Cells and its components(Anatomy) Easy explanation
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The document discusses the structure and components of human cells, highlighting the roles of the cell membrane, cytoplasm, and nucleus. It details various organelles such as the endoplasmic reticulum, Golgi apparatus, mitochondria, and ribosomes, along with their specific functions. Additionally, it explains the fluid mosaic model of the cell membrane and the importance of the cytoskeleton in maintaining cell shape and organization.
Cells and its components(Anatomy) Easy explanation
- 1. CELLS AND ITS COMPONENTS SWATILEKHA DAS (RN, MSN)
- 2. • CELL STRUCTURE • CELL MEMBRANE • CYTOPLASM • NUCLEUS
- 3. STRUCTURE OF A CELL Cell forms the structural unit of all tissues and organs of the body. Different cells perform different functions. e.g. nerve cell helps in conduction, cells of intestine help in absorption and muscle cell helps in contraction.
- 4. Human cell is eukaryotic. It consists of: A. Cell Membrane B. Cytoplasm C. Nucleus
- 5. CELL WITH VARIOUS ORGANELLES
- 6. A. CELL MEMBRANE The cytoplasm of a cell is bound on the outer aspect by cell membrane which is also known as plasma membrane or plasmalemma. It is 7.5 nm thick. It is trilaminar structure consisting of phospholipid layer sandwiched between outer and inner protein layer. Function: It maintains the shape of the cell. Presents receptors on the surface of cell membrane, which are specific for particular molecules that are enzymes or hormones. It helps in exocytosis and endocytosis.
- 7. FLUID MOSAIC MODEL(Proposed by SJ Singer And GL Nicolson in 1972) • According to this model, the cell membrane consists of a phospholipid bilayer. It is made up of a polar head (hydrophilic) and a non polar tail(hydrophobic). • In aqueous solution phospholipids form a bilayer with the heads directed outwards and the tails directed inwards. • Presence of unsaturated fatty acids increases the fluidity and the flexibility of cell membrane. Almost half of the total mass of the cell membrane is formed of protein molecules. Some protein molecules are present within the cell membrane and are known as intrinsic proteins. The proteins which are held at the outer aspect of cell membrane are known as extrinsic proteins. Some proteins occupying the entire thickness of the cell membrane are known as transmembrane proteins.
- 9. B. CYTOPLASM • It is an aqueous substance in which cytoskeleton is dispersed while organelles and inclusion bodies are suspended. • Membrane bound bodies in the cytoplasm are known as cell organelles. • The organelles found in a cell are endoplasmic reticulum, golgi apparatus, peroxisome, mitochondria, ribosome, centrosome and lysosome.
- 10. 1. ENDOPLASMIC RETICULUM Endoplasmic reticulum is a double membrane bound interconnected network of tubules, vesicles or flattened sacs. a. Rough endoplasmic reticulum(rER)- is involved in synthesis of proteins. b. Smooth endoplasmic reticulum(sER)- is involved in lipid synthesis.
- 11. 2. GOLGI APPARATUS It is made up of anastomosing tubules of membranes and vesicles. It helps in formation of secretary products of carbohydrates.
- 12. 3. PEROXISOMES Peroxisomes are also known as microbodies and are membrane bound organelles. They are involved in catabolic pathway. It results in the production of H2O2 which is cytotoxic.
- 13. 4. MITOCHONDRIA • It is a double membrane bound organelle. Although the shape of mitochondria is variable but usually it is elongated, cigar shaped. It localizes inside the cell at a site of maximum energy requirement. An active cell, like liver cell contains as many as 2000 mitochondria. Very few mitochondria are present in an inactive cell. • Each mitochondria consists of four compartments. Outer membrane, inner membrane, matrix bound by outer and inner membrane, space present between the two membranes containing enzymes. • The inner membrane is thrown into folds called cristae. Aerobic respiration takes place in the matrix which is enhanced by the cristae.
- 15. 5. RIBOSOMES Complexes of RNA and proteins are ribosomes. They lie either freely in cytoplasm of cells or are found attached to endoplasmic reticulum or can even be present in the mitochondria. They are the principal organelles involved in protein synthesis.
- 16. 6. CENTROSOME There is a pair of centrioles in each cell. Each centriole has two cylindrical bodies placed at right angles to each other. Transverse section of the centriole shows three tubules in single group and thus 9 groups of tubules. They help in synthesis of microtubules during cell division.
- 17. 7. (a) LYSOSOME They are vesicle like structures, which contain enzymes, which include proteases, carbohydratases, lipases, hydrolytic enzymes etc. Lysosomal enzymes help in destruction of bacteria. All cells contain lysosomes except mature erythrocytes.
- 18. (b) CYTOPLASMIC INCLUSIONS Circumscribed masses present in the cytoplasm are called as cytoplasmic inclusions. They can be: Lipid droplets Glycogen granules Pigments Proteins
- 19. 8. CYTOSKELETON It is the skeleton formed of fibres within the cytoplasm of a cell. It maintains the shape of the cell and helps in movement of the organelles present in the cell. Microfilaments Intermediate filaments Microtubules
- 20. C. NUCLEUS It is the largest organelle of the cell. It consists of a nuclear membrane surrounding the nucleoplasm. Nucleolus is suspended in the nucleoplasm.
- 22. i) Nuclear membrane- It is a double membrane bound structure. Nuclear membrane consists of numerous pores which regulate the exchange of metabolites between nucleus and cytoplasm. ii) Nucleoplasm- it is a gel like substance containing genetic material. When the cell is at rest, the nucleoplasm appears as a dark staining. Nucleoplasm contains thread like material called nuclear chromatin. iii) Nucleolus- cells which are involved with active protein synthesis have one or more nucleoli in their nucleoplasm. The ribosomal RNA is transcribed in the nucleolus.