Cell Manipulation Microscope http://www.cellmanipulationmicroscope.com Find lots of comprehensive information about cell manipulation microscopes Wed, 08 Aug 2007 04:56:15 +0000 http://wordpress.org/?v=2.2.1 en Chromosomes and Sexual Reproduction http://www.cellmanipulationmicroscope.com/cellmanipulation/chromosomes-and-sexual-reproduction/ http://www.cellmanipulationmicroscope.com/cellmanipulation/chromosomes-and-sexual-reproduction/#comments Thu, 07 Jun 2007 18:37:04 +0000 cellmanipulationmicroscope http://cellmanipulationmicroscope.com/?p=9 Chromosomes

Immediately after DNA replication a human cell will have 46 “double chromosomes”. In each double chromosome there are two copies of that chromosome’s DNA molecule. During mitosis the double chromosomes are split to produce 92 “single chromosomes”, half of which go into each daughter cell. During meiosis, there are two chromosome separation steps which assure that each of the four daughter cells gets one copy of each of the 23 types of chromosome.
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]]> http://www.cellmanipulationmicroscope.com/cellmanipulation/chromosomes-and-sexual-reproduction/feed/ The Cell Cycle http://www.cellmanipulationmicroscope.com/cellmanipulation/the-cell-cycle/ http://www.cellmanipulationmicroscope.com/cellmanipulation/the-cell-cycle/#comments Thu, 07 Jun 2007 18:35:40 +0000 cellmanipulationmicroscope http://cellmanipulationmicroscope.com/?p=8 The cell cycle or cell-division cycle (CDC) is the series of events in a eukaryotic cell between one cell division and the next. Thus, it is the process by which a single-cell fertilized egg develops into a mature organism and the process by which hair, skin, blood cells, and some internal organs are renewed. A specialized form of cell division is responsible for cellular differentiation during embryogenesis and morphogenesis, as well as for the maintenance of stem cells during adult life.

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]]> http://www.cellmanipulationmicroscope.com/cellmanipulation/the-cell-cycle/feed/ Phases of the Cell Cycle http://www.cellmanipulationmicroscope.com/cellmanipulation/phases-of-the-cell-cycle/ http://www.cellmanipulationmicroscope.com/cellmanipulation/phases-of-the-cell-cycle/#comments Thu, 07 Jun 2007 18:34:31 +0000 cellmanipulationmicroscope http://cellmanipulationmicroscope.com/?p=7 The Cell Cycle

Interphase
Metaphase
Mitosis

The cell cycle of a typical eukaryotic cell has four phases. The relatively brief M phase consists of nuclear division (mitosis) and cytoplasmic division (cytokinesis). After M phase, the daughter cells each begin interphase of a new cycle. Although the various stages of interphase are not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of specialized biochemical processes that prepare the cell for initiation of cell division. The first phase within interphase is called G1 (G indicating gap); during this phase the biosynthetic activities of the cell, which had been considerably slowed down during M phase, resume at a high rate. The ensuing S phase starts when DNA synthesis commences; when it is complete, all of the chromosomes have been replicated. The cell then enters the G2 phase, which lasts until the cell enters the next round of mitosis. Metabolic activity, cell growth, and cell differentiation all occur during interphase.

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]]> http://www.cellmanipulationmicroscope.com/cellmanipulation/phases-of-the-cell-cycle/feed/ Cyclins and Cyclin-Dependent Kinases http://www.cellmanipulationmicroscope.com/cellmanipulation/cyclins-and-cyclin-dependent-kinases/ http://www.cellmanipulationmicroscope.com/cellmanipulation/cyclins-and-cyclin-dependent-kinases/#comments Thu, 07 Jun 2007 18:31:35 +0000 cellmanipulationmicroscope http://cellmanipulationmicroscope.com/?p=6 Cyclins and cyclin-dependent kinases (CDKs) are the two critical classes of molecules in regulation of cell cycle progression. Cyclins form the regulatory subunits and CDKs the catalytic subunits of an activated heterodimer; cyclins have no catalytic activity and CDKs are inactive in the absence of a partner cyclin. When activated by a bound cyclin, CDKs perform a common biochemical reaction called phosphorylation that activates or inactivates target proteins to orchestrate coordinated entry into the next phase of the cell cycle. Different cyclin-CDK combinations determine the downstream proteins targeted.

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]]> http://www.cellmanipulationmicroscope.com/cellmanipulation/cyclins-and-cyclin-dependent-kinases/feed/ Checkpoints, Synchronisation of Cell Cultures, and Observation of Cell Cycles http://www.cellmanipulationmicroscope.com/cellmanipulation/checkpoints-synchronisation-of-cell-cultures-and-observation-of-cell-cycles/ http://www.cellmanipulationmicroscope.com/cellmanipulation/checkpoints-synchronisation-of-cell-cultures-and-observation-of-cell-cycles/#comments Thu, 07 Jun 2007 18:29:47 +0000 cellmanipulationmicroscope http://cellmanipulationmicroscope.com/?p=5 Checkpoints

Checkpoints are used by the cell to monitor and regulate the progress of the cell cycle. If a cell fails to meet the requirements of a phase it will not be allowed to proceed to the next phase until the requirements have been met. Several checkpoints are designed to ensure that damaged or incomplete DNA is not passed on to daughter cells. At the end of the G1 phase, G2 phase and after DNA has been replicated in the S phase it is checked for damages. At the end of the M phase a checkpoint is present to stop cytokinesis in case the chromosomes are not properly aligned on the mitotic spindle.

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