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DNA, Replication and Protein Synthesis. We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest… J. D. Watson F. H. C. Crick Nature (magazine) April 25, 1953. - PowerPoint PPT Presentation
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1
We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest…
J. D. Watson F. H. C. Crick
Nature (magazine) April 25, 1953
DNA, Replication and Protein Synthesis
1953 - Watson and Crick Propose the structure of
DNA.
1951 - Pauling’s research on proteins gives insight into the structure of DNA.
1952 – Franklin’s work with X-ray diffraction gives further clues as to the structure of DNA.
2
All the activities of the cell are controlled by DNA.DNA is located in the nucleus of the cell.
A Chromosomeis tightly coiled DNA.
When a chromosome is unraveled, it reveals DNA’s double helix shape.
Just before cell division DNA coils to form chromosomes.
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What Is The Structure of DNA?What Is The Structure of DNA?
P PP P
S SSS
Purines Pyrimidines
AdenineAdenine GuanineGuanineCytosineCytosine ThymineThymine
BBAASSEE
SUGAR (SUGAR (deoxyribose)deoxyribose)
PHOSPHATEPHOSPHATE
Structure of Structure of Nucleotide:Nucleotide:
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What Is The Structure of DNA?What Is The Structure of DNA?
P
S
CC
P
S
CC
P
S
GG
P
SGG
P
S
TT
P
S
TT
P
S
AA
P
S
AA
DNA Forms a Ladder Shape DNA Forms a Ladder Shape called a “Double Helix.”called a “Double Helix.”
Complimentary Pairs Are:
CytosineCytosine GuanineGuanine
AdenineAdenine ThymineThymine
CC – – GG
AA – – TT
Sid
es o
f Ladder
Sid
es o
f Ladder
RungRung
RungRung
RungRung
RungRung
Sid
es o
f Ladder
Sid
es o
f Ladder
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TT AA
CC
TT
GG CC
GG
AA
GG
CC
TT AA
GGCC
TT
AA
GG
CC
Replication
Replication
DNA is doubled so
DNA is doubled so
each cell will have an
each cell will have an
exact copy of DNA.
exact copy of DNA.
Cell Growth and Cell Growth and “Everyday Activity” “Everyday Activity”
~ Protein Synthesis ~ Protein Synthesis ~~
Transcription Transcription
TranslationTranslation
““Replic
ated D
NA”
Replicate
d DNA”
is given to
each ce
ll.
is given to
each ce
ll.
The Life Cycle of The Life Cycle of the Cellthe Cell
Cytokinesis Cytoplasm is
divided up into each cell.
MET LEUTHRARG
DNADNA
RNARNA
RNARNA
DNADNA
TT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
TT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
TranscriptionTranscription
ReplicationReplication
TranslationTranslation
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GGCCTT AA
26 letter Alphabet…26 letter Alphabet…A B C D E F G H I J K L M N O P Q R S T U V W X Y ZA B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Richard dog black The belongs to small. Richard dog black The belongs to small.
The small black dog belongs to Richard. The small black dog belongs to Richard.
t e s a l R b h l a T d c a o g b g e l l n m s r o k o I c h d . t e s a l R b h l a T d c a o g b g e l l n m s r o k o I c h d .
to direct all of the cell’s activities.to direct all of the cell’s activities.
Which is meaningless…Which is meaningless…
Unless…Unless…
The letters are put together in a meaningful way:The letters are put together in a meaningful way:
DNA uses a four letter alphabetDNA uses a four letter alphabet
DNA works the same way.DNA works the same way.
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TT AA
GG
CC
TT
AA
GG CC
TT
AA
GG
CC
TT
AA
GG
CC
TT AA
GGCC
TT
AA
GG
CC
The most important characteristic of DNA is the code which occurs in complementary
pairs AA, TT, CC and GG. They are the 4 letter alphabet
of the genetic codegenetic code which controls the activities of the cell.
GG
AA
TT
AA
CC
TT
CC
GG
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TT AA
CC
TT
GG CC
GG
AA
GG
CC
TT AA
GGCC
TT
AA
GG
CC
GG
AA
TT
AA
CC
TTTT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
This “double helix structure” makes it possible for DNA to make an exact copy
of itself.
GG
AA
TT
AA
CC
TT
CC
GG
Free-floating nucleotides attach
themselves to each side.
DNA “unzips itself.”
AA TT
GG CC
CC GG
TT AA
CC GG
AA TT
GG CC
TT AA
CC GG
This is known asThis is known asreplication.replication.
11
22
DNAPolymerase
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When cells divide, they must make a copy of the DNA so the two resulting cells each have the exact same copy
of genetic code.
Mitosis:Mitosis:Dividing the DNADividing the DNA
Cytokinesis:Cytokinesis:Dividing of the cellDividing of the cell
10
Cell DivisionCell DivisionThe newly formed cell receives The newly formed cell receives
the replicated copy of DNA.the replicated copy of DNA.
TT AA
CC
TT
GG CC
GG
AA
GG
CC
TT AA
GGCC
TT
AA
GG
CC
TT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
The free-floating nucleotides in the nucleus attach themselves to each side of the ladder.
AA TT
GG CC
CC GG
TT AA
CC GG
AA TT
GG CC
TT AA
CC GGOnce replication has occurred,
Plant cell division:Animal cell division:
the cell can now divide into two.
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http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html
Here is a practice website if you are connected to the internet:
12 Cells must make a copy of DNA (replication) before the cell divides so that each cell has a copy of the genetic code.
Question: What is the genetic code used for?
Why are proteins important?Why are proteins important?Answer: making proteins
Proteins are what make us different.
But proteins also make sure
that some things stay the
same.
Blood cell with Blood cell with an an incorrectincorrect DNA DNA
sequence for sequence for shape.shape.
Blood cell with Blood cell with the the correctcorrect
DNA sequence DNA sequence for shape.for shape.
13DNA carries the genetic code, but it never leaves the nucleus of the cell.
So how does DNA direct the activities from the
nucleus?The Answer Is… RNA.
14
What is What is RNARNA??11
33
22
Messenger RNAMessenger RNA(mRNA)(mRNA)
Transfer RNATransfer RNA(tRNA)(tRNA)
Ribosomal RNARibosomal RNA(rRNA)(rRNA)
MET ARG
THR
LEU
I take the message from DNA to the
ribosome.
mRNA tells us the order of the amino
acids in making proteins.
We stay in the ribosome and help with the bonding of
amino acids.Ribosome
rRNA
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What Is The Structure of RNA?What Is The Structure of RNA?
P PP P
S SSS
Purines Pyrimidines
AdenineAdenine GuanineGuanineCytosineCytosine UracilUracil
BBAASSEE
SUGAR SUGAR (ribose)(ribose)
PHOSPHATEPHOSPHATE
Structure of Structure of Nucleotide:Nucleotide:
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How does How does RNARNA differ from differ from DNADNA??
Ribose Dexoyribose
Sugar in RNA is riboseribose instead of deoxyribosedeoxyribose.
The nitrogen base in RNA uraciluracil replaces thyminethymine.
RNA is generally single strandedsingle stranded rather than double strandeddouble stranded.
11
33
22
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Protein SynthesisProtein Synthesis
Replication
Replication
Cell GrowthCell GrowthProtein Synthesis:Protein Synthesis:
TranscriptionTranscription
TranslationTranslation
Cell
Cell
Divisi
on
Divisi
on
TranscriptionTranscription
TranslationTranslation Protein SynthesisProtein Synthesis
DNA makes messenger RNA (mRNA), and then it is sent to the ribosome.
mRNA serves as the code sotransfer RNA (tRNA) can placethe amino acids in sequence.
The protein is made from the coded message.
11
22 33
MET
LEU
THRARGMET ARG
THR
LEU
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TTTTTTTT
TT TTTT
TranscriptionTranscriptionDNA writes its code to make mRNA.DNA writes its code to make mRNA.
TT TTTT
DNA
RNA
mRNA
message sent
toTTTTTTTT
DNA
RNA
Next is translation
19 The genetic code is built into triplets of The genetic code is built into triplets of nucleotides. nucleotides. (i.e. UGC)(i.e. UGC)
These sequences code for specific amino These sequences code for specific amino acids. acids. (i.e. UGC codes for serine)(i.e. UGC codes for serine)
mRNA triplet code is called a mRNA triplet code is called a codoncodon. . (i.e. UGC on mRNA)(i.e. UGC on mRNA)
tRNA triplet code is called an tRNA triplet code is called an anti-codonanti-codon. . (i.e. ACG on mRNA)(i.e. ACG on mRNA)
The circle chart refers to the The circle chart refers to the codon codon to to identify the amino acid. identify the amino acid. (i.e. UGC codes for (i.e. UGC codes for serine)serine)
In this next activity you will learn this In this next activity you will learn this “secret code” and make proteins. “secret code” and make proteins.
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UU
GGAACC
AACCUUGG
AACCUU
GG
AACC
UU
GG
AACCUU
GG
UUGGAA CC UU
GG AACC
UU
GGAA
CC
UU
GGAA
CC
AACCUU
GG
AACC
UU
GG
AACC UU
GG
AA CC UUGG AA CC UU
GG
AACCUU
GG
AACCUU
GG
AACC
UU
GG
AACC
UU
GG
AACC
UU
GG
AACCUU
GG
AACCUUGG
TyptophanTyptophan
Proline
Proline
StopStop
Tyrosine
Tyrosine
Serine
Serine
Leuci
ne
Leuci
ne
Phenyla
l-
Phenyla
l-anin
eanin
eG
lycin
eG
lycin
e
Glu
tam
ic
Glu
tam
ic
Acid
Acid
Aspartic
Aspartic
Acid
Acid
Alanine
Alanine
ValineValine
LeucineLeucine
Thre
onin
e
Thre
onin
e
Aspar
agin
e
Aspar
agin
e
ArginineArginine
Histdine
Histdine
Isole
ucin
eIs
ole
ucin
e
Glu
tam
ine
Glu
tam
ine
SerineSerine
LysineLysine
Meth
ionin
e
Meth
ionin
e Arg
inin
eA
rgin
ine
mRNA CodonmRNA Codon
mRNA CodonmRNA Codon mRNA CodonmRNA Codon
mRNA CodonmRNA Codon
anticodonanticodon
tRN
AtR
NA
VAL
anticodonanticodon
tRN
AtR
NA
LEU
anticodonanticodon
tRN
AtR
NA
PRO
anticodonanticodon
tRN
AtR
NA
MET
This Is the “start” codon and begins the amino
acid chain.
21 TranslationTranslationThe ribosome and tRNA helps The ribosome and tRNA helps assemble the protein chain of amino assemble the protein chain of amino acids.acids. Replication
Replication
Cell GrowthCell GrowthProtein Synthesis:Protein Synthesis:
TranscriptionTranscription
TranslationTranslation
Cell
Cell
Divisio
n
Divisio
n
MET LEUTHRARG
The amino acids are bonded together to start the protein chain.
22 Mutations – Mistakes In DNAMutations – Mistakes In DNACorrect Sequence:
MET TYRTHRARG
MET TYRTHRHIS
TAC GCA ATATGGAUG CGU UAUACC
Substitution
DNAmRNA
TAC GTA ATATGG
AUG CAU UAUACC
DNA
mRNA
THE FTT ATECAT
THE FAT ATECAT
Point Mutation
23
MET TYRTYRPRO
THE FFA TAT ETCA
Insertion of another “G”
TAC GGC GAT AATGAUG CCG CUA UUAC
DNAmRNA
MET PROVAL
THE ATC TEATA
Deletion of “G”
TAC CAT TAGGAAUG GUA AUCCU
DNAmRNA
Frameshift MutationsInsertion Deletion
Mutations – Mistakes In DNAMutations – Mistakes In DNACorrect Sequence:
MET TYRTHRARG
TAC GCA ATATGGAUG CGU UAUACC
DNAmRNA
THE FAT ATECAT
24
TT AA
CC
TT
GG CC
GG
AA
GG
CC
TT AA
GGCC
TT
AA
GG
CC
Replication
Replication
DNA is doubled so
DNA is doubled so
each cell will have an
each cell will have an
exact copy of DNA.
exact copy of DNA.
Cell Growth and Cell Growth and “Everyday Activity” “Everyday Activity”
~ Protein Synthesis ~ Protein Synthesis ~~
Transcription Transcription
TranslationTranslation
““Replic
ated D
NA”
Replicate
d DNA”
is given to
each ce
ll.
is given to
each ce
ll.
The Life Cycle of The Life Cycle of the Cellthe Cell
Cytokinesis Cytoplasm is
divided up into each cell.
MET LEUTHRARG
DNADNA
RNARNA
RNARNA
DNADNA
TT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
TT
CC
GG
AA
GG
TT
CC
AA
GG
AA
TT
CC
GG
CC
AA
GG
TT
CC
TranscriptionTranscription
ReplicationReplication
TranslationTranslation
25
DNA Strand – DNA Strand – DNA Strand 1 2
Genes Genes Proteins Proteins Traits Traits
3 4 5
IntronsDoes not code for protein
ExonsCode for Protein
EnhancerAttracts RNA polymerase
to this section of DNA
PromoterSequences
TATA BoxHelps position RNA Polymerase close to
gene
6RNA
Polymerase
This allows millions of different possibilities for
proteins.
1 2 3 4 5 6
1 3 5
pre-mRNA
mRNA (after splice)
Protein-aProtein-a
26
DNA Strand 1 2
Genes Genes Proteins Proteins Traits Traits
5 4 15
Introns
Exons
6RNA
Polymerase
Exons 1 & 5 in this gene are used to make a different Exons 1 & 5 in this gene are used to make a different protein. protein.
pre-mRNA
mRNA (after splice)
1 2 5 4 15 6
1 5 15
Think of the variety of proteins that can Think of the variety of proteins that can be coded using different combinations of be coded using different combinations of
exons!!!exons!!!
Protein-bProtein-b
TATA BoxHelps position RNA Polymerase close to
gene
27 Remember:It is our proteins that make us…
Unique(different)
Proteins are what make us different.
But, proteins also make sure
that some things stay the
same.
Blood cell with Blood cell with an an incorrectincorrect DNA DNA
sequence for sequence for shape.shape.
Blood cell with Blood cell with the the correctcorrect
DNA sequence DNA sequence for shape.for shape.
andSimilar.(same)
28
We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest…
J. D. Watson F. H. C. Crick
Nature (magazine) April 25, 1953
DNA Proteins What We Are
