Bios 208 1st Edition Lecture 27 Outline of Last Lecture I. The Key Roles of Cell DivisionII. Binary Fission in BacteriaIII. Cellular Organization of the Genetic MaterialIV. Distribution of Chromosomes During Eukaryotic Cell DivisionV. Phases of the Cell CycleVI. CytokinesisVII. The Evolution of MitosisOutline of Current Lecture I. The Cell Cycle Control SystemII. The Cell Cycle Clock: Cyclins and Cyclin Dependent KinasesIII. Stop and Go Signs: Internal and External Signals at the CheckpointsIV. Loss of Cell Cycle Controls in Cancer CellsCurrent LectureI. The Cell Cycle Control SystemA. The sequential events of the cell cycle are directed by a distinct cell cycle control system,which is similar to a clockB. The cell cycle control system is regulated by both internal and external controlsC. The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is receivedD. For many cells, the G1 checkpoint seems to be the most importantE. If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divideF. If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a non-dividing state called the G0 phaseII. The Cell Cycle Clock: Cyclins and Cyclin Dependent KinasesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. Two types of regulatory proteins are involved in cell cycle control: cyclins and cyclin-dependent kinases (Cdks)B. Cdks activity fluctuates during the cell cycle because it is controlled by cyclins, so named because their concentrations vary with the cell cycleC. MPF (maturation-promoting factor) is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phaseIII. Stop and Go Signs: Internal and External Signals at the CheckpointsA. An example of an internal signal is that kinetochores not attached to spindle microtubules send a molecular signal that delays anaphaseB. Some external signals are growth factors, proteins released by certain cells that stimulate other cells to divideC. For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in cultureD. A clear example of external signals is density-dependent inhibition, in which crowded cells stop dividingE. Most animal cells also exhibit anchorage dependence, in which they must be attached toa substratum in order to divideF. Cancer cells exhibit neither density-dependent inhibition nor anchorage dependenceIV. Loss of Cell Cycle Controls in Cancer CellsA. Cancer cells do not respond normally to the body’s control mechanismsB. Cancer cells may not need growth factors to grow and divideC. They may make their own growth factorD. They may convey a growth factor’s signal without the presence of the growth factorE. They may have an abnormal cell cycle control
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