• Cell biology

    THE CELL AND CELL THEORY

    Landmarks in the study of a cell Soon after Anton Van Leeuwenhoek invented the microscope, Robert Hooke in 1665 observed a piece of cork under the microscope and found it to be made of small compartments which he called “cells” (Latin cell = small room). In 1672, Leeuwenhoek observed bacteria, sperms and red blood corpuscles, all of which were cells. Much later, in 1831, Robert Brown, an Englishman observed that all cells had a centrally positioned body which he termed the nucleus. The cell theory In 1838 M.J. Schleiden and Theodore Schwann formulated the “cell theory.” Which maintains that: all organisms are composed of cells. cell is the structural and…

  • Biochemistry

    COMPONENTS OF THE CELL

    The major components of the cell are cell membrane cytoplasm nucleus Cell membrane (Plasma membrane) Each cell has a limiting boundary, the cell membrane, plasma membrane or plasmalemma. It is a living membrane, outermost in animal cells but internal to cell wall in plant cells. It is flexible and can fold in (as in food vacuoles of Amoeba) or fold out (as in the formation of pseudopodia of Amoeba) The plasma membrane is made of proteins and lipids and several models were of Life proposed regarding the arrangement of proteins and lipids. The fluid mosaic model proposed by Singer and Nicholson (1972) is widely accepted. According to the fluid mosaic model,…

  • 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…

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