Cells
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Cells

Cells

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  • All cycled words are organelles, except for plasma membrane
  • Remind students that in 2D diagram, SER can appear not connected to RER
  • Light microscope – cell membrane, nucleus, cytoplasm Electron microscope – all can be seen

Cells Presentation Transcript

  • 1. Chapter 2 CellsCells The Building Blocks of Life
  • 2. • Cells observed under the light microscope. Animal CellPlant Cell Recollection ActivityRecollection Activity
  • 3. • Drawing of cells observed under the light microscope. Animal CellPlant Cell Recollection ActivityRecollection Activity
  • 4. • Drawing of cells observed under the light microscope. Animal CellPlant Cell Recollection ActivityRecollection Activity
  • 5. • Are the basic structural and functional units of life • Cells can exist: – Singly as independent unicellular organisms – As part of multicellular organisms • Such cells are modified for specific functions What are Cells?
  • 6. Amoeba Feeding
  • 7. What characteristics would a cell need to carry out its functions? What characteristics would a cell need to carry out its functions? •Area for respiration •Area for reactions •Control Centre •Storage of genetic material •Barrier to control movement of materials
  • 8. Cell Structure: PROTOPLASM – The Living Matter of Cells Cell Structure: PROTOPLASM – The Living Matter of Cells PropertiesProperties •Mixture •70-90% water •Mineral salts and organic compounds (2) Cytoplasm(2) Cytoplasm (3) Plasma/Cell(3) Plasma/Cell membranemembrane (1) Nucleus(1) Nucleus Consists of:Consists of:
  • 9. Cell Structure: (1) Nucleus – The Control Centre Cell Structure: (1) Nucleus – The Control Centre StructureStructure • Nuclear membrane/envelope • Nucleolus • Chromatin • Nucleoplasm FunctionFunction • Control centre for cell’s activities • Control cell division • Contains genetic materials
  • 10. Chromatin condenses during cell division chromatin chromosome histones
  • 11. Cell Structure: (2) Cytoplasm – The laboratory Cell Structure: (2) Cytoplasm – The laboratory PropertiesProperties • Colloidal (glue-like); • Mainly water with salts & sugars • Larger molecules of fats & proteins • Endless chemical reactions taking place • With many small structures called organelles
  • 12. Cell Structure: (2) Cytoplasm – The Control Centre Cell Structure: (2) Cytoplasm – The Control Centre Organelles in the cytoplasmOrganelles in the cytoplasm Present in Plant & Animal Cells a)Ribosomes b)Rough Endoplasmic Reticulum (RER) c)Smooth Endoplasmic Reticulum (SER) d)Golgi Apparatus/Body e)Mitochondria f)Vacuole(s) Present in Plant Cells only a) Chloroplasts
  • 13. Cell Structure: (2a) Ribosomes Cell Structure: (2a) Ribosomes StructureStructure Small Round Structures Either attached to ER or lie freely in cytoplasm FunctionFunction Protein synthesis Ribosomes on RER: Proteins are transported out of the cell Free Ribosomes: Proteins used within the cytoplasm of the cell
  • 14. Cell Structure: (2b) Rough Endoplasmic Reticulum (RER) Cell Structure: (2b) Rough Endoplasmic Reticulum (RER) StructureStructure Membrane network continuous with the nuclear envelope. Ribosomes attached to its outer surface. FunctionFunction Transports proteins made by ribosomes to the golgi apparatus for secretion out of the cell.
  • 15. 2D diagram to show RER
  • 16. Cell Structure: (2c) Smooth Endoplasmic Reticulum (SER) Cell Structure: (2c) Smooth Endoplasmic Reticulum (SER) StructureStructure Membrane network connected to the RER Absence of Ribosomes FunctionFunction Synthesizes substances such as fats and steroids (e.g sex hormones) Detoxification
  • 17. 2D diagram to show SER
  • 18. Cell Structure: (2d) Golgi apparatus/body Cell Structure: (2d) Golgi apparatus/body StructureStructure Stack of flattened spaces surrounded by membranes FunctionFunction Stores and modifies substances made by the ER Packages these substances in vesicles for secretion out of the cell
  • 19. 2D diagram to show Golgi body
  • 20. Synthesis and Transport of substances out of the cell
  • 21. cristae Cell Structure: (2e) Mitochondria Cell Structure: (2e) Mitochondria StructureStructure Sausage-shaped organelles Highly folded internal membrane (cristae) Double membrane FunctionFunction Carries out cellular respiration During respiration, Glucose is oxidised to release energy Energy stored in small molecules called ATP
  • 22. Cell Structure: (2f) Vacuole(s) Cell Structure: (2f) Vacuole(s) StructureStructure Fluid filled space enclosed by a membrane FunctionFunction Animal Cell •Many small vacuoles •Contains water and food substances • Usually exists temporarily Plant Cell •One large central vacuole •Contains cell sap (Dissolved substances e.g sugars, mineral salts and amino acids)
  • 23. Cell Structure: (2g) Centrioles Cell Structure: (2g) Centrioles FunctionFunction  Plays a part in cell division
  • 24. Cell Structure: (2h) Chloroplasts Cell Structure: (2h) Chloroplasts StructureStructure Disc-like structures found in leaf cells Contains a chlorophyll - green pigment FunctionFunction Carries out photosynthesis Chlorophyll absorbs light energy which is converted to chemical energy
  • 25. Cell Structure: (2) Plasma/Cell Membrane Cell Structure: (2) Plasma/Cell Membrane PropertiesProperties • Present in ALL living cells • Made up of fats and proteins • Porous • Partially permeable • Controls the exchange the substances between the cells and their environment
  • 26. Cellulose Cell Wall • Function –Provides shape to the plant cells –Protects cell from injury • Adaptation –Cellulose is a hard structure –Fully permeable
  • 27. Comparing plant and animal cellComparing plant and animal cellComparing plant and animal cellComparing plant and animal cell Plant Cell Animal Cell
  • 28. Cells Have Large Surface Area-to-Volume Ratio
  • 29. Observing Cells Microscopes are required to visualize cells. • Light microscopes – can magnify objects up to 1000 x – Light micrographs are colour images • Electron microscopes – can magnify objects up to 200 000 x – Electron micrographs are black-and-white images
  • 30. 2.1 Cell structure and organisation • Two ways of cutting a cell Longitudinal (top-down) Transverse (sideways)
  • 31. Endomembrane System • Putting it all together  DNA directs RNA synthesis  RNA exits nucleus through a nuclear pore into RER  ribosomes in RER synthesise protein  proteins travel along RER  proteins are modified in RER and lipids are made in SER
  • 32. Endomembrane System • Putting it all together  vesicles containing the proteins and lipids bud off from the ER  ER vesicles merge with Golgi body  proteins and lipids enter Golgi body  each is fully modified as it passes through layers of Golgi body  modified products are tagged, sorted and bud off in Golgi vesicles
  • 33. Endomembrane System • Putting it all together  Golgi vesicles either merge with the plasma membrane and release their contents OR remain in the cell and serve a purpose
  • 34. Transport Pathway by ER & GA
  • 35. Differences between an animal cell and a plant cell Animal cell Plant cell Chloroplast absent Chloroplast present Cellulose cell wall absent Cellulose cell wall present Contains vacuoles which are small and numerous Contains one to a few large vacuoles filled with cell sap The cytoplasm fills the cell The cytoplasm is reduced to a thin lining Centrioles present Centrioles absent
  • 36. Division of Labour • In a multicellular organism, each type of cell specialises in performing one particular function. E.g. -The red blood cells in humans specialise in carrying oxygen around the body. -The guard cells in a plant regulates gaseous exchange. • Thus the functions of a multicellular organism as a whole are divided among its different specialised cells (performing a particular function efficiently). This dividing up of the functions is called division of labour.
  • 37. DifferentiationDifferentiation
  • 38. DifferentiationDifferentiation Red blood cell Muscle cell Epithelial cell Nerve cell Xylem vessel cell Root Hair cell
  • 39. Process in which cell becomes specialised and acquire special structures and functions. Process in which cell becomes specialised and acquire special structures and functions. DifferentiationDifferentiation
  • 40. From Cells to Tissues Within a multicellular organism, Cells of the same type are often arranged in groups to form a simple tissue. Some simple animal tissues are designed to: Move a bone/organ by contraction Protect the structures beneath them Muscle tissue Epithelial tissue
  • 41. From Cells to Tissues Within a multicellular organism, Cells of different types can be arranged in groups to form a complex tissue. The different cells work together to perform A SINGLE function. Some complex animal tissues are designed to: Carry electrical impulses Join all parts of the organism Nerve tissue Connective tissue
  • 42. Some simple plant tissues are designed to: Protect a plant against injury and drying-out of its inner parts Epidermal tissue Some complex plant tissues are designed to: Vascular tissue Carry out photosynthesis Photosynthetic tissue Transport food and water to various parts of a plant From Cells to Tissues
  • 43. From Tissues to Organs • Different tissues in organisms are often grouped together to form an organ. It is responsible for carrying out more complex functions. •Most animal organs (heart, lungs, skin) are made up of connecting tissues and some other specialised tissues. The stomach wall consists of glandular, muscular and connective tissues The heart consist of muscular, blood and connective tissues An organ performs a number of different functions. E.g. Our liver stores food and produces bile.
  • 44. • Most plants have organs such as leaves, stems, roots and flowers epidermis vascular tissues vascular bundle epidermis • Every plant organ often performs many different functions. For example, the stem of a plant has 3 main functions: 1. It transports water with dissolved mineral salts from the roots to the leaves. 2. It carries food from the leaves to other parts of the plant. 3. It provides support to the plant to stand upright.
  • 45. From Organs to Systems •Different organs are then linked together to form a body system. The functions performed by a body system are more complex than those performed by the organs. •A number of systems are found in complex organisms to carry out essential bodily functions, such as: - Ensure genetic diversity - Digest food - Eliminate wastes, etc. •An organism is made up of different systems working effectively individually as well as together in a group.
  • 46. nose trachea bronchus lungs Respiratory system Blood circulatory system Takes in oxygen from the surroundings. Releases carbon dioxide and water vapour into the surroundings. Carries food, oxygen and water to various parts of the body and carries wastes away to be removed. Muscular system Enables movement Male reproductive system Produces sperms for reproduction
  • 47. From Systems to Organisms • Different types of multicellular organisms are made up of different numbers and types of systems. Heart muscle cell (a cell) Heart muscle (a tissue) A group of similar cells that are specialised to perform a certain function together to form a tissues. The heart (an organ) A group of specialised tissues that are gathered in a certain part of the body to perform a particular functions together to form an organ. Circulatory system Various organs that work together to perform a major function in the body to form a system. Different systems work individually, but together, they make up the whole organism.
  • 48. CCellsells TTissuesissues SSystemsystems OOrgansrgans OOrganismrganism Simple Tissues: Cells of the same type work together to perform a specific function Simple Tissues: Cells of the same type work together to perform a specific function Complex Tissues: Several types of cells work together to perform a specific function Complex Tissues: Several types of cells work together to perform a specific function Different tissues work together to perform a specific function Different tissues work together to perform a specific function Several organs working together for a common purpose Several organs working together for a common purpose Various systems work together to form the organism Various systems work together to form the organism