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Introduction to Cells: The Smallest Units of Life

Learn about cells, the smallest functional unit of life, and how they make up all living things. Explore the cell theory, cell types (prokaryotic and eukaryotic), and the structure and function of important organelles.

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Introduction to Cells: The Smallest Units of Life

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  1. The Cell

  2. What is a Cell? Cell- • The smallest functional unit of life • all living things are composed of cells.

  3. All Living Things Share Five Characteristics • Reproduce • Need energy • Produce wastes • Grow • Respond and adapt to their environment

  4. Cell Theory • Development of Cell Theory • 1590 – compound microscope invented • 1665 – Robert Hooke noticed structures while viewing slices of cork – cells • 1700 – Anton van Leeuwenhoek observes living cells with a microscope • 1700 + - more structures identified as technology gets better • 1838 – Schwann and Schleiden proposed that plant and animal tissue are made of cells

  5. The Cell Theory • All organisms are composed of one or more cells. • The cell is the smallest function unit of life. • All cells are produced from other cells.

  6. 1. Prokaryotic 2. Eukaryotic Types of Cells All living things are composed of one of two types of cells:

  7. Prokaryotic

  8. Eukaryotic Plant Animal

  9. Prokaryotic Cells General Characteristics • No organized nucleus-genetic material in the cytoplasm

  10. Bacteria • Blue green algae Prokaryotic Cells

  11. Prokaryotic Cells General Characteristics • No organized nucleus-genetic material in the cytoplasm • Chromosome may be in a circular shape called a plasmid

  12. plasmid

  13. Prokaryotic Cells General Characteristics • No organized nucleus-genetic material in the cytoplasm • Chromosome may be in a circular shape called a plasmid • No organized organelles except for ribosomes (for making protein) • Smaller than eukaryotic cells • Oldest known form of life

  14. Anatomy of a Bacterium Chromosome in cytoplasm Cytoplasm Cell membrane

  15. Eukaryotic Cells Generally • Organized nucleus • Organized organelles • Larger than prokaryotic cells

  16. 1. Plant 2. Animal Eukaryotic Cells • Two types

  17. Plant vs. Animals Plant cells and animal cells differ in a few ways. 1) Only plant cells contain chloroplasts 2) Plant cells contain a LARGE central vacuole 3) Only plant cells contain a cell wall • Only animal cells contain lysosomes • Animal cells have centrioles

  18. Organelles Structure & Function • Nucleus • Large dark round spot inside Plant & Animal cells. • Controls the daily activities of the cell. • The “brain” of the cell. “Library” Nucleus

  19. Organelles Structure & Function Inside the Nucleus • Nucleolus • Dark spot inside nucleus • Produces RNA and ribosomes • Is involved in protein synthesis Nucleolus

  20. Organelles Structure & Function Inside the Nucleus Chromosomes • DNA is organized with proteins into multiple, linear chromosomes • Chromatin is the term used to represent the mass of stringy, entangled chromosomes observed during interphase (between cell divisions)

  21. Chromosome Chromatin

  22. Organelles Structure & Function Inside the Nucleus • Nucleoplasm • Jelly-like fluid • Medium supporting the contents of the nucleus

  23. Organelles Structure & Function • Cytoplasm • Gel like substance inside the cell • Dissolves nutrients throughout the cell • Suspends organelles • keeps them from banging into each other.

  24. Organelles Structure & Function • Mitochondrion • organelle within all cells • looks like a long worm inside a sandwich bag • power house of the cell • produces ATP • site of cellular respiration

  25. Vacuole • a hollow organelle • Plant cells contain a LARGE central vacuole • Used for storage within the cell • stores water, nutrients and waste

  26. large central vacuole vacuole

  27. Ribosomes • very very small snowman shaped organelles • responsible for protein synthesis • RIBS = protein • RIBS = RIBoSomes

  28. Endoplasmic Reticulum (ER) • long system of tubes and canals throughout cell • provides for intracellular transport of molecules • like a subway system in a city • Two types of Endoplasmic Reticulum • Rough ER – ribosomes attached to the ER • Smooth ER - no ribosomes attached

  29. Smooth ER Rough ER

  30. Golgi Complex • looks like a stack of pancakes • packages materials (proteins…) for export • intercellular transport • like a shipping department for an industrial factory

  31. Lysosome • Spherical bodies • Contains enzymes • Intracellular digestion

  32. Centrioles • Rod-like structures containing microtubules • Cell division in animals

  33. Chloroplast • organelle within plant cells only • captures light energy • site of photosynthesis

  34. Cell Wall • The thick outer wall of a plant cell • Provides structure and support to plant • Made up of cellulose • Plants do not have bones

  35. Cell Membrane • Retains cell contents • a phospholipid bilayer • controls what enters and leaves the cell.

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