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38 Cards in this Set
- Front
- Back
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What is the nuclear lamina?
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What laminates the inside of the nuclear membrane - on the inner side - bound to it.
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What is the nuclear lamina's function?
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To maintain the sherical shape of the nucleus when the nuclear envelope breaks down during interphase.
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What happens to the nuclear lamina after interphase?
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It breaks down due to hyperphosphorylation of its proteins.
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What is the nuclear lamina made of?
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3 Intermediate filament-like proteins
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What 3 things are related to / associated with the nuclear lamina?
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1. Marginal heterochromatin (in)
2. Inner nuclear membrane (ext) 3. Nuclear pore complex |
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What are the IF-like proteins that make up the nuclear lamina?
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Lamins A/B/C
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What is the function of each lamin protein?
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Lamins A/C interact w/ marginal heterochromatin
Lamin B binds inner nuclear membrane via LBR |
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What is LBR?
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Lamin B-receptor - on the inner nuclear membrane, it is an integral membrane protein.
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Why is Lamin B so important?
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Because it stays attached to the nuclear lamina during mitosis so that when the nuclear envelope reforms it will have a skeleton to do it onto.
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What happens if no lamin-B?
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No nuclear envelope = no nucleus
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What causes the nuclear lamina to break down at interphase?
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Hyperphosphorylation of Lamins A and C
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When during mitosis does the nuclear lamina break down?
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During prophase
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When does the nuclear lamina reform?
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During telophase
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What happens when lamins are mutated?
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The nuclear lamina is disorganized and DNA synthesis is inhibited
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How are the lamins encoded?
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Lamins A/C = one gene, LMNA
Lamin B = its own gene |
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What are 3 results of LMNA mutation?
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1. Muscular dystrophy
2. Cardiomyopathy 3. Premature aging |
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What is a lamin mutation called?
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Laminopathy
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What makes up by far the most of the nuclear matrix?
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Internal nuclear matrix - 99%
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What is the main function of the internal nuclear matrix?
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Gives NONRANDOM order to chromatin
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What does the nonrandom order conferred by nuclear internal matrix do?
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Ensures normal duplication and transcription of genes.
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What happens if the internal nuclear matrix is abnormal?
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Cancer or cellular necrosis
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3 Things we know about the internal Nuclear Matrix:
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1. Chromosomes are positioned nonrandomly
2. Matrix proteins are tissue specific 3. Nuclear matrix functions in DNA replication/transcription. |
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Stages in the cell cycle:
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G1
S G2 M |
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What happens in G1
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Chromatids de-condense; RNA and protein synthesis begin
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What happens in S
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DNA and histones synthesized
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What happens in G2
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Preparation for mitosis
Centrosome is duplicated |
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What happens in M
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Cells round up, nuclear envelope disintegrates, chromotin condenses to form chromatids which line up and segregate to daughter cells.
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What is Interphase?
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G1-S-G2
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What is Generation Time?
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The time for one revolution through all phases (G1-G1)
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Which phase is most variable?
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G1
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What is the function of Mitosis?
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To restore the 2N condition to the 4N product of Sphase
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What are the steps in mitosis?
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PPMATC
Prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokinesis |
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Prophase
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-hyperphosphorylation
-chromatin-tid condensation -Centrosomes form spindle poles |
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Prometaphase
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formation of mitotic spindles
Microtubules/kinetochores appear (astral/polar/kinetochore) Nuclear envelope disintegrates |
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Metaphase
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chromosomes align at equator
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Anaphase
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Chromosomes move to opposite poles
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Telophase
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formation of daughter nuclei
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Cytokinesis
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Completely separate cells
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