Lecture Notes: RNA - Ribonucleic Acid

Introduction to RNA

• RNA stands for ribonucleic acid, a type of nucleic acid like DNA.
• RNA is made up of nucleotides, which are monomers that join to form polymers, similar to DNA.
• RNA Nucleotides:
  • Contains a ribose sugar, unlike DNA's deoxyribose.
  • Four types of bases: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U) (no Thymine).
  • Includes phosphate groups.

Structure of RNA

• RNA is usually single-stranded, unlike the double-stranded DNA.
• Nucleotides are linked by phosphodiester bonds.

Types of RNA

1. Messenger RNA (mRNA)

• Known as mRNA; single-stranded and linear.
• Has a 5' to 3' directionality, similar to DNA.
• Codons:
  • Every three bases on mRNA form a codon.
  • Number of codons = total bases / 3.
  • Example: 210 bases = 70 codons.

2. Transfer RNA (tRNA)

• tRNA is similar in some aspects to mRNA but has a distinct structure.
• Structure:
  • Folded into a 3D structure that resembles a cloverleaf in 2D drawings.
  • Contains a fixed base region CCA at the 3' end.
  • Has one anticodon (a specific triplet base highlighted in green).
  • Can form hydrogen bonds within its chain.
• Functionality:
  • Attaches to specific amino acids at the 3' end.

3. Ribosomal RNA (rRNA)

• Comprises part of the ribosome structure, along with proteins.
• Structure:
  • Forms a 3D structure by coiling and folding.
  • Composed of a longer and a shorter rRNA, forming a large and small subunit of the ribosome, respectively.
• Ribosome Composition:
  • Made up of rRNAs and proteins.
  • No need to memorize specific protein names.

Key Points

• RNA is essential for various cellular processes, including protein synthesis.
• Understanding the structure and types of RNA helps in understanding its functions in cells.

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These notes cover the key points from the lesson and can be used as a study aid to understand RNA's structure and function.