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Cell structure & functions for class 9 by Susanta Kumar Panda
The document explains the definition and significance of cells, classifying them into prokaryotic and eukaryotic categories, with examples of each type. It describes the structure and functions of various cellular components, including the cell membrane, organelles like ribosomes and the Golgi apparatus, and processes like protein synthesis and transport. Additionally, it contrasts plant and animal cells, particularly in their structural features and functions.
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Cell structure & functions for class 9 by Susanta Kumar Panda
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- 7. Definition of Cell… Acell is the smallest unit that is capable of performing life functions.
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- 9. Examples of Cells AmoebaProteus Plant Stem Red Blood Cell Nerve Cell Bacteria
- 10. The Two MajorCategories of Cells…. The countless cells on earth fall into two categories:
- 12. PROKARYOTIC They arethe simplest form of life. No nucleus. Do not have structures surrounded by membranes (organelles) Few internal structures They are unicellular_(One-celled organisms). Example: Bacteria
- 13. ribosomes cell wall plasma membrane foodgranule prokaryotic flagellum cytoplasm nucleoid (DNA)
- 14. are themost complex form of life. They have nucleus Contain organelles surrounded by membranes They are multicellular organisms (composed of many cells). Most living organisms Examples: animals and plants. Eukaryotic
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- 16. Prokaryotes & Eukaryotes… Similarities & differences Both surrounded by plasma membrane, but very different Prokaryotes – Archaebacteria and Eubacteria Eukaryotes – everything else
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- 20. Difference Between Plant& Animal Cells… Plants have Cell wall – provides strength & rigidity Have chloroplasts, photosynthetic Animals have Other organelle not found in plants (lysosomes formed from Golgi) Centrioles, important in cell division
- 23. All livingcells (eukaryotes and prokaryotes) have cell membranes Made mainly of phospholipids and proteins ▪ Animal cell membranes contain cholesterol Functions: ▪ Separate the cell from the external environment ▪ Controls passage in and out of cell
- 24. Outer membraneof cell that controls movement in and out of the cell Double layer
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- 26. Cell Wall Rigid structureoutside cell membrane • Found in plants, fungi, bacteria, some protists (not animals) • Made of cellulose (plants), chitin (fungi) or other material (bacteria) • Supports and protects cell
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- 28. ORGANELLES Cell Parts CELL STRUCTUREAND FUNCTION
- 30. nuclear pores nuclear pore nuclear envelope nucleolus histone protein chromosome DNANucleus Function protects DNA Structure nuclear envelope double membrane membrane fused in spots to create pores allows large macromolecules to pass through What kind of molecules need to pass through?
- 31. Function ribosomeproduction ▪ build ribosome subunits from rRNA & proteins ▪ exit through nuclear pores to cytoplasm & combine to form functional ribosomes small subunit large subunit ribosome rRNA & proteins nucleolus
- 32. small subunit large subunitRibosomes Function proteinproduction Structure rRNA & protein 2 subunits combine 0.08mm Ribosomes Rough ER Smooth ER
- 33. membrane proteins Types ofRibosomes Free ribosomes ◦ suspended in cytosol ◦ synthesize proteins that function in cytosol Bound ribosomes ◦ attached to endoplasmic reticulum ◦ synthesize proteins for export or for membranes
- 34. Function • processesproteins • manufactures membranes • synthesis & hydrolysis of many compounds Structure • membrane connected to nuclear envelope & extends throughout cell
- 35. Types of ER Rough ER (RER) – Has ribosomes attached Site of protein synthesis Smooth ER (SER) Complex molecules built here Continuous with RER
- 36. Membrane production Many metabolicprocesses • synthesis synthesize lipids oils, phospholipids, steroids & sex hormones • hydrolysis hydrolyze glycogen into glucose in liver detoxify drugs & poisons in liver ex. alcohol & barbiturates
- 37. Produce proteins forexport out of cell • protein secreting cells • packaged into transport vesicles for export
- 38. Golgi Apparatus Function finishes, sorts, tags & ships cell products ships products in vesicles membrane sacs Structure Stack of flattened membranes “pita bread” like transport vesicles secretory vesicles
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- 40. Vesicles Transport… ERcontents pinch off into vesicles - membrane- bound sacs that store and transport substances in cells vesicle budding from rough ER fusion of vesicle with Golgi apparatus migrating transport vesicle protein ribosome
- 41. The movementof macromolecules such as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and both require the expenditure of energy (ATP).
- 42. Produces energythrough chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates
- 43. Cytoplasm Cytosol (cytoplasm) Cellular fluid surrounding organelles Site of many cellular reactions Found between cell membrane and nucleus
- 44. Lysosomes Lysosomes –special vesicles that store and transport powerful digestive enzymes and other reactive substances within a cell Double membrane protects cell from being digested Break down Food particles Unneeded proteins, carbohydrates, etc.. Disease-causing microorganisms
- 45. Vacuoles Large membranousstorage sacs found mainly in plants. Stores water, nutrients, waste products and pigments ○ Give certain plants bright colors (beets, carrots, flowers)
- 46. CILIA AND FLAGELLA… Hairlike organelles that extend from the surface of the cell Assist in movement Cilia – short and present in large numbers Flagella – long and less numerous
- 47. Chromosomes… In nucleus Made of DNA Contain instructions for traits & characteristics
- 48. Chloroplast Usually foundin plant cells Contains green chlorophyll Where photosynthesis takes place
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