Exam 2 Flashcards
What is mainly responsible for the attraction between histones and DNA?
Histones have a positive charge and DNA has a negative charge
What is the region of a chromosome where spindle fibers attach?
Centromere
What surrounds the centromere?
Heterochromatin
What is the physical role of centromeres?
Act as the site of assembly for kinetochore
What type of sequences make up euchromatin?
Unique
Is crossing over common in euchromatin or heterochromatin?
Euchromatin
Is DNA methylation high or low in euchromatin?
Low
What type of sequences make up heterochromatin?
Repeated
What is the double-stranded DNA in between two nucleosome cores that holds the cores of the histone together?
Linker DNA
When is heterochromatin replicated?
Late S phase
What are centromeres necessary for?
Chromosome seperation
Briefly describe the structure of a nucleosome.
Segment of DNA wound around eight core histone proteins
Is transcription more frequent in euchromatin or heterochromatin?
Euchromatin
Is DNA methylation high or low in heterochromatin?
High
What is the function of a telomere?
Protects the end of chromosomes from deterioration and from fusion with neighboring chromosomes
What is the multiprotein structure responsible for the events during chromosome seperation?
Kinetochore
What health relevance do shortened telomeres have?
Shorter life span and an increased incidence of disease
Where is Euchromatin located?
On chromosome arms
What does DNase I sensitivity correlate with?
Gene activity
What histone modification is commonly occuring in heterochromatin?
Hypoacetylation
What is a small cylindrical cell organelle, located near the nucleus in the cytoplasm of most eukaryotic cells, that divides in perpendicular fashion during mitosis?
Centriole
What histone modification is commonly occuring in euchromatin?
Hyperacetylation
Where is heterochromatin located?
At centromeres, telomeres, and other specific places
What is the basic unit of DNA packaging in eukaryotes?
Nucleosome
