Term
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Definition
| Has 2 unit membranes that cover nucleus. Outer membrane is continuous with the ER system |
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Term
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Definition
| mesh-work of filaments that underlies the nuclear envelope. Composed of Lamins A, B and C. |
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Term
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Definition
| Provide structure by anchoring proteins in the membrane to the lamina. Also, proteins that are bound to chromatin are also bound to the lamina at the edge of the nucleus, keeping the chromatin in the proper location in the nucleus. |
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Term
| When is nuclear lamina not present? |
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Definition
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Term
| What is the function of nuclear pores? |
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Definition
| Involved in passage of nuclear and cytosolic molecules and the Free diffusion of small molecules (proteins <50 Kda) |
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Term
| Nuclear Localization sequence (NLS) |
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Definition
Basic amino acid rich sequence
(Lys-Lys-Lys-Arg-Lys). Are required for nuclear import. |
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Term
| What is the process of nuclear import? |
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Definition
Protein harboring an NLS is bound
by Importin alpha/beta complex. Importin-beta binds to the face of the pore. Cargo and importin complex enter the nucleus (Dissociation requires GTP-hydrolysis). |
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Term
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Definition
| transport factors. examples include importins |
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Term
| Why is RNA export a critical part of viral infection? |
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Definition
| Some viral genes are not processed appropriately and thus would be trapped in the nucleus. Viral proteins facilitate this action, which raises the possibility of targeting this export to combat the virus |
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Term
| Nuclear Export Sequence (NES) |
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Definition
Hydrophobic sequence:
Leu-X1-2-Leu-X2-3-Leu-X-Leu (X=any amino acid) |
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Term
| Basic mechanism of nuclear export |
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Definition
1. Exportin binds protein: e.g. the karyopherin Crm1
2. Transit through pore (GTP-hydrolysis)
Note: Ran (a GTP binding protein) is critical for mediating export |
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Term
| Why is Cyclin D1 mutation often cause cancer? |
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Definition
| Mutated form cannot be exported from the nucleus. thus, cell continues going through cell cycle when it shouldn't |
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Term
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Definition
| non-membrane bound sub-nuclear body that is the site of rRNA synthesis and ribosome assembly |
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Term
| Order of chromatin structure (smallest to highest) |
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Definition
| nucleosomes to 30 nm fiber |
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Term
| What is the relationship between Cyclins and CDK |
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Definition
| Binding of cyclins activates CDK, pushing cell through cell cycle |
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Term
| Effects of phosphorylation of proteins by Cdk |
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Definition
| Inactivation of proteins that inhibit cell cycle (Rb) and Activation/modification of proteins that are needed for cell cycle progression (replication proteins and lamins) |
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Term
| How Rb inhibition can eventually help lead to cancer |
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Definition
| RB inhibits transition from G1 to S. Cdk-Cyclin D inactivates RB by phosphorylation, allowing movement into S phase. If you lose RB, it becomes much easier to get from G1 to S phase. The increased replication leads to increased mutations and eventually cancer. However, mutation in RB alone does not cause cancer; cancer requires several mutations of multiple proteins. |
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Term
| Characteristics of nuclei in interphase |
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Definition
| chromosomes not discernible, nuclear envelope present, |
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Term
| Characteristics of nuclei in prophase |
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Definition
| Chromosomes become discernible, nuclear envelope and lamina break down |
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Term
| Characteristics of nuclei in metaphase |
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Definition
| chromosomes line up on metaphase plate. mitotic spindle (microtubules) apparent |
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Term
| Characteristics of nuclei in anaphase |
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Definition
| sister chromatids separate and are pulled along spindle |
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Term
| characteristics of nuclei in telophase |
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Definition
| chromatids are in separate poles. cleavage furrow apparent. cytokinesis (actin-dependent process) begins |
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Term
| characteristics of nuclei after cytokinesis is complete |
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Definition
| nuclear envelope reforms and chromosomes decondense |
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Term
| Fluorescence in situ hybridization (FISH) |
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Definition
Fluorescently labeled piece of DNA
hybridizes with the chromosome spread. It is used to detect and localize the presence or absence of specific DNA sequences on chromosomes |
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Term
| Chromosome painting/ spectral karyotyping (SKY) |
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Definition
| Visual entire chromosome/karyotype by FISH by labeling DNA with different color probes |
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Term
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Definition
| protective caps on the ends of chromosomes that shorten as we age (replication problem). |
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Term
| effect of UV light on DNA |
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Definition
| causes thymidine dimers, can be detected via specific antibodies |
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Term
| Effect of cisplatin (CDDP) on DNA |
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Definition
| Kills cancer cells by cross-linking DNA |
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