Chapter 33: Nucleic Acids Flashcards
What is the first level of DNA packaging?
Wrapping of DNA around histones to create a nucleosome structure
What is the second level of DNA packaging?
“Beads on a string” form of chromatin
Beads = nucleosomes
String= linker DNA
_____ are the major proteins of chromatin
Histones
What are the five different histones of most eukaryotic species?
H1, H2A, H2B, H3, & H4
Histones are small basic proteins with many _____ and _____ residues
Lysine and arginine
Histones are ____ charged particles
Positively
DNA is _____ charged
Negatively
+ charge of Histone allows interaction with - charged ___
DNA
What histones make up a histone octamer?
2 each of H2A, H2B, H3, & H4
What does DNA wrap around to form a nucleosome?
Histone octamer
Histone modifications can lead to…
Gene activation or gene repression
Study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than alterations to the DNA sequence is ____
Epigenetics
Histone tails are important in
Epigenetic regulation
Epigenetic “marks” tell your genes to
switch on/off & to speak loud/soft
What does “beads on a string” consist of?
Nucleosomes connected by linker DNA
Chromatosomes are part of the ___ level
Second
What is a chromatosome?
Nucleosome (DNA wrapped around histone octamer) with one bound linker histone (H1)