DNA

1
DOUBLE HELIX
DNA
WATSON AND CRICK
1953
2
DNA FUNCTION

• CONTROL CELL FUNCTIONS
• STORE HEREDITARY INSTRUCTIONS
• COPY THOSE HEREDITARY INSTRUCTIONS TO A NEW
  GENERATION
• CHANGE FOR EVOLUTION
• GIVE INSTRUCTIONS FOR PROTEIN SYNTHESIS

3
Four nucleotides form DNA

• Five carbon sugar ( deoxyribose )
• phosphate group
• nitrogen-containing base
• adenine, guanine, thymine, cytosine

4
NITROGENATED BASE
PHOSPHATE GROUP
NUCLEOTIDE
SUGAR (RIBOSE)
5
GENERAL STRUCTURE OF A NEUCLOTIDE
A
GUANINE
6
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7
Title
RIBOSE
8
Title
9
Title
10
Title
11
Title
12
Title
DEOXYRIBOSE
13
TIMINA
-
-
P
P
P
-
GUANINA
14
DNA structure

• Two parallel strands of nucleotides
• twisted into a double helix
• Adenine -- Thymine
• Guanine -- Cytosine
• linked by hydrogen bonds

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DNA
THE NITROGENATED BASES UNITE BY HYDROGEN BONDS
COMPLEMENTARY BASES
THYMINE
ADENINE
GUANINE
CITOSINE
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DNA Structure
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
18
DNA Structure
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
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NUCLEUS
DNA
DUPLICATION
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DUPLICATION

• THE DNA UNWINDS
• EACH PARENT STRAND IS CONSERVED
• A NEW COMPLEMENTARY STRAND IS ASSEMBLED
• adenine always pairs with thymine
• guanine always pairs with cytosine

21
DNA Duplication
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
22
DNA Duplication
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
THE DNA UNWINDS
23
DNA Duplication
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
THE DNA UNWINDS Each nucleotide templates
the complementary one of the new strain.
24
DNA Duplication
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
THE DNA UNWINDS Each nucleotide templates
the complementary new strain.
25
DNA Duplication
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
-T -A -C -G -A -C -T -A -C -G -C -T -G -T -C
A- T- G- C- T- G- A- T- G- C- G- A- C- A- G-
THE DNA UNWINDS Each nucleotide templates
the complementary new strain. EACH PARENT STRAND
IS CONSERVED A NEW COMPLEMENTARY STRAND IS
ASSEMBLED adenine always pairs with
thymine guanine always pairs with cytosine
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RNA
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DNA
WATSON AND CRICK
DOUBLE HELIX
1953
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CELLULAR CONTROLS
ACID NUCLETIC STRUCTURE
DNA
RNA
DOUBLE chains in all the cells
SIMPLE chain in all the cells
EXPRESION OF THE GENETIC INFORMATION (PROTEIN
SYNTHESIS)
CELLULAR CONTROL GIVES THE MESSAGES
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NUCLEIC ACIDS
STRUCTURES
TRANSLATION
DNA
RNA
TRANSCRIPTION
proteins
30
NUCLEUS
DNA
DUPLICATION
TRANSCRIPTION
RNA
31
TRANSCRIPTION
A
C
T
T
G
C
A
T
T
G
G
G
C
G
A
A
A
C
T
C
C
G
T
A
C
A
G
T
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TRANSCRIPTION
A
T
T
C
G
C
A
T
T
G
G
G
C
G
A
A
T
G
C
C
A
C
C
G
T
A
C
A
G
T
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TRANSCRIPTION
T
A
C
T
G
C
A
T
T
G
G
G
C
RNA
G
A
T
G
C
C
A
C
U
C
A
G
U
A
C
G
T
A
C
A
G
T
34
NUCLEUS
DNA
DUPLICATION
TRANSCRIPTION
RNA
RIBOSOMES
TRANSLATION
PROTEINS
35
PROTEIN SYNTHESIS
TRANSCRIPTION
TRANSLATION
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TYPES OF RNA
38
TRANSLATION
AMINOACIDS
THR
PHE
MET
ALA
GLY
mRNA
39
PROTEIN
SEQUENCE OF AMINOACIDS
40
REPLICATION
DNA
TRANSCRIPTION
RNA
TRANSLATION
PROTEIN