Chapter 24: Part 3: Structure of chromosomes

Chromatin

eukaryotic DNA is package as … which is DNA and associated porteins

Condensed

during mitosis we have ____ chromatin

Amorphous or decondensed

during interphase we have _ chromatin

Heterochromatin

condensed, gene poor, replicates mid/late in cell cycle, repetitive DNA, area includes the telomeres and centromere

Euchromatin

decondensed, gene rich; replicates early in cell cycle, in the arms of the chromosome and is a unique sequence

Nucleosome

fundamental packaging unit for DNA In eukaryotic nucleus is the ….

Histone

the core of a nucleosome is unit is a ____

200 bp

about how many bp of DNA are wrapped around a histone

Oreo

found analogy to the structure of a histone used in class

Basic

histones (acid/base) are …

H1

this part of the histone binds the linker DNA between nucelosomes

Variants

histone _ carry out specific functions on chromosomes such as marking centromeres and playing a role in DNA repair

Amino

this terminal on histone tails are the basic end, they emerge from the core nucleosome structure

Histone code

post translational modifications generate a _

Epigenetics

defined as mitotic or meiotically heritable changes to gene function that do not involve changes in DNA sequence

Writers

enzymes that add post translational modifications to histones

Erasers

enzymes that remove post translational modifications to histones

Readers

proteins that detect and bind to post translational markers

Writers, erasers, readers

there are _ of the histone code

Chromatin immunoprecipitation (ChIP)

used to map the location of histone marks throughout the genome, through use an of antibody that recognizes a specific post translational modification

Micrococcal nuclease

used to decrease the chromatin into pieces, that will then be precipitated to find the chunks with an Ab tag, to extract that DNA and sequence regions with a specific histone mark (ChIP)

DNA sequence per million reads

SPMR stands for, and shows us that epigenetic histone marks are distributed differently across a gene

Territories

the eukaryotic interphase chromatin is arranged in chromosome _

Interchromatin compartment

part of the chromosome territories that is analogous to a highway

Heterochromatin

the chromatin arranged on the outer edge of the nucleus is likely …

Euchromatin

the chromatin arranged on the inner most part of the nucleus is likely…

Looped domains

chromosome territories are thought to be organized into __

Topologically associated domains

TAD structures in chromosome territories are…

lncRNA

able to bring DNA regions together in chromatin

Xist

marks the inactive X chromosome

Tsix

marks the active X chromosome

Barr Body

inactive X chromosome

Long noncoding RNA

X chromosome inactivation involves a _

Female

all calico cats are ___ (gender) because the coat color gene resides on the __ chromosome , and inactivation is a random event

Structural maintenance chromosomes (SMC)

proteins that maintain the structure and integrity of chromosomes following DNA replication

5

SMCs consist of __ distinct domains

2 heads, hinge, 2 alpha helices

5 domains of SMCs

Cohesions

link sister chromatids together after replication and keep them together as the chromosomes condense at metaphase (SMC of eukaryotic cells)

Condensins

essential for chromosomal condensation as cells enter mitosis (SMC of eukaryotic cells)

Dimers

bacterial SMC proteins form ____ that have been overserved by electron microscopy

Condensins

models have proposed the role of _ in chromatin condenstation is to stabilize the loops by binding at the base (wrapping around DNA)

S through metaphase

when are cohesins encircling the DNA (cell cycle steps)

Prophase through end of G1

when are condensins on the DNA (cell cycle steps)

Separase

what enzyme cleaves and releases cohesin SMCs from the DNA after metaphase

Boundary complexes

generate loops that wrap e coli chromosome around small basic histone like proteins