Unit 10.5 : Transcription and Translation

two parts of gene expression

  1. transcription (making an mRNA copy of a DNA gene)

  2. translation (making a protein from an mRNA copy of a gene)

how many amino acids do we have

  • 20

3 types of RNA and their functions

  • mRNA (messenger RNA): carries a copy of DNA instructions for a gene to the cytoplasm

  • rRNA (ribosomal RNA): RNA molecules in a ribosome

  • tRNA (transfer RNA): brings over an amino acid to a growing protein chain

where transcription occurs

  • cytoplasm

template for transcription

  • DNA ( a single gene at a time)

enzyme required for transcription

  • RNA polymerase

final product of transcription

  • mRNA copy of a gene

modifications that must be made to RNA before sending it to a ribosome

  • introns (interrupting sequences) must be removed

  • extrons (expressed sequences) must be spliced together

  • a cap and a tail must be added

where translation occurs

  • cytoplasm

template for translation

  • mRNA

structure required for translation

  • ribosome

final product of translation

  • protein

amino acid sequence from a DNA sequence

  • how the ribosome knows where to start making the protein

    • the start codon (AUG)

  • what determines the amino acid (codon or anticodon)

    • the codon

codons versus anticodons

  • codons are found in the mRNA; anticodons are found on the tRNA. codons are used to determine the amino acids

AUG

  • start codons, encodes for methionine

definitions

  • transcription: making an mRNA copy of a DNA gene

  • translation: making a protein from an mRNA

  • amino acid: monomer of a protein

  • codon: triplet of nucleotides that usually encodes for a specific amino acid (exception: 3 stop codons)

  • start codon: AUG, also encodes for methionine

  • stop codon: 3 stop codons, they do not code for a specific amino acid

  • promoter: binding site for RNA polymerase, tells the cell where the gene begins on the chromosome

  • terminator: sequence of nucleotides at the end of a gene that signals where the gene ends. RNA polymerase falls off here

  • intron: interrupting sequence of nucleotides the is cut out of mRNA before the mRNA leaves the nucleus. does not contribute to the production of a protein

  • exon: expresses sequence of nucleotides that contributes to the production of a protein