Chapter 10 Flashcards
What happens in the 1st level of organization of DNA packaging in to chromatin?
forms 10nm fiber involving nucleosomes
What happens in the 2nd level of organization of DNA packaging in to chromatin?
superhelical coiling of nucleosomes to generate a 30nm fiber
What happens in the 3rd level of organization of DNA packaging in to chromatin?
looping the 30nm fiber to generate a 300nm fiber involving interphase matrix proteins
What happens in the 4th level of organization of DNA packaging in to chromatin?
chromosome condensed and form 700nm per sister chromatid
What happens in the 5th level of organization of DNA packaging in to chromatin?
forms 1400nm for entire metaphase chromosome
Where is chromatin?
spread out in nucleus
What chromatin occupies most of the nucleus?
euchromatin
Which chromatin is more densely packed?
heterochromatin
Heterochromatin is similar to what?
chromosome at mitosis densely packed
Where is heterochromatin found at?
centromeres
What does heterochromatin form?
forms discrete clumps and aggregate into a chromocenter
Constitutive heterochromatin?
region that are always heterochromatic
What does constitutive heterochromatin contain?
multiple copies of non-transcribed repeats
How many and what kind of genes do constitutive heterochromatin have?
few genes and inactivated genes
Facultative heterochromatin
euchromatin regions converted to a heterochromatic state
What are 3 events that are associated with causing the condensation of euchromatin to heterochromatin?
a. reduced acetylation of histone proteins
b. increased methylation of histone proteins
c. hypermethylation of cytosine bases in DNA
What is Giemsa stain used for?
for staining process to generate G-bands allowing each chromosome to be identified by its characteristic banding pattern
What has lower GC content and what has higher GC content?
bands have lower GC content and interbands have higher GC content
Genes tend to be concentrated in regions of?
higher GC content (interbands)
