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Nucleoproteins and Chromatin Organization: From Nucleosomes to Histone Modifications, Quizzes of Molecular biology

Definitions and terms related to nucleoproteins, chromatin organization, and histone modifications. Topics include the role of nucleoproteins in dna packaging, chromatin fiber organization, histone composition, and modifications such as acetylation, methylation, and phosphorylation.

Typology: Quizzes

2010/2011

Uploaded on 10/09/2011

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TERM 1
BIOL 308 Lecture 7 What is a nucleoprotein?
DEFINITION 1
Specific protein that assists in the wrapping and tight
packaging of linear DNA molecules
TERM 2
Long thin strands of nucleoprotein -->
chromatin -->
DEFINITION 2
Get organized into chromatin fibers which are further
condensed and called CHROMOSOMES!
TERM 3
How is chromatin organized? What is the
fundamental unit of organization?
DEFINITION 3
-Chromatin is organized like beads on a string-nucleosome
TERM 4
What does each nucleoside contain?
DEFINITION 4
-octet of histones which is wrapped by DNA
TERM 5
Two important aspects of chromatin
organization?
DEFINITION 5
HISTONES package DNATopoisomerase aid in chromatin
organization b/c it is important for supercoiing
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BIOL 308 Lecture 7 What is a nucleoprotein?

Specific protein that assists in the wrapping and tight packaging of linear DNA molecules TERM 2

Long thin strands of nucleoprotein -->

chromatin -->

DEFINITION 2 Get organized into chromatin fibers which are further condensed and called CHROMOSOMES! TERM 3

How is chromatin organized? What is the

fundamental unit of organization?

DEFINITION 3 -Chromatin is organized like beads on a string-nucleosome TERM 4

What does each nucleoside contain?

DEFINITION 4 -octet of histones which is wrapped by DNA TERM 5

Two important aspects of chromatin

organization?

DEFINITION 5 HISTONES package DNATopoisomerase aid in chromatin organization b/c it is important for supercoiing

What do loops of chromatin fibers attach

to?

Scaffold proteins --> frames around which things are built TERM 7

More organization

DEFINITION 7 10 nm nucleosome fiber condenses into 30 nm diameter fiber who is in it's predominant form at the interphase nucleus TERM 8

Euchromatin vs. Heterochromatin

DEFINITION 8 Euchromatin consists of transcriptionally active DNA (susceptible to DNAse activity)Heterochromatin consists of transcriptionally inactive DNA that is less susceptible to DNase TERM 9

What is constitutive heterochromatin? Where

is it found?

DEFINITION 9 -highly condensed inactive chromatin consisting if highly repeating DNA sequences-found in centromeres and telomeres TERM 10

What is facultative

heterochromatin?

DEFINITION 10 -not active in any particular tissues-forms under specific circumstances to silence gene expression

T/F: Histone proteins are highly conserved

(same in nearly all organisms)

TRUE - they are vital! TERM 17

Reformation of Nucleosomes

DEFINITION 17 -reformation necessary because DNA replication involves disassembly of nucleosomes-newly replicated DNA immediately packaged, first bind H3 + H4 tetramers, then H2A + H2B dimers and finally H1 is last. TERM 18

What are chaperone proteins? What do they

do?

DEFINITION 18 -negatively charged proteins that assist in histone assembly- they are negatively charged because histones themselves are positively charged (due to several +ve lysines) TERM 19

What is the function of the N-terminal tails of

Histone?

DEFINITION 19 -direct DNA wrapping --> necessary for the formation and stabilization of the 30 nm fiber TERM 20

Mod. of chromatin is necessary for replication

to start. What are the three mods?

DEFINITION 20

  1. Acetylation of lysine in histone tail --> associated with active gene expression (acetylated form is negative)2)Methylation of histone tail --> associated with active/inactive expression3) Phosphorylation (serine) --> generally associated with active geneModificaitons neutralize parts of the tail

What does acetylation of lysine and

phosphorylation due to the protein?

Reduces the overall positive charge of the protein TERM 22

In the DNase test, what happens if a signal is

produced? What if there is no signal?

DEFINITION 22 Signal - no gene expressionNo signal - gene expression in progress, DNA free of histones for digestion with DNase