Download Transcription & Translation

Major Constituents of Cell
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Nucleus

Largest organelle (5 m in diameter)


Nuclear envelope


some anuclear or multinucleate
two unit membranes held together at nuclear pores
Nucleoplasm

chromatin (thread-like matter) = DNA and protein

nucleoli = dark masses where ribosomes produced
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Kornberg & DNA polymerization

http://www.johnkyrk.com/DNAreplication.html

http://www.cellsalive.com/mitosis.htm
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Control of Cell Division

Surface-to-volume ratio of
cells

Contact inhibition
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Endoplasmic Reticulum
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Ribosomes

Granules of protein and RNA


found in nucleoli, free in cytosol and on rough ER
Uses directions in messenger RNA to assemble
amino acids into proteins specified by the genetic
code (DNA)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein Synthesis

DNA serves as master blueprint for protein
synthesis

Genes are segments of DNA carrying instructions
for a polypeptide chain

Triplets of nucleotide bases form the genetic
library

Each triplet specifies coding for an amino acid
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
From DNA to Protein
Nuclear
envelope
Transcription
DNA
Pre-mRNA
RNA Processing
mRNA
Ribosome
Translation
Polypeptide
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.33
From DNA to Protein
DNA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.33
From DNA to Protein
Transcription
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
DNA
Figure 3.33
From DNA to Protein
Transcription
DNA
Pre-mRNA
RNA Processing
mRNA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.33
From DNA to Protein
Nuclear
envelope
Transcription
DNA
Pre-mRNA
RNA Processing
mRNA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.33
From DNA to Protein
Nuclear
envelope
Transcription
DNA
Pre-mRNA
RNA Processing
mRNA
Ribosome
Translation
Polypeptide
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.33
Roles of the Three Types of RNA



Messenger RNA (mRNA) – carries the genetic
information (codons) from DNA
Transfer RNAs (tRNAs) – carries amino acids
contains anti-codon
Ribosomal RNA (rRNA) – a structural component
of ribosomes
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
http://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synthesis%20-%20long.html
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Coding
strand
Transcription
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
RNA
nucleotides
mRNA
RNA
nucleotides
RNA
polymerase
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
mRNA synthesis is terminated
DNA
(a)
mRNA transcript
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
(a)
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
(a)
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
RNA
nucleotides
mRNA synthesis begins
(a)
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
RNA
nucleotides
mRNA synthesis begins
mRNA
(a)
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
RNA
nucleotides
mRNA
RNA
nucleotides
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
(a)
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Coding
strand
Termination signal
Promoter
Template
strand
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
RNA
nucleotides
mRNA
RNA
nucleotides
RNA
polymerase
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
mRNA synthesis is terminated
DNA
(a)
mRNA transcript
Coding strand
RNA polymerase
Unwinding
of DNA
Rewinding of DNA
Template strand
RNA
nucleotides
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.34
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Released mRNA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.36
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Released mRNA
1
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Small ribosomal
subunit
Codon 15 Codon 16 Codon 17
Direction of
ribosome advance
Portion of mRNA
already translated
Large
ribosomal
subunit
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.36
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Amino acids
Released mRNA
1
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Aminoacyl-tRNA
synthetase
Small ribosomal
subunit
Codon 15 Codon 16 Codon 17
tRNA
Direction of
ribosome advance
Portion of mRNA
already translated
Large
ribosomal
subunit
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
Figure 3.36
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Amino acids
Released mRNA
1
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
tRNA
Aminoacyl-tRNA
synthetase
Small ribosomal
subunit
Codon 15 Codon 16 Codon 17
Direction of
ribosome advance
Portion of mRNA
already translated
tRNA “head”
bearing
anticodon
Large
ribosomal
subunit
2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Incoming aminoacyltRNA hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
Figure 3.36
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Amino acids
Released mRNA
1
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
tRNA
Aminoacyl-tRNA
synthetase
Small ribosomal
subunit
Codon 15 Codon 16 Codon 17
Direction of
ribosome advance
Portion of mRNA
already translated
tRNA “head”
bearing
anticodon
Large
ribosomal
subunit
2
3
As the ribosome
moves along the
mRNA, a new amino
acid is added to the
growing protein chain
and the tRNA in the A
site is translocated
to the P site.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Incoming aminoacyltRNA hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
Figure 3.36
Nucleus
Nuclear membrane
RNA polymerase
Nuclear pore
mRNA
Template strand
of DNA
Amino acids
Released mRNA
1
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
tRNA
Aminoacyl-tRNA
synthetase
Small ribosomal
subunit
Codon 15 Codon 16 Codon 17
Direction of
ribosome advance
Portion of mRNA
already translated
tRNA “head”
bearing
anticodon
Large
ribosomal
subunit
2
4
Once its amino acid is
released, tRNA is
ratcheted to the E site
and then released to
reenter the cytoplasmic
pool, ready to be
recharged with a new
amino acid.
3
As the ribosome
moves along the
mRNA, a new amino
acid is added to the
growing protein chain
and the tRNA in the A
site is translocated
to the P site.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Incoming aminoacyltRNA hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
Figure 3.36
Genetic Code

RNA codons code for
amino acids
according to a
genetic code

mutations

multiple codons
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.35
http://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synthesis%20-%20long.html
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Information Transfer from DNA to RNA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.38
Developmental Aspects of Cells

All cells of the body contain the same DNA but
Genes of specific cells are turned on or off (i.e., by
methylation of their DNA)

Cell specialization is determined by the kind of
proteins that are made in that cell
muscle cell vs. nerve cell
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Endoplasmic Reticulum (ER)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.18a, c
Golgi Complex
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Signal Mechanism of Protein Synthesis

mRNA – ribosome complex is directed to rough
ER by a signal-recognition particle (SRP)
Cytosol
Transport
vesicle
budding off
Coatomercoated
transport
vesicle
Ribosomes
mRNA
5
3
4
2
1
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
ER
membrane
Sugar
group
Released
Signal glycoprotein
sequence
Growing removed
polypeptide
ER
cisterna
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Signal Mechanism of Protein Synthesis
Cytosol
mRNA
1
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Signal Mechanism of Protein Synthesis
Cytosol
mRNA
2
1
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
Growing
polypeptide
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Signal Mechanism of Protein Synthesis
Cytosol
Ribosomes
mRNA
3
2
1
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
Growing
polypeptide
Signal
sequence
removed
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Signal Mechanism of Protein Synthesis
Cytosol
Ribosomes
mRNA
3
4
2
1
Released
glycoprotein
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
Growing
polypeptide
Signal
sequence
removed
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Signal Mechanism of Protein Synthesis
Cytosol
Transport
vesicle
budding off
5
Ribosomes
mRNA
3
4
Sugar
group
2
1
Released
glycoprotein
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
Growing
polypeptide
Signal
sequence
removed
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Signal Mechanism of Protein Synthesis
Cytosol
Transport
vesicle
budding off
Coatomercoated
transport
vesicle
5
Ribosomes
mRNA
3
4
Sugar
group
2
1
Released
glycoprotein
Signal
Receptor
sequence site
Signalrecognition
particle
(SRP)
Growing
polypeptide
Signal
sequence
removed
ER
cisterna
ER
membrane
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.19
Role of the Golgi Apparatus
Cisterna
Rough ER
Proteins in cisterna
Phagosome
Membrane
Vesicle
Lysosomes containing acid
hydrolase enzymes
Pathway 3
Golgi
apparatus
Vesicle incorporated
into plasma membrane
Coatomer
coat
Pathway 2
Secretory vesicles
Pathway 1
Plasma membrane
Proteins
Secretion by exocytosis
Extracellular fluid
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3.21