• Q & A

    Q & A on Cell Structure

    Q: What is cell theory? Cell theory asserts that the cell is the constituent unit of living beings. Before the discovery of the cell, it was not recognized that living beings were made of building blocks like cells. The cell theory is one of the basic theories of Biology. Q:  Are there living beings without cells? Viruses are considered the only living beings that do not have cells. Viruses are constituted by genetic material (DNA or RNA) enwrapped by a protein capsule. They do not have membranes and cell organelles nor do they have self-metabolism. Q:  In 1665 Robert Hooke, an English scientist, published his book Micrographia, in which he…

  • A level biology

    What is the function of Golgi body?

    The Golgi body is actually a pile or stack of membranous structures called cisternae. The numbers of cisternae in a single stack vary between 6-8. In some protists, however, the number could extend up to 60. The Golgi bodies are found in both plant & animal cells. The cisternae of Golgi body have four structural components i.e., cis-Golgi, endo-Golgi, medial-Golgi and trans-Golgi. The vesicles extending from endoplasmic reticulum fuse with the network. These vesicles then enter the stacks of Golgi body and finally reach the trans-Golgi. The different regions of Golgi apparatus contain different types of enzymes. These enzymes have certain specific tasks assigned to them. Vesicles leave the Golgi…

  • Biochemistry,  Q & A

    Q & A ON CELL RESPIRATION

    1. How do cells obtain the energy they need to function? Cells obtain energy for their metabolic reactions from breaking down organic molecules with a high energy content. This energy is mostly stored as ATP molecules. The process of obtaining energy in order to produce ATP molecules is called cellular respiration. 2. What compound is phosphorylated for ATP formation? What is the resulting compound when ATP releases energy? ATP, or adenosine triphosphate, is formed after the binding of one phosphate molecule (phosphorylation) to one ADP (adenosine diphosphate) molecule. This is a process that stores energy in the produced ATP molecule. When ATP provides energy to the cellular metabolism, it releases…

  • Genetics,  Q & A

    Q & A ON CELL CYCLE AND CELL DIVISION

    Q 1. Define cell cycle Ans. The sequence of events by which cell duplicates its genome, synthesis of other constituents of the cell and eventually divides into two daughters cell. Q2. Name the phases of cell cycle Ans. A) Interphase B) M Phase Q3. What is the G1phase of the interphase? Ans. The G1 phase Corresponds to interval between mitosis & initiation of DNA replication. Q4. Which phase follows the S phase in the cell cycle? Ans. G2 Phase Q5. What is mitosis? Ans. Cell divides equally to produce identical daughter cell so that they receive an equal number of chromosomes as that of its parents cell.  Q6. What is meiosis? Ans. It…

  • Q & A

    Q & A ON REPRODUCTION IN ORGANISMS

    Q1. What is life span? Ans: Life span is the period from birth to natural death of an organism. Q2. Define clone. Ans: The individuals that are morphologically and genetically similar to the parent are called clone. Q3. Mention the different means/ methods of asexual reproduction with example. Ans:  Cell division – Protista, Monera Binary fission – Amoeba, Paramecium Budding – Yeast Zoospores (microscopic motile endogenous spores) – aquatic fungi, chlamydomonas Conidia (microscopic immotile exogenous spores)- pencillium External buds – hydra Internal buds like gemmules – sponges (spongilla) Q4.Unicellular organisms are immortal. Justify. Ans: Single celled organisms like amoeba & bacteria reproduce by cell division and there is no natural…

  • Biochemistry,  Cell biology

    OXIDATIVE PHOSPHORYLATION, ELECTRON TRANSPORT CHAIN

    OXIDATIVE PHOSPHORYLATION It is the main source of energy of our cell. Takes place in Mitochondria. Movement of protons through inner mitochondrial membrane leads to ATP production DEFINITION Oxidative phosphorylation includes the coupling of the oxidation of NADH or FADH2 by the respiratory chain with the synthesis of ATP via gradient of protons across the inner mitochondrial membrane. ELECTRON TRANSPORT CHAIN An electron transport chain consists of a properly arranged & oriented set of electron carriers transporting electrons in a specific sequence from a reduced nicotinamide coenzyme (NADH) or a reduced flavin prosthetic group (FADH2) to molecular O2. The inner mitochondrial membrane carries an electron transport chain called the mitochondrial respiratory chain,…

  • Biochemistry

    CELLULAR RESPIRATION

    Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP) and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process as weak so-called “high-energy” bonds are replaced by stronger bonds in the products. Respiration is one of the key ways a cell gains useful energy to fuel cellular activity. Cellular respiration is considered an exothermic redox reaction. The overall reaction is broken into many smaller ones when it occurs in the body, most of which are redox…

  • 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…

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