:
DNA is historical record
❖
You got your genes at the Parent’s store
❖
So did they
❖
ad infinitum
❖
Conclude: Your genes are not your own. They are a copy of
a copy of a copy of a copy…
❖
They contain a record of who (what) you were
4
5
What’s milk got?
❖
‘milk sugar’ = lactose =
http://commons.wikimedia.org/wiki/File:Alpha-lactose-from-xtal-3D-balls.png
6
Imagine a normal mammal...
❖
not some bizarro cross-species-suckling human!
❖
...where do you get milk?
❖
...when do you get milk?
❖
❖
when do you no longer get milk?
Is it pointful to build milk-processing bioMachines (enzymes)
for your entire life
7
If you don’t digest it...
❖
gut bacteria in your colon will!
❖
result: ‘copious amounts’* of gas (CO2, methane, H2)
*Wikipedia’s descriptor
8
Lactose in humans
❖
Who’s a mutant: those of you that can digest lactose, or those
that cannot?
❖
Better way to look at it is ‘lactase persistence’: the continued
ability to produce lactose-digesting enzymes
❖
“Ancestral” state: only babies need digest lactose b/c primary
source is mother’s milk
❖
“Derived” state: hey! I think I’ll suck on a cow/camel/goat teat!
(ewww!)
❖
So: who’s the mutant?
What’s in a gene?
Promoter
Controls
‘regulatory region’
❖
❖
Go!
Product instructions
‘coding sequence’
A ‘gene’ is…
❖
instructions for what to make (‘coding sequence’
❖
instructions about where, when, how much to make
(specified by the regulatory regions)
Changes in any of these can give rise to changes in
appearance--phenotype
9
10
Whence milk-induced
gases?
How did humans ‘learn’ (genetically) to drink milk?
How many times was this discover made?
Where? When?
11
Caveat!
❖
This is ongoing research
❖
So we’re discussing preliminary results based on initial
datasets
Whodunnit? Smoking guns
Shown: DNA sequences with points of variability marked
12
Smoking & non-smoking
guns
LP
sequences
LNP
sequences
13
Whodunnit? Smoking guns
14
Contrasting hypotheses
Single
origin
All lacexpressors
will have
same
change(s)
Cause of
change will
be common
to all
sequences
Occam:
Simplest = most
likely
Multiple
origins
All lacexpressors
will NOT
have same
change(s)
15
Camel or cow milk? Yes.
Human
(chimpanzee sequence)
16
And it goes like this...
“This result would justify the hypothesis that the
European T13910 and East African G13907 LP
alleles might have arisen because of a common
domestication event of the cattle whereas the
C3712- G13915 allele in Arabia most likely arose
due to the separate domestication event of camels.”
17
Concept: mutation clock
❖
Things fall apart
❖
Some things are irrelevant
❖
Those things can be reasonably be presumed to fall apart at
constant rate
❖
Calibrate to reliable externals: fossil record, ancestries,
migrations… and you get the mutation clock
18
Do wild animals resemble
cats, dogs, cattle?
❖
OK, maybe cats...
❖
Where did these docile, man-serving little blessings come
from?
❖
The same place as corn, broccoli, tomatoes…
❖
We made that
19
Domestication
20
http://www.spiegel.de/international/zeitgeist/neolithic-immigration-how-middle-eastern-milk-drinkers-conqueredeurope-a-723310.html
References (not trivial!)
❖
❖
Blue eyes
❖
“Blue eye cool in humans may be caused by a perfectly associated
founder mutation in a regulatory element located within the HERC2
gene inhibiting OCA2 expression”
❖
Human Genetics 123:177 2008
Milk
❖
“Independent Introduction of Two Lactase-Persistence Alleles into
Human Populations Reflects Different History of Adaptation to Milk
Culture”
❖
American Journal of Human Genetics 82: 52-72 2008
21
22
Resources
❖
HHMI: lactase movie
❖
http://www.hhmi.org/biointeractive/evolution/Lactase_Regulation/01.html