DNA Replication and RNA Transcription and Translation

Overview

• DNA serves as the molecular basis of heredity.
• The processes include replication, transcription, and translation.
• Replication creates identical DNA strands.
• Transcription converts DNA into messenger RNA (mRNA).
• Translation decodes mRNA into amino acids, forming proteins essential for life functions.

DNA Structure

• DNA is a double helix, a twisted ladder structure.
• Consists of base pairs: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).

DNA Replication

• Essential for heredity: allows cells to divide with identical DNA.
• Process:
  • DNA strands separate like a ladder splitting.
  • Each strand serves as a template to construct a new complementary strand.
  • Pairing rules: A-T and G-C.
• Results in two identical DNA molecules.

Gene Expression

• Gene expression involves the conversion of DNA information into proteins.
• DNA vs. Chromosome vs. Gene:
  • DNA: Molecule with genetic information.
  • Chromosome: DNA packaged with proteins in a structured form.
  • Gene: Section of DNA coding for a trait/protein.

RNA and Transcription

• RNA stands for ribonucleic acid.
• RNA differs from DNA: RNA has ribose sugar; DNA has deoxyribose.
• Transcription is the process of converting a gene into mRNA.
• mRNA (messenger RNA) carries genetic information from DNA to the ribosome.
• Base Pairing in Transcription:
  • A in DNA pairs with U (Uracil) in RNA.
  • T in DNA pairs with A in RNA.
  • G pairs with C, and C pairs with G.

Translation

• Process where mRNA is decoded into a protein.
• Codon: Sequence of three bases in mRNA, coding for an amino acid.
• Ribosome: Site where translation occurs.
• tRNA (transfer RNA) brings amino acids to the ribosome, matching mRNA codons.
• Amino Acids: Building blocks of proteins.
• 64 possible codons, coding for 20 amino acids (overlap allows multiple codons per amino acid).

Proteins

• Proteins are sequences of amino acids.
• Perform various functions in the body (e.g., enzymes, structural).

Key Concepts

• Replication: DNA duplication before cell division.
• Transcription: Making mRNA from DNA template.
• Translation: Synthesizing proteins from mRNA template.
• Central Dogma: Flow of genetic information: DNA -> RNA -> Protein.

Additional Notes

• DNA replication is essential for cell division.
• RNA transcription allows genetic information to exit the nucleus.
• Translation is crucial in protein synthesis.
• Understanding the processes is key to grasping molecular biology.