Your “Do Now” 2/23
(On ½ sheet of paper)
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What is DNA replication?
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What has to happen to DNA before it can be replicated?
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What is the name of the chemicals that “unzip” it?
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What can happen if DNA is not copied perfectly?
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Where does a mutation have to happen if it gets passed
on to somebody’s kids?
http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related
http://www.pbs.org/wgbh/aso/tryit/dna/#
Agenda
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2/24
Notes #3
Practice probs (partners)
Get Candy Lab & DNA Replication
Activity in
Final day for Test Retakes
Progress reports home today
Phone calls home this afternoon
Learning Target

I can explain the process of protein
synthesis and how proteins
determine our traits
CH 12 Notes #3
Protein Synthesis
Protein Synthesis:
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Process of making proteins from
a DNA template
We need proteins for:
1)
2)
3)
4)
Traits
Cell Structure
Hormones
chemical reactions
Some basics: RNA

RNA = Ribonucleic acid
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Single stranded
Can leave nucleus to go into cytoplasm
RNA uses A, C, G, and Uracil (U)
There are 3 types of RNA:
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Messenger RNA (mRNA)
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Makes copies of DNA inside nucleus
Transfer RNA (tRNA)
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Brings amino acids to
ribosomes during translation
There are 2 major parts to protein
synthesis
A.
Transcription
B.
Translation
Part A: Transcription

Making an RNA template from the
DNA
Step 1: Unzip the DNA
Step 2: mRNA attaches to DNA
template
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Similar to DNA
replication
Base-paring
BUT: RNA uses
U’s instead of T’s
Step 3: mRNA moves out of the
nucleus & into the cytoplasm

Important: DNA
stays in the
nucleus!
Let’s try some DNA TRANSCRIPTION
DNA
Sequence:
mRNA
Sequence:
AGA TAC
UCU AUG
CCT GAC
GGA CUG
Part B: Translation
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The process of using mRNA to make
proteins
Proteins are made up of long strands
of chemicals called amino acids
Part B: Translation
Step 1: mRNA moves to a ribosome
Step 2: the ribosome “reads” mRNA
nucleotides 3 at a time
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Each set of 3 nucleotides is called a
codon
Step 3: tRNA brings an amino
acid (AA) to connect to mRNA
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Each tRNA has an set of three bases that
match-up to the mRNA’s codons
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called anti-codons
Example
mRNA codon:
UCC
tRNA Anti-codon: A G G
Reading the mRNA code to build proteins
Practice: UAG = _____________
GGG = _______________
AAC = ____________
Step 4: Creating a Protein
Example: AAG = Phenylalanine
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Amino acids are
connected by
peptide bonds
to form a
protein
DNA translation must be accurate
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Amino acids must be in the correct
order to build the right protein
If mutations in the DNA happen,
the wrong protein will be made
http://www.pbs.org/wgbh/aso/tryit/dna/#
Overview of Protein Synthesis
DNA
Transcription
RNA
Translation
Protein
http://www.youtube.com/watch?v=erOP76_qLWA&feature=related
Practice Problem
DNA sequence: ATA GCC UAA
 What is the mRNA strand?
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UAU CGG AUU
What is the amino acid chain?
What is the amino acid chain?
UAU CGG AUU