Cell Structure and Function

Most relevant information about the cell, its discovery, types and various kinds of organelles and their function. it also focus on how molecules are transported across the cell membrane.
2018/2019

1. CELL STRUCTURE AND FUNCTION Presented by: Fasama Hilton Kollie Lecturer, Department of Biology Mother Patern College of Health Sciences CHP’T-2 September 17, 2018

2. LESSON OUTLINE Overview of cell Definition and Discovery of the cell Cell Theory and Principle of the Cell Theory Characteristic of Cell Types of Cell Major Plant Cell Organelles Overview of Organelles (Bacteria-like & Membranous Organelles) Nucleus, Ribosomes, Endoplasmic Reticulum, Golgi Apparatus, Chloroplas t, Mitochondria, Cytoplasm, Microbodies, Vacuole…

3. Cytoskeleton Overview of cytoskeleton Microtubules, Microfilaments, Motor proteins Intermediate Filament Membrane and Cell Wall Cell membrane Cell wall LESSON OUTLINE CONT.

4. Movement Across Cell Membrane Passive Transport Simple diffusion Facilitated diffusion Osmosis Hypotonic, Isotonic and Hypertonic solutions Active Transport Endocytosis Pinocytosis and Phagocytosis Exocytosis LESSON OUTLINE CONT.

5. LESSON OBJECTIVE By the end of this session, the learners will be able to ; Define cell, cell theory, and organelle Demonstrate plant and animal cell Identify and describe the major plant cell organelles Discuss cytoskeleton Describe plant cell wall and membrane Describe the movement of substance across the cell membrane

6. What is cell?

7. CELLS From latin - cella , meaning "Small room“ The basic structural, functional, and biological unit of all known living organisms O ften called the " building blocks of life " Plant cells

8. DISCOVERY OF CELLS Robert Hooke (Mid-1600s) Observed sliver of cork Saw “row of empty boxes” Coined the term “ C ell”

9. CELL THEORY Matthias Schleiden (1838) All plants are made up of cell Schleiden Schwann Virchow Theodor Schwann (1839) All animals are made up of cell Rudolf Virchow (1855) All cells comes from preexisting cells

10. PRINCIPLES OF CELL THEORY All living things are made of one or more cells The Cell is the s mallest living unit of structure and function of all organisms All cells arise from preexisting cells through cell division Schleiden Schwann Virchow

11. Cell Size CHARACTERISTICS OF CELL

12. Cells Have Large Surface Area-to-Volume Ratio

13. Cell Shape A cell’s shape reflects its function Bacteria cell Plant cell Red blood cell

14. CELL TYPES Prokaryotic Eukaryotic

15. PROKARYOTIC CELLS First form of life on earth Single-celled organisms Cell type of bacteria and archaea A prokaryotic cell contain three architectural regions: Cell envelop Cytoplasmic region Flagella and pili

16. PROKARYOTIC CELLS Lack membrane-bound organelles Nucleoid :region of DNA concentration Most are the smallest of all organisms ranging from 0.5 – 2.0 µm in diameter

17. EUKARYOTIC CELLS Nucleus bound by membrane Include fungi , protist , plant , and animal cells Possess many organelles Animal cell

18. Representative Animal Cell

19. Representative Plant Cell

20. CHARACTERISTICS OF ALL CELLS Contain a surrounding membrane ( plasma membrane ) Protoplasm – cell contents in thick fluid Control center with DNAs

21. Plasma Membrane Nucleus (DNA) Protoplasm Organelles CHARACTERISTICS OF ALL CELLS CONT.

22. MAJOR PLANT CELL ORGANELLES “ Little organs ” Specialized subunit within a cell that has specific function Cellular machinery Two general kinds: Bacteria-like organelles Derived from membranes

23. Bacteria-Like Organelles Derived from symbiotic bacteria Ancient association Endosymbiotic theory Evolution of modern cells from cells & symbiotic bacteria

24. Release & store energy Types: Mitochondria (release energy) Chloroplasts (store energy) Bacteria-Like Organelles Mitochondria Chloroplast

25. Cytoplasm Viscous fluid containing organelles C omponents of cytoplasm: Interconnected filaments & fibers Fluid = cytosol Organelles (not nucleus) Storage substances ( Examples ) Cytoplasm

26. Membranous Organelles Functional components within cytoplasm Bound by membranes Nucleus Ribosomes Endoplasmic reticulum Golgi Apparatus Lysosomes Vacuole Microbodies

27. Nucleus Control center of cell Double membrane Contains: Chromosomes (DNA) Nucleolus Nuclear envelop Nuclear pole

28. Nucleus and It’s Components Nucleus Nuclear envelop Outer membrane Inner membrane N Chromatin Nucleolus Nuclear pore Nuclear envelop Nucleoplasm Chromatin Nucleolus Nuclear pole

29. Site of protein synthesis Usually exit in large numbers in living cells Ribosomes Organelles that direct the synthesis of proteins using genetic instruction in the form of messenger RNA Ribosomes

30. Free ribosomes Suspended in the cytosol Synthesize proteins that function in cytosol Types of Ribosomes Free Ribosomes Bound Ribosomes Bound ribosomes Attached to endoplasmic reticulum Synthesize proteins for export or for membranes Proteins work within endomembrane system or outside cell

31. Network of interconnected membranes Helps move substances within cells Serves as assembly site for making proteins, lipids … Two types; Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Endoplasmic Reticulum ER

32. Ribosomes attached to surface Manufacture protein Contain cisternae May modify proteins from ribosomes Rough Endoplasmic Reticulum Rough ER

33. Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules Carbohydrates Lipids Smooth ER

34. Golgi Apparatus A complex of vesicles and folded membranes involved in secretion and intracellular transport Transport vesicles Consist of stacks of cisternae, known as Golgi stacks Consist of two main networks: Cis Golgi Network (CGN) Trans Golgi Network (TGN)

35. It modify , sort and package the macromolecules that are synthesized by the cell They are also involved in the transport of lipid molecules around the cell It is also a major site of carbohydrate synthesis Golgi Apparatus Function

36. Molecules Transport Via GA

37. Lysosomes Spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules Contain digestive enzymes Functions: Aid in cell renewal Break down old cell parts Digests invaders

38. Membrane bound storage sacs Single membrane structure Contents: water, food, wastes, enzymes Function: Isolating harmful materials Storing waste products Storing valuable water in a plant cell Balancing the ph of a cell Storing proteins for seed germination Vacuole

39. Single membrane–enclosed organelles Found in cells of plants, protozoa, and animals Usually a vesicle with spherical shape Constitute: peroxisomes, glyoxysomes… Function: Contain enzymes that participate in biochemical reactions in cells D etoxification of peroxides Photorespiration in plants Microbodies

40. Chloroplasts Organelle within the cells of plants and green algae that is the site of photosynthesis Contains green chlorophyll pigment Double membrane structure Chloroplast is a type of plastid Include leucoplasts and chromoplasts

41. Chloroplast Cont. Endosymbiotic theory explains the origin of chloroplast Which has a two membranes and; A small circular chromosome

42. Endosymbiotic Theory

43. Mitochondria O rganelles that are the cell’s “ power plant ” It breaks down sugar to store its chemical energy in ATP Consist of; Double membrane, Matrix , Thylakoids, Stoma, Mitochondria DNA Production of energy for cell is its most prominent function

44. CYTOSKELETON Filaments & fibers Made of 3 fiber types Microtubules Microfilaments Intermediate filaments 3 functions: Mechanical support Anchor organelles Help move substances

45. Long hollow tubes in the cytoskeleton M ade up of a protein called Tubulin Function; Helps maintain cell shape Movement of multicellular organisms through water Cilia and Flagella All movement controlled by microtubules involves “ walking molecules” Microtubules:

46. Cilia & Flagella Cilia : Short hair-like projections Used to move substances outside human cells Flagella: Whip-like extensions Found on sperm cells

47. Made up of globular protein called actin Function: Helps living cell change shape Help in the movement of cell content around the vacuole in a circular motion known as cytoplasmic streaming Microfilaments:

48. A type of cytoskeletal elements made of multiple strands of fibrous proteins wound together Average diameter of 8-10nm Function: Help in holding the nucleus in its permanent position Control the shape of the nucleus Intermediate Filaments:

49. “ Walking molecule ” Motor proteins require energy for movement Involve in many movement in cells These include; Chloroplast moving from the bottom to the side of a cell Cyclosis Motor Proteins

50. “ Plasma membrane ” Membranes are barriers that control what enters and leaves the cell Fluid mosaic model provides a broader description of the cell membrane MEMBRANES AND CELL WALLS Cell Membrane:

51. Fluid Mosaic Model

52. Protective layer that surrounds the plasma membrane Plant cell wall consist primary of cellulose Plant cell wall consist of two components: Primary cell wall Secondary cell wall Cell Wall

53. MOVEMENT ACROSS CELL MEMBRANES Passive Transport Active Transport Endocytosis Phagocytosis & Pinocytosis Exocytosis

54. Passive Transport No energy required Move due to gradient Movement is down the concentration gradient High moves toward low Consist of 3 types: Simple Diffusion Facilitated diffusion Osmosis

55. Simple Diffusion: Molecules move to equalize concentration

56. Movement of specific molecules down a concentration gradient Pass through membranes via specific carrier protein Selection is by size , shape , charge Facilitated Diffusion:

57. Channels (are specific) help molecule or ions enter or leave the cell Facilitated Diffusion Cont. Channels usually are transport proteins ( A quaporin facilitate the movement of water)

58. Process of Facilitated Transport

59. Osmosis: Special form of diffusion Fluid flows from lower solute concentration to higher Requires selective permeable membrane

60. Solvent + Solute = Solution Hypotonic Solutes in cell more than outside Outside solvent will flow into cell Isotonic Solutes equal inside & out of cell Hypertonic Solutes greater outside cell Fluid will flow out of cell Solution Difference & Cell

61. Effect of Osmosis On Cells

62. Active Transport Molecular movement Requires energy (against concentration gradient) Eg : S odium-potassium pump

63. Endocytosis Movement of large material Particles, organisms ,large molecules Movement is into cell Cytoplasm Vesicle Outside cell

64. Forms of Endocytosis Phagocytosis – “cell eating” Pinocytosis – “cell drinking”

65. Exocytosis Reverse of endocytosis Cell discharges material

66. REFERENCE Nabor , Murray W., INTRODUCTION TO BOTANY , Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings, 1301 Sansome St., San Francisco, CA 94111 Kingsley R. Stern, James E. Bidlack & Shelley H. Jansky ., INTRODUCTORY PLANT BIOLOGY , Copyright © 2008 by The McGraw-Hill Companies, Inc. Published by McGraw-Hill, 1221 Avenue of the Americas, New Yours, NY 10020. www.mhhe.com Movement across membranes http:// www.biologymad.com/resources/diffusionrevision.pdf Google Advance Image search