Gene Expression

• Protein


  A polymer that is made of one or more polypeptide chains folded into a functional 3D shape
• Protein Synthesis


  the formation of proteins by using information contained in DNA
• Amino Acid


  Building blocks of protein
• Polypeptide


  A polymer of many amino acids linked together by peptide bonds.
• Peptide bond


  Bond that joins two neighbouring amino acids together in a polypeptide chain
• Triplet


  A sequence of three consecutive bases in DNA that codes for an amino acid
• Ribosome


  Organelle where translation takes place
• DNA


  Large molecule in the nucleus made of nucleotides that carries the genetic code
• Gene


  A section of DNA that codes for the production of one polypeptide chain
• Transcription


  The process of creating a strand of mRNA from a template strand of DNA
• Promoter region


  region of DNA that RNA polymerase attaches to begin transcription.
• Terminator region


  region on gene that marks the end of transcription
• RNA polymerase


  enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template
• mRNA


  messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
• Template strand


  the strand of DNA that is used as a template to make mRNA using complementary base pairing
• Coding Strand


  the strand of DNA that is not used for transcription and is identical in sequence to mRNA, except it contains uracil instead of thymine
• Translation


  Process of amino acids joining together in correct sequence using mRNA as a template
• tRNA


  transfer RNA; type of RNA that carries amino acids to the ribosome
• rRNA


  ribosomal RNA; type of RNA that makes up part of the ribosome
• Codon


  A sequence of three consecutive bases in mRNA
• Anticodon


  A sequence of three consecutive bases in tRNA
• Degeneracy


  most amino acids are encoded by several codons
• Start codon


  AUG - the codon that signals to ribosomes to begin translation
• Stop codon


  codon that signals to ribosomes to stop translation
• Purines


  Bases with a double-ring structure (A and G)
• Pyrimidines


  Bases with a single-ring structure (C and T)
• Nucleotide


  monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base
• DNA vs RNA structure

  DNA has Thymine and RNA has Uracil

  DNA has deoxyribose and RNA has ribose

  DNA is double stranded and RNA is single stranded
• Mutagen


  An environmental agent that causes a change to the DNA base sequence

  
• Examples of mutagens


  UV radiation, x rays, cigarette smoke

  
• Mutation


  A permanent change in the DNA base sequence
• Point Mutation


  A gene mutation in which a single base pair in DNA has been changed

  
• Substitution


  A mutation in which a nucleotide is replaced with a different nucleotide

  
• Nonsense mutation


  A mutation that codes for a stop codon, resulting in a shorter and usually nonfunctional protein.

  
• Missense mutation


  A substitution mutation that results in a codon that codes for a different amino acid.

  
• Effect of a missense mutation on the protein


  A change in amino acid will result in the protein folding differently which will affect its function.
• Silent mutation


  A substitution mutation that codes for the same amino acid because of degeneracy of the code

  
• Effect of a silent mutation on the protein


  No effect because the length and order of bases is exactly the same, and the final protein folds correctly and therefore functions correctly.
• Deletion mutation


  A loss of a nucleotide in the DNA sequence

  
• Insertion mutation


  An addition of a nucleotide in the DNA sequence