DNA,RNA,Genes

• chromosomes: made up of DNA and histones proteins that wrap around DNA
• Histones: help support DNA
• Gene: section of DNA that codes for proteins
• functional RNA( t/mRNA) : gene that don't code for polypeptides
• genome: complete set of genes in cell
• proteome: full range of proteins able to produce
• introns: non-coding regions of DNA

  exons: coding regions of DNA
• multiple repeat: short lengths of DNA that are repeated multiple times
• alleles: different forms of same gene

  different due to order of bases
• homologous pair: pair of matching chromosomes
• locus: alleles for same characteristic found at fixed point on chromosome
• tRNA: (transfer)

  • single coiled nucleotide strand
  • function in cytoplasm
  • carries amino acids to ribosomes
  • specific sequence, 3 bases at one end (anticodon)
• mRNA:(messenger)

  • single coiled nucleotide strand
  • function in cytoplasm/nucleus
  • carries genetic code to ribosomes
  • 3 adjacent bases - codons
• Eukaryotic DNA:

  • long and linear
  • DNA wound around histone
  • has introns
• Prokaryotic DNA:

  • shorter and circular
  • DNA isn't wound around histones
  • no introns
• Transcription: one gene on DNA is copied into mRNA

  DNA---> mRNA (transcription)

  mRNA---> polypeptide (translation)
• transcription:

  1. RNA polymerase unwinds DNA, breaks H bonds between base pairs
  2. free RNA nucleotides pair up with exposed bases, thymine replaced with uracil
  3. RNA polymerase joins sugar phosphate backbone in newly formed pre-mRNA
  4. pre-mRNA detaches from DNA
  5. mRNA splicing occurs
  6. mRNA leaves nucleus via nuclear pore
• Translation:

  • mRNA attaches to ribosome
  • tRNA anticodons bind to complementary mRNA codons
  • tRNA brings specific amino acid
  • amino acids join by peptide bonds using ATP
  • tRNA released after amino acid joined to polypeptide
  • ribosomes moves along mRNA strand to form polypeptide
• genetic code: sequence of codons in mRNA which code for specific amino acids
• genetic code = degenerate: more codons code for single amino acid
• AUG- start codon ( met a.a)

  UAC- complementary anticodon (tRNA)

  UAG- stop codon
• describe how a gene is a code for the production of a polypeptide do not include details about transcription or translation (3)

  consists of nucleotide sequence in triplets which determines order of amino acid in a sequence in the polypeptide
• name the fixed position occupied by a gene on a DNA molecule

  locus