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Agenda for Monday, February 1, 2016
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While You Are Waiting - #1
Checking homework
Translation video clip
Discussion on Translation
Assignment: Using the Genetic Code
Homework: Pages 26 - 28
While You Are Waiting
• What part of the DNA molecule allows it to
store, copy and transmit information?
Check Your Homework
CCGCCG
TGCATC
CTATTC
GACCGAUGU
A=T T=A
C=G A=U
GGCGGC
ACGTAG
TCTGAG
CTGGCTACA
UCUGAG
CCGCCG
Check Your Homework
AGACUC
DNA
2
The DNA is unzipped and unwound to allow free nucleotides
to base pair to the template strand of DNA to form the
mRNA molecule
Content Objectives:
• I will be able to describe the role of
ribosomes in protein synthesis
• I will be able to describe the “central dogma”
of molecular biology
Interesting Pharmacology
• Alpha-Amanitin, derived
from the poisonous
Amanita Phalloides
mushroom, inhibits
eukaryotic RNA
polymerases, particularly
RNA polymerase II.
Ingestion of small amounts
of alpha-amanitin initially
causes GI problems, but
can rapidly result in death.
Application Question
You are a doctor and teenager comes into the ER who just
ingested what he thought was a psychedelic mushroom.
His girlfriend who took him to the hospital said that she
saw him eat a red mushroom with yellow dots sprinkled
all over it.
What is the mechanism of the toxin now in his system?
– Aminita poisoning: inhibits RNA polymerase II important
in eukaryotic cell transcription.
– Note there is no cure for the toxin, supportive care and
activated charcoal are the only treatments. Very often
people die of liver and renal toxic syndromes caused by
the alpha-aminitine toxin.
Translation
Key Definitions: (write them down at the bottom of page 22)
1. Translation:
Conversion of mRNA to protein
2. Codon:
3 mRNA nucleotides
3. Anticodon:
3 tRNA nucleotides that are
complimentary to the mRNA codon
Translation Video Clip
Click image to
view video clip
RIBOSOMAL STRUCTURE
Beginning of translation
Assembly of polypeptide
Completing the polypeptide
TRANSLATION (p.24)
Initiation overview
• Initiation
– Initiator tRNA (methionine) binds to the small
ribosomal subunit
RIBOSOMAL STRUCTURE
Elongation overview
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•
•
•
Current tRNA in the P-site
New tRNA added to A-site
Amino acids are bound together
E-site tRNA ejected
RIBOSOMAL STRUCTURE
Termination overview
• When the codon in the A-site is a stop codon
(UAG, UAA, or UGA) protein synthesis is
completed
RIBOSOMAL STRUCTURE
Genetic Code
Let’s find the
amino acid for
the mRNA
codon AUG
Assignment:
• Time to practice!!!
• In your packet, complete #1-10 on pages 23
and 24
Clinical Correlations
• Some Compounds that inhibit protein synthesis
in prokaryotic rRNA are utilized as antibiotics.
Streptomycin, Tetracycline, Chloramphenicol,
and Erythromycin inhibit protein synthesis on the
prokaryotic (70S) ribosomes and are used to treat
a variety of infections.
• Question: What organelle in Eukaryotes could
also be affected by these drugs and create
adverse affects in humans?
– Mitochondria
Homework:
• Pages 26-28 in the DNA packet