• Diffusion
    Cell biology,  O level biology

    Diffusion – Movement of Substances

    Table of Contents Diffusion Defination Diffusion is the net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement. What is Diffusion  The molecules of a gas such as oxygen are moving about all the time. So are the molecules of a liquid or a substance such as sugar dissolved in water. As a result of this movement, the molecules spread themselves out evenly to fill all the available space (Figure). Diffusion This process is called diffusion. How are substances transported by diffusion? One effect of diffusion is that the…

  • Cell biology,  Video Notes

    CELL JUNCTION

    The cells of epithelial and other tissues are held together by various types of cell junctions, that can be categorized into 3- main groups – (I) Adhesive junctions The cells of epithelial tissue and even cardiac muscles are difficult to separate due to the presence of adhesive junctions. Such junctions are of 2-types (a) Adherens junctions (b) Desmosomes (a) Adherens junctions (Zonulae adherens) – Such junctions are common in the epithelial living of intestine where they form a ‘belt’ encircling the apical portion of cells and binding them to surrounding cells. Such junctions are formed by calcium -dependant-linkages of cadherin (protein) molecules and cement the cells for providing a pathway…

  • Biochemistry,  Cell biology

    BLOOD CLOTTING (HAEMOSTASIS)

    The clot or coagulam is a dark -reddish-brown ‘scum’ formed mainly by a network of threads in which dead or damaged blood elements are trapped. It is the property of plasma. Normal blood clotting time is 3−10 min. The clot inside the blood vessels is called a thrombus. A moving thrombus is called embolus. In haemophilia (a sex-linked disease) the blood clotting is delayed. According to Macferlane hypothesis, there are 13−factors responsible for blood clotting (or coagulation). The 4−factors are primary and 9−factors are accessory for this process. Primary factors Fibrinogen Prothrombin Thromboplastin (Thrombokinase) Calcium ions  The first 3−factors are proteinaceous in nature. The Prothrombin (II factor) is synthesized in…

  • types_of_carbohydrates
    Biochemistry,  Biology,  Cell biology

    CARBOHYDRATES

    Table of Contents Carbohydrates are classified into two types on the basis of molecular weight. Micromolecules – Monosaccharides and Oligosaccharides (Including Disaccharides) Macromolecules – Polysaccharides The micromolecules have the molecular weight of < 1000 Daltons whereas themacromolecules have > 1000 Daltons as molecular weight. Why do we need carbohydrates in our food? Carbohydrates provides about 50-70% of total energy. We need average carbohydrate requirement in an adult is ~ 400g per day. Essential elements in the constitution of carbohydrate – C. H. O General Formula – *Cx (H2O)y (Containing more than one-OH groups). The polyhydroxy aldehydes or ketones can also be called as saccharides 80% of the dry weight of…

  • Biochemistry,  Cell biology,  Q & A

    What is the function of the cell membrane?

    The cell membrane is otherwise called a Plasma membrane. It may be defined as the thin, elastic, semipermeable living membrane that serves as a boundary for the Cytoplasm. The Cell membrane is made up of glycoproteins and phospholipids. The Functions of the Cell membrane are as follows: Cell membrane or Plasma membrane is a semipermeable membrane present around the Protoplasm. It acts as a boundary to the cell. It gives a definite shape to the Cell. It gives Mechanical support to the Cell. It protects cell contents. It regulates the exchange of materials into and out of the cell. The Sites for cell recognition are located on the surface of the Plasma…

  • 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. Transport chain called the mitochondrial respiratory chain, which forms the final path for electron…

  • Cell biology

    ANIMAL TISSUE

    As mentioned earlier, cells are the smallest units of life. In complex organisms, cells group together with one another based on similar structure and function to form tissues. Tissues provide the numerous functions of organs necessary to maintain biological life. This lab exercise seeks to introduce the various tissues found in the human body and to familiarize you with their composition and function. The study of tissues is called histology and is important to the understanding of how the human body is able to function as a unit. Classifications of Tissues The human body is composed of four basic types of tissues; epithelium, connective, muscular, and nervous tissues. These tissues…

  • Cell biology,  MCQ

    HOMEOSTASIS

    Q1) The relationship between mineral and water is know as: A) Ascent of sap B) Osmoregulation C) Excretion D) All of them Q2) The cell sap having solution of: A) One types B) Two types C) Three types D) Four types Q3) The water potential not more than: A) 1 B) 100 C) 1000 D) 10 Q4) The shrinkage of protoplasm is know as: A) Normal B) Turgid C) Plasmolysis D) Deplasrnolysid  Q5) The homeostasis means: A) Osmoregulation B) Excretion C) Both of these D) None of these Q6) In plant temperature maintained by: A) Osmosis B) Diffusion C) Inhibitions D) Transpiration Q7) Transpiration is take place through: A) Stomata…

  • Cell biology,  MCQ

    EXCRETION

    Q1) Unwanted substances excreted by plants are: A) Uric acid B) Ammonia C) Latex D) Urea Q2) Solid crystalline substance called uric acid excreted as Solid waste in: A) Insects B) Planty helminthes C) Vertebrates D) Annelids Q3) Nephrons are connected with: A) Respiratory system B) Nervous system C) Circulatory system D) Excretory system Q4) Which of  the following substance is completely reabsorbed from the filtrate in the renal tubule under the normal condition: A) Glucose B) Urea C) Water D) Salt Q5) The flame cell system is found in: A) Cockroach B) Earthworm C) Planaria D) Vertebrates Q6) Conical Projections in the I.S of kidney’s is called: A) Nephrons B)…

  • 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,…