DNA: The Code of Life
Introduction to DNA
DNA, or Deoxyribonucleic Acid, is the molecule that contains the genetic
instructions for the development, functioning, growth, and reproduction of all
known organisms and many viruses. DNA molecules are composed of two chains
that coil around each other to form a double helix.
Structure of DNA
Nucleotides: DNA is made up of units called nucleotides. Each nucleotide
consists of:
o A phosphate group
o A sugar molecule (deoxyribose)
o One of four nitrogenous bases: Adenine (A), Thymine (T), Cytosine
(C), and Guanine (G).
Double Helix: The structure of DNA is a double helix, resembling a
twisted ladder. The sugar and phosphate form the backbone, while the
nitrogenous bases form the rungs.
Base Pairing: Bases pair in a specific way: Adenine pairs with Thymine (A-
T), and Cytosine pairs with Guanine (C-G). This pairing is due to hydrogen
bonding.
DNA Replication
DNA replication is the process by which DNA makes a copy of itself during cell
division. It ensures that each new cell receives an exact copy of the DNA.
Steps of Replication:
1. Unwinding of the DNA Helix: Enzymes called helicases unwind
the double helix, creating a replication fork.
2. Base Pairing: Free nucleotides in the cell match up with the
exposed bases on each strand.
3. Formation of New DNA Strands: DNA polymerase enzymes link
the nucleotides together to form two new DNA strands, each
complementary to one of the original strands.
Transcription and Translation
The processes of transcription and translation are how cells read the genetic
instructions in DNA to make proteins.
Transcription:
o The process of copying a segment of DNA into RNA (Ribonucleic
Acid).
o RNA differs from DNA in that it is single-stranded and uses Uracil (U)
instead of Thymine (T).
Introduction to DNA
DNA, or Deoxyribonucleic Acid, is the molecule that contains the genetic
instructions for the development, functioning, growth, and reproduction of all
known organisms and many viruses. DNA molecules are composed of two chains
that coil around each other to form a double helix.
Structure of DNA
Nucleotides: DNA is made up of units called nucleotides. Each nucleotide
consists of:
o A phosphate group
o A sugar molecule (deoxyribose)
o One of four nitrogenous bases: Adenine (A), Thymine (T), Cytosine
(C), and Guanine (G).
Double Helix: The structure of DNA is a double helix, resembling a
twisted ladder. The sugar and phosphate form the backbone, while the
nitrogenous bases form the rungs.
Base Pairing: Bases pair in a specific way: Adenine pairs with Thymine (A-
T), and Cytosine pairs with Guanine (C-G). This pairing is due to hydrogen
bonding.
DNA Replication
DNA replication is the process by which DNA makes a copy of itself during cell
division. It ensures that each new cell receives an exact copy of the DNA.
Steps of Replication:
1. Unwinding of the DNA Helix: Enzymes called helicases unwind
the double helix, creating a replication fork.
2. Base Pairing: Free nucleotides in the cell match up with the
exposed bases on each strand.
3. Formation of New DNA Strands: DNA polymerase enzymes link
the nucleotides together to form two new DNA strands, each
complementary to one of the original strands.
Transcription and Translation
The processes of transcription and translation are how cells read the genetic
instructions in DNA to make proteins.
Transcription:
o The process of copying a segment of DNA into RNA (Ribonucleic
Acid).
o RNA differs from DNA in that it is single-stranded and uses Uracil (U)
instead of Thymine (T).
