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Nucleic Acids
TWO MAIN TYPES
DNA- Deoxyribonucleic Acid
RNA- Ribonucleic Acid
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•DNA is present in the nucleus of all cells
in all living organisms.
•It is exactly the same in every cell of that organism
•DNA controls all the chemical changes which
take place in cells
•The kind of cell which is formed, (muscle, blood,
nerve etc) is controlled by DNA
•The kind of organism which is produced (buttercup,giraffe,
herring, human etc) is controlled by DNA
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DNA & RNA are very large molecules made
up of a long chain of monomers
The monomers are called nucleotides
Each nucleotide is made up of
1)
a sugar called Deoxyribose/Ribose
2)
a phosphate group -PO4 and
3)
A nitrogen base
Nucleotide Sugars:
Ribose & Deoxyribose
Ribose is a five carbon monosacharride (sugar)
found only in RNA
Deoxyribose is a five carbon sugar
only found in DNA
Both molecules may be represented by the symbol
4
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The Nitrogen bases
The four Nitrogen bases in DNA are
Adenine
(A)
Thymine
(T)
Cytosine
(C)
Guanine
(G)
NITROGEN BASES
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Nucleotides
The deoxyribose, the phosphate and one of the bases
Combine to form a nucleotide
PO4
adenine
deoxyribose
NUCLEOTIDES
Joined nucleotides
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A molecule of DNA is
formed by millions of
nucleotides joined
together in a long
chain
PO4
PO4
PO4
PO4
sugar-phosphate
backbone
+ bases
The nucleotides are
attached by a covalent
bond between the
sugar and the
phosphate.
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DNA consists of a double strand of nucleotides
joined together by a hydrogen bond between the
Nitrogen bases
In what type of molecules do hydrogen bonds
form?
Which is easier to break a covalent bond or a
hydrogen bond?
2-stranded DNA
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
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Bonding 1
The bases always pair up in the same way
Adenine forms a bond with Thymine
Adenine
Thymine
and Cytosine bonds with Guanine
Cytosine
Guanine
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Bonding 2
PO4
PO4
adenine
thymine
PO4
PO4
cytosine
guanine
PO4
PO4
PO4
PO4
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Pairing up
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
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The paired strands are coiled into a spiral called
A DOUBLE HELIX
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THE DOUBLE HELIX
bases
sugar-phosphate
chain
DNA vs. RNA
DNA
RNA
1) Contains the Sugar Deoxyribose
2)Two Strands (Double
Stranded)
3)Contains the Nitrogen base
THYMINE
4)Found only in the nucleus
5) Only type is DNA
1) Contains the sugar
Ribose
2)One strand
Function: Instructions to make
proteins, contains the genetic
code.
Function: Runs protein synthesis
and is a copy of DNA
3)Contains the Nitrogen Base
URACIL
4)Found in the nucleus and
cytoplasm
5)Types include rRNA, tRNA and
mRNA
DNA VS RNA