DNA Structure and Composition

Structure of DNA

• DNA has a unique double-helix structure, resembling a twisted ladder.
• The "rungs" of the ladder are made up of pairs of nucleotides.
• Each nucleotide consists of three parts: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base.
• There are four types of nitrogenous bases in DNA: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
• The bases pair in a specific way: Adenine always pairs with Thymine (A-T) and Cytosine always pairs with Guanine (C-G).

Function of DNA

• The sequence of bases along a DNA strand forms a code, known as the genetic code.
• The code is read in groups of three bases, called codons.
• Each codon specifies a particular amino acid, which are the building blocks of proteins.
• DNA provides the instructions for making proteins through a process called protein synthesis.
• Protein synthesis involves two main steps: transcription and translation.
• Transcription: DNA is transcribed into messenger RNA (mRNA) in the cell nucleus.
• Translation: mRNA travels to the ribosome in the cytoplasm, where it is translated into a specific protein.

Replication

• DNA can replicate itself, ensuring that each new cell has an identical copy of the DNA.
• Replication is crucial for growth, repair, and reproduction.

Importance of DNA

• DNA variations (mutations) are the source of genetic diversity in populations, driving evolution and adaptation.
• DNA is passed from parents to offspring, carrying traits from one generation to the next.
• Understanding DNA helps us comprehend how organisms are built and how they function at a molecular level.
• It also opens the door to biotechnological advances, such as genetic engineering and medical research.

Protein Synthesis

• Proteins are built from amino acids, which are specified by codons in the DNA code.
• Protein synthesis involves the translation of mRNA into a specific protein.

RNA

• Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome.
• mRNA is transcribed from DNA in the cell nucleus.

tRNA and Codon

• tRNA (transfer RNA) carries amino acids to the ribosome during protein synthesis.
• Each tRNA molecule has a specific anticodon that binds to a specific codon on the mRNA.
• The codon specifies the amino acid that the tRNA carries.