BIO 151 12 The Cell Cycle
Terms
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- Cyclin Dependent Kinase (CDK)
- a protein kinase that is only active when complexed with a cyclin
- Problem with cancer cells
- 1. ignorme signals that regulate cell cycle. 2. divide excessively and invade other tissues. 3 no density depend inhibition 4. no anchorage dependence. 5.don't stop divdng when growth factors depleted.
- cytokinesis - animal vs plant cells
- results in 2 genetically ident daughter cells in both - but dividing is dft. Animal... by cleavage furrow - contractile ring of actin filaments. Plant... cell plate forms from golgi vesicle aligning in center of cell. build up an form plate then lengthen to membrane - out of cell plate grows the cell wall.
- function of nonkinetochore microtubules
- they elongate cell during anaphase
- chromatin
- complex of DNA and associated protein molecules
- G2 checkpoint
- MPF
- G1 checkpoint
- most important; "restriction point" . if cell receives go-ahead signal from here, it will usually complete the cycle and divide; if it doesn't receive go-ahead, will exit cycle and switch into G0 phase
- Interphase
- Account for about 90% of cell cycle. Phase where cell grows and copies its chromosomes in preparation for cell division. Consists of G1, S, and G2 phases
- metaphase plate
- Where chromosomes convene on the imaginary plane equally between the spindle's two poles
- Anchorage dependence
- to divide, cells must be attached to a substratum
- centrosome
- Also known as microtubule organizing center - contains a pair of centrioles at the center (centrioles not present in plant cells)
- Metaphase
- Centrosomes at opposite poles, centromeres line up on metaphase plate, spindle fully formed
- centrosome
- In animal cells, a subcellular region containing material that functions throughtout the cell cycle to organize the cell's microtubules
- Mitotis M Phase
- Accounts for about 10% of cell cycle and consists of mitosis and cytokinesis.
- Prometaphase
- frag of nuclear envelope, chroms more condensed, mtubules attach to kinetochores, non-kinetochore mtub interact with mtubes from opposite pole
- Stages of Mitosis
- Prophase, Prometaphase, Metaphase, Anaphase, Telophase (then Cytokinesis)
- MPF buildup
- what is the go ahead signal for a cell to pass teh G2 checkpoint and enter mitosis?
- somatic cells
- all body cells except reproductive cells (each contain 46 chromosomes made up of two sets of 23 - one set from each parent)
- centromere
- the specialized region where the two sister chromatids are most closely attached - like a waist.
- PDGF
- platelet derived growth factor - helps repair wounds - required for divis of fibroplasts - after injury, this would be released by platelets at injured site resulting in fibroblast proliferation to heal wound.
- checkpoint
- critical control points, stop and go-ahead signals can regulate the cell cycle
- Prophase
- chromatin fibers begin to coil into chromosomes, nucleoli disappear, mitotic spindle forms, centrosomes move away from each other
- chromosomes
- packaged DNA molecules
- compare/contrast benign / cancer tumor
- both have abnormal cells. benign- stays at orig site and can be surg removed. Cancer cells from malign spread from original site and may impair function of 1 or more organs
- M Phase
- Phase when cell divides.
- metaphase
- What phase does MPF activity peak?
- the degradation of cyclin
- the decline of MPF activity at the end of mitotis is due to...
- mitosis
- division of the cells nucleus, the usual method of cell division, characterized typically by the resolving of the chromatin of the nucleus into a threadlike form, which condenses into chromosomes, each of which separates longitudinally into two parts, one part of each chromosome being retained in each of two new cells resulting from the original cell
- cleavage
- In animal cells, cytokinesis occurs by this process
- growth factor
- protein released by certain cells that stimulates other cells to divide.
- meiosis
- It results in the production of four genetically distinct (different) cells. Reduces the number of chromosomes from 46 to 23.
- S Phase
- In between G1 and G2 phases. Known as Synthesis where chromosomes are duplicated
- G1
- MPF recycled in what phase (after cyclin degraded)?
- cell cycle
- life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells.
- cytokinesis
- division of the cytoplasm
- G1 phase
- First part of Interphase - First Gap
- cell division
- reproduction of cells
- Telophase
- daughter nuclei form at 2 poles, nuc envelopes reform, chromatin relaxes uncoil. Mitosis ends.
- transformation
- process that converts a normal cell to a cancer cell.
- metastasis
- spread of cancer cells to location distant from their original site
- 2
- How many chromatids are in a duplicated chromosome?
- Kinetochore
- On each of the two sister chromatides, the structure of proteins associated with specific sections of chromosomal DNA at the centromere
- sister chromatids
- Resulting from each duplicated chromome, the two chromatids that each contain identical DNA molecule that are initially attached all along their lengths by adhesive proteins called cohesions.
- G0 phase
- what phase are most of your body cells in
- cleavage furrow formation
- Drug B blocks function of actin. what aspect of cell cycle would be most distrupted by this drug?
- HeLa Cells
- cancers that can go on dividing indefinitely in culture if they are given a continual supply of nutrients. have been dvding since 1951 when removed from Henrietta Lacks tumor. Normal cells divide 20-50 times before age and die.
- anaphase
- What phase does cyclin component of MPF get degraded?
- cyclin
- protein whose concentration cyclically fluctuates in the cell (starts building up in late S phase continues through G2)
- Aster
- radial arry of short microtubules that extend from each centrosome (together with centrosomes, spindle microtubules creates the mitotic spindle)
- APC
- anaphase promoting signal - (M checkpoint)
- gametes
- reproductive cells (either sperm or eggs) - only have 23 chromosomes in humans
- cleavage furrow
- a shallow groove in the cell surface near the old metaphase plate - like a drawstring. actin microfilaments and myosin molecules interact contracting the ring pinching the cytoplasm and producing 2 new separate cells.
- by phosphorylating various proteins
- How does MPF promote Mitosis
- cell plate
- During telophase, vesicles from golgi move along microtubules to middle of the cell and create this. Cell wall grows out of this.
- MPF
- allows cell to pass through G2 checkpoint because cyclin accumulated and connected with CDK, initiating events of mitosis.
- Anaphase
- sister chrmtids sep and move to opposite poles - poles move farther apart
- Mitotic Spindle
- fibers composed of microtubules and proteins, guides chromatid movement, fibers made of microtubules and associated proteins that begins to form in the cytoplasm during prophase
- benign tumor
- abnormal cells that remain at the orig site
- Regulation of cell cycle
- driven by chem signals present in cytoplasm (not suggested until 1970's)
- cells with more that one nucleus
- In cells of some organisms, mitosis occurs w/o cytokinesis. This results in...
- from after s phase until end of metaphase. (anaphase starts to pull apart)
- In what stage of cell cycle does a chromosome consist of 2 ident chromatids
- G1 (b/c has not duplicated during s phase yet)
- a cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in what phase?
- MPF
- maturation promoting factor or Mphase promoting factor (cyclin + cdk)
- Density Dependent inhibition
- crowded cells stop dividing
- malignant tumor
- lump that becomes invasive enough to impair funct of one or more organs
- replication of DNA (b/c happen in s phase of Interphase
- which does not occur in mitosis? condensation of chromos, DNA replication, sep of sis chrmtids, spindle formation, or sep of spindle poles.
- Protein kinases
- enzymes that activate or inactivate other proteins by phosphorylating them - give go ahead signals at G1 and G2 checkpoints.
- cell cycle control system
- cyclically operating set of molecules in the cell that trigger and coordinates events of the cell cycle
- genome
- a cells endowment of DNA or its genetic information