translation

Overview of Protein Synthesis

  • Protein synthesis refers to the process of creating proteins within cells, involving two key stages: transcription and translation.

Types of Nucleic Acids

DNA and RNA

  • DNA: Contains genetic information.

  • RNA: Plays a crucial role in protein synthesis.

    • Composed of:

      1. A five-carbon sugar (ribose for RNA).

      2. A phosphate group.

      3. A nitrogenous base.

Differences Between RNA and DNA

Feature

RNA

DNA

Sugar

Ribose

Deoxyribose

Base

Uracil (U)

Thymine (T)

Structure

Single-stranded

Double-stranded

Types of RNA

  1. Messenger RNA (mRNA): Carries DNA's message from the nucleus to the ribosome.

  2. Transfer RNA (tRNA): Delivers the appropriate amino acids to the ribosome for protein assembly.

  3. Ribosomal RNA (rRNA): Forms part of the ribosome, facilitating the translation process.

Stages of Protein Synthesis

1. Transcription

  • Occurs in the nucleus

  • mRNA is synthesized from the DNA template:

    • RNA Polymerase unwinds the DNA and synthesizes mRNA based on the complementary base pairing.

    • Example: For DNA segment TAC CGA, mRNA will be AUG CUG.

2. Translation

  • Occurs at the ribosome

  • mRNA is read in codons (groups of three bases) to assemble proteins:

    • Codon: A series of three mRNA bases correlating to a specific amino acid.

    • tRNA brings corresponding amino acids to the ribosome.

    • Example of translation:

      • mRNA: AUG GCU AGC UGA results in a protein sequence: Met-Ala-Ser-Stop.

Importance of Proteins

  • Proteins are fundamental to numerous bodily functions and structures:

    • Components of enzymes, hormones, and cellular structures.

    • Proteins shape is crucial for function; the order of amino acids and their arrangement is vital.

Denaturation of Proteins

  • Factors causing protein denaturation include:

    • Heat: Changes protein structure and function.

    • pH Levels: Deviations can affect protein stability.

    • Chemicals: Exposure to heavy metals or harsh chemicals can denature proteins.

Summary of Protein Synthesis Steps

  • Transcription:

    • DNA unzips, mRNA is made in the nucleus.

  • Translation:

    • mRNA travels to the ribosome where amino acids are added, forming a specific protein.

Practice

  • Given a DNA sequence, transcribe into mRNA and then translate into the corresponding amino acid sequence using the genetic code chart.