Cells and Life


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Cells and Life

  1. 1. Cells and Life
  2. 2. Understanding Cells English scientist Robert Hooke first identified cells over 300 years ago while looking at cork under a microscope he built.
  3. 3. Understanding Cells Cork is actually made of water-resistant cells that separate the outer bark from the delicate interior bark.
  4. 4. Understanding Cells • Cork has a unique set of properties not found in any other naturally existing material. It is: • impermeable to gas and liquid • lightweight • rot resistant • fire resistant • termite resistant • soft • buoyant
  5. 5. Understanding Cells • In the cork Hooke saw small openings similar to a bee’s honeycomb. The openings reminded him of the small rooms, called cells, where monks lived. • Hooke named these small structures cells.
  6. 6. Cell Theory • Scientists made better microscopes than Hooke’s. • They looked for cells in places such as pond water and blood. • The newer microscopes made it possible for scientists to see different structures inside cells.
  7. 7. Cell Theory • A scientist named Matthias Schleiden looked at plant cells. • Another scientist, Theodore studied animal cells. Schwann, • Later, Rudolf Virchow said all cells come from cells that already exist. • The observations made by these scientists became known as the cell theory.
  8. 8. Cell Theory The Cell Theory states: 1. All living things are made of one or more cells. 2. The cell is the smallest unit of life. 3. All new cells come from pre-existing cells.
  9. 9. Basic Cell Substances • The cell theory raised more questions for scientists. Scientists began to look into what cells are made of. • Cells are made of smaller parts called macromolecules that form when many small molecules join together. • Macromolecules cannot function without one of the most important substances in cells - water.
  10. 10. Basic Cell Substances • The main ingredient in every cell is water. Making up more than 70 percent of a cell. • Water also surrounds cells, helping to insulate your body. This helps your body maintain a stable internal environment, or homeostasis. • Water also is useful because it can dissolve other substances, such as salt. • For substances to move into and out of a cell, they must be dissolved in a liquid.
  11. 11. Macromolecules in Cells • All cells contain other substances besides water that help cells do what they do. • There are four types of macromolecules in cells. They are nucleic acids, proteins, lipids, and carbohydrates. • Each type of macromolecule has its own function in a cell. These functions range from growth and communication to movement and storage.
  12. 12. Macromolecules in Cells Nucleic Acids • Both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are nucleic acids. • Nucleic acids are important because they contain the genetic material of a cell. This information is passed from parents to offspring. • Nucleic acids are macromolecules formed when long chains of molecules called nucleotides join together.
  13. 13. Macromolecules in Cells Nucleic Acids DNA
  14. 14. Macromolecules in Cells Nucleic Acids DNA
  15. 15. Macromolecules in Cells Nucleic Acids DNA
  16. 16. Macromolecules in Cells Nucleic Acids DNA
  17. 17. Macromolecules in Cells Nucleic Acids DNA
  18. 18. Macromolecules in Cells Nucleic Acids DNA RNA
  19. 19. Macromolecules in Cells Nucleic Acids • DNA includes instructions for cell growth, for cell reproduction, and for cell processes that enable a cell to respond to its environment. • DNA is used to make RNA. RNA is used to make proteins. • The order of nucleotides in DNA and RNA is important. A change in the order of the nucleotides can change the information in a cell.
  20. 20. Macromolecules in Cells Proteins • The macromolecules necessary for almost everything cells do are proteins. • A protein is a macromolecule made of long chains of amino acid molecules. • RNA contains instructions for joining amino acids together to build the protein.
  21. 21. Macromolecules in Cells Proteins Amino Acids
  22. 22. Macromolecules in Cells Proteins Chain of Amino Acids
  23. 23. Macromolecules in Cells Proteins Chain of Amino Acids
  24. 24. Macromolecules in Cells Proteins • A protein can contain 100 to 10,000’s amino acids. • Cells have hundreds of proteins. • Each protein has its own function. For example some: • help cells communicate with other cells • move substances around inside cells • help to break down nutrients in food • make up supporting structures (like hair, horns, and feathers)
  25. 25. Macromolecules in Cells Lipids • A lipid is a large macromolecule that does not dissolve in water. Because lipids do not dissolve in water, they protect cells. • Lipids also are a large part of the cell membrane. • Lipids store energy for cells and help with cell communication. • Cholesterol and vitamin A are lipids.
  26. 26. Macromolecules in Cells Lipids Cell Membrane
  27. 27. Macromolecules in Cells Carbohydrates • One sugar molecule, two sugar molecules, or a long chain of sugar molecules make up carbohydrates. • Carbohydrates store energy, provide structural support for cells, and help cells communicate.
  28. 28. Macromolecules in Cells Carbohydrates • Sugars and starches are carbohydrates that store energy. Fruits contain sugars. Bread and pasta are mostly starch. • The energy stored in sugars and starches can be released quickly through chemical reactions in cells. • Cellulose is a carbohydrate in the cell walls of plants.
  29. 29. Macromolecules in Cells Carbohydrate Sugars
  30. 30. Macromolecules in Cells Carbohydrate Starch chain of glucose
  31. 31. Macromolecules in Cells Carbohydrate Cellulose many chains of glucose bunched together