DNA structure + Protein synthesis

• What is a nucleotide and describe the structure

  • Nucleotide= small parts that make up DNA
  • Made up of: One sugar and phosphate molecule plus a base
  • Made up of 4 bases: A-T and C-G (complimentary pairs)
• What do the order of different bases form?

  • A code
  • Each group of 3 bases code for an amino acid
  • The amino acids join together to form a specific protein
  • The type and order of amino acid determines the protein
  • There are 20 types of amino acids
• Describe the process of protein synthesis

  • Transcription: DNA is too big to leave nucleus so enzyme called RNA Polymerase reads the code and makes an mRNA copy complementary to the DNA
  • mRNA leaves nucleus and goes to ribosome
  • Translation: Ribosome reads the mRNA sequence in triplets called codons and each codon codes for a specific amino acid
  • tRNA brings the complimentary anti codon to each codon, this carries an amino acid
  • Ribosomes join these amino acids together in the correct order forming a polypeptide chain
  • Once the chain is complete it folds into a specific shape, forming a functional protein
• What are the three functions proteins could have?

  • Enzymes: Biological catalysts speeding up rates of reaction
  • Hormones; chemical messengers sending signals around the body
  • Structural proteins: Strong proteins forming structures such as collagen