Monday, February 25, 2008

The Cell Cycle.

Cell Division..........................Why?
- To make new cells
- Continuity of life: Asexual reproduction, growth, repair, and renewal
- Cell cycle: Make a copy of a preexisting cell (Daughter cells)



What's in a cell that smells so sweet.......ehhh







- Nucleus: Chromosomes, DNA
- Cytoskeleton: "Scaffolding" or "Skeleton"; The internal framework of a cell, composed largely of actin filaments and microtubules (spindle fibers). Also includes Centrioles (in animaks).



The Nucleus:
Its function: to protect DNA
It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression.
The Nuclear Envelope: a double membrane that contains pores to allow large marcromolecules to pass through such as ribosomes.
The Cytoskeleton:
Its function: to provide structural support, maintain shape of cell, provide anchorage for organelles via protein fibers (microfilaments, intermediate filaments, and microtubules).
The cell may become motile by cilia, lamellipodia or flagella.
The cytoskeleton also organizes structures within the cell and its activities.




Centrioles:

One of two cylindrical cellular structures that are composed of nine triplet microtubules and form the asters during mitosis.
Centrioles are involved in the organization of the mitotic spindle and in the completion of cytokinesis.
Centrioles are an important part of centrosomes, which are involved in organizing microtubules in the cytoplasm.



They organize spindle fibers and guide chromosmes in mitosis.


Daughter Cells:
During mitosis, an exact copy of DNA is made from the parent cell to be passed to the daughter cells.
Cytokinesis: division of orgnanelles and cytoplasm





Mitosis:





Interphase: Defined only by the absence of cell division. During interphase, the cell obtains nutrients, and duplicates its chromatids. Most eukaryotic cells spend approximately 90% of its life in Interphase. "Every day job": produces RNA, synthesize proteins and enzymes, prepares for duplication if triggered.

Prophase: Stage during which the chromosomes condense and become visible, the nuclear membrane breaks down, and the spindle apparatus forms at opposite poles of the cell.

Pro-Metaphase: The stage of mitosis or meiosis in which the nuclear membrane disintegrates, the centrioles reach the poles of the cell, and the chromosomes continue to contract.

Metaphase: Condensed chromosomes align in the middle of the cell before being separated into each of the two daughter cells.

Anaphase: The chromosomes move from the equatorial plate toward opposite ends of the nuclear spindle.

Telophase: The chromosomes of daughter cells are grouped in new nuclei.

Cytokinesis: The division of the cytoplasm of a cell following the division of the nucleus.


Cell Life Cycle:





















Interphase:

Divided into three phases:
-G1: first gap
Cell doing everyday job
Cell grows
-S: DNA Synthesis: Copies chromosomes
-G2: second gap
Prepares for division
Cell grows more
Produces organelles, proteins, and membranes







FIN




Oh tomorrows sherpa is...............Maria

2 comments:

chandrakant said...

Can you tell me which resolution power is best for the see chromosome in the microscope and details of techniques for chormosome slide preparation and staining.

you can mail me on my mail id chandpatel712in@gmail.com

sunrise-sunset said...

Loved the vid. I think that it's really going to help me...