Organization of Nuclear Envelope + Contents

Question 1

Nuclear envelope consists of two double PL bilayers, what are these attached to?

Answer 1

Outer- continuous with the ER

outer- associated with nuclear lamina, chromatin and ribonucleoproteins (histones, etc)

Question 2

The inner membrane is associated with

Answer 2

chromatin, nuclear lamina, and ribonucleoproteins

Question 3

the nuclear lamina has ____ kinds of ____ filaments

Answer 3

3, intermediate

Question 4

During mitosis or meiosis, nuclear lamins are

Answer 4

phosphorylated, and dissolves

Question 5

After cell division the lamina is

Answer 5

dephosphorylated, reforms

Question 6

Hutchinson-Gilford progeria

Answer 6

nuclear lamina disease

Question 7

Nuclear lamin genes are

Answer 7

a, b, and c

Question 8

nuclear lamin genes code for

Answer 8

at least seven proteins

Question 9

Lamin proteins do what?

Answer 9

interact to form dimers

Question 10

Lamin proteins consist of

Answer 10

alpha helical regions of two chains that interact to form a coil

Question 11

Interphase: the mechanics

Answer 11

organized into functional domains
chromosomes each occupy a discrete region of the nucleus
regions are closely associated with nuclear membranes via lamins
gene transcription occurs on periphery of these domains
RNA processing and transport are thought to occur in spaces (channels) referred to as itnerchromosomal domains that separate the domains

Question 12

Replication factories are

Answer 12

distinct functional bodies where replication appears to take place

Question 13

nuclear speckles

Answer 13

concentrate mRNA splicing machinery

Question 14

PML bodies

Answer 14

sites of accumulation factors and chromatin modifying proteins, but function unknown

Question 15

source of PML body’s name

Answer 15

transcription factors involved in acute “promyelocytic leukemia”

Question 16

cajal bodies

Answer 16

contain the protein coilin

may be sites of ribonucleoprotein assembly and processing

Question 17

Karyopherins: kinds and function

Answer 17

these are import/export proteins involved in translocating proteins into the nucleus

consist of alpha and beta

involved with RAN molecule

Question 18

Exportins are

Answer 18

karyopherins, involved with RAN

Question 19

RAN is necessary for both

Answer 19

nuclear import/export

Question 20

Directionality of transport is determined by

Answer 20

unequal concentrations of RAN/GTP in the nucleus

Question 21

Req. for a functional chromosome

Answer 21

telomeric seq at end; centromeric seql replication and initiation sequence

Question 22

the nucleolus is

Answer 22

not an organelle but a region

Question 23

a given nucleus may have several (one word, plural)

Answer 23

nucleoluses

Question 24

Regions of the Nucleolus (3)

Answer 24

Fibrillar center (made of tightly coiled, non-transcribed chromatin)

Dense fibrils (consist of ribonuceloproteins (RNPs): SITE OF ACTIVE TRANSCRIPTION OF RNA

Granulues: contains maturing ribosomal units, precursors of RNPS

Question 25

Nucleolus may not be an organelle, but it’s a region within the nucleus where ________ is transcribed. Chromatin from at least 10 chromosomes in the human genome contributes to

Answer 25

rRNA; the formation of the nucleolus

Question 26

rRNA

Answer 26

Synthesized by 100+ RNA polymerases I molecules

Each RNA polymerase I synthesizes one rRNA fibril

rRNA precursor: 45S
Oriented perpendicularly to chromatin axis
Cleaved into 28s, 18s, 5.8s rRNAs

Question 27

small rRNA consists of

Answer 27

18S rRNA +proteins (40S)

Question 28

Large ribosomal subunit

Answer 28

28S+5.8S+(5S rRNA) + proteins (60S)