Biology Notes

Bone Marrow Bone marrow is the tissue comprising the  middle  of  massive  bones. It is the  region   wherein  new blood cells are produced. Bone marrow  contains  two  styles of  stem cells: hemopoietic ( that could  produce blood cells) and stromal ( that can  produce  fat , cartilage and bone). There are two  sorts of  bone marrow:  purple  marrow (also  known as  myeloid tissue) and yellow marrow. Red blood cells, platelets and  most  white blood cells  rise up  in  crimson  marrow;  some  white blood cells  broaden  in yellow marrow. The  color  of yellow marrow is  because of  the much  better   number  of  fat  cells. Both  forms of  bone marrow contain  severa  blood vessels and capillaries. At birth, all bone marrow is  crimson . With age,  increasingly ...

Structure Of Enzyme Structure Of Enzyme: Enzymes are complex organic compounds partly or completely composed of proteins. According to their composition the enzymes are of two types. Simple protein enzymes: These are purely proteineous enzymes, no other group is attached with these enzymes. Conjugated Enzymes: These enzymes contain a non-protein group. These enzymes are also called holoenzymes. These enzymes are explained by Euter in 1932. The hollow enzymes are of two parts. 1. Apoenzymes; This is the protein part of enzyme. 2. Prosthetic group: This is the non protein part of enzyme. Based on prosthetic group the holoenzyme are of two types. a) with inorganic ions: When the prosthetic group is an inorganic ion, it is called co factor, such as magnesium, calcium k, Mn, etc. e.g Phosphatase,Carboxylase, Peptidase, Amidase etc. b) With Organic Compound: When the prosthetic group is an organic compound, the organic compound is called co-enzyme. It ...

Endoplasmic Reticulum (Structure and Function). Endoplasmic reticulum  It is a network of channels present throughout the cell most of these channels are continuous with the plasma membrane toward the outer side on their inner side. They are in contact with the nuclear membrane.   The entire system of channel is called endoplasmic reticulum.  Morphologically  Endoplasmic reticulum occurs in three forms. 1. Cisternae:  The channels of Endoplasmic Reticulum are composed of spherical or tubular membranes are called cisternae. (pancreas, notochord,brain).  2. Vesicles the vesicle are oval membrane-bounded vascular structure having the diameter of 25 to 500 micrometre.  3.Tubules The tubules are branched structure forming the reticular system along with the cisternae and vesicle. Types of Endoplasmic Reticulum:   There are two types  1. Granular or rough endoplasmic reticulum.    Ri...

Lysosomes (Structure and Function) ( Lysosomes in Urdu) lysosomes The word lysosome is taken from Greek word (Lyso= digestive,splitting+ soma=body) so, they are concerned with breaking activities. These are present in most animals and few plants cell . They are absent in bacteria and mature mammalian erythrocyte. Structure Lysosome are 0.5 to 0.2 micro metre in size. They are bounded by a single membrane, this membrane forms a simple check and  this sac contains several hydrolytic enzymes like acid phosphatase. According to a recent estimate a lysosome contain up to 40 types of hydrolytic enzymes. All lysosomal enzymes are acid hydrolysis optimally active at the pH 5 maintained within lysosomes. Formation They are formed by Golgi bodies. Kinds of Lysosomes Morphologically there are four types.  The first is primary lysosome and other three (heterophagosome, autophagosome And residual bodies) have been grouped together as secondary lysosome. Disease...

Cell Wall The outermost boundary in most of the plant cell is cell wall. It is present in plants, Fungi, bacteria and absent in animals. Cell walls have different structures and chemical compositions. Cell wall is non living and secreted by the protoplasm . Formation of cell wall takes place at telophase of cell division.        In a young cell, the cell wall is thin and delicate, but in large cell, it becomes thick and strong. The cell wall consist of three layers. i) Primary Wall It is found around a young plant cell on the outer side of Cell Membrane. The primary wall is very thin, elastic and capable of great extension. It consist of cellulose l, hemicellulose, pectin and sugar compounds. The cellulose molecules are arranged in a criss cross manner. ii) Secondary Wall: It is formed on the inner surface of the primary wall. It is much thick and rigid. It is composed of inorganic salts, silica, waxes, cutin, lignin, etc iii) Middle Lamel...

Action Of Enzyme (Mechanism Of Action of Enzyme) The specificity of enzyme is very important in the metabolism of living system its catalytic activity is restricted to a reaction or a group of related reaction. For example: Urease is specific for urea substrate.  Enzymes combined with their substrate and form Complex, called enzyme substrate Complex. Enzymes have an active site with which a substrate molecule is attached. The Action Of Enzyme depends upon the structure of enzyme.  It has three dimensional structure. It has an active site which is of a particular size and shape. This active site is attached with Substrate.   Two theories have been proposed about the action of enzyme. I) Key Lock Theory: This theory has proposed by Fischer in 1898, and it has improved by Paul filder and D.D woods. According to this theory the enzyme is attached with specific substrate by its active site to form an association this association is like a lock and key ...

The Enzymes What are Enzymes? Enz ymes are the compounds which are partly or entirely proteineous in nature, considered as bio catalyst,and increase the rate of biochemical reaction. These are specific for that reaction and not consumed in the process.   The term enzyme was used by a scientist Friedrich kuhne in 1878. summer in 1926 isolated urease enzyme . It was a significant breakthrough in the study of enzymes. By this Discovery protein nature of enzyme was known.   Properties of enzymes     The characteristics of enzymes are as follows  i) Small amount: Enzymes are required in very small amount in the biochemical reaction as compared to the amount of substrate. ii) Remain unaffected  : Enzymes remain unaffected in the reaction in which they are used as biocatalyst these are not consumed during the reaction and can be used again and again.   iii) specific for reaction  Enzymes are specific for a particular reaction or...