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DNA
Replication
and
Protein Synthesis
DNA
• Deoxyribonucleic Acid
– Controls cells activities
– Contains organism’s traits
– Contains messages to produce
proteins
DNA
• Monomer- Nucleotide
DNA
DNA- Base Pairs
Adenine bonds with Thymine
Cytosine bonds with Guanine
DNA- Base Pairs
• Just remember:
AT Common Grounds
A bonds
with T
C bonds
with G
DNA structure
• James Watson
and Francis Crick
1953
Shaped like a ladder
Sides- alternating
sugars and
phosphates
Steps-base pairs
joined by hydrogen
bonds
DNA Structure
• Then ladder
is twisted
forming a
double helix
DNA and RNA
DNA
RNA
Strands
Double strand Single strand
Sugar
Deoxyribose
ribose
Base
pairs
A-T
C-G
A-U
C-G
Uracil is substituted for
thymine
Location
Nucleus only
Moves from nucleus to
cytoplasm
DNA and RNA
DNA Replication
• During mitosis- chromosomes
(DNA) are copied (replicated)
• Every cell gets a complete set of
chromosomes
• Replication- process in which
DNA is copied
DNA Replication
• Steps to DNA replication
– 1. Chemical bonds split between base
pairs, DNA is unzipped
– 2. Free nucleotide bases pair up with
complementary base on DNA strands.
Each original strand is called a template.
– 3. Sugars and phosphates bond between
free nucleotides
– 4. Result is 2 identical molecules of DNA.
Each new molecule consists of one old
strand and one new strand
DNA Replication
DNA
Replication
Note: Each new
DNA molecule
is made of one
old strand
and one new
strand
DNA Replication Links
• http://www.lpscience.fatcow.co
m/jwanamaker/animations/DNA%
20Replication%20%20long%20.html
Types of RNA
• mRNA- messenger RNA- single strand
copied from one side of the DNA
molecule in the nucleus. Moves to
the cytoplasm. “Carries the
message”
• tRNA- transfer RNA- carries the
amino acids to make a protein.
Carries them to the ribosome and
mRNA.
• rRNA- ribosomal RNA- bonds with
mRNA, site where tRNA brings amino
acids to form a protein
Types of RNA
mRNA
tRNA
rRNA
Protein Synthesis
Transcription and Translation
• Transcription- one side of a DNA
molecule is copied forming a
mRNA molecule
• Translation- protein is formed by
joining Amino Acids
-sequence of mRNA bases is
converted into an amino acid
sequence
Central Dogma of Gene
Expression
Protein Synthesis
Transcription
• 1. DNA unzips
• 2. Free floating
nucleotides bond to
one side of DNA
(Uracil bonds with
Adenine)
• 3. Nucleotides are
joined together
• 4. mRNA leaves the
nucleus and enters
the cytoplasm
Protein Synthesis
Translation
• Codon- set of
three bases
on mRNA,
each one
codes for one
amino acid
Protein Synthesis Translation
Determine the chain of Amino Acids for the following codons
AUG
CAG
UAU
GAU GUU UUA CCU UAG
Met Gln Tyr Asp Val Leu Pro Stop
U
C
A
G
U
Phe
C
Ser
A
Tyr
G
Cys
U
Phe
Ser
Tyr
Cys
C
Leu
Ser
STOP
STOP
A
Leu
Leu
Ser
Pro
STOP
His
Trp
Arg
G
U
Leu
Pro
His
Arg
C
Leu
Pro
Gln
Arg
A
Leu
Ile
Pro
Thr
Gln
Asn
Arg
Ser
G
U
Ile
Thr
Asn
Ser
C
Ile
Thr
Lys
Arg
A
Met (Start)
Thr
Lys
Arg
G
Val
Ala
Asp
Gly
U
Val
Ala
Asp
Gly
C
Val
Ala
Glu
Gly
A
Val
Ala
Glu
Gly
G
Protein Synthesis
Translation
Anti-codon- three bases on the tRNA molecule
that is the complement to the bases in a codon.
Protein Synthesis
Steps of Translation
• 1. Ribosome attaches to mRNA
• 2. tRNA with anti-codon that is the
complement of the codon attaches to
mRNA carrying a specific amino acid
• 3. Ribosome slides to second codon
• 4. Second tRNA with complementary anticodon bonds with second codon
• 5. Amino acid from 1st tRNA bonds with
amino acid attached to 2nd tRNA
• 6. Ribosome continues down mRNA
creating a chain of amino acids until a stop
codon is reached
Protein Synthesis
Steps of Translation
TC G TTC A AA
template
Strand
AG
T
T
C AAGT
U C G UU C A A A
mRNA
A
A
TTC
G
A
C
T
template
Strand
AG
T
T
C AAGT
U C G UU C A A A
Nucleus
mRNA
Cytoplasm
Ribosome
A
A
TTC
G
A
C
T
Template
Strand
AG
T
T
C AAGT
U C G UU C A A A
Nucleus
mRNA
Cytoplasm
U C G UU C A A A
A
A
TTC
G
A
C
T
Template
Strand
AG
T
T
C AAGT
Nucleus
Cytoplasm
U C G UU C A A A
A
A
TTC
G
A
C
T
template
Strand
AG
T
T
C AAGT
Nucleus
AA1
Cytoplasm
tRNA’s
AGC
U C G UU C A A A
A
A
TTC
G
A
C
T
template
Strand
AG
T
T
C AAGT
Nucleus
ATP
AA1
•AA2
Cytoplasm
tRNA’s
AGC AAG
U C G UU C A A A
A
A
TTC
G
A
C
T
Template
Strand
AG
T
T
C AAGT
AA1
Nucleus
ATP
AA1
•AA2
AA3
Cytoplasm
AAG U U U
U C G UU C A A A
A
A
TTC
G
A
C
T
template
Strand
AG
T
T
C AAGT
AA1
Nucleus
AGC
AA1
•AA2
AA3
Cytoplasm
AAG U U U
U C G UU C A A A
A
A
TTC
G
A
C
T
Template
Strand
AG
T
T
C AAGT
AA1
Nucleus
AGC
AA1
•AA2
AA3
Cytoplasm
AAG U U U
U C G UU C A A A
A
A
TTC
G
A
C
T
Template
Strand
AG
T
T
C AAGT
AA1
Nucleus
AGC
AA1
•AA2
AA3
Cytoplasm
UUU
U C G UU C A A A
Protein Synthesis links
• http://www.lpscience.fatcow.co
m/jwanamaker/animations/Protei
n%20Synthesis%20%20long.html
• http://www.wisconline.com/objects/index_tj.asp?
objid=AP1302
Mistakes in the
Genetic Code
• Mutation- a change in the
genetic code
• Mutagen- any substance that
causes a mutation to occur
– Examples: chemicals,
radiation, high temps
Types of Mutations
• Point mutation- change, deletion
or insertion of one base pair
• 1. Substitution mutation
– one base replaced by another
– often has no effect on phenotype
• Example
GGU = glycine
GGC = glycine
Types of Mutations
• 2. Frame shift mutation- deletion or
addition/insertion of a base
– Codons get shifted
Example:
GGG
CUU
CCU
ACU
Gly
Leu
Pro
Thr
Suppose third G in first codon is lost, then:
GGC
UUC
CUA
CU
Gly
Phe
Leu
Types of Mutations
• 3. Inversion mutation- part of the
genetic code breaks off and is
inserted in reverse order
•
AUCCGCUCUAA
•
AUCUCGCCUAA
Types of Mutations
• 4. Chromosomal mutation- whole
chromosome is added or deleted
– Caused by non-disjunction
– http://www.youtube.com/watch?v=
eDbK0cxKKsk
Genetic Technology
• Selective breeding- farmers choose
organisms with desirable traits to breed
– Increases frequency of desired allele in
population
• Genetic Engineering- faster method of
increasing desired allele in population
– Small fragment of DNA is cut or cleaved
from one organism and fragment is
inserted into a host organism
– Also called recombinant DNAconnecting fragments of DNA from
different sources
Transgenic organism- organism containing
fragments of foreign DNA
Food Genetic Engineering- GMO
• Genetically Modified Foods
– Rice, tomatoes, corn, and other common
food products have been genetically
modified to withstand harsher
temperatures, grow larger, be preserved
longer on shelves, make toxins so pests
don’t eat them. Vitamins and minerals
can also be added to foods to make them
more nutritious.
Examples of Genetically
Modified organisms
Zebra Fish
Salmon
With growth hormone
Examples of Genetically
Modified Organisms
Examples of Genetically
Modified organisms
Most Soybeans and corn
Can be made:
Disease resistant
Pest resistant
Drought resistant
Bananas with vaccines
Featherless
chickens
Examples of genetically
modified Organisms
Cat glows red under UV light
Transformation( Recombinant
DNA Technology)
Use bacteria as vectors to
place beneficial genes
inside organisms
Can mass produce the
beneficial genes so that it
can be used for medicine,
therapy, etc.
Have a quick turn around
time for the product to be
made.
Example- Human Insulin
made by bacteria to treat
diabetes
Gene Therapy: take out bad gene and place
in good gene from another organism
• Used for cancer therapy, replacing
missing factors and enzymes in
organism
Genetic Technology
Gel Electrophoresis
• Fragments of DNA are separated
by weight
• Matching bands can be used to
identify the source of the DNA
• Gel Electrophoresis is used to
make a DNA Fingerprint
• Link:
http://www.lpscience.fatcow.co
m/jwanamaker/animations/Chro
m%26Elpho.html
Gel Electrophoresis
DNA Fingerprinting
• Which suspect
committed the
crime?
Suspect 2
DNA Fingerprinting
Various DNA samples in an assault
investigation are shown in the figure
on the right.
• Blood samples of DNA were loaded
into the following lanes:
• 1- known blood sample of the
victim
• 2- known blood sample from the
defendant
• 3- female fraction from a swab of
the victim
• 4- male fraction from the swab of
the victim
What can you conclude about the
defendant/suspect?
Blood samples
victim
defendant
Swab from victim
female fraction
male fraction
• He is guilty
• Suspect might be guilty,
but more evidence is
needed
• Swab is from the wrong
victim
• The suspect must be
excluded as a source of
the DNA in the evidence
• NONE of the above
1
2
3
4
DNA
Fingerprinting
• DNA fingerprint
analysis is shown
for a single locus
for a man, a
woman, and their
four children.
Which child is
least likely to be
the offspring of
this couple?
Child 2
Child 1
Child 2
Mother
Father
Child 3
Child 4
Stem Cells
• Stem cells are
undifferentiated cells
that have the potential
to develop into many
different cell types in
the body with a more
specialized function,
such as a muscle cell,
a red blood cell, or a
brain cell.
Stem Cell references
• http://learn.genetics.utah.edu/co
ntent/tech/stemcells/scfuture/
• http://learn.genetics.utah.edu/co
ntent/tech/stemcells/quickref/
Cloning
• Cloning - the creation of an
organism that is an exact
genetic copy of another.
• Clone a mouse
• http://learn.genetics.utah.edu/co
ntent/tech/cloning/clickandclone
/