Prakash World's

The cytoplasm of nearly all eukaryotic cells contains mitochondria ; especially abundant in cells and parts of cells that are associated with active processes. For example, in cardiac muscle, mitochondria surround the contractile elements . Hummingbird flight muscle is one of the richest sources of mitochondria known . Thus, from their distribution alone one would suspect that they are involved in energy production.  Multicellular organisms probably could not exist without mitochondria . Through oxidative phosphoryation mitochondria make efficient use of nutrient molecules . They are the reason that we need oxygen at all.  The double-membraned mitochondria create distinct compartments within the organelle , and are themselves very different in structure and in function.  Electron micrographs have revealed the three dimensional structure of mitochondria. Mitochondria in situ can be free in the cytoplasm or packed in among more rigid structures , ...

DNA   DNA, or deoxyribonucleic acid, is usually a double-helix and has two strands running in opposite directions . ( There are some examples of viral DNA which are single-stranded ). Each chain is a polymer of subunits called nucleotides (hence the name polynucleotide ) .  Each strand has a backbone made up of ( deoxy-ribose) sugar molecules linked together by phosphate groups . The 3' C of a sugar molecule is connected through a phosphate group to the 5' C of the next sugar . This linkage is also called 3'-5' phosphodiester linkage . All DNA strands are read from the 5' to the 3' end where the 5' end terminates in a phosphate group and the 3' end terminates in a sugar molecule .  Each sugar molecule is covalently linked to one of 4 possible bases ( A denine, G uanine, C ytosine and T hymine ). A and G are double - ringed larger molecules (called purines ); C and T are single - ringed smaller molecule...

  Antigen The immune system is the body’s defense against infectious organisms and other invaders . Through a series of steps called the immune response , the immune system attacks of organisms and substance that invade body system and cause disease . The immune system protects the body system from possibly harmful substances by recognizing and responding to antigens.   Antigens are substance (usually proteins ) on the surface of cells virus’s fungi or bacteria . Non living substances such as toxins, chemicals drugs and foreign particle (such as splinter) can be also antigens . The immune system recognizes and destroys substance that contains antigens. An antigen ( from antibody generating ) or immunogen i s a substance that prompts the generation of antibodies and can cause immune responses . In immunology , an antigen is the substance that binds specifically to the respective antibody. Antigens are usually proteins or polysaccharides...

An electroencephalogram (EEG) is a painless procedure that uses small, flat metal discs ( electrodes) attached to scalp to detect electrical activity in brain. Brain cells communicate via electrical impulses and are active all the time, even when we asleep . This activity shows up as wavy lines on an EEG recording. An EEG is one of the main diagnostic tests for epilepsy. An EEG may also play a role in diagnosing other brain disorders. Wave patterns Delta waves . Delta is the frequency range up to 4 Hz. It tends to be the highest in amplitude and the slowest waves. It is seen normally in adults in slow wave sleep . It is also seen normally in babies. Theta waves . Theta is the frequency range from 4 Hz to 7 Hz. Theta is seen normally in young children . Excess theta for age represents abnormal activity . On the contrary this range has been associated ...

Electrocardiogram, EKG or ECG :   An EKG is part of the initial evaluation of a patient who is suspected to have a heart related problem . Small sticky electrodes are applied to the patient's chest, arms and legs . Wires are used to connect the patient to an EKG machine . A technician records the EKG. The electrical activity created by the patient's heart is processed by the EKG machine and then printed on a special graph paper. This is then interpreted by physician. It takes a few minutes to apply the EKG electrodes, and one minute to make the actual recording. The EKG is extremely safe and there is no risk involved. Electrocardiography (EKG, ECG ) tracings show a characteristic pattern of electrical impulses that are generated by the heart. The different parts of an EKG tracing of a heartbeat are called the P wave , the QRS complex , the ST segment , and the T wave. The P wave is a record of the movement of ...

Neutron activation analysis ( NAA ) is a nuclear process used for determining the concentrations of elements in a vast amount of materials. NAA relies on excitation by neutrons so that the treated sample emits gamma-rays . It allows the precise identification and quantification of the elements , above all of the trace elements in the sample. The method is based on neutron activation and therefore requires a source of neutrons. The sample is bombarded with neutrons, causing the elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element are well known . Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the elements within it. A particular advantage of this technique is that it does not destroy the sample, and thus has been used for analysis of works of art and historical artifacts. Neutron Activation Anal...

Ultrasound is high frequency mechanical vibrations or pressure waves above a frequency the human ear can hear . Ultrasound uses sound waves above 20 KHz. Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes to aid in the diagnosis and treatment of patients. Ultrasound uses a pulse-echo technique of imaging the body. Pulses transmitted into patient and give rise to echoes when they encounter interfaces/reflectors caused by variations in the " acousitc impedence " between different tissues . Echo signals are amplified electronically and displayed on a monitor using shades of grey (from black to white), stronger reflectors = brighter shades of grey and appear white in an image . Those with no echoes will appear black , such as a full bladder . The ultrasound image ( sonographic / echographic) is based on mechanical oscillations of the crystal ...

Proteins are the " workhorse " molecules of life , taking part in essentially every structure and activity of life. They are building materials for living cells , appearing in the structures inside the cell and within the cell membrane . They carry oxygen, they build tissue , they copy DNA for the next generation - they do all the work in any organism. While many of the proteins are structural proteins , many are regulatory proteins called enzymes .  They contain carbon, hydrogen , and oxygen like the carbohydrates and lipids , but they also contain nitrogen and often sulfur and phosphorus. Protein molecules are often very large and are made up of hundreds to thousands of amino acid units. The 20 amino acids are combined in different ways to make up the 100,000 or so different proteins in the human body . Some of these proteins are in solution in the blood and other fluids of the body, and some are in solid form as the framework of tis...

Scope and methods of biophysics Biophysics is the branch of science concerned with the experimental and theoretical study of biological system using the background and concept of physics. It is a molecular science . It seeks to explain biological functions in terms of molecular structures and properties of specific molecules . The size of these molecules varies from small fatty acids and sugars to macromolecules like protein and elongated DNA molecules. These molecules , the sole building blocks of living organisms assemble cells, tissues, organs. Biophysics has been classified as: 1. Molecular Biophysics 2. Biophysics of cell 3. Biophysics of complex system  Molecular Biophysics It is concerned with the study of the structure and physiochemical properties of biologically functional molecules ; biopolymers, proteins and nucleic acids. Its objective is to disclose the physical mechanism responsible for the ...