Protein synthesis

• Describe eukaryotic DNA and where it is stored:

  Linear DNA that exists as chromosomes- thread like structure- one long molecule
• What is the protein eukaryotic DNA often wrapped around?

  Histones
• Why is eukaryotic DNA wrapped around histones?

  It is wrapped tightly into a compact chromosome, so it can fit into the nucleus and it supports the DNA.
• In eukaryotic cells, what has similar DNA to prokaryotic cells?

  Mitochondria and chloroplasts jhave their own DNA similar to prokaryotic cells, circular and shorter, not associated with any histones.
• Describe prokaryotic DNA:

  exists as chromosomes but molecules shorter and circular, it condenses by supercoiling instead of being associated with a protein.
• Gene:


  a sequence of DNA bases that code for a polypeptide or functional RNA
• What functions do genes that dont code for a polypeptide code for?

  They code for functional RNA, which perfrom tasks in protein synthesis like tRNA and RRNA which form parts of ribososomes.
• What are the sections of functional RNA called?

  Introns
• Why are Introns removed during protein synthesis?

  So they don't affect the amino sequence
• What are non-coding repeats and where do they occur?

  They are regions of multiple repeats in the genome, but they do not code for amino acids.
• Allele:


  Different versions of a gene. Slightly different versions of the same polypeptide.
• locus meaning:


  the location of a gene on a chromosome.
• What is mRNA?

  It carries genetic code from the DNA to the ribosomes where its used to make a protein during translation
• What is Transfer DNA/ tRNA?

  It carries amino acids that are used to make proteins to the ribosomes in translation.
• Describe tRNA shape:

  ☘SHAPE with hydrogen bonds between specific base pairs that hold the shape. tRNA has three specific bases at one end that is called anticodon. They have an amino acid binding site.
• Describe Splicing:

  The introns and exons are both copied in transcription in pre-mRNA, where exons are joined together.
• Does splicing occur in mRNA prokaryotes?

  No, there are no introns, mRNA is produced directly from DNA.
• The genetic code has three properties:

  Degenerate(amino acids coded for by many triplets), Non-Overlapping(no shared bases in triplets), Universal (the same base triplets=same amino acids in all living things)
• Gametes are haploid (n) (half chromosomes) and normal body cells are Diploid (2n)
• Types of mutation: Substitution, Deletion, Insertion, Duplication, Inversion, Addition, Translocation.
• Pre-mRNA

  The mRNA molecule before it is spliced
• Translation

  The site of protein synthesis
• In eukaryotic cells the pre-mRNA is then spliced to remove the introns leaving just a strand of exons
• The mRNA then moves out of the nucleus through a pore
• The mRNA then attaches to a ribosome in the cytoplasm which is the site of next stage of protein synthesis called translation
• Splicing

  The process of removing introns from pre-mRNA leaving just a strand of exons
• TRANSCRIPTION PART 1 - RNA attaches to the beginning of a gene and hydrogen bonds are broken by DNA helicase, exposing bases.
• TRANSCRIPTION PART 2 - Strand is used a template, RNA polymerase lines up free RNA nucleotides attracted to the exposed bases- complementary base pairing- and joined together by RNA polymerase.
• TRANSCRIPTION PART 3 RNA polymerase moves along DNA assembly a mRNA strand and hydrogen bonds form between strands until a stop signal where mRNA detatches from DNA.
• TRANSLATION PART 1 - mRNA has moved out of the nuclear pore and attached to a ribosome where tRNA brings amino acids. ATP provides energy for protein synthesis. Anti- codon (tRNA) complementary to the codon on mRNA.
• TRANSLATION PART 2- amino acids joined by a peptide bond forming a polypeptide chain until theres a stop signal. Then it moves away from ribosome.
• Proteome definition:

  All the proteins a cell can produce.