DNA THE CODE OF LIFE
Nucleic acids have been called “the molecules of life” or the “most extraordinary molecules
on earth” as they have the capacity to store all the information that control cellular activity
and the development of an entire organism.
They do this by controlling the synthesis of proteins. Proteins not only make up much of the
structure of the body but, as enzymes are proteins, they also control the chemical processes
inside cells. In this way they ultimately control the structure and functioning of all living
organisms.
The two nucleic acids found in cells are:
1. Deoxyribonucleic acid DNA
2. Ribonucleic acid RNA
DEOXYRIBONUCLEIC ACID
DNA is found mainly in the nucleus the cell where it forms an important part of
chromosomes that make up the chromatin network.
Chromatin is chromosomal material made up of DNA, RNA and histone proteins as found in
a non-dividing cell
The DNA molecule is coiled so that these long structures can fit inside the nucleus.
EXTRACELLULAR DNA
Small amounts of DNA are found outside the nucleus in mitochondria in plants and animals
and in chloroplasts in plants. This is called extranuclear DNA.
DNA MADE UP
The shape of DNA is rather like a long, twisted ladder. The two strands twist to form a
stable, three-dimensional double helix.
UNITS THAT MAKE MODEL OF A DNA MOLECULE
UP DNA
, The DNA molecule is a long chain, polymer, made up of small units [monomers].
The building blocks called nucleotides. Nucleotide made up of:
Sugar molecule- deoxyribose (S)
Phosphate molecule (P)
Nitrogenous base which may be:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
These four bases are the foundation of the genetic code, instructing cells on how to
synthesize enzymes and other proteins.
As they are four different nitrogenous bases, they are four different nucleotides.
Sugar
(deoxyribos Nitrogenous
base
Phosphate
HOW THE DOUBLE HELIX IS MADE UP
The outer two strands of the ladder of formed by a chain of alternating
sugar/phosphate links. The bonds between the sugar and phosphate molecules are
strong
The rungs of the ladder are formed from pairs of bases linked by weak hydrogen
bonds.
The base pairs are attached to the sugar molecules
HOW THE FOUR BASE PAIRS LINK UP
The shape and size of the four bases differ so that.
Adenine will only bond with thymine or uracil by means of two hydrogen bonds eg
A=T, A=U.
Cytosine will only bond with guanine by means of three hydrogen bonds eg C=G
HOW THE BASE PAIRS ARE CLASSIFIED
There are 2 groups of nitrogenous bases- purines and pyrimidines
Nucleic acids have been called “the molecules of life” or the “most extraordinary molecules
on earth” as they have the capacity to store all the information that control cellular activity
and the development of an entire organism.
They do this by controlling the synthesis of proteins. Proteins not only make up much of the
structure of the body but, as enzymes are proteins, they also control the chemical processes
inside cells. In this way they ultimately control the structure and functioning of all living
organisms.
The two nucleic acids found in cells are:
1. Deoxyribonucleic acid DNA
2. Ribonucleic acid RNA
DEOXYRIBONUCLEIC ACID
DNA is found mainly in the nucleus the cell where it forms an important part of
chromosomes that make up the chromatin network.
Chromatin is chromosomal material made up of DNA, RNA and histone proteins as found in
a non-dividing cell
The DNA molecule is coiled so that these long structures can fit inside the nucleus.
EXTRACELLULAR DNA
Small amounts of DNA are found outside the nucleus in mitochondria in plants and animals
and in chloroplasts in plants. This is called extranuclear DNA.
DNA MADE UP
The shape of DNA is rather like a long, twisted ladder. The two strands twist to form a
stable, three-dimensional double helix.
UNITS THAT MAKE MODEL OF A DNA MOLECULE
UP DNA
, The DNA molecule is a long chain, polymer, made up of small units [monomers].
The building blocks called nucleotides. Nucleotide made up of:
Sugar molecule- deoxyribose (S)
Phosphate molecule (P)
Nitrogenous base which may be:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
These four bases are the foundation of the genetic code, instructing cells on how to
synthesize enzymes and other proteins.
As they are four different nitrogenous bases, they are four different nucleotides.
Sugar
(deoxyribos Nitrogenous
base
Phosphate
HOW THE DOUBLE HELIX IS MADE UP
The outer two strands of the ladder of formed by a chain of alternating
sugar/phosphate links. The bonds between the sugar and phosphate molecules are
strong
The rungs of the ladder are formed from pairs of bases linked by weak hydrogen
bonds.
The base pairs are attached to the sugar molecules
HOW THE FOUR BASE PAIRS LINK UP
The shape and size of the four bases differ so that.
Adenine will only bond with thymine or uracil by means of two hydrogen bonds eg
A=T, A=U.
Cytosine will only bond with guanine by means of three hydrogen bonds eg C=G
HOW THE BASE PAIRS ARE CLASSIFIED
There are 2 groups of nitrogenous bases- purines and pyrimidines
