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Cell structure
This document provides an overview of cell structure and function. It describes the key differences between prokaryotic and eukaryotic cells, as well as plant and animal cells. The major organelles of the cell are defined, including their structures and functions. Specifically, it outlines the roles of the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, cytoskeleton, and cell membrane in cellular processes like transport and protein synthesis. Molecular transport mechanisms like diffusion, osmosis, active transport, endocytosis, and exocytosis are also summarized.
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Cell structure
- 1. THE CELL BYDR. SAKINA RUHI MBBS, MD(BIOCHEMISTRY) SENIOR LECTURER,DEPARTMENT OF BIOCHEMISTRY,IMS, SHAHALAM
- 2. 2 OUTLINE •Difference between prokaryotic & Eukaryotic cell . • Difference between Animal & Plant cell • Different cell organelles & Its function • Cell Membrane • Molecular movements & Cell-transport mechanism
- 3. 3 Cell Theory • 1. All living things are made of cells. • 2. New cells are produced from existing cells • 3. Cells are the basic unit of structure and function in living things.
- 4. 4 Prokaryotes vs.Eukaryotes • Prokaryotes (bacteria) nucleus not well defined and very few organelles. • Eukaryotes (protists, fungi, plants and animals) larger,more complex,DNA is inside the nucleus
- 5. 5 Plant CellsVs. Animal Cells • Only plant cells contain: • Cell wall • Chloroplasts • Large central vacuoles • Only animal cells contain: • Centrioles
- 6.
- 7. 7 CYTOPLASM •Viscous fluid containing organelles • components of cytoplasm • Interconnected filaments & fibers • Fluid = cytosol • Organelles (not nucleus) • storage substance
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- 9. 9 Nucleus •Repository for genetic material • Directs activities of the cell • Usually single, some cells several, • RBC none • Contains • Chromosomes • Nucleolus
- 10. 10 Nuclear Envelope • Separates nucleus from rest of cell by two phospholipid bilayer membrane Double membrane Has pores
- 11. 11 Nucleolus •Directs synthesis of RNA • Nucleolus is mainly involved in the assembly of ribosomes
- 12. 12 Endoplasmic reticulum • Largest internal membrane • Composed of Lipid bilayer • Serves as system of channels from the nucleus • Functions in storage and secretion • Two types • Rough endoplasmic reticulum • Smooth endoplasmic reticulum
- 13.
- 14. 14 Smooth EndoplasmicReticulum • No attached ribosomes • Has enzymes that help build molecules • Carbohydrates • Lipids
- 15. 15 Rough EndoplasmicReticulum • Ribosomes attached to the surface • Manufacture protiens • Not all ribosomes attached to rough ER • May modify proteins from ribosomes
- 16. 16 Ribosomes •Ribosomes are RNA-protein complexes composed of two subunits that join and attach to messenger RNA. • site of protein synthesis • assembled in nucleoli
- 17. 17 Golgi Apparatus Packaging & shipping station of cell collect, pack, and distribute molecules synthesized at one location in the cell and utilized at another location
- 18. 18 HOW GolgiApparatus Functions 1. Molecules come in vesicles 2. Vesicles fuse with Golgi membrane 3. Molecules may be modified by Golgi 4. Molecules pinched-off in separate vesicle 5. Vesicle leaves Golgi apparatus 6. Vesicles may combine with plasma membrane to secrete contents
- 19.
- 20. 20 Mitochondria A."Powerhouse of the cell" - cellular metabolism B. Structure- outer and inner membranes, cristae C. Have their own DNA
- 21. 21 Mitochondria •Break down fuel molecules (cellular respiration) • Glucose • Fatty acids • Release energy • ATP
- 22. 22 Lysosomes •Contain digestive enzymes • Functions • Aid in cell renewal • Break down old cell parts • Digests invaders
- 23. 23 Cytoplasm Phagocytosis Food vesicle Endoplasmic reticulum Golgi apparatus Lysosomes Plasma membrane Digestion of phagocytized food particles or cells Transport vesicle Old or damaged organelle Breakdown of old Extracellular organelle fluid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 24. 24 PEROXISOMES Peroxisomes–are single membrane cellular organelle,also called microbodies Catalase and peroxidase: the enzymes of peroxizomes destroy unwanted peroxides & other free radicals
- 25. 25 Cytoskeleton •Network of protein filaments • Maintains shape • Involved in cell movement
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- 27. 27 Cell Membrane • Regulates what enters and leaves the cell and provides support and protection • Structure – lipid bilayer with embedded proteins
- 28.
- 29. 29 Membrane Proteins 1. Channels or transporters • Move molecules in one direction 2. Receptors • Recognize certain chemicals
- 30. 30 Membrane Proteins 3. Glycoproteins • Identify cell type 4. Enzymes • Catalyze production of substances
- 31. 31 TRANSPORT MECHANISM classified into Passive Transport (i)simple diffusion (ii)facilitated diffusion (iii) ion exchange Active Transport Pumps –can drive molecules against the gradient using energy
- 32. 32 Simple Diffusion Particles move from an area of high concentration to an area of lower concentration No energy is required very slow
- 33. 33 Osmosis •Diffusion of water through a selectively permeable membrane
- 34. 34 Facilitated Diffusion • Molecules move through protein channels. • Carrier mediated process • No energy required
- 35. 35 ION CHANNELS • Membrane have special devices called ion channels • For quick transport of Na +,K+ ,Cl + and Ca ++ • They remain close and open on response to stimulus • They are also called as gated channels • Important for nerve impulse propogation,synaptic transmission
- 36. 36 Active Transport • Carried our by protein pumps found in the membrane • Energy is required
- 37. 37 • MolecularmovAemcenttive Transport • Requires energy (against gradient) • Example is sodium-potassium pump
- 38. Endocytosis 38 •Cell takes material into cell by infolding of the cell membrane • Phagocytosis – eating – cell engulfs large particles • Pinocytosis – drinking – cell takes in liquid
- 39. 39 • PlasmamPemrobrcanee ssusr rooufn dEs mnatderoialcytosis • Edges of membrane meet • Membranes fuse to form vesicle
- 40. 40 Exocytosis •Cell releases large amounts of material
- 41. 41 Transport system • Classified as Uniport , Symport and Antiport • UNIPORT-Carries single solute across the membrane e.g – glucose transporter in most cells ,calcium pump • CO TRANSPORT –If transfer of one molecule depend on simultaneous transfer of another molecule. • (i)SYMPORT (ii) ANTIPORT
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- 43. 43 • SYMPORT-Transportercarries two solutes in same direction . • eg-sodium dependent glucose transport • ANTIPORT –Carries two solutes or ions in opposite direction • eg sodium pump,sodium bicarbonate exchange in RBC
- 44.