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Histology Exam I > Cell Nucleus > Flashcards

Cell Nucleus Flashcards

1
Q

What are the three major components of the nucleus

A

Nuclear Envelope, Nucleolus, and chromatin

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2
Q

Describe nuclear envelope

A

two membrane system (inner an outer, differ in structure and fxn) perforated by nuclear pores that separates the nucleoplasm from the cytoplasm

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3
Q

What processes are taken place in the nucleolus?

A

site of rRNA synthesis and regulation of the cell cycle

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4
Q

Contents of chromatin

A

nuclear material containing DNA and various nuclear proteins

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5
Q

What is the nucleoplasm

A

nuclear content (not chromatin) and nucleolus

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6
Q

What separates the inner and outer membrane of the nuclear envelope?

A

the perinuclear cisternal space, which is continuous with the cisternal space of RER

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7
Q

Describe Outer nuclear membrane

A

continuous with rER and contains ribosomal docking proteins for polyribosomes

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8
Q

Describe Inner nuclear membrane

A

supported by nuclear lamina and contains lamin receptors and lamin-associated proteins that secure its attachment to nuclear lamina

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9
Q

What is the nuclear lamina?

A

rigid network that of intermediate protein filaments that supports inner membrane of nuclear envelope…scaffolding of chromatin, membrane of nucelar envelope and spacing of nuclear pore complex… essential for DNA replication and transcription

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10
Q

What is the nuclear lamina composed of?

A

mainly lamin A/C proteins, attached to inner membrane through lamin B protein

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11
Q

What do lamin A/C proteins form?

A

form intermediate filaments that are crossed linked into an orthganal lattice

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12
Q

How does lamin B attach lamin A/C proteins to membrane?

A

through interactions with lamin receptors in inner membrane

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13
Q

What are the lamin receptors in inner membrane and what do they bind?

A

nurim (binds lamin A), emerin (binds lamin A and B), and lamin B receptor (binds lamin B)

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14
Q

What are laminopathies and what regions of the body are affacted?

A

tissue specific diseases that affect striated muscle, nerve or skeletal development and premature aging caused by mutations in lamin and their receptors

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15
Q

EDMD (muscular dystrophy)

A

laminopathy characterized by muscle weakness and wasting in the upper and lower limbs and cardiomyopathy

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16
Q

X-linked EDMD

A

caused by mutations in emerin

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17
Q

AD EDMD

A

caused by mutations in lamin A/C proteins

18
Q

How is the nuclear envelope formed?

A

from the merging of the inner and outer cell membrane

19
Q

NPC composition

A

eight multidomain protein subunits arranged in a central framework insterted between a cytoplasmic ring and a nucleoplasmic ring, attached to a terminal ring.

20
Q

Cryoelectron Tomography CET

A

version of electronmicroscopy where 3D images are crated from 2D ones

21
Q

How does the central pore of the NPC behave?

A

as a gated channel or bidirectional communication gate

22
Q

How are large particles imported to nucleus?

A

Contain NLS (nuclear localization AA seq) that binds to importin receptors in a GTP-dependent fashion controlled by RAN signalling

23
Q

ow are large particles exported from nucleus?

A

proteins with NES seq bind to exportin and to RAN-GTP molecule

24
Q

Nucleosomes

A

smallest unit of chromatin and first level of folding… dna coiling (2 loops) around protein core of 8 histones (h1-h4)

25
Q

DNA packaging seq

A

Nucleosome-chromatin fibrils-chromosome scaffold- chromosome

26
Q

What are the three locations where heterochromatin is in the nucleus? (names)

A

marginal chromatin, karyosomes, and nucleolar associated chromatin

27
Q

Karyosomes

A

discrete bodies of chromatin irregular in size and shpe that are found throughout nucleus

28
Q

Does the nucleolus have a membrane?

A

no

29
Q

Nucleolin and Nucleostemin

A

shuttling proteins in nucleolus that relocalized to nucleoplasm for non-nucleolar fxns

30
Q

What are the three distinct regions of the nucleolus?

A

Fiblrillar centers, fibrillar material, and granular material

31
Q

Fibrillar centers

A

corresponding to
chromatin containing repeated rRNA
genes and presence of RNA
polymerase I.

32
Q

Fibrillar material

A

where nascent rRNA is present and
undergoing some processing. Site of
nucleolin.

33
Q

Granular Material

A

site of initial ribosomal
assembly and contains densely
packed pre-ribosomal particles. Site
of nucleostemin.

34
Q

Nucleolonema

A

network formed by granular and fibrillar material

35
Q

Pyknosis

A

condensation of chromatin leading to shrinkage of the nuclei (dense basophilic masses).

36
Q

Karryorrhexis

A

fragmentation of nuclei (usually are proceeded by

pyknosis).

37
Q

Karyolysis

A

disappearance of nuclei proteins due to complete dissolution of DNA (increased DNAase).

38
Q

Human Karyotype is a spread of what stage of mitosis?

A

metaphase

39
Q

aneuploidy

A

abnormal number of chromosomes

40
Q

Kleinfelter’s Syndrome

A

male phenotype and no secondary sex characteristics (XXY)

41
Q

Turner’s Syndrome

A

(XO) females do not develop ovaries

42
Q

What is FISH technique used for?

A

evaluation and diagnosis o genetic disorders

Histology Exam I (6 decks)

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