Molec Cell Ch 5 - Genome Orgnaization

Humans have a total of __ chromosomes, organized as __ pairs.

46, 23.

This represents about 2 meters of DNA.

Eukaryotic chromosomes are linear and contain thousands of genes.

True

______ can be used to observe chromosomal abnormalities in individuals.

Karyotypes

________ associate chromosomal aberrations with phenotypic anomalies

Cytogeneticists

Most eukaryotic genes contain introns.

true

Closely related species can have different chromosomal numbers.

True

important regions of eukaryotic chromosomes:

Centromere, telomere, replication origins.

_______ is the point of junction between sister chromosomes.

Centromere

_________ are the stable ends of linear chromosomes.

Telomeres

________ are sequences where DNA replication begins.

Replication origins

Mitotic chromosomes are extremely condensed (and duplicated)

Interphase chromosomes are less condensed (and unduplicated). They maintain their own location within the nucleus.

The nucleus is the site where rRNA genes (rDNA) are being transcribed into rRNA. rRNA is located on 10 chromosomes.

_________ are the basic units of eukaryotic chromosome structure.

Histones

An ______ of histones organizes to produce a _______, around which 147bp of DNA wraps

Octomer; nucleosome

Linker histone _____ binds DNA that is exiting the nucleosome and allows tighter packing.

H1

Nucleosome are organized into loops by ________.

SMC complexes.

Loops are associated with gene regulation and sequence specific ________.

Clamp proteins

Clamp proteins are associated with certain cell types/developmental stages.

True

Mitotic chromosomes undergoes about 10-fold more condensation.

True

Cohesins are replaced with different SMC ring proteins-___________

Condensin I and Condensin II

There are levels of DNA compaction.

What is the function of each chromosomal structural element?

Centromere, Telomere, and Ori:

Access to different regions of DNA is dynamic and must be regulated. ATP-dependent chromatin remodeling complexes use ATP to move histones.

True

_____ can be modified. The H3-N-terminal domain is most documented.

Histones

Histones organization produces regions of _________ and regions of _________ along chromosomes.

heterochromatin ; euchromatin

________ is always heterochromatic, centromeres and telomeres.

Constitutive heterochromatin

__________ is related to the differentiation state of the cell-varies by chromosome, cell types, developmental state.

Facultative heterochromatin

________ is actively being transcribed.

Active euchromatin

________ is available for transcription.

Quiescent euchromatin

_________ modifications are recognized by heterochromatin specific proteins. _________ proteins and associated ________ proteins put the mark on adjacent histones.

Histone ; reader ; writer

____________ ___________ results in gene silencing of a whole chromosome through heterochromatin formation.

X-chromosome inactivation (its random nature produces the calico cat fur pattern).

Histone modifications are passed down during DNA replication and about 1/2 of the old, marked histones will be distributed to each daughter strand.

True (example of epigenetic inheritance)

How does the composition of a nucleosome correlate with its function?

What mechanisms are used to remodel chromatin structure?

What is the effect of chromatin remodeling on the function of the cell?

How are genes organized on chromosomes?