Molecular and Cellular Biology (3)
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Describe the process of FISH (Fluorescence In Situ Hybridization.
Spectral karyotyping uses fluorescent probes that bind to unique locations on chromosomes. These chromosomal probes fluoresce in a unique color that allow differentiation under UV microscopy.
Do chromosomes in Interphase have a set location within the nucleus?
Interphase chromosomes occupy discrete territories in the nucleus, but with relatively symmetrical 3D location of homologous chromosomes
Describe the nuclear envelope.
The nuclear envelope is a double membrane structure that is continuous with the rough ER. The outermembrane is studded with ribosomes.
What is the nuclear Lamina?
It is a meshwork of filamentous proteins underlying the nuclear envelop. There are three types of Lamin Proteins (A B C). It is interrupted by nuclear pores.
What roles to Lamin Associated Proteins play?
These inner nuclear membrane proteins tether the lamina to the nuclear membrane. (Emerin)
While DNA binding proteins tether chromatin to the lamina. (Lap2B)
Nuclear lamina proteins respond to the _____ cell cycle control signal by disassembling.
Lamin proteins are _____ as a result of mitotic cyclin/CDK (cyclin dependent kinase) activity in the lead-up to mitosis, leading to rapid _____ of the lamina – a unique feature of this type of intermediate filament, other classes of which are typically very stable.
_____ of lamins by phosphatases occurs as cells transition from M phase of the cell cycle back into the G1 phase, allowing _____ of the nuclear lamina (and associated nuclear membrane) around the newly segregated chromosomes.
Describe the nuclear pore's physical characteristics.
3000-4000 per cell
Donut-shaped structure 70-100nm
Central Channel is 9nm
125 MDa in size
Composed of 50-100 proteins
What is the function of the nucleoporin?
Involved in passage of nuclear and cytosolic molecules.
Free diffusion of small molecules through pore.
Active transport of larger molecules.
Mitotic CDKs phosphorylate multiple membrane-linked components to achieve nuclear _____ and _____ leading into mitosis.
What is the role of the nuclear localization sequence?
A basic amino acid rich sequence that are required for nuclear import.
What is the nuclear Export sequence?
Alternating Leucine amino acid chain that allows for the export of proteins to be exported from the nucleus.
What are the classes of proteins that are shuttled out of the nucleus by the use of NES?
Small proteins that need to be actively excluded.
Assembled ribosomal subunits (a form of RNP) and proteins in other RNP complexes.
Large NLS-containing proteins that may function in both places.
What is the Nucleolus?
It is the site of rDNA clustering, rRNA synthesis and ribosome assembly withing the nucleus.
What are speckles?
RNA processing centers.
What are cajal bodies?
possible splicing centers/RNA processing/associate with nucleolus.
What are PML bodies?
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