1. Cell structure & functions Department of Applied Science King Saud University/ Community College By: Murad Sawalha

2.  Introduction  Eucaryotic cell structure  Procaryotic cell structure  Differences between Procaryotic & Eukaryotic cells. Eukaryotic cells.  Reproduction of organisms & their cells. cells.  Gram stain Outline

3. Introduction - Cell is defined as the fundamental living unit of any organism. - Cell is important to produce energy for metabolism (all chemical reactions within a cell) - Cell can mutate (change genetically) as a result of accidental changes in its genetic material (DNA). - Some microrganisms are procaryotic, some are eucaryotic, & some are not cells at all (Viruses) - Viruses are composed of only a few genes protected by a protien coat, & may contain few enzymes. - Cytology: the study of the structure and functions of cells.

4. Eucaryotic cell structure Eucaryotic cells: have a true nucleus, & the DNA is enclosed by a nuclear membrane. Eucaryotic cells: have a true nucleus, & the DNA is enclosed by a nuclear membrane. They are 10 times larger than Procaryotic cells. They are 10 times larger than Procaryotic cells.

5. Cell membrane It’s composed of large molecules of protiens & phospholipids (certain types of fats). It’s composed of large molecules of protiens & phospholipids (certain types of fats). The cell membrane is seperating the contents of the cell from the outside world. The cell membrane is seperating the contents of the cell from the outside world. It has the property of selective permiability: only certain substances may enter & leave the cell It has the property of selective permiability: only certain substances may enter & leave the cell

6. Cell Membrane Phospholipid bi-layer that separates the cell from its environment. Phospholipid bi-layer that separates the cell from its environment. Selectively permeable to allow substances to pass into and out of the cell. Selectively permeable to allow substances to pass into and out of the cell.

7. Nucleus Double membrane-control, & integrates the functions of the entire cell. Double membrane-control, & integrates the functions of the entire cell. Consider the command center of the cell. Consider the command center of the cell. Separates the genetic material from the rest of the cell. Separates the genetic material from the rest of the cell.

8. Parts of the nucleus: Chromatin - genetic material of cell in its non-dividing state. Chromatin - genetic material of cell in its non-dividing state. Nucleoplasm is the gelatenous matrix of the nucleus, like cytoplasm. Nucleoplasm is the gelatenous matrix of the nucleus, like cytoplasm. Nucleolus - dark-staining structure in the nucleus that plays a role in making ribosomes. Nucleolus - dark-staining structure in the nucleus that plays a role in making ribosomes. Nuclear envelope - double membrane structure that separates nucleus from cytoplasm. Nuclear envelope - double membrane structure that separates nucleus from cytoplasm.

9. Cytoplasm Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures (organelles). Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures (organelles). Fluid around the organelles called cytosol. Fluid around the organelles called cytosol. Most of the cells metabolic reactions occur in the cytoplasm. Most of the cells metabolic reactions occur in the cytoplasm.

10. The Endoplasmic Reticulum The endoplasmic reticulum (ER) The endoplasmic reticulum (ER) –Accounts for more than half the total membranes in many eukaryotic cells –The ER membrane: is continuous with the nuclear envelope There are two distinct regions of ER There are two distinct regions of ER –Smooth ER, which lacks ribosomes –Rough ER, which contains ribosomes

11. Rough Endoplasmic Reticulum Network of continuous sacs, studded with ribosomes. Network of continuous sacs, studded with ribosomes. Manufactures, pro- cesses, and transports proteins for export from cell (vesicles) Manufactures, pro- cesses, and transports proteins for export from cell (vesicles) Continuous with nuclear envelope. Continuous with nuclear envelope.

12. Smooth Endoplasmic Reticulum Similar in appearance to rough ER, but without the ribosomes. Similar in appearance to rough ER, but without the ribosomes. Involved in the production of lipids, carbohydrate metabolism, and detoxification of drugs and poisons. Involved in the production of lipids, carbohydrate metabolism, and detoxification of drugs and poisons. Stores calcium. Stores calcium.

13. Ribosomes Are the sites of protein synthesis. Are the sites of protein synthesis. Found attached to the Rough endoplasmic reticulum or free in the cytoplasm. Found attached to the Rough endoplasmic reticulum or free in the cytoplasm. 60% RNA and 40% protein. 60% RNA and 40% protein. Protein released from the ER are not mature, need further processing in Golgi complex before they are able to perform their function within or outside the cell. Protein released from the ER are not mature, need further processing in Golgi complex before they are able to perform their function within or outside the cell.

14. Golgi Apparatus Modifies proteins and lipids made by the ER and prepares them for export from the cell (exocytosis). Modifies proteins and lipids made by the ER and prepares them for export from the cell (exocytosis). Encloses digestive enyzymes into membranes to form lysosomes. Encloses digestive enyzymes into membranes to form lysosomes. Consists of flattened membranous sacs called cisternae Consists of flattened membranous sacs called cisternae

15. Lysosome Single membrane bound structure. Single membrane bound structure. Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell. Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell. Originate at the Golgi complex. Originate at the Golgi complex. Are the Are the

16. Lysosome They contain lysozymes & other digestive enzymes that breakdown foreign material taken into the cell by phagocytosis (e.g Amebas, and certain types of WBCs “phagocyte”). They contain lysozymes & other digestive enzymes that breakdown foreign material taken into the cell by phagocytosis (e.g Amebas, and certain types of WBCs “phagocyte”). Also these enzymes may breakdown parts of the cell or destroy the entire cell by process called autolysis if the cell damaged or deteriorated. Also these enzymes may breakdown parts of the cell or destroy the entire cell by process called autolysis if the cell damaged or deteriorated. They contain up to 40 enzymes for digestion They contain up to 40 enzymes for digestion

17. Peroxisomes They are similar to lysosome but smaller. They are similar to lysosome but smaller. Peroxisomes contain the enzyme catalase, which breakdown of hydrogen peroxide into water and oxygen. Peroxisomes contain the enzyme catalase, which breakdown of hydrogen peroxide into water and oxygen. Found mainly in liver and kidney cells Found mainly in liver and kidney cells Main function is detoxification of toxic materials. Main function is detoxification of toxic materials.

18. Mitochondrion Membrane bound organelles that are the site of cellular respiration (ATP production) Membrane bound organelles that are the site of cellular respiration (ATP production) Mitochondria are enclosed by two membranes Mitochondria are enclosed by two membranes –A smooth outer membrane –An inner membrane folded into cristae

19. Chloroplast Site of photosynthesis Site of photosynthesis Membrane bound structure. Membrane bound structure. Contains chlorophyll Contains chlorophyll Found only in plants Found only in plants

20. Cytoskeleton The cytoskeleton The cytoskeleton –Is a network of fibers extending throughout the cytoplasm Microtubule 0.25 µm Microfilaments

21. Roles of the Cytoskeleton: Support, Motility, and Regulation The cytoskeleton The cytoskeleton – Gives mechanical support to the cell –Is involved in cell motility, which utilizes motor proteins

22. Components of cytoskeleton: 1) Microfilaments Solid rods of globular proteins. Solid rods of globular proteins. Important component of cytoskeleton which offers support to cell structure. Important component of cytoskeleton which offers support to cell structure.

23. Components of cytoskeleton: 2) Microtubules Microtubules Microtubules –Shape the cell –Guide movement of organelles –Help separate the chromosome copies in dividing cells

24. Components of cytoskeleton: 2) Microtubules Centrosomes and Centrioles The centrosome The centrosome –Is considered to be a “microtubule-organizing center” –Contains a pair of centrioles

25. Components of cytoskeleton: 2) Microtubules Centrioles Found only in animal cells. Found only in animal cells. Self-replicating Self-replicating Made of bundles of microtubules. Made of bundles of microtubules. Help in organizing cell division. Help in organizing cell division.

26. Cell Wall Protects and gives rigidity to plant cells Protects and gives rigidity to plant cells Formed from fibrils of cellulose molecules in a “matrix” of polysaccharides and glycoproteins. Formed from fibrils of cellulose molecules in a “matrix” of polysaccharides and glycoproteins.

27. Cilia and Flagella External appendages from the cell membrane that aid in locomotion of the cell. External appendages from the cell membrane that aid in locomotion of the cell. Cilia also help to move substance past the membrane. Cilia also help to move substance past the membrane.

28. Animal Cell vs. Plant Cell

29. Prokaryotic vs. Eukaryotic

30. Procaryotic cell strucure Are about 10 times smaller than eucaryotic cells. Are about 10 times smaller than eucaryotic cells. Reproduction of these cells by binary fission. Reproduction of these cells by binary fission. Binary fission: the simple division of one cell into two cells, following DNA replication, & the formation of a separating membrane & cell wall. Binary fission: the simple division of one cell into two cells, following DNA replication, & the formation of a separating membrane & cell wall.

31. Procaryotic cell strucure Cytoplasm is surrounded by a cell membrane, a cell wall (usually), & sometimes a capsule or slime layer. Cytoplasm is surrounded by a cell membrane, a cell wall (usually), & sometimes a capsule or slime layer.