Quá trình dịch mã ở Eukaryote và Prokaryote

1
PROTEIN
PROTEIN
SYNTHESIS
SYNTHESIS
copyright cmassengale
DNA
DNA
and
and
Genes
Genes
2copyright cmassengale
DNA
DNA
•
DNA contains
DNA contains
genes
genes
,
,
sequences of nucleotide
sequences of nucleotide
bases
bases
•
These Genes code for
These Genes code for
polypeptides (proteins)
polypeptides (proteins)

•
Proteins
Proteins
are used to build
are used to build
cells and do much of the
cells and do much of the
work inside cells
work inside cells


3copyright cmassengale
4
Genes & Proteins
Genes & Proteins

Proteins are made of
Proteins are made of
amino acids
amino acids
linked
linked
together by peptide
together by peptide
bonds
bonds

20
20
different amino acids

different amino acids
exist
exist
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5
Amino Acid Structure
Amino Acid Structure
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6
Polypeptides
Polypeptides
•
Amino acid
Amino acid
chains are
chains are
called
called
polypeptides
polypeptides
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7
DNA Begins the Process
DNA Begins the Process
•
DNA
DNA
is found inside the
is found inside the
nucleus

nucleus
•
Proteins
Proteins
, however, are made
, however, are made
in the
in the
cytoplasm
cytoplasm
of cells by
of cells by
organelles called
organelles called
ribosomes
ribosomes
•
Ribosomes may be
Ribosomes may be
free
free
in
in
the cytosol or
the cytosol or
attached
attached
to
to
the

the
surface of rough ER
surface of rough ER
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8
Starting with DNA
Starting with DNA
•
DNA ‘s code
DNA ‘s code
must be
must be
copied
copied


and taken to the cytosol
and taken to the cytosol
•
In the cytoplasm, this
In the cytoplasm, this
code
code
must be read
must be read
so
so
amino acids
amino acids

can be assembled to make
can be assembled to make
polypeptides (proteins)
polypeptides (proteins)
•
This process is called
This process is called
PROTEIN SYNTHESIS
PROTEIN SYNTHESIS
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RNA
RNA
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10
Roles of RNA and DNA
•
DNA
DNA
is the MASTER
is the MASTER
PLAN
PLAN
•
RNA
RNA
is the
is the
BLUEPRINT of the
BLUEPRINT of the

Master Plan
Master Plan
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11
RNA Differs from DNA
RNA Differs from DNA
•
RNA has a sugar
RNA has a sugar
ribose
ribose
DNA has a sugar
DNA has a sugar
deoxyribose
deoxyribose
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12
Other Differences
Other Differences
•
RNA contains the
RNA contains the
base
base
uracil (U
uracil (U
)
)
DNA has
DNA has

thymine
thymine
(T)
(T)
•
RNA molecule is
RNA molecule is
single-stranded
single-stranded
DNA is
DNA is
double-
double-
stranded
stranded
DNA
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13
Structure of RNA
Structure of RNA
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14
.
Three Types of RNA
Three Types of RNA
•
Messenger RNA (mRNA)
Messenger RNA (mRNA)
copies
copies

DNA’s code & carries the
DNA’s code & carries the
genetic information to the
genetic information to the
ribosomes
ribosomes
•
Ribosomal RNA (rRNA)
Ribosomal RNA (rRNA)
, along
, along
with protein, makes up the
with protein, makes up the
ribosomes
ribosomes
•
Transfer RNA (tRNA)
Transfer RNA (tRNA)
transfers
transfers
amino acids to the ribosomes
amino acids to the ribosomes
where proteins are synthesized
where proteins are synthesized
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15
Messenger RNA
•
Long
Long

Straight
Straight
chain
chain
of Nucleotides
of Nucleotides
•
Made in the
Made in the
Nucleus
Nucleus
•
Copies DNA
Copies DNA
& leaves
& leaves
through nuclear
through nuclear
pores
pores
•
Contains the
Contains the
Nitrogen Bases
Nitrogen Bases
A, G,
A, G,
C, U ( no T )
C, U ( no T )
copyright cmassengale

16
Messenger RNA (mRNA)
Messenger RNA (mRNA)
•
Carries the information for a
Carries the information for a
specific protein
specific protein
•
Made up of
Made up of
500 to 1000
500 to 1000
nucleotides long
nucleotides long
•
Sequence of 3 bases called
Sequence of 3 bases called
codon
codon
•
AUG
AUG
– methionine or
– methionine or
start codon
start codon
•
UAA, UAG, or UGA
UAA, UAG, or UGA

–
–
stop codons
stop codons
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17
Ribosomal RNA (rRNA)
Ribosomal RNA (rRNA)
•
rRNA is a single
rRNA is a single
strand
strand
100 to 3000
100 to 3000
nucleotides
nucleotides
long
long
•
Globular
Globular
in shape
in shape
•
Made inside the
Made inside the
nucleus
nucleus
of a cell

of a cell
•
Associates with
Associates with
proteins to form
proteins to form
ribosomes
ribosomes
•
Site of
Site of
protein
protein
Synthesis
Synthesis
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18
The Genetic Code
•
A
A
codon
codon
designates an
designates an
amino acid
amino acid
•
An amino acid may have
An amino acid may have

more than one codon
more than one codon
•
There are 20 amino acids,
There are 20 amino acids,
but
but
64 possible codons
64 possible codons
•
Some codons tell the
Some codons tell the
ribosome to
ribosome to
stop
stop
translating
translating
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19
The Genetic Code


•
Use the
code by
reading from
the center to
the outside
•

Example:
AUG codes
for
Methionine
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20
Name the Amino Acids
•
GGG?
GGG?
•
UCA?
UCA?
•
CAU?
CAU?
•
GCA?
GCA?
•
AAA?
AAA?
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21
Remember the
Remember the
Complementary Bases
Complementary Bases
On DNA:
On DNA:

A-T
A-T


C-G
C-G
On RNA:
On RNA:


A-U
A-U


C-G
C-G
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22
Transfer RNA (tRNA)
Transfer RNA (tRNA)
•
Clover-leaf
Clover-leaf
shape
shape
•
Single stranded molecule
Single stranded molecule

with attachment site at
with attachment site at
one end for an
one end for an
amino acid
amino acid
•
Opposite end has three
Opposite end has three
nucleotide bases called
nucleotide bases called
the
the
anticodon
anticodon
copyright cmassengale
23
Transfer RNA
Transfer RNA
amino acid
amino acid
attachment site
attachment site
U A C
anticodon
anticodon
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24
Codons and Anticodons
•

The 3 bases of an
The 3 bases of an
anticodon are
anticodon are
complementary
complementary
to
to
the 3 bases of a
the 3 bases of a
codon
codon
•
Example: Codon ACU
Example: Codon ACU


Anticodon UGA
Anticodon UGA
UGA
ACU
copyright cmassengale
Transcription
Transcription
and
and
Translation
Translation
25copyright cmassengale