PROTEIN SYNTHESIS
PROTEIN SYNTHESIS

The base sequence of DNA codes for the amino
acids that make up a protein (one gene codes for
one polypeptide).
PROTEIN SYNTHESIS
The base sequence of DNA codes for the amino
acids that make up a protein (one gene codes for
one polypeptide).
 A sequence of 3 bases in DNA, a triplet, codes for
an amino acid.

PROTEIN SYNTHESIS
The base sequence of DNA codes for the amino
acids that make up a protein (one gene codes for
one polypeptide).
 A sequence of 3 bases in DNA, a triplet, codes for
an amino acid.
 Protein synthesis takes place in cell organelles
called ribosomes, which are found in the
cytoplasm.

PROTEIN SYNTHESIS
The base sequence of DNA codes for the amino
acids that make up a protein (one gene codes for
one polypeptide).
 A sequence of 3 bases in DNA, a triplet, codes for
an amino acid.
 Protein synthesis takes place in cell organelles
called ribosomes, which are found in the
cytoplasm.
 A carrier molecule takes the code from DNA in
the nucleus to the ribosomes in the cytoplasm.

PROTEIN SYNTHESIS

The carrier molecule is messenger ribonucleic
acid (mRNA)
PROTEIN SYNTHESIS
The carrier molecule is messenger ribonucleic
acid (mRNA)
 RNA are nucleic acids like DNA but there are
some key differences:

PROTEIN SYNTHESIS
The carrier molecule is messenger ribonucleic
acid (mRNA)
 RNA are nucleic acids like DNA but there are
some key differences:
- There are 3 different forms on RNA – messenger
RNA (mRNA), transfer RNA (tRNA), and
ribosomal RNA (rRNA). They each have a
different function.

PROTEIN SYNTHESIS
The carrier molecule is messenger ribonucleic
acid (mRNA)
 RNA are nucleic acids like DNA but there are
some key differences:
- There are 3 different forms on RNA – messenger
RNA (mRNA), transfer RNA (tRNA), and
ribosomal RNA (rRNA). They each have a
different function.
- RNA is single stranded – though folding can
make RNA appear double stranded at times.

PROTEIN SYNTHESIS
The carrier molecule is messenger ribonucleic
acid (mRNA)
 RNA are nucleic acids like DNA but there are
some key differences:
- There are 3 different forms on RNA – messenger
RNA (mRNA), transfer RNA (tRNA), and
ribosomal RNA (rRNA). They each have a
different function.
- RNA is single stranded – though folding can
make RNA appear double stranded at times.
- The sugar in RNA is ribose

PROTEIN SYNTHESIS
The carrier molecule is messenger ribonucleic
acid (mRNA)
 RNA are nucleic acids like DNA but there are
some key differences:
- There are 3 different forms on RNA – messenger
RNA (mRNA), transfer RNA (tRNA), and
ribosomal RNA (rRNA). They each have a
different function.
- RNA is single stranded – though folding can
make RNA appear double stranded at times.
- The sugar in RNA is ribose
- The base uracil (u) replaces the base thymine (T)
found in DNA.

STAGES OF PROTEIN SYNTHESIS
Transcription:
Every gene has 3 regions.
- The promoter which turns the gene ‘on’ and ‘off’
and signals the site of transcription

STAGES OF PROTEIN SYNTHESIS
Transcription:
Every gene has 3 regions.
- The promoter which turns the gene ‘on’ and ‘off’
and signals the site of transcription
- The coding region which has the base sequence
for the protein

STAGES OF PROTEIN SYNTHESIS
Transcription:
Every gene has 3 regions.
- The promoter which turns the gene ‘on’ and ‘off’
and signals the site of transcription
- The coding region which has the base sequence
for the protein
- The terminator which signals the end point of
transcription.

STAGES OF PROTEIN SYNTHESIS
Transcription:
Every gene has 3 regions.
- The promoter which turns the gene ‘on’ and ‘off’
and signals the site of transcription
- The coding region which has the base sequence
for the protein
- The terminator which signals the end point of
transcription.
o In transcription, the enzyme RNA polymerase
binds to the promoter and the DNA ‘unwinds’
and ‘unzips’ here.

TRANSCRIPTION CONT.

Only one of the two strands of DNA (the template
strand) is copied to become mRNA in
transcription.
TRANSCRIPTION CONT.
Only one of the two strands of DNA (the template
strand) is copied to become mRNA in
transcription.
 A now pairs with U (uracil) in mRNA instead of
T.

TRANSCRIPTION CONT.
Only one of the two strands of DNA (the template
strand) is copied to become mRNA in
transcription.
 A now pairs with U (uracil) in mRNA instead of
T.
 When RNA polymerase reaches the terminator
sequence, transcription is completed; mRNA
detaches, the 2 DNA strands re-join and the helix
reforms.
**Drawing on board**

TRANSCRIPTION CONT

The mRNA is the primary transcript and is
‘edited’.
TRANSCRIPTION CONT
The mRNA is the primary transcript and is
‘edited’.
 There are regions of the DNA (introns) which are
NOT needed to make the protein.

TRANSCRIPTION CONT
The mRNA is the primary transcript and is
‘edited’.
 There are regions of the DNA (introns) which are
NOT needed to make the protein.
 The introns are cut out of the mRNA and the
regions that ARE needed for the formation of the
protein (exons) are spliced (pushed) together to
give the final transcript (version) of mRNA.

TRANSCRIPTION CONT
The mRNA is the primary transcript and is
‘edited’.
 There are regions of the DNA (introns) which are
NOT needed to make the protein.
 The introns are cut out of the mRNA and the
regions that ARE needed for the formation of the
protein (exons) are spliced (pushed) together to
give the final transcript (version) of mRNA.
 Depending on what exons are pushed together,
there can be more than one version of the final
transcript.

TRANSCRIPTION CONT
The mRNA is the primary transcript and is
‘edited’.
 There are regions of the DNA (introns) which are
NOT needed to make the protein.
 The introns are cut out of the mRNA and the
regions that ARE needed for the formation of the
protein (exons) are spliced (pushed) together to
give the final transcript (version) of mRNA.
 Depending on what exons are pushed together,
there can be more than one version of the final
transcript.
 Therefore, there can be one gene coding for more
than one polypeptide.
