Nucleic Acids: DNA & RNA Structure and Function

Nucleic Acids: DNA & RNA Structure and Function

• Nucleic acids are linear polymers that store and transmit genetic information
• DNA and RNA are types of nucleic acids
• DNA is deoxyribonucleic acid; RNA is ribonucleic acid
• DNA is typically a double helix; RNA is typically single-stranded
• Both DNA and RNA are composed of nucleotides
• Nucleotides consist of a sugar, a phosphate group, and a nitrogenous base

Nucleotide Structure

• The sugar in DNA is deoxyribose; in RNA, it is ribose
• The phosphate group links the sugars together
• Nitrogenous bases:
  • Purines (Adenine, Guanine): Double-ring structures
  • Pyrimidines (Cytosine, Thymine, Uracil): Single-ring structures
  • Thymine is found in DNA; Uracil is found in RNA

DNA Structure

• DNA forms a double helix
• The two strands are antiparallel (run in opposite directions)
• Bases pair via hydrogen bonds:
  • Adenine pairs with Thymine
  • Guanine pairs with Cytosine
• The sugar-phosphate backbone is on the outside; the bases are on the inside.

RNA Structure

• RNA is typically single-stranded
• RNA uses uracil instead of thymine
• Different types of RNA exist (mRNA, tRNA, rRNA) with specialized roles

DNA Packaging

• DNA is packaged tightly to fit within cells
• DNA wraps around histone proteins to form nucleosomes
• Nucleosomes condense into tightly coiled fibres
• Further coiling occurs to form chromosomes

Chargaff's Rules

• In DNA, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine

DNA Replication

• DNA replicates to create copies of the molecule for cell division, ensuring identical genetic information is passed on.

Central Dogma

• DNA --> RNA --> Protein
• Transcription converts DNA information into mRNA
• Translation converts mRNA information into a protein

Gene Structure

• Genes are sections of DNA (or RNA) coding for a particular protein
• Genes consist of exons (coding regions) and introns (non-coding regions)
• Regulatory regions control the gene's expression
• mRNA undergoes processing to remove introns before translation

Types of RNA

• mRNA: Messanger RNA, carries genetic code for protein synthesis
• rRNA: Ribosomal RNA, a component of ribosomes for protein synthesis
• tRNA: Transfer RNA, facilitates amino acid delivery during translation
• snRNA,snoRNA, miRNA, siRNA, IncRNA: Other types of RNA with roles in gene regulation.

Transcription

• The process of creating an RNA copy of a DNA template
• The process of initiating, elongating, and terminating synthesis of RNA

Translation

• The process of converting mRNA to a polypeptide chain
• Occurs in the ribosomes with the help of tRNA
• Amino acids are added to a growing polypeptide chain

This quiz covers the essential concepts of nucleic acids, focusing on DNA and RNA's structure and function. It includes details about nucleotide composition, the double helix form of DNA, and the unique characteristics of RNA. Test your understanding of genetic information storage and transmission.