BIOLOGY

Short Note On Nucleus

THE NUCLEUS The nucleus is the largest and most prominent organelle in the animal cell. Almost all eukaryote cells have a nucleus — red blood cells in mammals and phloem cells in plants are an exception. Every nucleus is surrounded by a nuclear envelope. This consists of two membranes that are separated by a gap of 20 to 40 nm. ...

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Cell Membrane Structure, Functions and Chemical Composition

CELL MEMBRANE Plasma membrane or cell membrane is the outer most boundary of the cell. However, in most plant cells, it is covered by a cell wall. Structure Under electron microscope it is a bilayered structure. This structure is delicate and elastic. It has some ability to repair itself. Models of Cell Membrane Structure: There are two models of cell ...

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Difference Between Plant and Animal Cells

ANIMAL AND PLANT CELLS HAVE SOME FEATURES IN COMMON In animals and plants each cell is surrounded by a very thin plasma (cell surface) membrane, which is too thin to be seen with a light microscope. Cell has a nucleus which is a relatively large structure. The deeply staining material in the nucleus is called chromatin and is mass of ...

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Enzyme Quiz

ENZYMES MCQs A metabolic pathway is a: (A) Route taken by chemicals through a solution (B) Sequence of enzyme controlled reactions (C) Route taken by a single particular enzyme (D) Routes taken by all enzymes in a specific medium Energy must be added for a chemical reaction to start. This is energy of: (A) Activation (B) Entropy (C) Enthalpy (D) ...

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Properties of Enzymes, Co-factor and Enzyme Action

FACTS ABOUT ENZYMES The catalytic activity of an enzyme is due to active site. It is a small portion of enzyme consisting of few amino acids. The enzyme and its substrate react with each other through active sites. The active site is a three dimensional cavity bearing a specific charge. Most of the enzymes have a non-protein part known as ...

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Types of Enzyme Inhibition

HOW INHIBITORS HELP TO CONTROL METABOLISM? Many metabolic pathways are self-controlling. When a substance is needed, a particular pathway is activated to produce it. When enough has been produced, the pathway is deactivated. This happens because some enzymes in a metabolic pathway are inhibited by the end product. When the product is once more in short supply, the inhibition is ...

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Lock and Key Theory & Induce Fit Theory

 ENZYMES Any molecule that increases the rate of a chemical reaction without being used up during that reaction is catalyst. Biological catalysts are primarily protein molecules known as enzymes. Enzymes control reactions in living cells. An active enzyme may speed up a particular reaction, but living organisms do not need all reactions to be going at the maximum rate all ...

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Nucleic acid, DNA and RNA

NUCLEIC ACIDS  Nucleic acids are so called because they are slightly acidic and present mainly in the nucleus. The two types of nucleic acid, DNA and RNA, both contain carbon, hydrogen, oxygen, nitrogen and phosphorus. Nucleic acids are polymers of nucleotides. Nucleotides are the building blocks of nucleic acids. A nucleotide consists of three units: A sugar (ribose or deoxyribose), ...

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Proteins, Characteristics, Structure and Types

THE PROTEINS Proteins are polymers of amino acids, the compounds containing carbon, nitrogen, oxygen and hydrogen Proteins are the most abundant organic compounds in cells. They are over 50% of total dry weight of the cell. About 170 types of amino acids are present in the cells and tissues. Of these, about 25 types are involved in the formation of ...

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Genetic Cloning Procedure and Importance of Cloning

CLONING: Cloning is a technique in which identical copies are produced by asexual means. A cell or individual and all its asexually produced off springs. EXPLANATION: All members of a clone are genetically identical except when a mutation occurs. In 1997 scientists in Scotland succeeded in cloning a sheep (dolly). Other mammalian species (mice and cows) have since been cloned. ...

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