Protein synthesis

• Proteins

  Polymers of amino acids
• Bonds that hold amino acids together

  Peptide bonds
• Polypeptide


  Chain of amino acids bonded by peptide bonds to form a polypeptide
• Primary structure of a protein


  Sequence of amino acids in a polypeptide chain
• Correct primary structure

  Ensures hydrogen and disulfide and ionic bonds form in the correct place (between the R groups of specific amino acids)to fold the protein into its correct tertiary structure
• What does RNA stand for?


  Ribonucleic acid
• RNA features

  • An important information carrying molecule
  • Transfers genetic information from the nucleus to the ribosomes
  • Single stranded and shorter than DNA
• What are the three types of RNA?

  • mRNA
  • tRNA
  • rRNA
  • (Ribosomes are made of ribosomal RNA associated with protein)
• RNA nucleotides structure

  
• What are the complimentary base pairing of RNA?

  • Adenine= uracil (instead of thymine)
  • Cytosine=Guanine
• What is the difference between DNA and RNA structure?

  DNA: Double-stranded, deoxyribose sugar, thymine base, longer RNA: Single-stranded, ribose sugar, uracil base, shorter
• Difference between mRNA and tRNA structure?

  mRNA: linear, carries genetic information from DNA to ribosomes, NO double stranded sections, NO amino acid attachment site, codon tRNA: cloverleaf-shaped, carries amino acids to ribosomes during protein synthesis, some double stranded sections but main body is single stranded, HAS an amino acid attachment site, Anticodon
• How does mRNA differ from DNA?

  • Single stranded, not double stranded
  • It’s shorter than DNA
  • Contains ribose instead of deoxyribose
  • Contains uracil instead of thymine
• How does tRNA differ from DNA?

  • It’s single stranded but DOES have double stranded sections
  • It is shorter than DNA
  • It contains ribose instead of deoxyribose
  • It contains uracil instead of thymine
  • Has an amino acid attachment site
  • It is folded into a cloverleaf shape
• Is mRNA linear or cloverleaf shaped?

  Linear
• Is tRNA linear or cloverleaf shaped?

  Cloverleaf shaped
• What is a gene?


  A base sequence on a section of DNA that codes for a polypeptide or functional RNA molecule (rRNA, tRNA)
• What does a gene occupy?

  A specific position on a DNA molecule on a chromosome called a locus
• In eukaryotic cells what is DNA called that is NON-coding?


  Introns- these are between genes and within genes
• In eukaryotic cells, what are the coding regions called?


  Exons
• In prokaryotic DNA there are no introns (non-coding regions) only exons (coding regions)
• What is a genome?

  A complete set of genes within a cell (organism)
• What is a proteome?

  The complete set/full range of proteins that a cell can produce (expressed by a genome)
• The genetic code

  • Universal=triplets code for the same amino acids in every species
  • Non-overlapping=triplets must be read in sequence (one base can’t be part of a different triplet)
  • It is degenerate=most amino acids are coded for by more than one triplet
  • 1 DNA strand is the coding strand=holds the genetic code
  • A set of 3 bases (triplet)codes for 1 amino acid
  • (64 triplets (4x4x4)only 20 amino acids)
• Evidence for evolution

  • The genetic code is universal=triplets code for the same amino acids in every species (we have all developed from one organism)
• What feature of the genetic code means that one amino acid can have more than one triplet coding for it?

  Degenerate
• What feature of the genetic code means that a single base in one triplet cannot be part of another triplet?

  Non-overlapping
• What feature of the genetic code means that every organism uses the same triplets to code for the same amino acids?

  Universal
• How many amino acids are coded for by more than one triplet?

  18
• How many amino acids have only 1 triplet coding for them?

  2
• How many triplet codes are possible?

  64

  (4x4x4)
• Why could it be possible for the gene for a specific polypeptide to contain more than the minimum number of triplets or bases?

  • Could have a stop triplet
  • May contain introns