Download ProteinSynthesis

PROTEIN
SYNTHESIS
copyright cmassengale
1
Starting with DNA
• DNA is the molecule that stores
genetic information in the nucleus.
• It is a “code” that builds the
molecules of life (proteins).
• DNA stays in the nucleus, but
molecules are built in the cytoplasm of
the cell.
• So, the code must be copied and
moved out into the cytoplasm, where
proteins are assembled.
• This process is called PROTEIN
2
SYNTHESIS
Genes & Proteins
 Proteins are made of amino
acids linked together by peptide
bonds
 20 different amino acids
 Amino acids chains are called
polypeptides
 Segment of DNA that codes for
the amino acid sequence in a
protein are called genes
3
RNA
copyright cmassengale
4
RNA
(ribonucleic acid)
• The nucleic acid that carries the
genetic information on DNA from
the nucleus out to the
cytoplasm, where proteins will
be made.
copyright cmassengale
5
RNA is similar to DNA
1. They both are made up of
nucleotides
2. They both have a sugar
3. They both have 4 nitrogen bases
4. They both have a phosphate
6
RNA Differs from DNA
DNA
RNA
1. DNA has a sugar
deoxyribose
1. RNA has a sugar
ribose
2. DNA contains the
base thymine (T)
2. RNA has uracil (U)
3. DNA molecule is
double-stranded
3. RNA is singlestranded
7
Roles of RNA and DNA
• DNA is the MASTER
PLAN
• RNA is the
BLUEPRINT of the
Master Plan
copyright cmassengale
8
Structure of RNA
copyright cmassengale
9
Types of RNA
copyright cmassengale
10
3 KINDS OF RNA
MESSENGER
_________________RNA (mRNA)
Copies the code from DNA and carries it out.
RIBOSOMAL
_________________RNA (rRNA)
With proteins, it forms ribosomes
TRANSFER
_________________RNA (tRNA)
Matches mRNA to “transfer” the correct
amino acids to make a protein.
rRNA and t-RNA images from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
mRNA image from http://wps.prenhall.com/wps/media/tmp/labeling/1140654_dyn.gif
Remember…
• The purpose of DNA is to store
and transmit the genetic code so
that……
• Proteins can be made.
copyright cmassengale
12
Pathway to Making a
Protein
DNA
mRNA
tRNA (ribosomes)
Protein
copyright cmassengale
14
Protein Synthesis
 The process of making
proteins from the code on
DNA.
 Two phases:
1. Transcription
2. Translation
copyright cmassengale
15
DNA  RNA  Protein
Nuclear
membrane
DNA
Transcription
Eukaryotic
Cell
Pre-mRNA
RNA Processing
mRNA
Ribosome
Translation
Protein
copyright cmassengale
16
Transcription
and
Translation
copyright cmassengale
17
Transcription
copyright cmassengale
18
Transcription
• The process of copying one
strand of DNA onto mRNA
• Follows the base pair rule.
copyright cmassengale
19
Template Strand
copyright cmassengale
20
21
What is the
enzyme
responsible for
the production of
the mRNA
molecule?
22
RNA Polymerase
 Enzyme found in the
nucleus
 Separates the two DNA
strands by breaking the
hydrogen bonds between
the bases
 Then moves along one of
the DNA strands and links
RNA nucleotides together
23
DNA
RNA Polymerase
pre-mRNA
24
Question:
 What would be the
complementary RNA strand
for the following DNA
sequence?
DNA 5’-GCGTATG-3’
25
Answer:
• DNA 5’-GCGTATG-3’
• RNA 3’-CGCAUAC-5’
26
You Practice!
• DNA
RNA
AATCGG
UUAGCC
• DNA
RNA
CATTAC
GUAAUG
• DNA
GCGATT
RNA
CGCUAA
copyright cmassengale
27
mRNA Processing
• After the DNA is
transcribed, the mRNA,
is edited
– The entire DNA strand is
copied.
– Introns (which don’t code for
proteins) are cut out.
– Exons (which do code for
proteins) are spliced back
together.copyright cmassengale
28
Result of Transcription
Introns are orange; Exons are green
mRNA Transcript
•mRNA leaves the nucleus and
goes to the ribosomes
copyright cmassengale
30
Messenger RNA (mRNA)
• ON the mRNA is a codon:
a group of 3 nucleotides
that will code for one amino
acid.
• AUG – methionine or start
codon
• UAA, UAG, or UGA – stop
codons
• GGC - Glycine
copyright cmassengale
31
The Genetic Code
• A codon designates an amino
acid
• There are 20 amino acids,
but 64 possible codons
copyright cmassengale
32
The Genetic Code
•Use the
code by
reading from
the center to
the outside
•Example:
AUG codes
for
Methionine
copyright cmassengale
33
Name the Amino Acids
•
•
•
•
•
GGG?
UCA?
CAU?
GCA?
AAA?
copyright cmassengale
34
Review
1. What happens in transcription
(step 1 of protein synthesis)?
The code in DNA is
copied onto an mRNA, in
the nucleus.
copyright cmassengale
35
Review
#2 Once the mRNA is made, it
leaves the nucleus and goes to a
ribosome
_____________.
copyright cmassengale
36
Review
• The mRNA is read by its
“words”, which are called:
codons
_________,
which are groups of
3 nucleotides.
copyright cmassengale
37
USE THE DNA CODE PROVIDED
TO MAKE A COMPLEMENTARY
RNA COPY
U C G G A C A U C C G U
A G C C T G T A G G C
A
Review #1
USE THE DNA CODE PROVIDED
TO MAKE A COMPLEMENTARY
RNA COPY
A A G U U C G U U A G C
T T C A A G C A A
T C
G
Review #2
Translation
copyright cmassengale
40
Translation
• Translation is the process of
using the mRNA’s code to
build a protein
mRNA
tRNA
copyright cmassengale
protein
41
Remember the types
of RNA?
Transfer RNA
(tRNA)
3 bases are
called a:
Anticodon
3 bases are
called a:
Messenger RNA
(mRNA)
Codon
42
Codons and Anticodons
• A codon is on mRNA.
• An anticodon is on
the tRNA and is a
complement to the
codon.
• Example: Codon ACU
Anticodon UGA
copyright cmassengale
UGA
ACU
43
THE mRNA strands’ codons determine the
complementary tRNA strands’ anticodons
C U G
G U A
tRNA
(anticodons)
U A C U U C
A U G A A G C A U G A
C
mRNA
(Codons)
Name the anticodons
to these codons:
•
•
•
•
•
CCU
UAG
GUC
AGU
CUA
GGA
AUC
CAG
UCA
GAU
copyright cmassengale
45
Translation Steps
1. Anticodons on the tRNA
match up with the codons
on mRNA.
2. Each tRNA carries one
amino acid.
3. The amino acids are joined
to form proteins.
(Happens in the ribosomes.)
copyright cmassengale
46
ANTICODON
___________
on tRNA
EACH tRNA
carries only
one kind of
amino acid
_____________
matches up with
CODON
________
on mRNA
Images modified from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
Translation
Copyright Pearson Prentice Hall
Translation
Lysine
mRNA
tRNA
Translation direction
Ribosome
Copyright Pearson Prentice Hall
Translation
Protein
Ribosome
tRNA
mRNA
Copyright Pearson Prentice Hall
End Product –The Protein!
• A sequence of amino acids
bonded together
aa2
aa1
aa3
aa4
aa5
aa199
copyright cmassengale
aa200
51
USE THE mRNA CODE PROVIDED
TO ADD THE COMPLEMENTARY tRNA
Anticodons
C U G
G U A
A U G A A G C A U G A
#7
U A C
C
U U C
USE THE mRNA CODE PROVIDED
TO ADD THE COMPLEMENTARY tRNA
C U G
G U A
U U C
U A C
A U G A A G C A U G A
#8
C
USE THE mRNA CODE PROVIDED
TO ADD THE COMPLEMENTARY tRNA
C U G
G U A
U A C U U C
A U G A A G C A U G A
#9
C
USE THE mRNA CODE PROVIDED
TO ADD THE COMPLEMENTARY tRNA
C U G
U U C G U A
A U G A A G C A U G A
#10
C
USE THE mRNA CODE PROVIDED
TO ADD THE COMPLEMENTARY tRNA
G
U A
C U G
A U G A A G C A U G A
#11
C
USE THE CODON WHEEL TO TELL THE
AMINO ACID SEQUENCE OF THE PROTEIN
THIS mRNA WILL MAKE
#12
GLUTAMINE - ALANINE - ALANINE - PHENYLALANINE
C
A
G
G
C
A
G
C U
U U
U
USE THE CODON WHEEL TO TELL THE
AMINO ACID SEQUENCE OF THE PROTEIN
THIS mRNA WILL MAKE
#13
VALINE -
SERINE - HISTIDINE - STOP
G U C A G C C A U U G A
REPLICATION
DNA → DNA ____________
TRANSCRIPTION
DNA → RNA ____________
RNA→ Protein TRANSLATION
___________
Closure
Fill in the blanks with the
correct process.
copyright cmassengale
60