Cellular Reproduction

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Cellular Reproduction

Cellular Reproduction is the process by which all living things

produce new organisms similar or identical to themselves. This is

essential in that if a species were not able to reproduce, that

species would quickly become extinct. Always, reproduction consists of

a basic pattern: the conversion by a parent organism of raw materials

into offspring or cells that will later develop into offspring.

(Encarta, 2) In almost all animal organisms, reproduction occurs

during or after the period of maximum growth. (Fichter, 16). But in

Plants, which continue to grow through out their lifetime, therefore

making the process more complex. Plants' reproduction is usually

caused by a stimulant, mostly environmental or growth factors. The

reproductive process, whether asexual or sexual always involves an

exchange in hereditary material from the parent(s) so that the new

organism may also be able to reproduce. Reproductive processes can be

categorized in many diffrent ways although the most common is to put

them into either asexual reproduction or sexual reproduction. Asexual

reproduction is the process by which a single organism gives rise to

two or more daughter cells. Most single celled organisms reproduce by

the asexual process known as fission, which is commonly called

mitosis. Fission (or Mitosis) is the division of one cell into two

identical daughter cells. Interphase, the first phase of the cell

cycle and also the phase before mitosis, starts as soon as the cell is

born. Interphase is broken up into three phases, G1, S, and G2.

During the G1 phase, the cell increases in mass except for the chromosomes,

which stay the same, uncoiled. Protein synthesis is also occurring

rapidly in this phase. If a cell doesn't divide further, it remains

permanently in the G1 phase. Next is the S phase, in which the mass of

the cell continues to increase, and DNA is duplicated, and then the

chromosomes divide to form identical sister chromatids attached by a

centromere. (Harold, 45). During the G2 phase of Interphase, the cell

becomes double its mass at birth, the chromosomes begin to shorten and

coil, and the centrioles appear, the cell is now ready to enter into

mitosis. In the first and longest phase of mitosis, prophase, the

chromosomes become visible and the centrioles split in half and then

move to opposite sides of th...

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...on’t seperate

correctly. This is called nondisjunction. There are three types of

nondisjunction, Trisomy- when a gamete with an extra chromosome is

fertiized with a normal gamete. Monosomy- when a gamete with one

chromosome is missing and is then fertilized by normal gamete. And

Trioloidy- where both zygotes have an extra chromosome. Reproduction

is as essential to a species as food, water, or shelter. If a species

cannot reproduce anymore, that species will eventually become extinct.

There are many means of reproduction but primarily only two: asexual

and sexual. In asexual reproduction, One organism gives a part or its

whole self, in order to give rise to two or more new organisms. During

sexual reproduction, two parents each form sex cells, which unite, and

eventually form a new individual.

Works cited

Biggs, Alton & others. Biology: The Dynamics of Life.

Glencoe McGraw-Hill.: New York, NY, 2000 Encarta Encyclopedia. CD-ROM.

1998 Fichter, Sheila. Reproduction. Universal Press: Columbus, OH,

1994 Harold, Christopher.

Cells: A Guided Tour. Simon and Schuster: New York, NY, 1987 O’Neil,


Cells. McMeel Publishing, Inc.: Atlanta, GA, 1990

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