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PROTEIN
SYNTHESIS
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DNA
and
Genes
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DNA
• DNA contains_______,
sequences of nucleotide
bases
• These Genes code for
___________ (proteins)
• ________ are used to
build cells and do much of
the work inside cells
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Genes & Proteins
 Proteins are made of
______________linked
together by peptide
bonds
 ____ different amino
acids exist
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Polypeptides
• Amino acid
chains are
called
__________
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DNA Begins the Process
• ______ is found inside the
_______
• _________, however, are
made in the _________ of
cells by organelles called
ribosomes
• Ribosomes may be free in the
cytosol or attached to the
_______________________
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Starting with DNA
• ______ ____must be copied
and taken to the cytosol
• In the cytoplasm, this
_______________ so amino
acids can be assembled to
make polypeptides (proteins)
• This process is called
_____________________
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RNA
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Roles of RNA and DNA
• _____ is the MASTER
PLAN
• _____ is the
BLUEPRINT of the
Master Plan
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RNA Differs from DNA
• RNA has a sugar _______
DNA has a sugar ___________
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Other Differences
•
•
RNA contains the
base ______ (U)
DNA has ______
(T)
RNA molecule is
______-______
DNA is ______________
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DNA
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Structure of RNA
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.
Three Types of RNA
• _________ ____ (mRNA) copies
DNA’s code & carries the
genetic information to the
ribosomes
• _________ ____ (rRNA), along
with protein, makes up the
ribosomes
• _________ ____ (tRNA)
transfers amino acids to the
ribosomes where proteins are
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synthesized
The Genetic Code
• A _____ designates an
_____ _____
• An amino acid may have more
than one codon
• There are 20 amino acids,
but _______________
• Some codons tell the
ribosome to ____ translating
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Remember the
Complementary Bases
On DNA:
A-T
C-G
On RNA:
A-U
C-G
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Codons and Anticodons
• The 3 bases of an
anticodon are
___________ to the
3 bases of a codon
• Example: Codon ACU
Anticodon UGA
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UGA
ACU
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Transcription
and
Translation
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Pathway to Making a
Protein
DNA
mRNA
tRNA (ribosomes)
Protein
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Protein Synthesis
 The _________ or
synthesis of ___________
(proteins)
 Two phases:
Transcription & Translation
 mRNA must be processed
before it leaves the nucleus
of eukaryotic cells
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Transcription
• The process of copying
the sequence of one
strand of DNA, the
______ ______
• mRNA copies the template
strand
• Requires the enzyme ____
___________
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Template Strand
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Question:
 What would be the
complementary RNA strand
for the following DNA
sequence?
DNA 5’-GCGTATG-3’
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Answer:
• DNA 5’-GCGTATG-3’
• RNA 3’-CGCAUAC-5’
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Transcription
• During transcription, RNA
polymerase binds to DNA and
______________________
• RNA Polymerase then uses
one strand of DNA as a
template to assemble
nucleotides into RNA
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RNA Polymerase
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mRNA Processing
• After the DNA is
transcribed into RNA,
______ must be done to
the nucleotide chain to
make the RNA functional
• _______, non-functional
segments of DNA are
snipped out of the chain
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mRNA Editing
• ______, segments of DNA that
code for proteins, are then
rejoined by the enzyme _____
• A guanine triphosphate cap is
added to the 5” end of the
newly copied mRNA
• A poly A tail is added to the 3’
end of the RNA
• The newly processed mRNA can
then leave
the nucleus
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Result of Transcription
CAP
New Transcript
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Tail
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mRNA Transcript
•mRNA leaves the nucleus
through its pores and goes to
the ribosomes
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Translation
• Translation is the process
of decoding the mRNA
into a polypeptide chain
• Ribosomes read mRNA
three bases or 1 _____
at a time and construct
the proteins
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Transcription
Translation
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Ribosomes
• Made of a large and small
subunit
• Composed of rRNA (40%)
and proteins (60%)
• Have ____ ______ for
tRNA attachment --- P
and A
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Step 1- Initiation
• mRNA ________
start codon AUG
attaches to the
small ribosomal
subunit
• Small subunit
attaches to large
ribosomal subunit
mRNA transcript
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Ribosomes
Large
subunit
P
Site
A
Site
mRNA
Small
subunit
A U G
C U A C U U C G
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Step 2 - Elongation
• As ribosome moves, two tRNA with
their amino acids move into site A and
P of the ribosome
• _______ _____ join the amino acids
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Initiation
aa2
aa1
2-tRNA
1-tRNA
anticodon
hydrogen
bonds
U A C
A U G
codon
G A U
C U A C U U C G A
mRNA
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Elongation
peptide bond
aa1
aa3
aa2
3-tRNA
1-tRNA
anticodon
hydrogen
bonds
U A C
A U G
codon
2-tRNA
G A A
G A U
C U A C U U C G A
mRNA
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aa1
peptide bond
aa3
aa2
1-tRNA
3-tRNA
U A C
(leaves)
2-tRNA
A U G
G A A
G A U
C U A C U U C G A
mRNA
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Ribosomes move over one codon
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aa1
peptide bonds
aa4
aa2
aa3
4-tRNA
2-tRNA
A U G
3-tRNA
G C U
G A U G A A
C U A C U U C G A A C U
mRNA
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aa1
peptide bonds
aa4
aa2
aa3
2-tRNA
4-tRNA
G A U
(leaves)
3-tRNA
A U G
G C U
G A A
C U A C U U C G A A C U
mRNA
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Ribosomes move over one codon
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aa1
peptide bonds
aa5
aa2
aa3
aa4
5-tRNA
U G A
3-tRNA
4-tRNA
G A A G C U
G C U A C U U C G A A C U
mRNA
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peptide bonds
aa1
aa5
aa2
aa3
aa4
5-tRNA
U G A
3-tRNA
G A A
4-tRNA
G C U
G C U A C U U C G A A C U
mRNA
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Ribosomes move over one codon
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aa4
aa5
Termination
aa199
aa3 primary
structure
aa2 of a protein
aa200
aa1
200-tRNA
A C U
terminator
or stop
codon
C A U G U U U A G
mRNA
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End Product –The Protein!
• The end products of protein
synthesis is a ______ ______
of a protein
• A sequence of amino acid
bonded together by peptide
bonds
aa2
aa1
aa3
aa4
aa5
aa199
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aa200
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Messenger RNA
(mRNA)
start
codon
mRNA
A U G G G C U C C A U C G G C G C A U A A
codon 1
protein methionine
codon 2
codon 3
glycine
serine
codon 4
isoleucine
codon 5
codon 6
glycine
alanine
codon 7
stop
codon
Primary structure of a protein
aa1
aa2
aa3
aa4
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peptidecopyright
bonds
aa5
aa6
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