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46 Cards in this Set
- Front
- Back
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? is chemical modification of histones (especially H1)
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Epigenetic Regulation
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core of 8 histone molecules + Histone H1 = ?
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nucleosomes
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Give the organization for CHROMATIN ORGANIZATION
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8 histones + H1
nucleosome 6 nucleosomes = Chromatin Fibril loop domains chromosome scaffold chormatin fibers chromosomes |
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DNA is doubled during ? phase of cell cycle
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S-Phase
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? is region located at end of chromosome and shortens with each cell division.
? is the enzyme that adds nucleotides to the ends of chromosomes |
telomeres
telomerase |
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After S-phase a cell will have ?n DNA
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4n
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? is image sorting software sorts chromosomes according to morphology
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karyotyping
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? is when chromosomes hybridized with combinations of special probes specific to particular chromosome loci.
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FISH
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? is the site of ribosomal RNA synthesis and ribosomal assembly
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Nucleolus
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? is a non-membranous intranuclear structure that has chromosomes containing rRNA genes
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Nucleolar Organizing Centers
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? is a non-membranous intranuclear structure that has large amounts of RIBOSOMAL RNA actively transcribed ribosomal genes
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Fibrillar Material (pars fibrosa)
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? is a non-membranous intranuclear structure that is the site of initial ribosomal ASSEMBLY containing densely packed pre-ribosomal particles
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pars granulosa (granular material)
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True or False
The intense basophilia seen in the nucleolus is due to heterochromatin. |
FALSE
staining is due to rRNA!!!! |
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Outer membrane of the Nuclear Envelope is continuous with what membrane?
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rER membrane
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Inner Membrane of the nuclear envelope is supported by a network of filaments called ? which are formed primarily of ?
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Nuclear Lamina
Lamins (intermediate filaments) |
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? serves as a scaffolding for chromatin attachment in NON-DIVIDING cells
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Lamins (intermediate filaments ---nuclear lamina)
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? are sites where inner and outer membranse fuse
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nuclear pores
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? are composed of multiple protein subunits called ? that mediate bidirectional nucleocytoplasmic transport
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Nuclear Pore Complex (NPC)
nucleoporins |
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? are found in the pore are thought to be ribosomes or protein passing through
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DENSE BODIES
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? is an attached signal sequence on large molecules destined for the nucleus
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Nuclear Localization Signal (NLS)
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? is a soluble cytpolasmic receptor that direct molecules to the appropriate NPC
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IMPORTIN (nuclear import receptor)
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? is a signal on proteins that directs them out of the nucleus
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Nuclear Export Signal (NES)
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? binds to GTP and proteins with a NES and transports them through the NPC into the cytoplasm where the GTP is hydrolysed and the protein released
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EXPORTIN
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? fully folded ribosomal subunits, proteins all forms of RNA
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NPCs Transport
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? can cross water filled channels of the nuclear membrane by DIFFUSION
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ions
small molecules |
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Stem cell populations are in ? phase and can be reactivated to enter cycle in response to injury of body tissues
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Go phase
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? are cells that rapdily divide as they transit from stem cells to terminally differentiated cells
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progenitors
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3 classifications of cells based on mitotic activity
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stable populations
static cell populations renewing cell populations |
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How can cell reneweal be measured?
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Level of mitotic activity (see the number of metaphases)
Flow Cytometry -cell cycle -Ki-67 (expression of molecules associated with proliferation) -loss of membrane tracking dyes |
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What happens during G1?
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LONGEST and most variable
-synthesis of RNA and proteins -nucleotides and enzymes needed for division accumulate |
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What happens during S phase
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Replication of DNA
replication of histones Centrioles duplicate |
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During what phase are cells stained?
with what stain do you use? |
S-Phase
Tritiated THYMIDINE BromodeoxyURIDINE |
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What happens during G2 Phase?
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No DNA synthesis
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When do cells leave the cycle to become Quiescent (Go)?
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G1 phase
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Cells that are terminal differentiated are in what stage?
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Go (quiescent)
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During G1 ---high levels of ? are triggered by DNA damage and prevent entry into S-PHASE
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p53 (tumor suppressor)
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defects in ? are seen in half of all malignancies and cancers due to the loss of G1 checkpoint
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p53
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? are a family of transcription factors required for expression of molecules required for cell cycle progression (including Cyclins and CDKs)
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E2F
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? binds to and inhibits E2F.
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Rb (retinoblastoma susceptibility protein)
Rb helps and prevents damaged cells from entering cycle |
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loss or inactiviation of Rb will cause?
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cancer
Rb binds to E2F to stop cell cycle progression. Without Rb damaged/mutated cells can progress through the RESTRICTION CHECKPOINT |
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What are the 2 checkpoints in G1?
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DNA Checkpoint --p53
Restriction Checkpoint --E2F + Rb |
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What is the checkpoint in S Phase
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Damage Checkpoint
--monitors quality of replicating DNA |
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What are the checkpoints in G2 Phase?
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DNA damage checkpoint
Unreplicated DNA checkpoint --prevents progression to mitosis until DNA synthesis is complete |
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What are the Mitosis (M phase) checkpoitns?
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Spindle Assembly Checkpoint
--detects failure of spindle fibers to attach to kinetochores :: arrested in METAPHASE Chromosome Segregation Checkpoint --blocks CYTOKINESIS until all chromosomes are separated |
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? is failure to arrest the cell cycle before mitosis resulting in aberrant chromosome segregation
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Mitotic Catstrophe
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if MITOTIC CATASTROPHE occurs...
the result is ? |
ANEUPLOIDY
--cells with aberrant chromosome number |
