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A Tour of the Cell

A Tour of the Cell. “cell”. In 1665, an English scientist named Robert Hooke coined the term "cell" after viewing slices of cork through a microscope. The term came from the Latin word cella which means "storeroom" or "small container". The Cell Theory.

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A Tour of the Cell

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  1. A Tour of the Cell

  2. “cell” • In 1665, an English scientist named Robert Hooke coined the term "cell" after viewing slices of cork through a microscope. • The term came from the Latin word cella which means "storeroom" or "small container".

  3. The Cell Theory 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells come from pre-existing cells.

  4. Microscope • Instrument for observing small objects

  5. Light Microscopes: Use visible light Magnify about 1000 times Not powerful enough to view internal cell structures Electron Microscopes: Electron beams used for magnification Magnify up to a million times Types of Microscopes

  6. Eyepiece Objective lens Arm Stage Focus Adjustment Source of light Base Different parts of a microscope

  7. Basic types of cells: Animal Cell Bacterial Cell Plant Cell

  8. Number of Cells • Organisms may be: • Unicellular – composed of one cell • Multicellular- composed of many cells

  9. Cells May be Prokaryotic • Prokaryotes lack a nucleus and organelles • Nucleoid region contains the DNA • Cell membrane & cell wall • First organisms to appear in fossil record

  10. Cells May be Eukaryotic • Have a nucleus and organelles • Two main types: Plant Cell Animal Cell

  11. Organelles • Very small in size • Can only be observed under a microscope • Have specific functions • Found throughout cytoplasm

  12. Golgi Apparatus • Stacks of flattened sacs • Modifies, stores, and repackages cell products in vesicles • Routes repackaged vesicles with chemical products to their destinations Transport vesicle

  13. Lysosome • Contain digestive enzymes • Break down food and worn out cell parts for cells • Programmed for cell death (release enzymes to break down & recycle cell parts)

  14. Smooth & Rough Endoplasmic Reticulum • Smooth ER lacks ribosomes & makes proteins USED In the cell • Rough ER has ribosomes on its surface & makes proteins to EXPORT

  15. Ribosomes • Site of protein synthesis • It could be found free in cytoplasm or on outer surface of ER

  16. Mitochondria • Cell Powerhouse • It provides the energy a cell needs to move, divide & etc . . . • It is the site of Cellular respiration • Burns sugar to produce ATP (energy) • Active cells like muscles have more mitochondria

  17. Cell Membrane • Surrounds the cell • Made of protein and phospholipids • Selectively permeable • Controls the movement of materials into and out of the cell

  18. Cytoplasm • Jelly-like substance enclosed by cell membrane • Provides a medium for chemical reactions to take place

  19. Nucleus • Controls the normal activities of the cell • Contains chromosomes; DNA • Each cell has a fixed number of chromosomes that carry genes • humans 46

  20. Nucleolus • Inside the nucleus • Makes ribosomes that make proteins

  21. Plant Cell Organelle:Chloroplast • Contain the green pigment chlorophyll • Traps sunlight to make glucose (sugar) through a process called photosynthesis

  22. Plant Cell Organelle:Cell Wall • Dead layer: Strong and rigid • Made of cellulose • Freely permeable • Protects and supports the enclosed substances • Gives shape to the cell

  23. Plant Cell Organelle:Vacuole • Have a large central vacuole • It plays roles in intracellular digestion and the release of cellular waste products

  24. white blood cell Amoeba red blood cell muscle cell sperm cheek cells nerve cell Paramecium Different kinds of animal cells

  25. Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria

  26. Differences between Plant Cells and Animal Cells Animal cells Plant cells Vacuole small or absent Large central vacuole Glycogen as food storage Starch as food storage Nucleus at the center Nucleus near cell wall Relatively smaller in size Relatively larger in size No cell wall Cell wall present

  27. Cell Membrane The cell membrane is made of proteins and 2 layers of phospholipids called the phospholipid bilayer.

  28. Contains 2 fatty acid chains that are nonpolar and a head that is polar. Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” in what crosses Phospholipids:

  29. Types of Transport across Cell Membranes Passive Transport: Diffusion • Doesn’t require energy • Moves high to low concentration • Example: Oxygen diffusing into a cell

  30. Types of Transport across Cell Membranes Passive Transport: Facilitated diffusion • Doesn’t require energy • Uses transport proteins to move high to low concentration • Example: Glucose or amino acids moving from blood into a cell.

  31. Osmosis Diffusion across a membrane • The passive transport of water across a selectively permeable membrane. • Moves from HIGH water potential (low solute) to LOW water potential (high solute) Semipermeable membrane

  32. Diffusion of H2O Across A Membrane High H2O potentialLow solute concentration Low H2O potentialHigh solute concentration

  33. Types of osmotic solutions • Hypertonic Solution: a solution whose solute concentration is higher than the solute concentration inside the cell • Animal cells will lose water and shrivel when placed in a hypertonic solution • Water moves out of the cell

  34. Cell in Hypertonic Solution 15% NaCL85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement?

  35. Types of osmotic solutions • Hypotonic Solution: a solution whose solute concentration is lower than the solute concentration inside the cell • Animal cells will swell and possibly burst when placed in a hypotonic solution • Water moves into the cell

  36. Cell in Hypotonic Solution 10% NaCL90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement?

  37. Types of osmotic solutions • Isotonic Solution: a solution whose solute concentration is equal to the solute concentration inside the cell • Animal cells retain their normal shape when placed in isotonic solutions • No net gain or loss of water inside the cell

  38. Cell in Isotonic Solution 10% NaCL90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________.

  39. Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic

  40. Types of Transport Across Cell Membranes Active Transport • Requires energy or ATP • Moves materials from LOW to HIGH concentration • AGAINST concentration gradient • A specific transport protein pumps a solute across a membrane.

  41. EX: Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out

  42. Exocytosis - moving materials out Endocytosis: Moving materials in Moving the “Big Stuff” • Too large  Must be packaged in membrane sacs • called vesicles • It requires energy

  43. Endocytosis • Phagocytosis: cell membrane takes in particle of solid material; “cell eating” • Pinocytosis: cell membrane takes in small droplet of liquid; “cell drinking”

  44. That’s it!

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