Chromatin Structure Part 2 Flashcards

1
Q

In a “normal” nucleosome

A
  • DNA coils around the histone octomer in a left handed coil

- and negatively supercoiled (right handed supercoils)

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2
Q

nucleosome core

A
  • histone octomer
  • 146 bp DNA
  • 1 3/4 turns
  • results from a limit digest of chromatin by micrococcal nuclease
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3
Q

complete nucleosome

A
  • contains 146 bp DNA + octomer (nucleosome core)
  • spacer of ~54 bp DNA
  • room enough for H1 histone to bind
  • definition does not include H1
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4
Q

linker DNA

A
  • variable

- holds cores together

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5
Q

linker histones

A

facilitates folding of 10 nm fiber (beads on a string) into 30 nm fiber

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6
Q

chromatin containing H1

A
  • nucleosomes with regular zigzag orientation
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7
Q

no H1

A
  • beads on a string
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8
Q

nucleosome ladders

A
  • microccal nuclease-generated nucleosome ladder of chromatin
  • if chromatin was uniform you would get a smear of DNA
  • provided evidence for particulate structure of chromatin.
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9
Q

transgenic marker genes

A
  • used to determine if piece of DNA has been successfully inserted into the genome of the host organism
  • gene from one organism put into another
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10
Q

selective markers

A
  • genes that protect the transformed organism or cell from a selective agent (usually an antibiotic)
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11
Q

screenable markers

A
  • genes that give transformed cells an identifiable characteristic to distinguish them from untransformed cell
  • do not confer resistance to a selective agent
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12
Q

example of screenable markers

A
  • GFP - fluoresces green when excited by UV light
  • luciferase - enzyme that converts energy of ATP into light
  • B-gal - convert colorless substrates into colored compounds that can be easily observed
  • can be used as reporter genes
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13
Q

reporter genes

A
  • usually attached to regulatory sequences of another gene of interest to test the effects of the regulatory sequences
  • products are readily quantifiable
  • measure genes activity level
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