All babies are born with a kind of prearrangedpattern as a result of a process of transmissionof genetic characteristics from the parent to the offspring , called HEREDITY. BEHAVIOR GENETICS combines the methods of genetics and psychology to study the inheritance of behavioral characteristics.
Physical Psychological characteristics: characteristics: height ability bone structure temperament the color of the emotional stability hair and eyes are are transmitted from inherited parents to offspring.
The hereditary pattern is transmitted at conception when female egg is fertilized but the male sperm cell. The union of the egg and the sperm within the mother’s body result in a new cell called a zygote.
During the prenatal period, when the fetus is in the mother’s womb, the systems and structures it will need to function as a separate being develop.
The hereditary units that we receive from our parents and transmit to our offspring are carried by microscopic particles known as CHROMOSOMES , colored bodies found within the nucleus of each cell in the body. The human cell contains 46 chromosomes arranged in 23 pairs.
Each chromosomes is composed of many individual hereditary units called Genes,which also occur in pairs – one gene in each pair comes from the sperm chromosomes and one gene from the ovum chromosomes. Thus, a child receives only half of each parent’s total genes. The complete set ofgenes is called the human Genome. The total number of genes in each human chromosomes is around 100,000.
One exception is identical twins, who is having developed from the same fertilized egg, have exactly the same chromosomes and genes.
The actual carrier of hereditary information within the genes is a complex nucleic acid called DNA (deoxyribonucleic acid). DNA gives special “ hereditary instructions” for the cellular development of the organism and these instructions are partially carried out by RNA .
The potential importance of the discovery of both DNA and RNA is that once we know how these substances give instructions and how the instructions are carried out, we may be able to correct faulty growth in mankind such as inherited abnormalities. These have been the work of scientists in what is referred to as genetic engineering
Test tube or in – vitro fertilization (IVF) ,CLONING and other experiments on the human life and nature are in active development in this age of highly advanced technology. These developments offer many marvels as science expands its growing ability to improve on nature.
This high tech baby making involves removing eggs from a female them outside the body with sperms from a male and then putting them back into a uterus to grow.
In the Kotulak and Gorner report (19950 , it says that in Vitro fertilization (IVF) has made possible every permutation of egg, sperm and womb. Because of this, human embryos may be mixed and matched, frozen and stored and may become the subjects of property disputes and make definitions of modern parenthood fuzzy. Through IVF , parents can now determine the sex and kind of children they want.
Scientists hugged the limelight ingenetic engineering in their campaign to put information about DNA to use quickly as possible in the treatment and prevention of human diseases
On January 17, 1994, by P.E. Dewitt were theworks of Dr. Francis Collins who leads a 15 year project at the U.S. National Institute of Health .The project is called the Human Genome Project which aims to draw the details of the human genome or the DNA . As reported DNA in theirhands has become both a blueprint and a drug, a pharmacological substance of extraordinary potency that can treat not just symptoms or diseases that cause them but also the imperfections in DNA that make people susceptible to a disease.
Four molecule “ Letters” called nucleotides – ADENINE (A), CYSTOSINE (C) , QUANINE (G) and THYNINE (T). By scanning a data base containing the complete sequence of letters , researchers could quickly end up at a particular gene’s front door.This process is used to locate defective or “ broken genes.” Once a “broken” gene is found , the next thing for the gene engineers is to come up with a strategy to replace bad nucleotide one letter at a time.
Cloning is duplicating a human embryo where the cells are simply copied with their genes intact. It seems like a simpleprocess; in fact , agricultural, researchershave used it to clone embryos from cattle, pigs, and other animals for more than a decade now
Dolly (5 July 1996 – 14 February 2003) was a female domestic sheep, and the first mammal to be cloned from an adult somatic cell, using theprocess of nuclear transfer. She was cloned by Ian Wilmut, Keith Campbell and colleagues atthe Roslin Institute near Edinburgh in Scotland. Shewas born on 5 July 1996 and she lived until the age of six. She has been called "the worlds most famous sheep" by sources including BBCNews and Scientific American. The cell used as the donor for the cloning of Dolly was taken from a mammary gland, and the production of a healthy clone therefore proved that a cell taken from a specific part of the body could recreate a whole individual. On Dollys name, Wilmut stated "Dolly isderived from a mammary gland cell and we couldntthink of a more impressive pair of glands than Dolly Partons".
Zone Pellucida – strip away an outer coating that is essential to development. Related to ethical issues, Many scientists and physicians strongly believe that it would be unethical to attempt to clone humans . With so many unknowns concerning reproductive cloning, the attempt to clone humans at this time is considered potentially dangerous and ethically irresponsible.
If both members of a gene pair are dominant, the individual will manifest the trait determined by the genes. If one dominant and the other is recessive, the individual will show the form of the trait determined by the dominant gene but will also carry the recessive gene, which may be expressed in a different way as a trait in the offspring. A recessive form of the trait will be expressed only if the genes contributed by both parents are recessive. The genes determining eye color, for example, act in a pattern of dominance and recessiveness. Blue eyes are recessive. Thus, for a child to be blue-eyed, both parents must be blue-eyed, or if one parent is brown- eyed parents can produce a blue-eyed only if both carry a gene for blue eyes.
For example, brown hair is a dominant trait overblonde hair. So if someone inherits a blonde hairgene from the mother and a brown hair gene fromthe father, they will have brown hair. The dominantallele for brown hair will override the blonde hairallele.Recessiveness A recessive trait is which requires two copies of the gene to show up. For example, blonde hair is recessive, so it will only be present in the child if both parents donate a blonde hair allele. This is sometimes called a double recessive.
Dominant Gene Recessive GeneBrown eyes Blue eyesDark or brunette hair Light, blond, and red hairCurly hair Straight hairNormal hair BaldnessNormal color vision Color BlindnessNormal hearing Congenital deafnessNormal coloring Night blindnessImmunity to poison ivy Susceptibility to poison ivyNormal blood Hemophilia – failure of blood to clot
We cannot tell what genes a person has inheritedsimply by looking at him. Looking at a person tells us his phenotype or genetic inheritance as noted in his observable characteristics. The person’sgenotype includes all genetic characteristics, seen and unseen, dominant and recessive. A person who has a dominant gene for brown skin and recessive gene for fair skin, for example, has a phenotype (appearance) of brown skin but a genotype (genetic makeup) of brown skin with a recessive gene for fair skin.
Similarities between organisms of any one kind are determined by heredity.Individuals of the same family have similar genes and traits . The reason is that each parent contributes half of his or her genes to his or her children. Some of the genes of a brother and sister are sometimes identical . So too , are some of the genes of parent and child.
1. Heredity has an important influence in determining intelligence 2. Environment has substantial effects on intelligence 3. Both heredity and environment play a profound role in a person’s score on intelligence test. Inheritance of Emotionality
Male and female chromosomes appearthe same when examined under themicroscope, except pair number 23, thesex chromosomes . The first 22 pairs arecalled Autosomes. Pair 23 determines thesex of the individual and carries genes forcertain traits the are called “sex – linked”.
a man marries a womanXHxh xHyH XH YHXH XHXH XHYHXh XhXH XhYH
Heredity and maturation do not mean the same thing. Heredity , as we have seen is the directionand pattern given by the genes to growth and development . Maturation is the completion of growth and development withinthe organism, the unfolding of an individual’s inherent traits or potentials.
Maturation is not the same as learning, sincechanges due to maturation are determined byheredity. For example , a newborn baby cannotlearn to walk, no matter how much instruction heis given. Only when his body structure hasdeveloped sufficiently due to maturation can betaught to walk.
The development of language following shortlyafter birth is achieved in the kind of orderlysequence that characterizes motor developmentin the average child. A great deal of learning goeson before a child utters his first word.
Human learning cannot be accounted for solely in terms of maturation but learning does take place most efficiently when the environmentalstimulation is keyed to the degree of maturation of the individual. A child can learn to read mostefficiently if he is given instruction in reading at a time when he has achieved a sufficient degree of maturation.
Environment includes all the conditionsinside and outside an organism that in any way influence its behavior , growth , development or life processes except the genes.
The external physical environment is made up of all the many things in the world that affect us directly ( as food does) and all the things that stimulate our sense organs (sight and sounds do).
The social environmentincludes all the human beingswho in any way influence us.All these social influencesoccur because as humanbeings , we must learn to livein the world and cope with theexigencies of life. We areable to learn a great manykinds of adaptive behaviorthat fit us to changingenvironmental situations.
“Great Qualities are partly the gift of God, partly the result of good training and effort” - Anonymous