Lab 3: Codes, Meaning,
Copying
DNA
Instructions for the
parts of living things
Why the instructions for
you are stored as hydrogen
interactions between ringy things
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DNA
Why care
about DNA?
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DNA
• It’s in all living things
• Interface between chemistry and ‘life’
• Easily understood molecule
• doesn’t ‘do’ anything
• Structure is based on H-bonding
• Structure IS function
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DNA
• So what does it mean to be “living”
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Things to do today:
• Make leap from Chemistry to Biology:
how can you get ‘you’
from C, H, O, N and P (finish next week)
• Describe HOW/WHY A goes with T and
G with C (and ‘not’ G with T)
• Discuss what took ‘them’ so long
• Mutations happen ALL THE TIME!
• Begin investigation into genetic
diseases
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DNA
Why Does A
“go with” T?
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• Party hats on• Starting point:
–
–
–
–
BLUE hats – L hand out, palm down
GREEN hats – L hand out, palm out (shake)
YELLOW hats – L hand out, palm up
RED hats – L hand out, palm out (shake)
• START with a strand of GGGTT ,‘right hand’ on
neighbor’s shoulder
• Make a matching strand (dbl-stranded DNA)
• Why do bases go together?
• Each strand ‘count off’ from their L to R, how do the
two directions compare?
Gua = Green
Cyt = Red
Ade = Blue
Thy = Yellow
• Separate strands; who partners with whom? What
external info do we need to re-create the missing
strand?
• Restart; RED hat turns hand palm up (put on purple
hat)
• it’s undergone chemical change… replicate &…?
GGGTT
Gua = Green
Cyt = Red
Ade = Blue
Thy = Yellow
DNA
• Why do atoms make bonds?
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DNA
• Why do atoms make bonds?
• What types of ‘bonds’ are there?
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DNA
• Why do atoms make bonds?
• What types of ‘bonds’ are there?
• Not all atoms play fair
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DNA
• Hydrogen bond/interaction
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
•Based on electronegativity
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
•Based on electronegativity
• Why not Carbon-Hydrogen?
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
• H-Bond Donors
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
• H-Bond Donors
• Positive charge (Hydrogen)
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
• H-Bond Donors
• Positive charge (Hydrogen)
• H-Bond Acceptors
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DNA
• Hydrogen bond/interaction
• When H bonds with ‘O’ or ‘N’
• H-Bond Donors
• Positive charge (Hydrogen)
• H-Bond Acceptors
• Negative charge (O, N)
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Oregano
Garlic
Basil
Salt
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Guanine
Cytosine
Thymine
Adenine
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Things you already ‘know’
• Pyrimidine (single ring), Purine
(double)
– PUR As Gold
– Big base = little name
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Take a look at the models
• Each group gets GC or AT pair. Investigate.
• Superimposability of GC, CG, AT, TA pairs
• High crimes and misdemeanors
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Anatomy of a basepair
Ornaments
-NH2
=O
-H
-OH
=NH
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Make your own GC or AT
Hydrogen bonds form between G-C pairs and A-T pairs.
Hydrogen bonds
Sugar-phosphate backbone
5
3
Guanine
Cytosine
Adenine
Thymine
DNA contains thymine,
whereas RNA contains uracil
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Freeman, Biological Science, 4.6b
3
5
BasePairer
Rubric is available via web page
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Basepairer
• Go to the ‘Lab03_DNA’ folder
• Launch ‘BasePairer’
• DON’T log in, that’s for homework
•
Write your names on the paper I hand out; return it at
end of class or zero credit
•
Basepairer group = genetic disease group
•
make a note of your group name & genetic disease
in your lab notebook
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Bad things happen to good
bases
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Bad things happen to Good Bases
Chargaff’s Rules didn’t lead to structure
WHY?
%A
%T
%G
%C
Mycobacterium
Yeast
15.1
31.3
14.6
32.9
34.9
18.7
35.4
17.1
Wheat
Sea Urchin
Marine Crab
Turtle
Rat
Human
27.3
32.8
47.3
29.7
28.6
30.9
27.1
32.1
47.3
27.9
28.4
29.4
22.7
17.7
2.7
22
21.4
19.9
22.8
17.3
2.7
21.3
21.5
19.8
Bad things happen to Good Bases
Tautomers
Bad things happen to Good Bases
Tautomers
Genetic Disease
• Spans the next month
–
–
–
–
SYMPTOMS AND DISTRIBUTION
DNA mutation, amino acid change
Probable influence on protein structure
Then you’ll share your findings with the
class
• Lets you apply your learning and
thinking to an actual disease
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Genetic Disease
• Write your names on the paper I hand
•
•
out; return it at end of class or zero
credit
Make note or your group name and
disease in your lab notebook
What is most important is that you
think well and integrate what you are
learning; being ‘right’ is secondary
* Letters and underlines only. CAN BE SEEN BY ME!
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Genetic Diseases
Due Today!!!
Part 1 of assignment
Turned in to me with all group members’
names on it.
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Genetic Diseases
• An example: hemoglobin/sickle cell
anemia
– Sufferers: one in 12 African Americans
has the TRAIT; overall, 1/5000
Americans suffer
– Common in areas with malaria
– symptoms: shortened lifespan (48-52),
see next slide
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A few thoughts
• “Google” is a great search engine
– Use quotes if needed
– Advanced search
– ‘scholar’
• Wikipedia
– User contributions
• Anybody can have a web page
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Homework
• Examining DNA/Intro Translation Assessor
• Transcribe & Translate (Vocab)
•Basepairer
–Group assignment (1/group)
–Written portion to Dropbox
•Quiz next week
–Emphasizes next week’s lab
–Study today’s material, too