Protein Synthesis
DNA Review
 The nucleotide bases will
point to the inside of the
DNA molecule while the
outside (backbone) of the
DNA molecule will be
made of the sugar and
phosphate molecules
 When complete the DNA
molecule forms a double
helix (two spiral sides
wrapped together)
CHROMOSOMES CONTAIN
DNA
 The nucleus contains
chromatin
 Chromatin is in pieces called
chromosomes
Protein Synthesis
Why is it important?
 Cells are controlled by enzymesenzymes are proteins
 Almost every substance made by the cell
is or contains a stuctural protein
Vocabulary
 Gene- a portion of DNA that codes for a proteinthe “recipe” for a protein
 mRNA- messenger RNA
 tRNA- transfer RNA- transfers amino acids
 Codon- mRNA’s complementary trio of bases
 Anticodon- tRNA’s complementary trio of bases
 Transcription- mRNA making a template of
DNA’s code
 Translation- tRNA “reading” mRNA’s code and
transferring the amino acids necessary to form a
protein
Two Steps to Protein
Synthesis
 Transcription- takes place in
the nucleus-mRNA makes
template of DNA’s code
 Translation- takes place on
the ribosome in the
cytoplasm- tRNA transfers
amino acids
Things to Remember
 DNA contains the “recipes” for proteinscalled genes
 DNA is made of the bases adenine,
thymine, guanine and cytosine
 A-T and C-G
 RNA is made of the bases adenine,
uracil, guanine and cytosine
 A-U and C-G
Transcription
 Takes place in the nucleus
 DNA unzips
 mRNA makes a template of the DNA
code
 mRNA copies the code three bases at a
time- this is a codon
Transcription- mRNA
forms codons
Translation- on the
ribosome, tRNA transfers
amino acids
Another Look
Another View
The four bases can combine in
64 different triplicate (codon)
combinations
 Each codon codes
for a specific amino
acid
Codon Chart
Another Codon Chart
Protein Structure
A Few of The Finished
Products! Proteins
Think About It Letters→ Words→ Sentences
Sam hit the ball.
 Bases→ Amino Acids→ Proteins
View It!
http://www.wisconline.com/objects/index_tj.asp?objID=A
P1302
http://www.pbs.org/wgbh/aso/tryit/dna/shoc
kwave.html
Wrap Up
 1. DNA message is transcribed into messenger
RNA (mRNA)
 2. mRNA leaves the nucleus and attaches to a
ribosome
 3. Each three letter codon will attract a matching
three letter anti-codon of transfer RNA (tRNA)
 4. Each tRNA is carrying an amino acid “on its
back”
 5. As the tRNA molecules line up, their amino
acids also line up
 6. As the amino acids are lined up, they
chemically bond to form a protein
Mutations- Any error in the
genetic code
Can happen when:
 DNA is making new copies of itself
(replication)
 DNA is being used to make messenger
RNA (transcription)
 Transfer RNA is being attracted to the
messenger RNA at the ribosome
(translation)
Types of Mutations
 Point mutations happen when
one or two bases are different
than they are supposed to be
 Frameshift mutations happen
when extra bases are added or
deleted