GMan - Chapter 7

  1. Chromatin
    DNA and proteins of chromosomes
  2. When do chromosomes develop
    When chromatin condenses prior to division
  3. Chromosome morphology
    • p (short arm) - centromere- q (long arm)
    • Image Upload 1
  4. Four types of chromosome morphology
    • Metacentric (equal length p and q arms)
    • Submetacentric (Slightly longer arms)
    • Acrocentric (Much longer q arms)
    • Telocentric (Little-to-no p arm)
  5. Differences between Eukaryote and Bacterial chromosomes
    • Bacterial DNA is associated with less protein
    • Bacterial DNA is found in the Nucloid
    • Bacerial cells do not contain chromatin
  6. Function of chromatin
    • Strength
    • Packaging
    • Regulation
  7. Chromomeres
    Dark bands associated with differential compacting of DNA
  8. Polytene Chromosomes
    • Large
    • Multiple strands of DNA
    • Paired homologs
  9. Puff regions
    • Areas of uncoiled DNA
    • Associated with high expression/activity
  10. Hitsone composition
    • Basic/Positively charged
    • Lots of lys and arg residues
  11. Nucleosome
    • Beads of histones and DNA (Beads on a string)
    • Contain 8 histone proteins (Octamer)
    • DNA is wound around 1.7 times (Left handed)
  12. Proteins of the Histone octamer
    • H2A-H2B Dimers
    • H3-H4 Dimers
  13. Core particle
    • Histone octamer
    • 146 BP of DNA
  14. Chromatin fibre
    • A length of Nucleosomes
    • And intervening linkers ~ 54bp
  15. Histone H1
    • 50% as common as other histones
    • Links nucleosomes (30nm fibre)
  16. 300nm Fibre
    Series of looped domains of the 30nm fibre
  17. Heterochromatin
    • Tightly packed
    • Transcriptionally inactive
    • 700nm fibre
  18. Euchromatin
    • Looser packing
    • Active transcription
  19. Packing ration calculation
    Length of DNA/Length of fibre
  20. Constitutive heterochromatin
    Highly condensed simple repeats
  21. Facultative heterochromatin
    • Variably condensed
    • Includes heterochromatin and euchromatin
  22. Chromosome territories
    Regions occupied by decondensed chromosomes during interphase
  23. Average human gene density
    • 1 Gene per 100kb
    • Protein coding genes are only 1.5% of the DNA
  24. Perecentage of the human genome containing repeating sequences
    • 50%
    • Believed to be the result of transposons
  25. Three main categories of repetitive DNA
    • Satellite DNA - Centromeres
    • Tandem repeats - Telomeres
    • Interspersed elements - Transposons
  26. Image Upload 2
    Image Upload 3
  27. What does VNTR mean?
    • Variable number tandem repeats
    • Applies to mini- & micro- satellites
  28. S- and L- INES, meaning
    • Short Interspersed elements
    • Long Interspersed elements
  29. Interspersed repetitive elements
    • SINES and LINES
    • Dispersed throughout the genome (not tandem repeats)
    • 1/3 of human genome
    • Jumping genes/retrotransposons
  30. Three noncoding sequences required for replication
    • Centromere
    • Origin of replication
    • Centromere
  31. Centromeres
    • Attached to kinetochores
    • Mediate chromosomal migration
    • Composed of satellite DNA
  32. Telomere sequence
    TTAGGG
  33. Telomerase
    • Restores telomerase
    • Ribonucleoprotein
    • Reverse transcriptase activity
  34. Hayflick limit
    Number of replications before senescence
  35. How is gene diversity maximized
    Alternative splicing
Author
Ant
ID
327673
Card Set
GMan - Chapter 7
Description
GMan
Updated