Download DNA is the Genetic Material

Gene
Entire nucleic acid sequence necessary for the
synthesis of a functional polypeptide (protein chain)
or functional RNA
Nucleic Acid Sequence
1. DNA (Deoxyribo Nucleic Acid)
2. RNA (Ribo Nucleic Acid)
DNA as Genetic Material



DNA encodes all the information in the cell
The composition of the DNA is the same in all cells within an
organism
 Variation among different cells is achieved by reading the
DNA differently
DNA contains four bases that encode all the information to make
an organism’s life
How is Information Encoded in
DNA?
DNA Consists of four kinds of bases
(A,C,G,T) joined to a sugar
phosphate backbone
 Bases carry the genetic information
while the phosphate backbone is
structural
 Two complementary strands of
bases (C-G) and (A-T)

DNA is a Polymer of
Deoxyribonucleotide Units
DEOXYRIBONUCLEOTIDE
DEOXY RIBO NUCLEOTIDE
Deoxyribonucleic Acid (DNA)
Nucleotide:
Phosphate group
5-carbon sugar
Nitrogenous base
DNA Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Sugar
(deoxyribose)
C3
C2
Nitrogenous base
(A, G, C, or T)
DNA Double Helix
“Rungs of ladder”
Nitrogenous
Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone
DNA Double Helix
5
O
3
3
O
P
5
O
C
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
DNA is Composed of Four
Different Ribonucleotides
NH2
C
N
C
N
CH
9
C N
C
N
H
H
Adenine
HN
O C
O
C
1
N
H
C
C
O
C
Two
Purines
N
H N
C
CH
9
C N
C
N
H2 N
H
Guanine
CH3
H
Thymine
Two
Pyrimidines
O
NH2
C
H
N
C
C 1 C
N
H
H
Cytosine
Nitrogenous Bases

PURINES
1. Adenine (A)
2. Guanine (G)

A or G
PYRIMIDINES
3. Thymine (T)
4. Cytosine (C)
T or C
BASE-PAIRINGS
Purines
Pyrimidines
Base
Pairs
Adenine (A)
Thymine (T)
A=T
Guanine (G)
Cytosine (C)
C G
3 H-bonds
G
C
# of
H-Bonds
2
3
BASE-PAIRINGS
H-bonds
G
C
T
A
Base Pairing Occurs
Through Hydrogen Bonds
G-C
A-T
Chargaff’s Rule

Adenine must pair with Thymine

Guanine must pair with Cytosine

Their amounts in a given DNA molecule will be about
the same.
T
A
G
C
Deoxy ribo nucleotide
Ribose= Five Carbon Sugar Molecule
HOCH2 O
OH
5´
H
4´
H
3´
HO
H
1´
2´ H
OH
Ribose (RNA)
HOCH2 O
OH
5´
H
4´
H
3´
HO
H
1´
2´ H
H
Deoxyribose (DNA)
Backbone Sugar Molecules
O
O P O
O
H2 C 5´ O OH
H H 1´
H 3´ 2´ H
O H
O P O
O
The DNA Backbone is a
Deoxyribose Polymer
Deoxyribose sugars are linked by
Phosphodiester Bonds
H2 C 5´ O OH
H H 1´
H 3´ 2´ H
O H
O P O
O
H2 C 5´ O OH
H H 1´
H 3´ 2´ H
HO H
5´-p
5´
3´-OH
3´
O
O P O
-
5´
O
5´
3´
H2 C 5´ O OH
H H
1´
H
-
3´ 2´
O
H
H
O P O
O
H2 C 5´ O OH
H H
1´
H
-
O3´ 2´
H
H
O P O
O
H2 C 5´ O OH
H H
1´
H
3´ 2´ H
HO H
3´
3´
5´
O
O P O
O
O P O
O
O
H2 C 5´ O OH
H
H 1´
H
3´ 2´
H
O
H
O P O
O
H2 C 5´ O OH
H
H 1´
H 3´ 2´ H
O
H
O P O
O
OH
H2 C 5´ O Base
H
H 1´
H
3´ 2´
H
O
H
O P O
O
OH
H2 C 5´ O Base
H
H 1´
H 3´ 2´ H
O
H
O P O
O
H2 C 5´ O OH
H
H 1´
OH
H2 C 5´ O Base
H
H 1´
H 3´ 2´ H
HO
H
H 3´ 2´ H
HO
H
DeoxyRibonucleotide
NH2
N
HC
O-
NH2
N
HC
N
CH
N
O
O
O
N
P O P O P OCH2 O
H
H
OOOH
H
HO
H
CH
N
N
HOCH2 O
H
H
H
HO
N
Deoxyadenosine
5´-triphosphate
(dATP)
H
H
DeoxyRibonucleoside Deoxyadenosine
O
O P O
O
C
CH3
HN
C
O
O C
C
N
H
H2 C
O
H
H
H
T
A
C
G
5´
3´
H
O
H NH2
O P O
C
H
N
C
O
O C
C
N
H
H2 C O
H
H
H
H
O
H O
O P O
C
CH3
HN
C
O
O C
C
H
H2 C O N
H
H
-
H
HO
H
H
T
A
3´
5´
G
C
=
A
T
Double-stranded DNA Forms
a Double Helix
Central Dogma of Biology
DNA, RNA, and the Flow of
Information
Replication
Transcription
Translation
Central Dogma
(Modifications)
(2)Ribozymes
Transcription
DNA
RNA
Translation
Protein
(1) Reverse
transcription
Replication
(2)Self Replication (3)Self Replication
RNA
A polymer composed of nucleotides that contain
the sugar ribose and one of the four bases
cytosine, adenine, guanine and uracile
 Polynucleotide containing ribose sugar and uracil
instead of thymine
 Genetic material of some viruses
 Primary agent for transferring information from
the genome to the protein synthetic machinery

RNA
NUCLEIC ACID,
 SINGLE STRAND,
 PO4,
 RIBOSE SUGAR.
 BASE PAIRS (N):
 U = URACIL
 A=ADENINE
 C=CYTOSINE
 G=GUANINE

URACIL
(U)
base with a single-ring structure
phosphate
group
sugar (ribose)
Types of RNA

Three types of RNA:
A. messenger RNA (mRNA)
B. transfer RNA (tRNA)
C. ribosome RNA (rRNA)

Remember: all produced in the nucleus!
A. Messenger RNA (mRNA)

Carries the information for a specific protein.

Made up of 500 to 1000 nucleotides long.

Made up of codons (sequence of three bases: AUG methionine).

Each codon, is specific for an amino acid.
A. Messenger RNA (mRNA)
start
codon
mRNA
A U G G G C U C C A U C G G C G C A U A A
codon 1
protein methionine
codon 2
codon 3
glycine
serine
codon 4
isoleucine
codon 5
codon 6
glycine
alanine
codon 7
stop
codon
Primary structure of a protein
aa1
aa2
aa3
peptide bonds
aa4
aa5
aa6
B. Transfer RNA (tRNA)





Made up of 75 to 80 nucleotides long.
Picks up the appropriate amino acid floating in the
cytoplasm (amino acid activating enzyme)
Transports amino acids to the mRNA.
Have anticodons that are complementary to mRNA
codons.
Recognizes the appropriate codons on the mRNA and
bonds to them with H-bonds.
anticodon
codon in mRNA
anticodon
amino acid
attachment site
tRNA MOLECULE
amino acid attachment site
amino
acid
OH
The structure of transfer RNA (tRNA)
B. Transfer RNA (tRNA)
amino acid
attachment site
methionine
U A
C
anticodon
amino acid
C. Ribosomal RNA (rRNA)

Made up of rRNA is 100 to 3000 nucleotides long.
Important structural component of a ribosome.

Associates with proteins to form ribosomes.

Ribosomes

Large and small subunits.

Composed of rRNA (40%) and proteins (60%).

Both units come together and help bind the mRNA and
tRNA.

Two sites for tRNA
a. P site (first and last tRNA will attach)
b. A site
Ribosomes
Origin
Cytosol
(eukaryotic
ribosome)
Chloroplasts
(prokaryotic
ribosome)
Complete Ribosomal rRNA
Proteins
ribosome subunit
components
80 S
40 S
18 S
C.30
60 S
5S
C.50
5.8 S
25 S
70 S
Mtochondrion 78 S
(prokaryotic
ribosome)
30 S
50 S
16 S
4.5 S
5 S
23 S
C. 24
C. 35
 30 S
 50 S
18 S
5S
26 S
C. 33
C. 35
Ribosomes
Large
subunit
P
Site
A
Site
mRNA
A U G
Small subunit
C U A C U U C G