General physiology of cell and cell membrane .pptx

This presentation tells about
the basic structural and functional unit of life which is cell.

1. General physiology

2. Cell The cell is basic unit of life. Cell is the structural and functional unit of life for all living beings. Each cell contains : 1. Water 2. Electrolytes 3. Proteins 4. Lipids 5. Carbohydrate

3. COMPONENTS OF CELL

4. WATER 70 – 75 % of cell is made up of water. It contains dissolved chemicals and suspended particles. It helps in the transport of substance from one part of the cell to another. All the chemical reactions occurring in the cell take place in solution in water.

5. ELECTROLYTES Major electrolytes include potassium, magnesium , sodium , phosphate, sulphate, bicarbonate, chloride, and calcium. They are dissolved in water. They are necessary for : 1. Cellular control mechanism 2. Regulation of water balance 3. Contraction and relaxation of muscles 4. Transmission of nerve impulses

6. PROTEINS THEY CONSTITUE 10-20% OF THE CELL MASS. THE ARE TWO TYPES : STRUCTURAL PROTEIN GLOBULAR PROTEIN STRUCTURAL PROTEINS : FORM CYTOSKELETON OF CILIA, AXONS, AND MITOTIC SPINDLE. PROVIDE Contractile mechanism for muscles. GLOBULAR PROTEINS : globular in structure. Made up of individual protein molecules.

7. LIPIDS They constitute 2% of cell mass. They are made up of phospholipids and cholesterol. They are insoluble in water. They form major constituents of the cell membrane. They are present in large quantities in fat cells.

8. CARBOHYDRATES They form around 1% of cell mass. They play a major role in providing nutrition to the cell. They present in extracellular fluid ( ECF) as glucose and are readily available for the cell. They are also stored as glycogen, which is used for providing energy to the body. 8

9. STRUCTURE OF CELL The cell is made up of two major parts : Nucleus Cytoplasm They covered by an envelope termed as Cell membrane

10. CELL MEMBRANE The cell membrane is a thin layer of membrane surrounding the cell. It covers both the nucleus and cytoplasm. It is semipermeable and is 7-10 nm thick. The membrane is principally made up of protein and lipids. Composition of cell Membrane Proteins 55% Phospholipids 25% Cholesterol 13% Carbohydrates 3%

11. The most accepted theory of the cell structure is fluid mosaic model proposed by Singer and Nicolson. The cell membrane is made up of two layers of lipids. It is made up of phospholipids and cholesterol. The hydrophobic portion of both these molecules occupies the centre of the membrane. The hydrophilic portion faces the surrounding water. The lipid bilayer is impermeable to water soluble substances such as ions and glucose. It is permeable to fat soluble substances such as oxygen and alcohol. 11

12. Function of lipids 1. Form the cell membrane 2. Selectively permeable , allow fat soluble substance to pass through them easily 3. Provide a framework for the arrangement of protein and carbohydrate molecules on the cell membrane 12

13. Protein They are globular masses floating in the lipid bilayer. They are mostly glycoprotein. The are of two types : 1. Integral protein 2. Peripheral prot ein INTEGRAL PROTEIN : Pass through the entire thickness of the membrane. They are closely associated with membrane lipid. PERIPHERAL PROTEIN : Are associated only to the surface. They maintain the cell shape and motility. 13

14. Function of protein Act as receptor Act as enzyme Act as carrier Act as pump Act as structural protein which provide framework for the cell. Form ion channels 14

15. Carbohydrates They are present on the outer surface of the cell. They are Glycoprotein (carbohydrate + protein) OR glycolipids (lipids + carbohydrate) Carbohydrate molecules form a thin layer throughout the surface of the cell membrane which is called glycocalyx. Act as receptor for binding hormones. Participate in immune reactions. Attach to glycocalyx of other cells. 15

16. MM

17. Nucleus Shape : spherical Covered by nuclear membrane Control centre of the cell It controls (A) chemical rxns occurring in the cell (B) reproduction of the cell It contains nucleolus and chromatin material. Mainly made up of water

18. Nuclear membrane Has two layers : (a) outer (b)inner The nuclear membrane has several thousand nuclear pores, allow low molecular weight substance to pass through them.

19. NUCLEOLI They are lightly stained structure in the nucleus. They synthesize and store RNAS AND PROTEINS.

20. CYTOPLASM The cytoplasm contains a fluid portion of the cell in which cell organelles are present. The fluid portion is called cytosol. Cytoplasm contains the cellular organelles : (A) MITOCHONDRIA (B) ENDOPLASMIC RETICULUM (C) RIBOSOMES (D) LYSOSOMES (E) GOLGI APPARATUS (F) CENTROSOMES

21. MITOCHONDRIA It is the powerhouse of the cell. It is present in the cytoplasm. It is sausage shaped structure It has two membranes (a) an outer membrane (b) an inner membrane The inner membrane is folded to form shelves called cristae. The inner portion of mitochondria is filled with matrix. The matrix contains dissolved enzymes required for kreb's cycle . They are self replicative. They produced in large numbers whenever extra energy is required. They contain large quantities of enzymes that convert food products to CO 2 and water by citric acid cycle . The energy liberated during the rxns is used to synthesis for high- energy molecules such as ATP ( ADENOSINE TRIPHOSPHATE) . 21

22. ENDOPLASMIC RETICULUM The endoplasmic reticulum is a network of tubular and flat vesicular structures interconnected with each other. The spaces between the tubules and the vesicles are filled with a watery fluid termed as endoplasmic matrix . The endoplasmic reticulum is of two types : 22 Rough endoplasmic reticulum Smooth endoplasmic reticulum They are with granular structures (ribosomes) on its outer surface. They are well developed in which cells actively involved in protein synthesis. They helps in the synthesis of proteins. They does not have ribosomes on its surface. It is found in abundance in Leydig cells and cells of the adrenal cortex( kidney) It is modified into skeletal and cardiac muscle to form sarcoplasmic reticulum. They help in (A) synthesis of lipids (B) Drug degradation (C) Glycogen metabolism (D) Control of calcium ion concentration

23. Ribosomes They are spherical particles found in both free and bound forms. They bound form is present on the outer surface on ER. Ribosomes are made up of RNA and proteins. They help in the synthesis of proteins. Free ribosomes synthesize cytoplasmic proteins such as haemoglobin and proteins found in peroxisomes and mitochondria. 23

24. GOLGI APPARATUS They resembles the smooth ER. It is made up of multiple layers of thin, flat vesicles lying near the nucleus. The Golgi Apparatus is a polarised structures with cis and trans sides. The Golgi Apparatus concentrates protein and polysaccharide. It helps in the synthesis of the carbohydrate portion of glycoprotein. It is the site of formation of lysosomal enzymes. 24

25. LYSOSOMES They are formed by the Golgi apparatus and are present throughout the cytoplasm. They are more acidic than the remaining parts of the cell because of the presence of H +. They are filled with hydrolytic enzymes. They help in the removal of unwanted, damaged substances and foreign bodies such as bacteria. 25

26. Peroxisomes They are similar to lysosomes formed from smooth ER. They contain oxidases and catalases. They cause breakdown of fatty acids by the process of beta oxidation. Oxidases generate and catalases break down hydrogen peroxide. Peroxisomes form the major site for oxygen utilisation in the cell. CENTROSOMES They are structure present near the nucleus. They are made up of structures called centrioles. They are two short cylinders arranged at right angle to each other. They are visible only during cell division. They control the steps of cell division. 26

27. Cytoskeleton The is a system of fibers that maintains the structure of cell. It permits the cell to change its shape. It helps in the movement of cell. Cytoskeleton is made up of : (A)Microfilaments (B) Intermediate filaments (C) Microtubules 27

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