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LB145Sec 001-004
Today’s Outline/Announcements
• Study Notes 6a Due.• Take up exam: Thursday
– View exam on Friday between 2-4pm in C-4.• Field Trip Sign-up.• Course Recap
– Membranes transport and proteins– How do proteins make energy?
• How are proteins made?• Introduction to DNA• Worksheet to follow along with today’s material.
Recap – Membranes and Proteins(Unit 1)
• What are proteins?• Where are proteins made?• What happens to them after they are made?• What do membrane proteins do?
Recap – Proteins and Energy(Unit 2)
• What is energy?• How is energy made in plants?• How is energy made in animals?• What role to proteins play in the production of
energy?
Fig. 17-4
DNAmolecule
Gene 1
Gene 2
Gene 3
DNAtemplatestrand
TRANSCRIPTION
TRANSLATION
mRNA
Protein
Codon
Amino acid
The Central Dogma of Molecular
Biology
Unit 3 – What Will You Learn?
• Structure of DNA/RNA.• How is DNA replicated?• How is RNA made?• How is RNA processed?• How does RNA make protein?• What happens to proteins after they are
made?
Structure of DNA and RNA
DNA Factoids
• Humans have 46 chromosomes.• Our 46 chromosomes have 3.2 billion base
pairs.• 99.9% of your base pair sequence is identical
to mine.• All living organisms on the planet have DNA.• We have ~24,000 genes.
DNA Factoids
• If stretched end-to-end, the DNA in 1 chromosome would stretch to ~ 2 inches.
• If tied together and stretched out, all the DNA in 1 cell would stretch to 6 feet!
• All the DNA in our body, if stretched out, could wrap around the earth 5 million times; it would reach the sun and back 70 times.
(50 trillionths of an inch wide)
What is DNA…
Campbell 8e, Fig. 16.21
© 2011 Pearson Education, Inc.
Stra
nd
2. RNA: RiboNucleicAcid
Stra
nd
2. RNA: RiboNucleicAcid
Stra
nd
Stra
nd
3’ carbon 3’ carbon
5’ carbon 5’ carbon
RNA nucleotide
1 of 4
1 of 4
RNA Bases
purines(2 rings)
pyrimidines(1 ring)
What is a nucleotide?
A molecule with a nitrogenous base, a ribose molecule and one or more phosphate groups.
ATP – Adenosine Triphosphate
Campbell 8e Fig. 8.8
High energy bonds!
ATP is a type of nucleotide… more specifically:a nucleoside triphosphate (or NTP)
5’
3’direction
of elongation
Nucleotides in DNA are nucleoside
monophosphate molecules.
Deoxyribonucleoside triphosphates (dNTPs) are bonded to DNA phosphodiester bonds.
Two types of bonds hold DNA together:1. Phosphodiester2. Hydrogen bonds
Base Pairing
Adenine pairs with Uracil in RNA
Purines Pyrimidines
Base Pairing
hydrogen bonds phosphodiester bonds
http://www.umass.edu/molvis/tutorials/dna/dnapairs.htm
Conceptual design and contents: Eric Martz Original Chime version: Eric Martz
Jmol implementation and current design: Angel Herráez Version 4.3, using Jmol 11.4
Offered under Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License
DNA Structure Tutorial
Where is DNA found in Eukaryotes?
Campbell 8e, Fig. 6.9b
How is DNA arranged in Eukaryotes?
http://ghr.nlm.nih.gov/handbook/illustrations/normalkaryotype
centromere
Short arm
Long arm
Origins of replication
Eukaryotes: DNA, Chromatin and Chromosomes
Campbell 8e, Fig. 16.21
Fig. 17-3b-3
(b) Eukaryotic cell
TRANSCRIPTION
Nuclearenvelope
DNA
Pre-mRNARNA PROCESSING
mRNA
TRANSLATION Ribosome
Polypeptide
Where is DNA found in Prokaryotes?
Campbell 8e, Fig. 6.6
Fig. 17-3a-2
(a) Bacterial cell
TRANSCRIPTIONDNA
mRNA
TRANSLATIONRibosome
Polypeptide
Application Question: Red Blood Cells
If you were to study red blood cells you might come across the claim that they have no DNA (or organelles!) – they are essentially membranous sacs filled with a protein called hemoglobin.- Given what you know about the composition
of DNA, how could you test this claim.Hint: Hershey and Chase
How could you test whether or not RBCs have DNA?
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Amino Acids vs DNA
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
DNA’s structure naturally lends itself to being replicated!!
DNA Strands Are Templates for DNA Synthesis
Watson and Crick suggested that the existing strands of DNA served as a template (pattern) for the production of new strands.
Biologists then proposed three alternative hypotheses:
– Semiconservative replication.– Conservative replication.– Dispersive replication.
The Meselson-Stahl Experiment
• Meselson and Stahl designedan experiment to provide more information about whether one of these hypotheses was correct.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Fig. 16-9-3
A T
GC
T A
TA
G C
(a) Parent molecule
A T
GC
T A
TA
G C
(c) “Daughter” DNA molecules, each consisting of one parental strand and one new strand
(b) Separation of strands
A T
GC
T A
TA
G C
A T
GC
T A
TA
G C
DNA Synthesis Requires a Template DNA Strand
For THURSDAY:1. StudyNotes 6b is due.2. Take up the exam.3. Exam viewing: Friday 2-4pm in C-4.4. Field Trip Sign-up