Cells and the cell theory

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Cells and the cell theory

  1. 1. Objectives • List scientists who contributed to the cell theory • List the components of the cell theory • Compare prokaryote and eukaryote cells • Label a plant and an animal cell • Know the functions of cell organelles
  2. 2. Early Contributions • Robert Hooke - First person to see cells, he was looking at cork and noted that he saw "a great many boxes. (1665) • Anton van Leeuwenhoek - Observed living cells in pond water, which he called "animalcules" (1673)
  3. 3. • Theodore Schwann - zoologist who observed tissues of animals had cells (1839) • Mattias Schleiden - botanist, observed tissues of plants contained cells ( 1845) • Rudolf Virchow - also reported that every living thing is made of up vital units, known as cells. He predicted that cells come from other cells. (1850 )
  4. 4. The Cell Theory • 1. Every living organism is made of one or more cells. • 2. The cell is the basic unit of structure and function. • 3. It is the smallest unit that can perform life functions. • 4. All cells arise from pre-existing cells. *Why is the Cell Theory called a Theory and not a Fact?
  5. 5. Cell Features ALL cells have these parts • Ribosomes – make protein for use by the organism • Cytoplasm – fluid material within cell • DNA – genetic material • Cytoskeleton – internal framework of cell • Cell Membrane – outer boundary, some things can cross the cell membrane
  6. 6. Comprehension Checkpoint Answer true or false 1.Robert Hooke was the first person to see cells. 2.Bacteria cells have a cell membrane. 3.The Cell Theory was developed by a single scientist. 4.Plant cells have cytoplasm. 5.Cells taken from fungi do not have DNA. 6.Cells can only come from pre-existing cells.
  7. 7. Prokaryote Cells • The first cells to inhabit the earth • Simple cells • Bacteria • These cells do NOT have a nucleus, their DNA is circular and floats in the cytoplasm Some bacteria have a tail-like structure called a flagella, that helps it to move. A capsule surrounds some bacteria and helps them avoid the body’s immune system
  8. 8. Bacteria-prokaryotic Bacteria that causes Anthrax
  9. 9. Eukaryotic Cells • Cells found in plants, animals, protists, and fungi • The cell is composed of 4 main parts: 1.Cell membrane 2.Cytoplasm 3.Nucleus – “control center” of cell, houses DNA 4.Organelles – small structures that carry out specific functions (“little organs”)
  10. 10. Nucleus • Usually found at center of cell • Has a nuclear membrane & nuclear pores • Contains cell’s DNA in one of 2 forms o chromatin - DNA bound to protein (non-dividing cell) o chromosomes - condensed structures seen in a dividing cell (look like Xs) • Also contains an organelle called nucleolus - which makes the cell’s ribosomes
  11. 11. Cell Organelles Mitochondria – this is the cell’s energy center. It turns food into a chemical energy called ATP. The mitochondria is sometimes called the “powerhouse” of the cell.
  12. 12. Cell Organelles Golgi Apparatus – processes, packages and secretes proteins. It is comparable to a factory or a post office. *A vesicle is used with the Golgi to transport substances outside cell, like a messenger delivering a package.
  13. 13. Cell Organelles Lysosome – Contains digestive enzymes, breaks things down, "suicide sac” Endoplasmic Reticulum – Transport, "intracellular highway". -Rough ER contains many ribosomes & is involved in protein synthesis -Smooth ER ribosomes not found on surface
  14. 14. Cell Organelles Cytoskeleton – Helps cell maintain support & shape; movement a. microtubules-hollow structures; also help build cilia flagella b. microfilaments-threadlike c. centrioles-only in animal cells; used during cell division (paired) Vacuole – storage area for water and other substaces, plant cells usually have a large central vacuole
  15. 15. Protein Production The cell is like a factory. Its product is protein which goes to body to serve different functions. 1.DNA has instructions to build protein 2.These instructions are sent to ribosomes 3.The ribosomes build protein and send it through ER 4.The proteins are delivered to golgi where they are completed and “tagged” for export outside cell
  16. 16. THE ANIMAL CELL
  17. 17. Cheek Cells Seen Through Microscope
  18. 18. Plant Cells • Have additional structures • CELL WALL – surrounds membrane & provides additional support • CHLOROPLASTS – contain green pigment, function in photosynthesis • CENTRAL VACUOLE – large water container in center of cell
  19. 19. PLANT CELL Can you identify the parts?
  20. 20. Anacharis Cells Viewed With a Microscope
  21. 21. Organelles With DNA • Mitochondria and chloroplasts have their own DNA (separate from the nucleus) • This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells.
  22. 22. CELL MEMBRANE • Selectively permeable; it regulates what comes into the cell and what leaves the cell • It is composed of a double layer of phospholipids with proteins embedded throughout

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