Structural organization of eukaryotic cells 1 (1)
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This document provides an overview of the structural organization and functions of eukaryotic cells. It begins with an introduction that defines eukaryotic cells as having a nucleus surrounded by a membrane, unlike prokaryotic cells. The document then discusses the organelles found in plant and animal cells through diagrams and descriptions, including the nucleus, endoplasmic reticulum, Golgi bodies, mitochondria, chloroplasts, and more. It explains the key functions of structures like the plasma membrane, cytoplasm, and other organelles. In the end, it provides differences between plant and animal cells.
Structural organization of eukaryotic cells 1 (1)
- 1. STRUCTURAL ORGANIZATION OF EUKARYOTIC CELLS AND THEIR FUNCTION Prepared by - Dwijottam Sarma Bordoloi (17/BBT/20) Bhargab Kumar Thakuria (17/BBT/06) Ashish Pratim Mahanta (17/BBT/60)
- 2. CONTENTS 1. Introduction 2. Diagrammatic Representation 3. Types 4. Structural Overview 5. Functions 6. Differences 7. References
- 3. INTRODUCTION Contains a prominent nucleus surrounded by a membrane. Contains numerous organelles unlike prokaryotic cell. The word Eukaryote which refer to any organism possessing eukaryotic cell is derived from the Greek word “eu karyon” in which “eu” means “true” and “karyon” means “nut/kernel” which is the “nucleus”. Eukaryotic Cell :
- 4. DIAGRAMMATIC REPRESENTATION Fig - A Eukaryotic Cell
- 6. Fig – PLANT CELL
- 7. Fig – ANIMAL CELL
- 8. STRUCTURAL OVERVIEW Eukaryotic Cell is an aqueous compartment surrounded by plasma membrane and cell wall (in case of plants only) and consists of protoplasm in which different types of cell organelles get embedded such as: i. Nucleus ii. Endoplasmic Reticulum iii. Golgi Bodies iv. Ribosome v. Mitochondria vi. Peroxisome vii. Vacuoles viii. Lysosomes (in animal cells only) ix. Centriole (in animal cells only) x. Chloroplast (in plant cells only)
- 9. STRUCTURAL OVERVIEW (CONTD…) The remaining structural components of eukaryotic cells include : Cytoskeleton Cilia and Flagella (found in animal cells)
- 10. FUNCTIONS Plasma Membrane • A fluid-like bilipid membranous layer composed of proteins and carbohydrates. • It separates the cell from its external environment, protects the cell and provides shape, stability and integrity of the cell. • It is selectively permeable i.e. it allows certain molecules or ions to pass through it by means of active or passive transport. • The Fluid Mosaic Model of the plasma membrane proposed by Singer and Nicholson in 1972 is the dominating and mostly widely accepted model at present.
- 11. Cytoplasm • Jelly-like substance composed of mainly water and found between the cell membrane and nucleus. • Organelles are found here and substances like salts may be dissolved in the cytoplasm. Nucleus • Largest organelle of the cell and is called the brain or control centre of the cell. • Dark, round and surrounded by a nuclear membrane that has nuclear pores on it.
- 12. Nucleus (contd…) • It contains the genetic information (DNA) on special strands called chromosomes and controls the functions of the entire cell by regulating gene expression. Endoplasmic Reticulum • Network of membranous canals filled with fluid, continuous with the nuclear membrane. • They carry materials throughout the cell and is the “transport system” of the cell. • They are of two types – Rough ER (which is rough in appearance and is lined with ribosomes ) and Smooth ER (which is smooth in appearance and doesn’t contain ribosomes).
- 13. Golgi Bodies • Stacks of flattened membranous stacks. • Moves materials within or outside the cell. • Temporarily stores proteins, modifies and packs macromolecules into useable forms called vesicles for cell secretion. Mitochondria • Round tube-like organelles that are surrounded by a double membrane. • Referred to as the powerhouse of the cell. • Releases food energy from food molecules through respiration in the form of ATP. Chemical Equation -
- 14. Lysosomes • Organelles containing digestive enzymes that degrades worn out cell parts. • Referred to as ”garbage collector” of the cell. Chloroplasts • Present in plants only, contains the green pigment chlorophyll for absorbing light energy from sunlight. • Responsible for performing photosynthesis in plants.
- 15. Ribosomes • Small particles found individually in the cytoplasm and also line the RER. • They consist of RNA, synthesize proteins and can be thought of as “factories” of the cell. • They consists of two subunits of unequal size – large and small subunits. In eukaryotes, the overall ribosome has a size of 80S; in dissociated form, the large subunit is 60S and the small subunit is 40S in size. Peroxisome • Contains the reducing enzyme catalase and usually some oxidases that oxidize certain organic substances. H O + H O 2H O + O catalase 2 2 2 2 2 2
- 16. Centrioles • Pair of cylindrical organelles near the nucleus involved in the development of spindle fibers that separate chromosomes during cycle division. • Made of microtubules. Cell Wall • Located outside the membrane only in plant cells, made up of cellulose. • Maintains the cell shape, provide protection and controls the passage of substances. Vacuoles • Fluid filled organelles enclosed by a membrane. • Store materials such as food, water, sugar, minerals and waste products.
- 17. Cytoskeleton • Made up of microtubules, actin and intermediate filaments. • Gives the cell its shape and help organize the cell’s parts and also help the cell to move. Cilia and Flagella • Cilia are hair-like structures of size 1-10 micrometers in length that move in waves. They can trap inhaled particles in the air and sweep mucus and dirt out of the lungs in the lining of trachea. • Flagella are like little tail 100-200 micrometers in length present in some bacteria that helps them to move or propel. Cilia Flagellum
- 18. DIFFERENCES Plant Cell Animal Cell 1. Possess a cellulosic cell wall which is the outermost boundary. 1. Doesn’t possess cell wall and outermost boundary is the plasma membrane. 2. Possess chloroplasts which perform photosynthesis. 2. Lacks chloroplasts. 3. Possess a big central vacuole. 3. Vacuoles are smaller in size. 4. Centrioles are absent. 4. Centrioles are present. 5. Lysosomes are absent. 5. Lysosomes are present. 6. Usually larger in size. 6. Comparatively smaller.
- 19. DIFFERENCES CONTD… Plant Cell Animal Cell 7. Reserve food is stored in the form of starch. 7. Reserve food is usually glycogen. 8. Nucleus lies on one side in the peripheral cytoplasm. 8. Nucleus usually lies in the centre. 9. Rectangular in shape. 9. Round in shape. 10. They have many simple units of Golgi apparatus called dictyosomes. 10. They have single highly complex Golgi. 11. They cannot change their shape. 11. They can change their shape.
- 20. REFFERENCES Websites – www.wikipedia.org/wiki/Eukaryote www.softschool.com/science/biology www.shmoop.com/biology-cells/all-eukaryotic-cells.html www.edu.pe.ca/gray/class_pages/rcfleming/cells www.majordifferences.com/2013/10/difference-plant- cell-vs-and-animal-cell.html?m=1 Books – Life Sciences, Fundamentals and Practice – I (Fifth edition) Pathfinder Publication, New Delhi, India By Pranav Kumar and Usha Mina