ch 4 molec nbio

  1. heterochromatin
    dark regions of DNA that are dense so don't have much transcription
  2. euchromatin
    lighter less dense regions of DNA that has greater transcription rate
  3. centromeres
    • spot on chromosomes where spindle fibers attach to
    • has kinetechores that act as attachment site for spindles
  4. telomeres
    • present in euks only
    • ends of linear DNA that don't code for anything
    • prevent chromosome deterioration and fusion w neighbouring chroms
    • telomerase can add more telomeres to the ends
    • can be used for age of the chromosome becuase it gets shorter after each replication until it can't get any smaller
  5. single nucleotide polymorphisms
    • the human genome is relatively the same bu every 1000 bases there will be different base there 
    • occurs in non-coding regions mostly and are essentially mutations
  6. copy number variation
    • variations in the number of times a specific dna sequence is repeated
    • they can be dublicated, deleted
    • numbers vary in individuals
  7. tandem repeats
    • short sequence of bases that're repeated x many times one after the other
    • type of copy#var
  8. enzymes involved with replication
    • helicase: uses ATP to break the H-bonds holding strands tgth
    • topoisomerase: relieves the tension in the strand created by helicase
    • single stranded binding proteins: bind to seperated strands so they don't reanneal
    • RNA primase: lays down RNA bases (RNA primers) to existing strand
    • DNA polymerase 3: uses ATP to add DNA bases starting from RNA primers. has exonuclease activity to proof-read
    • DNA polym 1: exonuclease activity. replaces RNA primers with DNA bases
    • ligase: creates phosphodiester bond, linking bases tgth

    okazaki fragments: segments of DNA created on lagging strand of DNA (the one that goes 3'-5')
  9. missense mutation
    • 1 aa replaced by another
    • not that serious if aa are similar (ie. both polar)
    • point mutation
  10. nonsense mutation
    • stop codon replaces regular codon
    • point mutation
  11. silent codon
    • codon changed with a new codon that codes for same aa
    • point mutation
  12. frameshift mutation
    causes a change in reading frame
  13. types of mutations
    • insertion/deletion: adding or taking out 1+nucleotides
    • inversions: whole segment is reversed from end-to-end
    • amplification: segment of chrom. is duplicated
    • translocation: recombination btwn non-hom. chromosomes
  14. transposon
    segment of dna that can move to other locations in the genome
  15. transposon structural elements
    • IS element: always present. Contains transposon gene in btwn inverted sequences on each end
    • composite: 2 similar or identical IS elements on either side of a central region
    • complex: transposon has additional genes
  16. transposase
    enzyme that transposon gene codes for that allows it to move to different locations
  17. loss of heterozygosity
    when one copy of a gene is deleted and the other is mutated
  18. Direct reversal
    • dna repair 
    • dna is directly repaired by photoreactivation if damage was caused by UV
  19. homology-dependent repair
    • info on one strand repaired by using the info on another
    • uses the seq on the other strand and replicates on it and then reattaches to its own strand
    • dna repair
  20. excision repair
    remove and replace defective bases
  21. post-replication repair
    mismatch repair pathway targets and replaces mismatched bases
  22. homologus recombination
    • -ds break repair
    • break is found and trimmed to make 2 ss DNA strands and then once they find the genome that compliments their strand then the DNA crosses over and DNA pol & ligase work to create new strand
  23. nonhomologus end joining
    • ds break repair
    • broken ends processed and stabilized then joined tgth
  24. core enzyme
    portion of the holoenzyme that does the transcription and has the binding site
  25. sigma factor
    part of holoenzyme that locates the promoter and orients enzyme appropriately
  26. shine-dalgarno seq
    prok mrna is polycis so these are what ribo binds to to transl. the diff proteins
  27. kozak sequence
    • present in euks
    • precedes start codon
  28. repressible enzyme
    anabolic enzyme that's inhibited by xs amount of product
  29. inducible enzyme
    catabolic enzyme that's activated by xs substrate
  30. transcription factors
    have DNA binding domain to regulate trancription of that gene when activated
Card Set
ch 4 molec nbio
ch 4 mcat