Cto - Nucleus

Front 1

What is the typical diameter of a nucleus?

Back 1

5-10 microns

Front 2

do nuclei stain acidophilic or basophilic with an H&E stain?

Back 2

basophilic

Front 3

which, euchromatin or heterochromatin, shows DNA that is actively being transcribed?

Back 3

euchromatin

Front 4

why is heterochromatin darkly stained?

Back 4

the DNA is condensed because it is not being actively transcribed.

Front 5

levels of what can give you clues about the activity level of the nucleus, and hence, the cell at large?

Back 5

euchromatin and heterochromatin

Front 6

Do the nucleoli stain basophilic or acidophilic in an H&E stain?

Back 6

basophilic (blue/purple)

Front 7

what two processes occur in the nucleoli?

Back 7

1) rRNA synthesis and 2) ribosomal subunit assembly

Front 8

How many membranes envelop the nucleus of the cell? What other organelle also has this number of membranes?

Back 8

2 membranes; mitochondrion

Front 9

what is the name of the space between the outer and inner membranes in a nucleus?

Back 9

perinuclear cisterna

Front 10

the outer nuclear membrane is continuous with which organelle in the cell?

Back 10

rough endoplasmic reticulum

Front 11

the perinuclear cisterna is continuous with which part of the extranuclear cell?

Back 11

the lumen of the RER.

Front 12

True or False, the outer nuclear membrane could be studded with ribosomes?

Back 12

True

Front 13

What is the name for the channels present in the nuclear envelope?

Back 13

Nuclear pores

Front 14

how many histones compose a nuclosome?

Back 14

8 (2 of each of 4 types of histones)

Front 15

what are the names for the histones that participate in the organization of DNA into nucleosomes?

Back 15

H2a, H2b, H3, H4

Front 16

which proteins are involved in assembling the nucleosomes into larger 30nm units? What is the name for these units?

Back 16

H1 histones and other acidic proteins; solenoid fibers

Front 17

what are the main components of the nucleoskeleton

Back 17

histones, acidic proteins, and other structures which help to organize the chromatin (DNA) into supercoils.

Front 18

what is the width measurement of a nucleosome

Back 18

11nm

Front 19

which structure supports the nucleur envelope on its internal surface?

Back 19

nuclear fibrous lamina

Front 20

nuclear lamins are found where and are composed of which type of cytoskeleton?

Back 20

on the inner surface of the nuclear envelope; intermediate filaments

Front 21

what are the name of 3 lamins found in the fibrous lamina in the nucleus?

Back 21

Lamins A, B, and C

Front 22

in which 3 activities are lamins A, B, and C involved?

Back 22

1) attachment of chromatin to the nuclear envelope, 2)structural integrity of the envelope, and 3)envelope reassembly following nuclear envelope breakdown during mitosis.

Front 23

breakdown of the nuclear envelope in mitosis is triggered by the phosphorylation of which nuclear proteins?

Back 23

lamins

Front 24

dephosphorylation of nuclear lamins has what effect on the integrity of the nucleus

Back 24

it triggers reassembly of the nuclear envelope

Front 25

the nuclear pore complexes (NPC) are composed of approximately how many proteins

Back 25

approximately 100 proteins

Front 26

what is the name for the proteins which make up the nuclear pore complex (NPC) and make a channel for transport of material into and out of the nucleus?

Back 26

nucleoporins

Front 27

how are small molecules (i.e. <40kD) granted entry to the nucleus?

Back 27

they diffuse freely

Front 28

what two important factors are key in getting large material into the nucleus, through the pores?

Back 28

1) import and export signals and 2) chaperons molecules

Front 29

what is an NLS (nuclear localization signal)?

Back 29

a peptide signal on a protein that signals the nucleus as the protein's destination

Front 30

which specific class of proteins are important in recognizing the NLS and facilitation entry into the nucleus for large material? These proteins are part of which larger class of proteins?

Back 30

Importins; Chaperons proteins

Front 31

Importins interact with which two things?

Back 31

the NLS on the protein entering the cell and the pore fibrils.

Front 32

True or false, the nucleolus has a single membrane while the nucleus envelope is composed of 2 membrane layers.

Back 32

False. The nucleolus has no mebrane.

Front 33

what is the NOR? which organelle does it compose?

Back 33

Nuclear organizing regions; nucleolus.

Front 34

how many chromosomes contain rDNA?

Back 34

10

Front 35

True or False: Red Blood Cells have large nuclei.

Back 35

False. They are anucleate.

Front 36

when looking at tumorous cells versus normal, healthy cells, what is an important ratio to consider

Back 36

nucleus:cytoplasm. Should be less nucleus than cytoplasm, on average.

Front 37

in which area can you normally find constitutive heterochromatin?

Back 37

along the inner nuclear membrane (next to fibrous lamina)

Front 38

which stains lighter: euchromatin or heterochromatin?

Back 38

euchromatin

Front 39

what are the two classes of heterochromatin?

Back 39

constitutive and facultative

Front 40

which type of heterochomatin is always condensed and very rarely transcribed?

Back 40

constitutive

Front 41

Does an abundance of euchromatin mean a cell is very active or dormant?

Back 41

active

Front 42

what is the name for the DNA in between nucleosomes?

Back 42

linker DNA

Front 43

protein scaffolding around which chromatids are wound is composed of what kind of proteins

Back 43

acidic proteins

Front 44

Fill in the Blank: As DNA condensation increases, transcriptional activity ______.

Back 44

decreases.

Front 45

while the rRNA is transcribed in the nucleolus, where is this rRNA combined with proteins to form ribosomal subunits?

Back 45

in the nucleolus, too.

Front 46

If a cell has large or multiple nucleoli, what does that say about the cell?

Back 46

the cell is very active

Front 47

what is contained in the fibrillar center of the nucleolus?

Back 47

rDNA not being transcribed

Front 48

what is contained in the dense fibrillar zone?

Back 48

rDNA being transcribed

Front 49

What occurs in the granular zone of the nucleolus?

Back 49

ribosome subunits are processed and packaged