Transcript RNA and Protein Synthesis

Protein Synthesis and
Gene Expression
Let’s Review DNA & RNA
 DNA: deoxyribonucleic
acid--contains sugar
deoxyribose.
 DNA is double
stranded.
 DNA contains bases
adenine, thymine,
guanine, cytosine.
 DNA never leaves the
nucleus.
 RNA: ribonucleic acid-contains sugar ribose.
 RNA is SINGLE
stranded.
 RNA contains bases
adenine, guanine,
cytosine and URACIL.
 RNA can leave the
nucleus.
Remember there are three types
of RNA
mRNA: messenger RNA
mRNA
tRNA: transfer RNA.
rRNA: ribosomal RNA
tRNA
towing
Overall process of protein
synthesis
transcription
DNA
translation
RNA
Protein
TRANSCRIPTION
translation
Takes place in the
nucleus
Moves out of nucleus
into the cytoplasm &
attach to ribosome
DNA’s tragedy
If I could only
get out there…
I’d show them
a thing or two!
DNA contains
volumes of
information about
making protein.
Unfortunately,
DNA is too huge
to leave the
ribosomes
nucleus.
nucleus
How does the cell solve this
problem….transcription
That’s where
mRNA comes in.
mRNA helps get
DNA’s message
out to the
ribosomes...
How do I tell
those guys what
I want them
to do?
I can help!
First, DNA unzips itself...
DNA unzips
itself, exposing
free nitrogen
bases.
First, DNA unzips itself...
DNA unzips
itself, exposing
free nitrogen
bases.
First, DNA unzips itself...
DNA unzips
itself, exposing
free nitrogen
bases.
First, DNA unzips itself...
DNA unzips
itself, exposing
free nitrogen
bases.
First, DNA unzips itself...
DNA unzips
itself, exposing
free nitrogen
bases.
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in a
complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
Next, mRNA is made...
mRNA is made
from the DNA
template
mRNA matches
with free DNA
nitrogen bases in
a complimentary
fashion
mRNA leaves the nucleus...
I hope he can
tell them what
to do!
DNA’s code is
copied to mRNA in
three letter groups
called codons.
After mRNA is
made from the
DNA template, it is
ready to leave the
nucleus.
The next step...Translation
mRNA meets the
Ribosomes!
(No, it’s not a new sitcom on Fox…)
mRNA tries to talk to the
ribosomes…
mRNA leaves the I have a message
for you! It’s
nucleus and
from DNA!
travels to the
cytoplasm, where
the ribosomes are
located.
Once there, mRNA
meets up with the
ribosomes
What does
he want now?
It’s always
something!
mRNA tries to talk to the
ribosomes…but is unsuccessful.
However, the
ribosomes cannot
understand the
message mRNA is
carrying.
Why don’t they
get it???
@%$!!
Why can’t we tell
what he’s saying?
We need a
translator!
tRNA Saves the Day!
Tyrosine
The boss will NOT
be happy about
this...
We won’t work until
we know what to do!
Where is that
translator?
Looks like trouble
for this cell…
I’d better help!
Now the cell
can make a
protein!
tRNA: Transfer RNA
Tyrosine
Chemically, tRNA
is clover-leaf
shaped.
At one end, it
carries an amino
acid.
At the other end, it
has a three letter
code known as an
anticodon.
Anticodon? What’s that?
This anticodon is the
complement to the
codons contained
within mRNA.
Can you find the
mRNA complement
to the anticodon on
tRNA?
Tyrosine
Some notes about Amino Acids
There are 20 known amino acids present
in living things.
How is it possible to get a group of four
letters to code for 20 things?
Put them into groups of three…
43 = 64 codes
Number of members in a group of nitrogen bases
Number of nitrogen bases
What’s a codon, anyway?
Here is what a codon
looks like. It is a
sequence of 3 bases.
How we determine
what amino acid each
codon codes for must
be read off of a codon
chart.
This is also known as
the genetic code.
Codon chart
Second Base
U
A
G
Phenylalanine
Phenylalanine
Leucine
Leucine
Serine
Serine
Serine
Serine
Tyrosine
Tyrosine
Stop
Stop
Cysteine
Cysteine
Stop
Tryptophan
U
C
A
G
C
Leucine
Leucine
Leucine
Leucine
Proline
Proline
Proline
Proline
Histidine
Histidine
Glutamine
Glutamine
Arginine
Arginine
Arginine
Arginine
U
C
A
G
A
Isoleucine
Isoleucine
Isoleucine
Methionine
Threonine
Threonine
Threonine
Threonine
Asparagine
Asparagine
Lysine
Lysine
Serine
Serine
Arginine
Arginine
U
C
A
G
Valine
Valine
Valine
Valine
Alanine
Alanine
Alanine
Alanine
Aspartic Acid
Aspartic Acid
Glutamic Acid
Glutamic Acid
Glycine
Glycine
Glycine
Glycine
U
C
A
G
U
First
Base
C
G
Third
Base
The Wonderful World of Amino
Acids
It is possible for some amino acids to
have more than one codon.
There are three stop codons…they are
UAA, UGA and UAG.
There is also one START codon…AUG.
How a Translator works…
First, the anticodons
on tRNA meet up
with the mRNA start
codon (AUG) at the
ribosome
Next, another tRNA
meets up with it’s
corresponding
mRNA.
Each tRNA carries
an amino acid.
Tyrosine
How a Translator works…
Once two amino
acids are made, a
bond forms between
them
This process
continues until a
stop codon on
mRNA is reached.
Tyrosine