Cell Bio- Nucleus

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syncytium

Back 1

secondary union of originally separate cells and the precursors are nonfunctional

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perinuclear cisterna

Back 2

space that separates inner and outer nuclear membrane

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nuclear lamina

Back 3

layer made of IF (lamin) that separates the nuclear envelope from regions of peripheral heterochromatin

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snRNPs- small nuclear ribonucleoprotein particles

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proteins that assist in splicing to produce mRNA

Front 5

Fibrillar region

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nucleolar region made of ribosomal DNA that codes for the production of rRNA that is actively being transcribed

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Granular region

Back 6

nucleolar region made of maturing preribosomal subunit particles

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Nucleolar-orgainizing regions

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parts of chromosomes 13, 14, 15, 21,and 22 gene loci that encode rRNA and are located in the Nucleolus

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heterochromatin

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highly condensed, transcriptionally inactive chromatin

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euchromatin

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extended, dispersed transcriptionally active chromatin

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constituitive heterochromatin

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heterochromatin that is never uncoiled

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facultative heterochromatin

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packed chromatin that contains coding sequences and may or man not be unfolded

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barr body

Back 12

type of facultative heterochromatin that is never uncoiled

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generation time

Back 13

time of one cell cycle and dependent mainly on the G1

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G1

Back 14

phase of cell cycle of synthesis of proteins and specialized functions of the cell

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S

Back 15

phase of cell cycle when DNA is duplicated and histones are produced

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G2

Back 16

phase of cell cycle when the cell is prepared for mitosis

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G0

Back 17

phase of cells that have left the cell cycle, called end cells

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stem cells

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cells of same type that haven't become sufficiently specialized and can undergo mitosis and continue to cycle.

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progenitor cells

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cells that can proliferate but usually lose capacity for self renewal and become committed to produce a single type of end cell

Hint 19

None

Front 20

Cyclin-dependent kinases

Back 20

proteins that for a complex with cyclins and then phosphorylate other proteins to initiate or block activities crucial to progress through cell cycle

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p53

Back 21

tumor suppressor protein that is a Cdk inhibitor and is absent in many cancers

Front 22

D-type Cyclins

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cyclins needed at the G1 checkpoint to activate Cdk 4 and 6 and allow cells to progress to the S phase

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MPF- M phase promoting factor

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a cyclin B-Cdc 2 complex with kinase activity that is the command to enter mitosis that accumulates in G2 at the checkpoint

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kinetochore

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protein structure that links centromere of chromosomes to spindle microtubules during mitosis

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telomerase

Back 25

enzyme that elongates existing telomere making cells 'immortal'. Only activated in cancer

Front 26

satellites

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DNA attached to short arms of chormosomes 13, 14, 15, 21 and 22 bye secondary constriction and contains rRNA genes. These fuse to form the nucleolus after mitosis

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apoptosis

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active form of cell death initiated by the cell. Programmed elimination of the cell

Front 28

caspases

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enzymes which degrade regulatory and structural proteins in nucleus and cytoplasm.

Front 29

What is they cytosolic side of the nucleus surrounded by?

Back 29

a thin loose network of IF and ribosomes actively synthesizing transmembrane proteins for the envelope

Front 30

what provides the structural framework to facilitate and organize the complex events of RNA and DNA synthesis and processing?

Back 30

nuclear matrix- including the nuclear lamina and steroid receptor binding sites

Front 31

What is the amount of protein synthesized in a cell related to?

Back 31

the size of the nucleolus

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What is the nucleolus composed of?

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Fibrillar regions, fibrillar centers, granular regions and nucleolar matrix

Front 33

what are the three forms (locations) of heterochromatin?

Back 33

peripheral, nucleolar associated, and chromatin islands

Front 34

2 types of heterochromatin

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constituitive or faculatative

Front 35

2 examples of constituitive heterochromatin?

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centromeric and satellite DNA

Front 36

3 phases of interphase

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G1, S, G2

Front 37

What is the maximum number of times an average cell divides

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50-60

Front 38

what are the two fates of daughter cells of stem cell division?

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remain stem cells and not differentiate more than parent, or become progenitor cells

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3 types of stem cells

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multipotential, pluripotential, or unipotential

Front 40

5 environmental regulators of cell division

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1)nutrients; 2) conact with neighboring cells 3)contact with ECM 4) hormones 5) growth factors

Front 41

how do growth factors regulate cell proliferation?

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through intracellular signalling cascades which ultimately regulate gene transcription and assemble and activation of the cell cycle control system

Front 42

What has a constant concentration throughout the cell cycle, and what has variable concentrations?

Back 42

cyclins go up and down through the cell cycle but Cdk has a constant concentration

Front 43

What are the two cell cycle checkpoints?

Back 43

G1 and G2

Front 44

What are cell cycle checkpoints dependent on?

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sufficient cdk-cyclin complexes to overcome inihibitions and proceed

Front 45

What phosphorylates the Rb gene product?

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D-Cdk complexes

Front 46

Which is the activated form of Rb? what does it do?

Back 46

unphosphorylated form and it inhibits transition for G1 --> S

Front 47

What signals excessive damage to genetic material and halts the cell cycle in G1?

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sufficient concentration of p53

Front 48

Which is the most regulated cell cycle phase?

Back 48

G1. G1 checkpoint very specific

Front 49

What is MPF inhibited by?

Back 49

incompletely replicated DNA

Front 50

what does MPF induce?

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chomosomes to condense, nuclear envelope to break, cells to round up, reorganization of cytoskeleton

Front 51

What signals chromosomes to condense

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phosphorylation of histone 1 by MPF

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what signals the nuclear envelope to break

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phosphorylation of lamin by MPF

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what signals the reorganization of the cytoskeleton?

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phosphorylation of microtubule associated protein by MPF

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What happens at the Metaphase checkpoint?

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tag cyclin with Ubiquitin, inactivate MPF

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when do chromosomes reach their most compact state?

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end of metaphase

Front 56

what is apoptosis regulated by

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coding of caspase genes

Front 57

Stages of apoptosis

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1) cell shrinkage 2) chromatin condensation (pyknosis) 3) formation of cytoplasmic blebs and apoptic bodies 4)phagocytosis by adjacent cells

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pyknosis

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chromatin condensation that occurs in apoptosis