Heredity in Living Organism

We need two things before we can start to build a house:
1. a plan of the house
2. a supply of building materials

The plan is needed because it tells us how and where to arrange the building materials. In the same way, when a new organism is built, a plan and building materials are also needed. 

The plan necessary to build a living organism is found inside the nuclei of its cells. The plan for building a house consists of lines drawn on a large sheet of paper. The plan for building a living organism consists of chemicals called genes. Genes instruct the body to make proteins. Proteins determine the shape of the body and how it behaves. Each gene controls the production of one particular protein, or occasionally a group of proteins. These genes are joined together to make long strands called chromosomes which are extremely small. 

Chromosomes and genes are made of deoxyribonucleic acid (DNA) which is a kind of plan showing how the body is to be built. It is often called the blue print for life - a blue is a kind of plan. Every cell in a living organism contains a copy of this plan. 

When cells divide, the DNA first copies itself. A copy of this plan is passed from one generation to the next. This is the reason we inherit characteristics  from our parents. 

Copying Genes

Every time a new cell is made in the body of an organism, the DNA is copied so that each new cell has its own identical copy of all the genes. The structure of the DNA molecule makes the genes easy to copy. A DNA strand separates down the middle, rather like the two halves of a zip fastener coming apart. Spare chemical bases then join up with the matching pairs on the separated strands. As a result, one strand of DNA makes two identical new strands.

Growth and Cell Division 

All living things grow from a fertilized egg-cell. The only way for the organism to grow is for this fertilized egg cell to divide into two, then four, eight, sixteen cells, and so on, until the new organism may contain millions of cells. 

This Is Natural Way To Divide The Cell Into Two

Stages of Cell Division As Shown In The Above Image:

1. Animal Cell About To Divide

2. The Nucleus Divides First

3. The Daughter Nuclei Separate And The Cytoplasm Pinches Off Between The Nuclei

4. Two Cells Are Formed

Each time a divides, the plans for making the organism are passed on to the new cell. Therefore, copies of the chromosomes and genes are made so that the plan is available in the new cells.

What Is Mitosis

In simple words we can define mitosis is a part of the cell cycle in which chromosomes in a cell nucleus are separated into two identical sets of chromosomes, and each set ends up in its own nucleus. When a cell is not dividing, we cannot see the chromosomes with an ordinary microscope. But when a nucleus starts to divide, the chromosomes can be seen as double threads. They show up quite clearly if the nucleus of the cell is stained with a special chemical dye. The chromosomes must make copies of themselves before the nucleus divides into two. 

About Affluenza - What is Affluenza

What is Affluenza?

At present there are many terms which are beyond the understanding of common man. Such one term is affluenza which means a psychological illness supposedly affecting rich young men. In other words, it is a general feeling of discomfort, illness, or unease whose exact cause is difficult to identify. Its symptoms may be a lack of motivation, feelings of guilt, and a sense of isolation. It is a term usually used by critics of consumerism which means the protection or promotion of the interests of consumers.

The following information may help you better understand it:
i. It is considered to have been used for the first time in 1954 but it gained legs as a concept with a PBS documentary of the same name and the subsequent book, Affluenza:
The All-Consuming Epidemic (2001).
ii. These works define affluenza as "a painful, contagious, socially transmitted condition of overload, debt, anxiety, and waste resulting from the dogged pursuit of more."
iii. The term "affluenza" has also been used to refer to an inability to understand the consequences of one's actions because of financial privilege, notably in the case of Ethan Couch.
iv. The term was used by a psychologist testifying for the defense during the sentencing phase of Couch's trial in juvenile court.
v. The expert argued that Couch's wealthy parents had coddled and pampered their son into a sense of irresponsibility which is a condition the expert termed "affluenza" to the point that Couch never developed a sense of right and wrong, or suffered any repercussions for bad behavior.
vi. The experts argue that affluenza causes overconsumption, "luxury fever," consumer debt, overwork, waste, and harm to the environment.
vii. The American Psychiatric Association does not recognized affluenza as a medical diagnosis malaise , and its invocation during Couch's trial attracted backlash from some medical experts and families of the four people killed in the crash. 
viii. The Diagnostic and Statistical Manual of Mental Disorders, published by the association, is widely used by mental health professionals and makes no mention of affluenza. Dr. Jeffrey Metzner, a forensic psychiatrist and clinical professor at the University of Colorado at Denver, said there are some similarities to the clinical diagnosis of narcissistic personality disorder. A person with that disorder feels entitled and doesn't care about other people's needs, he said. But he noted that U.S. law doesn't recognize narcissism as a legitimate defense.

Video Link Giving Information About Affluenza
Video Link 1

Doctors Planted A Man's Severed Hand in His Leg in China

Beijing China: Doctors in China after a historic operation managed to keep the hand alive by joining it to the leg of the same man who sustained severe injuries and then fitted it back after one month when his deep wounds were healed. This operation was performed in the capital of Hunan Province of Changsha China. According to the details given by the factory workers ' Zhu ' left hand was badly cut in the machine spinning blades . He was taken to Xiang local hospital for treatment but the wound was so serious that it needed some time to completely heal the wounds before the major operation to reconnect the severed hand to arm of the victim. However, if the doctors has waited, the hand of the injured man would have been lost due to the lack of blood circulation in the hand. So doctors planted his dismembered hand in his calf so that blood circulation could be maintained. After one month and 10 hours his hand was successfully taken out from the leg and reconnected to his arm by the doctors. According to local media the patient is now able to move his fingers on their hands , but it will take a few more days to be able to fully use his as normal.

Nervous System - For Students

What Are the Nerve Cells and Nerves

All nervous system from those of the simplest multicellular animal, to the human body, are made up of cells whose job is to carry 'messages', called nerve impulses, to and from all parts of the body. Like all other cells, a nerve cell or neuron has a nucleus and cytoplasm. Each neuron has several 'inputs' called dendrites, along which nerve impulses travel into the cell. Leading out from the cell, the cytoplasm forms a single long fibre, called the axon. From the axon impulses travel out to another nerve, or to a muscle or some other cell. Axons can be tiny, but the longest runs from the spinal cord down to your toes, and can be up to one metres long. It can take less than a fiftieth of a second for an itch signal to travel from your big toe to your brain.

Sensory Nerves

Nerves are bundles of axons or nerve fibres. There are two types of nerves. Sensory nerves carry messages to and from the skin and other sense organs.

Simple Definition:

1. Sensory neurons are nerve cells that transmit sensory information (sight, sound, feeling, etc.). They are activated by sensory input, and send projections to other elements of the nervous system, ultimately conveying sensory information to the brain or spinal cord.

Motor Nerves

Motor nerves communicate with the muscles, making them contract and relax so that we can move.

Synapses

Neurons do not touch one another. There are gaps between them called synapses. Messages cross the gap between one neuron and the next with the help of a chemical.

What is the Central Nervous System

Spinal Cord

Human and other vertebrate animals have a single tubular nerve cord, called the spinal cord. It is safely protected by the vertebrae, the bones of the backbone or spines. The brain is an enlarged and very complicated swelling on the end of the spinal cord. Together, the brain and spinal make up what is we call the central nervous system.

The central nervous system has many nerves branching from it. The human brain not only coordinates many activities in the body, it is also capable of remembering and thinking. A complex nervous system allows an animal to behave in a complex way. In fact, humans have the most highly developed nervous system and behaviour of any animal.