Transcript Protein Synthesis

Essentials of Anatomy & Physiology, 4th Edition
Martini / Bartholomew
3
Cell Structure
and Function
PowerPoint® Lecture Outlines
prepared by Alan Magid, Duke University
Slides 1 to 102
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
Key Note
The nucleus contains DNA, the genetic
instructions within chromosomes. The
instructions tell how to synthesize the
proteins that determine cell structure
and function. Chromosomes also
contain various proteins that control
expression of the genetic information.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
Properties of the Nucleus
• Exceeds other organelles in size
• Controls cell structure and function
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
Chromosome Structure
•
•
•
•
Location of DNA
Protein synthesis instructions
Chromatin – uncoiled version
Humans have 23 pairs
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
Chromosome
Structure
Figure 3-17
The Nucleus
Key Note
Genes are the functional units of DNA
that contain the instructions for making
one or more proteins. The creation of
specific proteins involves multiple
enzymes and three types of RNA.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
The Genetic Code – Chemical Language
• Triplet code
• Comprises three nitrogenous bases
• Specifies a particular amino acid
• A Gene
• Functional unit of heredity
• Sequence of triplet codes that codes for a
specific protein
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Nucleus
Protein Synthesis
• Transcription—the production of
RNA from a single strand of DNA
• Occurs in nucleus
• Produces messenger RNA (mRNA)
• Triplets specify codons on mRNA
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
DNA
RNA
polymerase
Codon
1
Codon
2
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Complementary
triplets
Promoter
Triplet 4
mRNA
strand
Codon
1
2
4
Codon
3
Codon 4
(stop signal)
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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DNA
Gene
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-18
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DNA
RNA
polymerase
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Triplet 4
Complementary
triplets
Promoter
2
4
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-18
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DNA
RNA
polymerase
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Triplet 4
Complementary
triplets
Promoter
Codon
1
2
4
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-18
4 of 5
DNA
RNA
polymerase
Codon
1
Codon
2
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Complementary
triplets
Promoter
Triplet 4
mRNA
strand
Codon
1
2
4
Codon
3
Codon 4
(stop signal)
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-18
5 of 5
The Nucleus
Protein Synthesis
• Translation—the assembling of a
protein by ribosomes, using the
information carried by the mRNA
molecule
• tRNAs carry amino acids
• Anticodons bind to mRNA
• Occurs in cytoplasm
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
NUCLEUS
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
mRNA
The small and large ribosomal
subunits interlock around the mRNA
strand.
Amino acid
Small
ribosomal
subunit
KEY
Adenine
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next
mRNA codon.
mRNA strand
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first
tRNA detaches as another tRNA
arrives.
Large
ribosomal
subunit
The chain elongates until the stop
codon is reached; the components
then separate.
Small ribosomal
subunit
Peptide bond
Completed
polypeptide
Stop
codon
Large
ribosomal
subunit
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Figure 3-19
1 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
2 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal
subunits interlock around the mRNA
strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Large
ribosomal
subunit
Figure 3-19
3 of 6
NUCLEUS
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
mRNA
The small and large ribosomal
subunits interlock around the mRNA
strand.
Amino acid
Small
ribosomal
subunit
KEY
Adenine
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Large
ribosomal
subunit
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next
mRNA codon.
Stop
codon
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
4 of 6
NUCLEUS
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
mRNA
The small and large ribosomal
subunits interlock around the mRNA
strand.
Amino acid
Small
ribosomal
subunit
KEY
Adenine
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next
mRNA codon.
mRNA strand
Large
ribosomal
subunit
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first
tRNA detaches as another tRNA
arrives.
Peptide bond
Stop
codon
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
5 of 6
NUCLEUS
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
mRNA
The small and large ribosomal
subunits interlock around the mRNA
strand.
Amino acid
Small
ribosomal
subunit
KEY
Adenine
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next
mRNA codon.
mRNA strand
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first
tRNA detaches as another tRNA
arrives.
Large
ribosomal
subunit
The chain elongates until the stop
codon is reached; the components
then separate.
Small ribosomal
subunit
Peptide bond
Completed
polypeptide
Stop
codon
Large
ribosomal
subunit
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
6 of 6
Coloring Workbook
The packet will be due the day before the
test.
You can now complete numbers 12
13 and 16.