Let

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Lets learn about Nucleic Acids
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• Nucleic acids are a very complex group of
  biological molecules.
• They are responsible for controlling all of a
  cells activity, much like the administration
  office in a school.
• There are TWO types of nucleic acids.
• DNA deoxyribonucleic acid
• Function DNA is the master copy of an
  organisms information code. It is like a
  blueprint of the organism. It contains all of
  the information about the organism. DNA stores
  the genetic code.
• RNA ribonucleic acid
• Function RNA carries out the instructions of
  the genetic code.

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Building Blocks of Nucleic Acids

• Nucleotides are the building blocks of nucleic
  acids.
• A nucleotide is a molecule made up of 3 parts
• A simple sugar
• a) The sugar deoxyribose is in DNA, and the sugar
  ribose is in RNA
• A phosphate group
• A nitrogenous base

Simple sugar
Nitrogenous Base
One nucleotide
Phosphate Group
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There are 4 different nucleotides found in
DNA. These 4 nucleotides differ only in their
nitrogenous bases, called bases for short.
Deoxyribose
Deoxyribose
Deoxyribose
Deoxyribose
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The 4 different nitrogenous bases found in DNA
are ADENINE (A) CYTOSINE (C) GUANINE (G) THYMINE
(T)
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There are also 4 different nucleotides found in
RNA. Three of them contain the same bases found
in DNA. One is different.
Ribose
Ribose
Ribose
Ribose
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The 4 different nitrogenous bases found in RNA
are ADENINE (A) CYTOSINE (C) GUANINE (G) URACIL
(U)
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The Structure of DNA
DNA Strands The 4 different nucleotides found in
DNA are joined to one another by covalent bonds
that connect the sugar of one nucleotide to the
phosphate group of the next nucleotide. This
repeating pattern of sugar-phosphate-sugar-phospha
te is called a sugar-phosphate backbone.
Sugar-phosphate backbone
Nitrogenous Bases
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The DNA molecule is made up of 2 of these
strands. The rules for how the nucleotides line
up are as follows Adenine will ALWAYS pair
up with Thymine it is complementary to
Thymine Cytosine will ALWAYS pair up with
Guanine it is complementary to Guanine
Strand 1
Strand 2
So, while the sequence of nucleotides along the
length of one of the two DNA strands can vary in
countless ways, the bases on the second strand of
DNA are determined by the sequence of the bases
on the first strand. Each base must pair up with
its complementary base.
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Lets practice matching up complementary bases in
the 2 strands of DNA.
A
T
G
C
Our second strand would be complementary and its
bases would be sequenced as follows
T
A
If our first strand has the bases sequenced in
the following way
C
G
G
C
T C A G C A T
A G T C G T A
T
A
A
T
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The Shape of the DNA molecule
The two strands of DNA nucleotides are wound
about each other. This forms a twisting shape
called a double helix. The sugar-phosphate
backbones are on the outside of the double helix,
and the nitrogenous bases are on the inside.