DNA: The Code of Life
1.1 Introduction: Nucleic Acids
There are 2 types of Nucleic acids:
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
Nucleic acids are made up of a phosphate group, a 5-carbon sugar portion and a nitrogenous base.
Phosphate
group
Sugar
Nucleic Acid
1.2 DNA
Functions and location of DNA
DNA is a molecule that contains genetic material for the formation and functioning of a living
organism.
It codes for the formation of a variety of proteins needed in the body.
It transmits hereditary traits and characteristics from parents to their offspring.
It is found in the nucleus of a cell (nuclear DNA), in the mitochondria (mitochondrial DNA) or
in chloroplasts of plants (chloroplastic DNA).
Structure of DNA
DNA is double stranded (double helix) and made up of units known as nucleotides. This
conclusion was put forward in by James Watson and Francis Crick, using X-ray diffractions
provided by Rosalind Franklin and Maurice Wilkins.
Each nucleotide contains deoxyribose sugar, a phosphate group
and nitrogenous bases of which DNA has four types.
Nitrogenous bases in DNA are: thymine, adenine, guanine and
cytosine.
These bases pair with each other according to complementary
base pairing. Thymine pairs with adenine and guanine pairs
with cytosine.
The two DNA strands are held together by weak hydrogen
bonds.
1.3 RNA
, Functions and location of RNA
RNA’s main function is to carry out protein synthesis.
Messenger RNA (mRNA) carries information from DNA found in the nucleus to ribosomes
outside of the nucleus.
Ribosomal RNA (rRNA) is involved in the formation of ribosomes.
Transfer RNA (tRNA) transfers amino acids from the cytoplasm to the ribosome to form
proteins.
rRNA is found on ribosome s in the cell's cytoplasm.
mRNA is found in the nucleus, but later leaves through nuclear pores into the cytoplasm to
settle on ribosomes.
Structure of RNA
RNA is a single stranded molecule and is also made up of nucleotides.
Each nucleotide contains ribose sugar, a phosphate group and nitrogenous bases of which
RNA has four types.
Nitrogenous bases in RNA are: Uracil (U), adenine (A), guanine (G) and cytosine (C).
1.4 DNA vs RNA
Similarities
Both Nucleic acids.
Both play an important role in the formation of proteins
Both contain bases guanine, cytosine and adenine.
Differences
DNA RNA
Double stranded Single stranded
Has thymine Has uracil
Large molecule Small molecule
Has deoxyribose sugar Has ribose sugar
Found in nucleus, Found only in nucleus and
mitochondria and chloroplasts cytoplasm
1.5 DNA Replication
The process whereby DNA makes an identical copy of itself. It takes place in the nucleus during
interphase.
1.1 Introduction: Nucleic Acids
There are 2 types of Nucleic acids:
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
Nucleic acids are made up of a phosphate group, a 5-carbon sugar portion and a nitrogenous base.
Phosphate
group
Sugar
Nucleic Acid
1.2 DNA
Functions and location of DNA
DNA is a molecule that contains genetic material for the formation and functioning of a living
organism.
It codes for the formation of a variety of proteins needed in the body.
It transmits hereditary traits and characteristics from parents to their offspring.
It is found in the nucleus of a cell (nuclear DNA), in the mitochondria (mitochondrial DNA) or
in chloroplasts of plants (chloroplastic DNA).
Structure of DNA
DNA is double stranded (double helix) and made up of units known as nucleotides. This
conclusion was put forward in by James Watson and Francis Crick, using X-ray diffractions
provided by Rosalind Franklin and Maurice Wilkins.
Each nucleotide contains deoxyribose sugar, a phosphate group
and nitrogenous bases of which DNA has four types.
Nitrogenous bases in DNA are: thymine, adenine, guanine and
cytosine.
These bases pair with each other according to complementary
base pairing. Thymine pairs with adenine and guanine pairs
with cytosine.
The two DNA strands are held together by weak hydrogen
bonds.
1.3 RNA
, Functions and location of RNA
RNA’s main function is to carry out protein synthesis.
Messenger RNA (mRNA) carries information from DNA found in the nucleus to ribosomes
outside of the nucleus.
Ribosomal RNA (rRNA) is involved in the formation of ribosomes.
Transfer RNA (tRNA) transfers amino acids from the cytoplasm to the ribosome to form
proteins.
rRNA is found on ribosome s in the cell's cytoplasm.
mRNA is found in the nucleus, but later leaves through nuclear pores into the cytoplasm to
settle on ribosomes.
Structure of RNA
RNA is a single stranded molecule and is also made up of nucleotides.
Each nucleotide contains ribose sugar, a phosphate group and nitrogenous bases of which
RNA has four types.
Nitrogenous bases in RNA are: Uracil (U), adenine (A), guanine (G) and cytosine (C).
1.4 DNA vs RNA
Similarities
Both Nucleic acids.
Both play an important role in the formation of proteins
Both contain bases guanine, cytosine and adenine.
Differences
DNA RNA
Double stranded Single stranded
Has thymine Has uracil
Large molecule Small molecule
Has deoxyribose sugar Has ribose sugar
Found in nucleus, Found only in nucleus and
mitochondria and chloroplasts cytoplasm
1.5 DNA Replication
The process whereby DNA makes an identical copy of itself. It takes place in the nucleus during
interphase.
