Reproduction, Biology

Reproduction

Living things do not arise spontaneously. They arise only from pre-existing living things This is one of the fundamental tenets of biology. The ability of an organism to reproduce its kind is characteristic of living things. Reproduction involves transmission of information by the remarkable hereditary material deoxyribonucleic acid (DNA) contained in the nucleus. The heredity material is subject to change or mutation. When provided with necessary conditions the DNA molecule is capable of replicating itself. The DNA codes for the information regarding structure and function of the organisms.

For example, DNA ensures that cats always produce kittens, never pups. In simple organisms such as protists, reproduction may be asexual. For example, a protist like amoeba reproduces by simple division. When the amoeba grows to a certain size it makes a duplicate copy of its DNA, each copy separating into a nucleus. The amoeba divides into two, each daughter amoeba thus possessing a nucleus with a copy of DNA. However, higher plants and animals reproduce sexually. This involves the union of a male gamete and female gamete. The male gamete is the sperm whereas the female gamete is the egg.

The sperm fertilizes the egg to form a zygote which then develops into a new individual. Each gamete has ope complete copy of genes (DNA) derived from its parents. So gametes are haploid. Union of two gametes and fusion of their nuclei result in the doubling of the DNA content in the zygole, which is hence diploid. All cells derived from the zygote are diploid. Thus, each offspring is not a mere duplicate of a single parent but is the product of the interaction of various genes (DNA) contributed by both mother and father. This results in genetic variation which is important from the point of view of evolution and adaptation. Thus, though an individual dies, it perpetuates itself by the process Of reproduction, and the race continues.

2499_Reproduction.png

Figure: Approaches to reproduction - (a) in asexual reproduction, one individual gives rise to offsprings which are identical to the parent. (b) In sexual reproduction, each parent contributes a sex cell; these join to give rise to the offspring which thus has the genes and traits of both parents.

Posted Date: 1/12/2013 2:22:55 AM | Location : United States







Related Discussions:- Reproduction, Assignment Help, Ask Question on Reproduction, Get Answer, Expert's Help, Reproduction Discussions

Write discussion on Reproduction
Your posts are moderated
Related Questions
Tricks of learn a classification (molusca,arthopoda,prifera etc.)

Q. Reduction in left ventricular? Vasodilators improve stroke volume, and reduce degree of regurgitation. This results from decrease in systemic vascular resistance and leads t

Pericarditis Pericarditis is a syndrome caused by inflammation of the pericardium. Causes i) Infections Bacterial : Pneumococci, Staphylococci, Streptococci,

Q. What are the types of chronic gastritis? Gastroscopic observation shows different types of chronic gastritis: 1. Superficial gastritis: gastric mucosa is red, oedematous,

Why can it be said that a recessive allele can remain hidden in the phenotype of an individual and revealed only when manifested in homozygosity in the offspring? A recessive a

Animal Tissue Culture: The term tissue culture refers to the culture of all organs, tissue fragments and dispersed cells on a suitable nutrient medium. It may be divided into

What is cytosolic cyclic AMP Healthy Person P takes a new drug that is a member of a drug family that results in  constant levels of cytosolic cyclic AMP (cAMP) in one and only

Why is it significant that exact copies of DNA are produced during replication? Producing exact copies make sure that when a cell divides, the offspring cells will receive the

Enumerate about the Baule unit  A mathematician from Gottingen by the name of B. Baule assisted Mitscherlich with his calculations.  The quantity of any growth factor (nutrient

Determine the Causal factors of nervous system Although, the brain and spinal cord are surrounded by tough membranes, enclosed in the bones of the skull and spinal vertebrae, a