Nucleic Acids and Protein Synthesis in Depth Notes

Overview of Nucleic Acids and Protein Synthesis

• Histology Technician Role: Studies tissues, cells, and bodily fluids to detect diseases, blood types, and drug concentrations.

Components of Nucleic Acids

• Nucleotide Structure:

  • Nitrogen-containing base
  • Sugar
  • Phosphate group

• Types of Nucleic Acids:

  • DNA (Deoxyribonucleic Acid): Genetic material in cell nuclei.
  • RNA (Ribonucleic Acid): Interprets genetic information for protein synthesis.
  • Both DNA and RNA are unbranched polymers of nucleotides.

Nucleic Acid Structure

• Characteristics:
  • Large molecules found in cell nuclei.
  • Store information and direct cellular growth and reproduction.
  • Composed of nucleotides with:
  • Nitrogen base
  • Five-carbon sugar (ribose in RNA, deoxyribose in DNA)
  • Phosphate group

Bases in Nucleic Acids

• Nitrogenous Bases:
  • Pyrimidines: Single ring structure (Cytosine (C), Thymine (T) in DNA; Uracil (U) in RNA).
  • Purines: Double ring structure (Adenine (A), Guanine (G) in both DNA and RNA).

Specific Bases and Their Structures

• DNA:
  • Bases: A, T, C, G
• RNA:
  • Bases: A, U, C, G

Pentose Sugars

• RNA Sugar: Ribose
• DNA Sugar: Deoxyribose (lacks an oxygen atom at the 2’ position).

Nucleoside and Nucleotide Formation

• Nucleoside:

  • Composed of nitrogen base and sugar.

• Nucleotide:

  • Formed when a phosphate group attaches to a nucleoside.

Primary Structure of Nucleic Acids

• Backbone Formation:
  • Nucleotides joined by phosphodiester bonds.
  • Phosphate group of one nucleotide binds to the 3’-OH of the sugar of another nucleotide.

DNA Double Helix Structure

• Description:
  • The structure resembles a spiral staircase formed by two strands of nucleotides held together by hydrogen bonds between complementary base pairs (A-T, G-C).

Base Pairing and DNA Replication

• Base Pairing Rules:

  • A pairs with T via 2 hydrogen bonds.
  • G pairs with C via 3 hydrogen bonds.

• DNA Replication Process:

  • Original DNA strands separate, and new complementary strands are synthesized.
  • Enzymes play crucial roles:
  • Helicase: Unwinds DNA helix.
  • DNA Polymerase: Synthesizes new strands.
  • Ligase: Joins Okazaki fragments on the lagging strand.

Transcription and Translation

• Transcription:

  • Synthesis of mRNA from DNA template.
  • Occurs in nucleus; mRNA exits to cytoplasm.

• Translation:

  • mRNA is translated into amino acids at ribosomes.
  • tRNA transports specific amino acids to the ribosome using anticodons.

Genetic Code

• Codons:
  • Sequences of three nucleotides representing amino acids.
  • Stop codons signal termination of protein synthesis; AUG is the start codon.

Types of Mutations

• Point Mutations: Replacement of one base with another.

• Deletion and Insertion Mutations: Change the reading frame of the genetic code.

• Effects of Mutations:

  • Can lead to dysfunctional proteins or diseases.
  • Genetic diseases arise from these mutations affecting enzyme functions.

Recombinant DNA and Genetic Engineering

• Recombinant DNA Technology: Combining DNA from different organisms for various applications, including therapeutic and diagnostic purposes.

• Polymerase Chain Reaction (PCR): Technique to amplify DNA segments rapidly.

Viruses and HIV/AIDS Treatment

• Viruses: Require host cells to reproduce, can cause various diseases.
• HIV: Retrovirus that targets immune cells, treatment includes nucleoside analogs to inhibit viral replication.

Conclusion

• Importance of Understanding Molecular Biology: Crucial for advancements in medicine, genetics, and biotechnology.

This summary encompasses the fundamental aspects of nucleic acids, their structures, functions in genetic expression, and their significance in health and disease.