• Biology

    COENZYMES

    Enzymes may be simple proteins or complex enzymes. A complex enzyme contains a non-protein part, called a prosthetic group (co-enzymes). Coenzymes are heat stable low molecular weight organic compound. The combined form of protein and the co-enzyme are called as holo-enzyme. The heat labile or unstable part of the holo-enzyme is called as apo-enzyme. The apo-enzyme gives necessary three-dimensional structures required for the enzymatic chemical reaction. Co-enzymes are very essential for the biological activities of the enzyme. Co-enzymes combine loosely with apo-enzyme and are released easily by dialysis. Most of the co-enzymes are derivatives of vitamin B complex group of substance. One molecule of the co-enzyme with its enzyme is sufficient…

  • Biochemistry

    Krebs (Citric Acid) Cycle

    It is also known as TriCarboxylic Acid (TCA) cycle.  In prokaryotic cells, the citric acid cycle occurs in the cytoplasm; in eukaryotic cells, the citric acid cycle takes place in the matrix of the mitochondria. The cycle was first elucidated by scientist “Sir Hans Adolf Krebs” (1900 to 1981). He shared the Nobel Prize for physiology and Medicine in 1953 with Fritz Albert Lipmann, the father of ATP cycle. The process oxidises glucose derivatives, fatty acids and amino acids to carbon dioxide (CO2) through a series of enzyme controlled steps. The purpose of the Krebs Cycle is to collect (eight) high-energy electrons from these fuels by oxidising them, which are transported…

  • Zoology

    KINGDOM PROTOCTISTA (UNICELLULAR EUKARYOTES)

    Protoctista is unicellular eukaryotes. Protozoa and diatoms and algae are included in it. They have membrane-bound organelles such as nucleus with chromosomes enclosed in the nuclear membrane, mitochondria, chloroplast (in photosynthetic protoctists only), Golgi bodies and endoplasmic reticulum. Mitochondria are the respiratory organelles. Protoctists are either photosynthetic, parasitic or saprotrophic. For locomotion, protoctists may have cilia or flagella (Fig.) having 9 + 2 microtubules unlike those of bacteria, which have the 9 + 1 arrangement of microtubules. They reproduce both asexually and sexually. Some protoctists are beneficial to humans while others are harmful. Classification of Protoctista The kingdom Protoctista includes – 1. Phylum Protozoa which has the following four classes…

  • Biochemistry

    Meiosis

    Meiosis is the type of cell division by which gametes (eggs or sperm) are formed. It involves two divisions and results in four different daughter cells that have 23 chromosomes. This ensures that, when an egg and a sperm unite during fertilization, the resulting embryo will have 46 chromosomes – the normal number for a human. The first meiotic division is called Meiosis I, and the second meiotic division is called Meiosis II. Meiosis I Meiosis one is identical to the stages of mitosis. The only difference is that each stage ends with an “I” to identify it is occurring during Meiosis I. please click here for mitosis Meiosis II…

  • Biochemistry

    Genes are made of DNA

    Today we are so familiar with the fact that DNA is the genetic material that it comes as quite a surprise to learn that this idea was considered ridiculous by most biologists until the 1940s and that experimental proof that human genes are made of DNA was not obtained until the 1970s. Why did it take so long to establish this fundamental fact of genetics? At first, it was thought that genes might be made of protein The first speculations about the chemical nature of genes were prompted by the discovery in the very early years of the twentieth century that genes are contained in chromosomes. Cytochemistry, in which cells…

  • Biochemistry

    Genetics

    Genetics is a science, which deals with the study and understanding of heredity, evolution, development, ecology, molecular biology and forensic science. A German scientist by name Gregor Johann Mendel was a first founder of Genetics, hence he is also known as the father of genetics. He first demonstrated the inheritance of traits in pea plants and later it was referred to as a Mendelian inheritance. The main concept behind studying genetics are: It explains how the traits are passed from parents to their It explains how the traits are passed from parents to their offsprings. It also explains about the gene and the number of chromosomes present in an individual…