CHROMOSOMES AND DNA

EXPLANATION:
Chromosome are thread like structure that appears inside the nucleus at the time of cell division.They were first observed by German embryologist Walther Fleming in 1882,when he was examining the rapidly division cell of Salamander Larvae.Since there discovery chromosomes have been found in cell of all eukaryotes.There number varies however from species to species.Penicilium,a fungus,has only one pair of chromosomes while some ferns have more than 50 pairs.A mosquito has 6 honeybee 32,corn20,sugarcane 80,frog 26 and a mouse has 40 chromsomes. Human cells have 46 chromosomes. Consist of 23 pairs.Each of these 46 chromosomes contain hundred or thousand of genes that play important rules in determining how a person body develop the functions.

The possessions of all these chromosomes is therefore, essential for survival.Missing of a part or whole of chromosomes leads to serious consequences,usually death occurs.

CHROMOSOMES

TYPES OF COLONING:
Typically a chromosomes is made of chromatids ,centromere , (primary constriction) and a secondary constriction.

Chromosomes may widely differ in apperance. They vary in size staining properties, the location of centromere,the relative length of two arms on either side of centromere, and the position of constricted regions along the arms.The particular ray of chromosomes that an individual possesses is called its karyotype. Karyotype show marked difference species and sometimes even among individuals of the same species.

The chromosomes are called telocentric, acrocentric,sub metacentric and metacentric depend upon the location of centromere between the middle and tip of chromosomes.

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COLONING

Coloning is a technology for achieving augenic aims.
DEFINITION:
CLONE: A clone is defined as a cell or individual and all its sexuality produce offspring.
INFORMATION:
All members of clone are genetically identical except when a mutation occur.

GENERAL: Generally no normal animal reproduce naturally by coloning.Several insects and many plant do, in some circumstances whereas few do so regularly.

HISTORY:  In 1997 scientist Scotland succeed in coloning of sheep.Other mammalian species( mice and cows) have since been coloned.In this nucleus from a fertilized egg is removed and a nucleus from a cell of a fully developed individual is inserted in its place.The altered zygote is than implanted in suitable womb where it complete its development. The new individual formed in this way is a genetically identical clone of the individual whose necleus was used.The coloning could make multiple copies of a desires genotype.

ANOTHER TYPE OF COLONING:  Another type of coloning is the division of single egg or early embryo in one or more separate embryos.This is the same process that normally  create identical twins.Offspring of this type of coloning are genetically identical but but carry chromosomes from each of the two paremtd. This type of coloning has already been used to produce genetically cattle and other form animals.
Man is likely to adopt coloning techniques for commercials production of valuable animals of known pedigree such as horses, etc.
At some places scientist are making attempts to clone human embryo which they believe can serve as transplant donor.There is lot of controversy on this issue as the whether human cloning should be attempt or not.

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DIGESTION IN INSECTIVOROUS PLANT

There are few plants that supplement their organic diet with organic compounds. These organic compounds are obtained by trapping and digesting insects and and small animals.All of the insectivorous plant are true autotrophs.but when they capture the prey,their growth become rapid.Apparently nitrogeneous compounds of animal body are of benefits to these plants.In some plants trapped insects are composed by bacteria.In others trapped insects are digested by enzymes secrets by leaves.The plant absorb nitrogenous compound thus formed.

Pitcher plants:( sarracenia pupurea)

Pitcher plant has leave modified into a sac aor a picture partially filled with water.The end of the leaf is modified to form a hood,which partially cover the open mouth of the pitchet. Small insects that fall into the picture are prevented from climbing out by numerous stiff hairs.The protiens of the trapped insects are decomposed by bacteria or enzyme and the product of this decay are absorbed by inner surface of the pitcher leaf.

Pitcher plant

SUNDEW

VENUS FLY TRAP (Dionaea muscipula)The leaf is bilobed with midrib between them.There is row of long stiff bristles along the margins of each lob.When an insect touches small sensitive hairs on the surface of leafe,the lobes quickly come together with their bristle interlocked.The trapped insects is than digested by the enzyme secreted from the glands on the leaf surface and the products ate then absorbed.

VENUS FLY TRAP

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DOUBLE HELICAL STRUCTURE OF DNA(WASTON AND CRICK'S MODEL)

Learning informally of franklin's result,before they were published in 1953, James waston and Francis Crick, two researchers in the university of Cambridg,quickly worked out likely structure of the DNA molecule which we now know was substantially correct.They They proposed that molecule is a single double helix,with the basis of two starnds pointed inward toward each other, theu forming base pairs.In their model base pairs always consist of purines,which are large, pointing toward pyrimidyens which are small, keeping the diameter 2 nm .Because hydrogen bond exist between the bases in the base pairs.The double helix is stabilized as a double DNA molecule composed of two antiparallel strands one chain running 5' to 3'.The base pairs are planer and stack 0.34nm apart as a result of hyperphobic interactions contributing to the overall stability of the molecule. In the double helix adenine forms two hydrogen bonds with thymine,while guanine form three hydrogen bonds with cytosine.Adenine will not form proper hydrogen bond s with cytosine.

X ray diffraction patterns suggested the double helical shape of DNA.

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FEMALE REPRODUCTIVE SYSTEM

The female reproductive system consist of an ovaries, the oviduc,uterus and the external genitalia.A pair of ovaries lies within the body cavity of the female.Germ cells in ovary produce many oogonia which decided mitotically to form primary oocytes.These are in closed in the groups of follicle cells.The primary oocytes divides mitotically into haploid secondary oocytes and first polar body.second meiotic division in the oocytes proceed as far as metaphase but is not completed until the oocytes is fertilized by the sperm.In human in human only one ovume usually discharged from the ovary at one time,this phenomena is called ovulation.

The human female reproductive system ( vagina)

The ovume is then transfferd to the oviduct generally called falopian tube or uterine tube open into uterus.The fertilization of ovume take place in the proximal part of the oviduct.The fertilized ovume enters the uterus where it is than implanted and undergoes further development. A placenta is place between the uterine and foetal tissues for the exchange of oxygen,carbon dioxide, wastes nutrients and other minerals.Uters open into vagina through varvex.Urethra and vagina have independent opening to the extercycle.

PLACENTAL STURUCTURE

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MALE REPRODUCTIVE SYSTEM

Man reproductive system 

(Male reproductive system):
consist of genitalia which consist the pair of testes which lie outside the body,in the sac like scrotum and male copulatory organ which is used to transfer sperms into the female reproductive tract.Each testes consist of highly complex system called seminiferous tubules,in which repeated division by the cell of germinal epithileum produce spermatogonia.These increase in size and differentiate into primary spermatocytes which undergo meiotic division to form secondary spermatocytes and spermatids.Eventually the spermatids differentiate into mature sperms.Fluid secreated by cetrli cells provides liquid medium protection and nourishment to sperms while that are in tubules.The sperms are than transferred to main duct of male reproductive travt, the VA's deference which forms highly convoluted epididymis.The sperms than pass through the urinogential duct and are discharge out.Between the seminiferous tubules are interstial cells which secrete testerones.This hormones is essential for the successful production of sperms and also controls the development of male secondary sexual characteristics during puberty.

Male reproductive system

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             SSSSS

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