Cell Cycle - Lecture notes Chapter 5 PDF

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Summary

The document details the process that occurs in the cell cycle, including more information on the process Interphase, Mitosis, and Cytokinesis. Also, images to get the idea of the process. Hopefully is a useful resource for you....

Description

CELL CYCLE & MITOSIS Cell Cycle  It is made of 4 parts.  Those 4 parts are divided into two phases the Interphase and Mitosis o

The pink, red, and pink arrow are in the interphase stage.

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The blue arrow is the Mitosis stage.

Interphase stage  During Interphase, the new cell grows and then carries out its normal functions.  During S phase, chromosomes are replicated. Once a cell enters S, it must complete the cycle because the chromosomes duplicate.  During G2, final preparations are made before entering Mitosis Chromosomes in G1 and S cell  There are 2 Chromosomes in the G1 cell. 

There are 2 Chromosomes in the S cell.

 In the S cell, each chromosome consists of 2 genetically identical sister chromatid. These are held together at the centromere.  A cell in G2 looks like the single cell to the left.

CELL CYCLE & MITOSIS  In S of animal cells, in addition to replicating chromosomes, the DNA are also replicated.

Mitosis

 Cytokinesis Is defined as the division of the nucleus. 

4 phases of Mitosis: o

Prophase

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Metaphase

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Anaphase

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Telophase

 Almost always, the entire cell splits in two which is called daughter cell.  Once M & C are complete, the new cells will be in G0 of Interphase.  When a cell leaves G2, it enters mitosis.  The purpose of mitosis is the separate the Cell of each replicated chromosome so that each daughter cell receives a full set of chromosomes.  The difference between the nucleus of a prophase cell compared to an interphase cell is that the chromatin are condense into chromosomes.  In addition, the nuclear envelope breaks down and filaments called mitotic spindle begin to form the spindle apparatus.

CELL CYCLE & MITOSIS

Stages of Mitosis  Prophase  Metaphase  Anaphase  Telophase Continuing Mitosis  Mitosis is defined as the replication of the nucleus. Almost always, at the end of telophase, the entire cell splits in two this is called daughter chromosomes.  This produces 2 cells that are genetically identical.  2 types of fungi – their bodies consist of tiny filaments. o

The top drawing shows separate cells. In the bottom, the nuclei are not in separate cells. This fungus is multinucleate.

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Multinucleate cells result when mitosis occurs but not Cytokinesis

The Four stages on Mitosis  Anaphase: Separated chromatids are pulled by spindle fibers to opposite poles.  Prophase: Replicated chromosomes condense.  Prophase: Single chromosomes unwind and relax.  Mitosis: Replicated chromosomes are positioned at the center of the cell.  Telophase: Nuclear envelope breaks down and spindle apparatus starts to form.  Telophase: Nuclear envelopes form around chromosomes and spindle breaks down.

CELL CYCLE & MITOSIS

Cell point Check points  The 4 purple rectangles on the cell cycle diagram are Stop Checkpoint.  If the cell cycle were not tightly regulated, cells would divide when it is not necessary, resulting in the disease we call Mutation.  Among the things checked for at the G1 checkpoint is damage to chromosomes. A protein called P53 Checks for damage. If the damage cannot be repaired the cell kills itself which is called Apoptosis....