Download Moleculer Genetics

Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 A gene codes for A protein.
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
 A group of three bases coding for an amino acid is
called a codon, and the meaning of each of the 64
codons is called the genetic code
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
 A group of three bases coding for an amino acid is
called a codon, and the meaning of each of the 64
codons is called the genetic code
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
 A group of three bases coding for an amino acid is
called a codon, and the meaning of each of the 64
codons is called the genetic code
 DNA is in the nucleus
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
 A group of three bases coding for an amino acid is
called a codon, and the meaning of each of the 64
codons is called the genetic code
 DNA is in the nucleus
Rosa Macaya
IES La Pobla de Segur
What does DNA do?
 DNA is made up of genes. A gene is a sequence of
DNA which codes for the sequence of amino acids in a
particular protein.
 1 gene codes for 1 protein.
 How does DNA determine the sequence of a.a.s?
 A group of three bases coding for an amino acid is
called a codon, and the meaning of each of the 64
codons is called the genetic code
 DNA is in the nucleus
 Proteins are made in the cytoplasm  the information
contained within DNA must be carried to the
cytoplasm.
 This process is called TRANSCRIPTION.
Rosa Macaya
IES La Pobla de Segur
Start of gene
Template strand
DNA
unwinds
& unzips at the start of •mRNA
a particular
bonds
chaingene.
dropsHoff
the DNA
DNA
re-winds.
This
continues
until
the
end
of
the
gene.
break
•Free activated mRNA nucleotides in the nucleus complementary
base pair with exposed DNA bases. (A – U, T – A, C – G, G – C)
RNA polymerase joins the mRNA nucleotides together, releasing
Rosa Macaya
IES La Pobla de Segur
theexits
phosphoryl
for
energy.
mRNA
nucleusgroups
via a nuclear
pore.
Carrying the information/ message
The codon (a triplet) AAU would code for……..
The Genetic Code
There are 20 essential
amino acids
Only 4 bases
The genetic code is a
TRIPLET CODE
3 bases code for 1 amino acid
If each coded 1 a.a
only 4 different types.
How many if a pair
coded for 1 a.a?
16
Still inadequate
What about if 3 coded
for 1 a.a?
64
Yeah!
Rosa Macaya
IES La Pobla de Segur
ATP
A bit more about tRNA
VAL
Amino-acid
A
C
C
Amino-acid
attachment site
Amino
acids
must
This
is then
called
combine withtRNA
the tRNA
AMINO-ACYL
molecule. The tRNA
This
is catalysed
bysaid
aminomolecule
is then
to
acylbetRNA
synthetase
ACTIVATED
Anti-codon
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IES La Pobla de Segur
ILE
MET
GLN
MET
GLN
VAL
GLN
Ribosome
Apeptide
peptide
reads
bond
the
is formed
formed
2ndcomplementary
codon.
between
Another
the
2
Another
tRNA
molecule
with
the
These
steps
are
repeated
until
the
ribosome
reads
a
STOP
A
bond
is
between
the
2
The Ribosome
ribosome
moves
along
the
mRNA
to
the
3rd
tRNA
mRNA
with
enters
a
complementary
the
cytoplasm
anticodon
&
joins
to
(UAC)
the
reads
along
until
a
start
codon
tRNA
amino
molecule
acids
on
with
top
of
the
the
complementary
1st
and
2nd
anti-codon
binds
to
the
3rd
codon.
The
2nd
tRNA
molecule
is
released.
codon. (ELONGATION
the
TERMINATION)
amino
acids
on
top
of
the
2nd
and 3rdbut
2This
codons
(6
bases)
are
exposed
codon.
releases
the
1st
tRNA
molecule
base
small
pairs
subunit
with
of
the
a
ribosome
start
codon
anti-codon
tRNA
binds
molecules.
to
this
2nd
codon.
(AUG)
is
Rosa found
Macaya
IES La Pobla de Segur
tRNA molecules.
not the a.a.
Base deletion
Where 1+ base pairs are deleted
Intended txt: A FRIEND WILL COLLECT MY MONEY
Actual txt:
Normal:
A FIEND WILL COLLECT MY MONEY
Consider
this….
UCA
CAU UAC
UGU GGU
Mutated: UCA CAU UAU GUG GU
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IES La Pobla de Segur
Haemophilia Sufferers:
Phenylalanine hydroxylase catalyses the reaction:
• Lack of a →
blood
clotting
Phenylalanine
tyrosine
(→protein
melanin)
(brown pigment)
• (Mutation in the factor (protein)
blood
PKU isclotting
causedfactor
by a gene)
gene mutation
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IES La Pobla de Segur