RNA & Protein Synthesis
I. Quick Review
A. What are some proteins you are made of?
Ex: keratin, hemoglobin, enzymes, antibodies
B. What are the building blocks of proteins?
Amino acids
C. What organelle makes proteins?
Ribosomes
D. Where are the instructions for
making a protein?
DNA!
E. Where is this molecule located
in cell?
Nucleus
Central Dogma
1.
2.
Photo credit: http://katiephd.com/wp-content/uploads/2011/01/central-dogma.jpg
The Structure of RNA
1. Phosphate group
2. 5-carbon sugar- ribose
3. Bases
i. Adenine
ii. Uracil
iii. Cytosine
iv. Guanine
Step 1: Transcription
1. During transcription, RNA polymerase binds
to DNA on gene and separates the DNA strands
2. Using one strand of DNA (the gene) as a
template, nucleotides are assembled into
mRNA (“messenger RNA”) which will leave the
nucleus and travel to ribosome
Transcription- nucleus
B. Translation
1. Translation is the process of decoding the
mRNA into a polypeptide chain (protein)
2. Ribosomes read mRNA three bases
(1 codon) at a time and construct the proteins
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3. mRNA transcript start codon AUG
attaches to the ribosome
4. Process continues until a stop codon.
video
End Product –The Protein!
5. The end products of protein synthesis is a
primary structure of a protein
6. A sequence of amino acid bonded together
by peptide bonds
aa2
aa1
aa3
aa4
aa5
aa199
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12
aa200
One gene,
one
polypeptide
Translation
Second base in codon
So how can you
tell what amino
acid will be
carried on the
tRNA? Use this
chart!
Try AUG codonwhat amino
acid? (use codon!)
First base in codon
Third
base
in
codon
Name the Amino Acids
•
•
•
•
•
GGG?
UCA?
CAU?
GCA?
AAA?
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• All of DNA Translation
A. Mutations: Any change in the
DNA sequence.
Main question:
how does that
affect the
proteins?
M
u
t
a
t
i
o
n
s
Ryan Clark of Pittsburgh Steelers
Photo source: http://www.dnalc.org/resources/3d/17-sickle-cell.html
1 base change in 438-base sequence.
Hemoglobin protein does not work properly to
carry oxygen.
Can’t Carry Oxygen
Tay Sachs
http://www.pbs.org/wgbh/nova/body/cracking-the-code-of-life.html
Time- 15:00-20:00



Inherited genetic mutation
HEXA gene codes for an enzyme that
breaks down fatty acids
Build up of fatty acids in the brain
Mistakes Happen!
B. A mutagen is any environmental agent that causes a
change in DNA
 Mutagens can be chemical or physical

Ex: UV rays, nuclear radiation, chemicals
(benzene, nicotine, pesticides, formaldehyde)
Photo credit:
http://www.mrwallpaper.com/wallpapers/Plane
Photo credit: http://www.realnewsreporter.com/wpcontent/uploads/2011/04/nuclear-429.n.jpg
C. Define point mutations:
change of 1 base in DNA sequence
Diseases Caused by Point Mutations
Colorblindness
 Hemophilia
 Cystic Fibrosis
Important:
 Tay Sachs
 If a mutation is inherited, then
 PKU
ALL the cells will have the

mutation
 If a mutation is caused by the
environment, ONLY the cells where
the DNA is mutated will be affected
Types of Point Mutations
Original Strand RNA:
AUG CCA ACA GAU CAG UAG CGC GUA
1. Substitution
AUG CCA ACA GAU CAG UAC CGC GUA
2. Insertion into original
ACU GCC AAC AGA UCA GUA GCG CGU A
3. Deletion from original
AGC CAA CAG AUC AGU AGC GCG UA
The cat ate the rat.

Substitution
The car ate the
rat.

Insertion
The caa tat eth era
t.

Deletion
Tec ata tet her at.
D. Frameshift Mutations
• Effects of insertions or deletions are
more dramatic
• Addition or deletion of a nucleotide
causes a shift in grouping of codons
• Changes like these are called
frameshift mutations
Some substitutions don’t cause
changes in the amino acids
GCC, GCA = alanine
CGG, AGG = arginine
Remember: there are extra amino acid
“words”: 20 A.A.’s, 64 codons!
Write this: if amino acid does not
CHANGE, the mutation is called
“silent”
Can you think of when
mutations might be GOOD?
• Genetic diversity
• Sickle cell anemia CAN protect someone
against malaria
• HIV resistance in humans
Mutations
Hypertrichosis
Chromosomal Mutations