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10/5/2016
Bio 100 (Paddack) Lecture 12 (10/5/16)
I.
DNA & RNA Structure
A. What? Why?
B. Nucleotide Structure: 3 parts
1. Phosphate group
2. Sugar
3. Nitrogenous bases
C. How RNA & DNA differ
D. DNA is a double-stranded helix
II.
DNA Replication
A. Three steps
B. Semi-conservative model
C. Speed
D. Accuracy
III.
Protein Synthesis
A. Genes to proteins: overview
B. Two Stages
1. Transcription
a. Initiation
b. Elongation
c. Termination & migration
2. Translation
a. Codons
b. tRNA
c. Ribosomes
Nucleic acids (DNA and RNA)…
…making organisms from molecules
?
RNA
Nucleotides
DNA
Nitrogenous Bases
Figure 10.2B
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DNA double helix:
- base pairs form “rungs”
- sugar-phosphate “backbone”
Figure 10.3D
RNA
Sugarphosphate
backbone
Pairs:
A-T
C-G
DNA
The 3D structure of DNA:
Double Helix
Figure 10.3C
James Watson and Francis Crick
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DNA replication
step 1: Helicase separates DNA strands
DNA ReplicationCopies of DNA are made for reproduction
Parental DNA
Separates – new
nucleotides bind
Two identical DNA molecules
From Figure 10.4A
DNA replication
step 2: DNA polymerase adds free
nucleotides to each parent strand
Replication animation
http://www.stolaf.edu/people/giannini/flashan
imat/molgenetics/dna-rna2.swf
DNA replication
step 3: new DNA double helices separate
Linking Genotype to Phenotype:
From DNA to Protein:
• Transcription
DNA  RNA
• Translation
RNA  Protein
Fig. 10.6A
https://www.dnalc.org/resources/3d/12-transcription-basic.html
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Transcription
step 1 (Initiation):
promoter switched on, allowing RNA
polymerase to attach & unzip DNA
Transcription
step 2 (Elongation):
RNA polymerase attaches nucleotides
to parent strands
Transcription
step 3 (Termination): termination, detachment,
migration of mRNA out of nucleus
https://www.youtube.com/watch?v=ztPkv7wc3yU
Making proteins from DNA
(through RNA):
The Genetic Code
•Codons code for the
20 possible amino
acids.
•This is the Genetic
Code.
Figure 10.8A
Figure 10.8A, B
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How do proteins link genotype to
phenotype?
Ribosomes
Lecture 12 (10/5/16): Study Questions
1.
Define DNA
2.
List 3 ways that RNA differs from DNA
3.
List & briefly define the 3 components of DNA &
RNA.
4.
List the 4 nitrogenous bases found within DNA
& the 4 in RNA.
5.
List which base-pairs occur within both DNA &
RNA
6.
Describe the overall structure of DNA including
the ‘backbone’, the ‘rungs’, and the overall shape.
7.
Who took the 1st picture that suggested that
there is a helical 3D structure of DNA?
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8.
Who figured out (& got the Nobel Prize) the full
3D structure of DNA?
9.
List & briefly explain the 3 steps we discussed
for DNA replication.
10. Explain what is meant by ‘semi-conservative
model’ for DNA replication.
11. Define: helicase, DNA polymerase, parent
strand, daughter strand.
12. How is it possible that DNA replication occurs
so quickly?
13. What makes the replication & transcription
process so accurate?
14. Protein synthesis consists of 2 broad phases.
List them and state where in the cell each occurs.
15. Define: translation, transcription, promoter,
RNA polymerase, mRNA, tRNA, ribosome, codon
16. List & briefly describe the 3 steps of the
Transcription phase of protein synthesis.
17. Describe what occurs during the Translation
phase of protein synthesis.
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