PROTEIN SYNTHESIS

• mRNA

  Takes DNA code to ribosome
• FOUR BASIC TYPES OF ORGANIC MOLECULE

  • Carbohydrates (sugars and starches)
  • Lipids (fats)
  • Proteins
  • Nucleic acids (DNA AND RNA)
• Polymers

  Long chains of similar subunits
• Macromolecules

  Large molecules, also called polymers
• Monomers

  Subunits of macromolecules
• Amino acids

  • 20 significant types in animals
• Proteins

  • Enzymes: all metabolic transformations, building up, rearranging, and breaking down of organic compounds, are done by enzymes, which are proteins
  • Transport: oxygen in the blood is carried by hemoglobin, everything that goes in or out of a cell (except water and a few gasses) is carried by proteins
  • Structure: collagen in skin, keratin in hair, crystallin in the eye
• DNA carries instructions to make certain proteins. These proteins then carry out the particular functions for and of that cell. Shape is critical to function.
• Types of nucleic acid

  • RNA (ribonucleic acid)
  • DNA (deoxyribonucleic acids)
• Nucleotide

  Has 3 parts: a sugar, a phosphate and a base
• Nucleic acid sugar

  Contains 5 carbons
• Protein synthesis

  1. Chromosomes are comprised of DNA, it is 'packaged' in a certain way that creates genes

  2. Genes are areas of chromosomes that can be 'expressed' individually (or collectively)

  3. When a gene is 'switched on', it is undergoing the process of protein synthesis to create a product that can influence a particular outcome

  4. Amino acids --> polypeptides --> proteins
• Exons

  Sections of DNA (or RNA) that code for proteins, retained in mature mRNA, few mutations as their function is to code for proteins
• Introns

  Noncoding sections of RNA or DNA encoding RNA, introns in-between, spliced out before the RNA is translated into a protein
• Transcription

  1. DNA unwinds at a particular gene, exposing the bases

  2. Free nucleotides join together in a complimentary sequence to the exposed section of DNA

  3. No thymine (T), Uracil (U) replaces T and bonds to A (Adenine)

  4. They form their own single strand of mRNA (messenger RNA)

  5. mRNA leaves the nucleus and travels to a ribosome
• Translation

  1. mRNA attaches to the ribosome where the nitrogen bases are 'read'

  2. Nitrogen bases are grouped in three's which is known as a 'codon' or 'triplets'

  3. tRNA (Transfer RNA) with an anticodon (a complimentary nitrogen base sequence to the codon's mRNA) is attracted to the mRNA strand

  4. tRNA brings an amino acid specific for the codon

  5. Amino acid is 'deposited' at the ribosome

  6. Further amino acids are brought together and form peptide bonds between them --> peptide chain --> proteins

  7. Peptide chain may be long enough to form a protein on its own OR joined with other polypeptides in the golgi apparatus to be packaged and distributed
• Enzymes

  Important proteins that influence the reaction in cells
• Transcription + translation = protein synthesis
• Mutations

  • Changing the DNA sequence (because there is a potential amino acid forming)
  • Changes of the structure of a gene, resulting in a different form that may be transmitted to subsequent generations
• Causes of mutations

  • Radioactive x-rays
  • Ultraviolet radiation
  • Certain chemicals
• Mutations can be helpful, e.g. seeing a different wavelength of light that can help you tell the difference between a normal fruit and a poisonous fruit
• Types of gene mutations

  • Substitution - something gets swapped
  • Insertion - one's been added
  • Deletion - one removed
• Frameshift mutation

  Caused by insertion and deletion