1. Chapter 7 The Cell and It’s Structures

2. Cell- smallest unit of matter that can carry on all the processes of life Discovery of the Cell 17 th century- The microscope was developed 1665- Robert Hooke- viewed a slice of cork; named the spaces, cells. 1673- Anton van Leeuwenhoek observed living cells in pond water. 1838- Matthias Schleiden- concluded all plants are made of cells. 1839- Theodor Schwann- said all animals are made of cells. 1855- Rudolf Virchow- stated that all cells come from pre-existing cells.

3. The Cell Theory All living things are composed of cells. Cells are the basic unit of structure and function in living things. New cells are produced from existing cells.

4. Cell Diversity Cells vary in size shape and internal organization- The human body has over 200 different cell types. Size of Cells Range From.2 microns – 2 meters in length See Figure 7 – 4 on page 193 Shape- depends on function

5. Internal Organization Terms to know for the rest of the year. Organelles - are cell components that perform a specific function. Prokaryotes - unicellular organisms that lack a nucleus and membrane bound organelles. Example Bacteria. Eukaryotes - organisms that have a nucleus and membrane bound organelles. Can be single celled Protists or multicellular organisms.

6. The Basic Cell Types

7. 7.2 Cell Structure Parts of a Eukaryotic Cell Cytoplasm- between the cell membrane and nucleus holds other organelles in a gelatin-like fluid called cytosol- also has dissolved salts minerals and organized molecules.

8. The Nucleus

9. Nucleus – contains the cell ’ s DNA which contains coded instructions for making proteins and other important molecules. Hereditary information is stored in the nucleus. Nuclear matrix is the protein skeleton that maintains the shape of the nucleus. Nuclear envelope is a double membrane on the outside of the nucleus. This is filled with thousands of nuclear pores.

10. Nuclear Envelope

11. Chromatin – DNA and associated proteins, Chromosomes form from chromatin prior to cell division. Nucleolus site of ribosome production, after being made the ribosomes leave the nucleus. For the Production of Proteins: RNA is copied from DNA. RNA controls protein synthesis. The RNA leaves the nucleus through the nuclear pores then goes to the ribosomes for protein synthesis.

12. Organelles that Store, Clean up, and Support Vacuoles store materials like water, salts, proteins (enzymes) carbohydrates and metabolic wastes Plants have a single large vacuole that is usually water filled to help support the plant. Contractile vacuoles are used in single celled organisms to pump excess water out of the cell.

13. Vesicles store and move materials between cell organelles and the cell surface. Lysosome contains digestive enzymes that get rid of proteins, carbohydrates, lipids, and DNA. Also digests old organelles, viruses and bacteria. (Also called suicide sacs) Lysosome

14. Cytoskeleton

15. Cytoskeleton maintains the shape of a cell and helps with cell movement. Microfilaments are made from a protein called Actin. Help with cell movement and contraction of muscle cells. Microtubules – hollow tubes help form spindle fibers that pull chromosomes apart during cell division. Centrioles help with cell division

16. Cilia – short hair-like structures that help a cell move found on single celled organisms and in multicellular organisms Flagella – long hair-like structures for movement. Example - sperm cell. Both cilia and flagella are made of 9 pairs of microtubules around a central pair of microtubules.

17. Cilia and Flagella

18. Movement of Cilia and Flagella

19. Organelles that build proteins Ribosomes - site of protein synthesis made up of protein and RNA has no membrane. found either free floating or attached to the ER

20. Endoplasmic Reticulum

21. Endoplasmic Reticulum (ER) - transports molecules from one part of the cell to another 2 types Rough ER- has ribosomes attached. Takes proteins to be exported from the cell or used in the cell membrane. Smooth ER- makes steroids, regulates calcium in muscle cells and breaks down toxins in the liver.

22. Golgi Apparatus (Bodies) Golgi Apparatus- modifies sorts, and packages proteins and other materials from the ER for storage in the cell or for export out of the cell.

23. Chloroplast Organelles that Capture and Release Energy Chloroplasts have a system of Thylakoids which are flattened sacs where photosynthesis takes place. Convert the energy from sunlight into chemical energy in glucose.

24. Mitochondria

25. Mitochondria- power house of the cells Transfers energy from organic compounds to ATP – Adenosine Triphosphate 2 layers Outer membrane- boundary between mitochondria and cytosol Inner membrane- called Cristae- site of chemical reactions Mitochondria and Chloroplasts have their own DNA and can make new mitochondria or chloroplasts when existing ones grow and divide.

26. Plant Cell Cellular Boundaries Cell wall – supports and protects the cell found in plant cells and most prokaryotes. Made of cellulose and are porous to allow water and gases to pass from cell to cell

27. Cell Membrane- regulates materials into and out of the cell. Selectively permeable- allows some materials in, keeps others out. Membrane made of lipids- phospholipids with hydrophilic and hydrophobic ends. Forms a lipid bi-layer. Membrane proteins- help move molecules through the bilayers Some form channels Others carry materials Carbohydrates help hold cells together or act as sites for viruses or chemical messengers to attach.

28. Cell Membrane Fluid Mosaic Model- the lipid bi-layer acts like a liquid instead of a solid. The lipids and proteins can move laterally within the membrane. So the pattern of lipids and proteins constantly changes.

29. Chapter 7 Section 3 Passive Transport The movement of materials across the cell membrane without using cellular energy is called passive transport. Every living cell exists in a liquid environment. One of the most important functions of the cell membrane is to keep the cell ’ s internal conditions relatively constant. It does this by regulating the movement of molecules from one side of the membrane to the other side.

30. Diffusion: The process by which particles move from an area of high concentration to an area of lower concentration. Diffusion depends upon random particle movements. Substances can diffuse across membranes. Equilibrium is reached when the concentration of the substance on both sides of the cell membrane is the same.

31. Facilitated Diffusion: Molecules that cannot directly diffuse across the membrane pass through special protein channels in a process known as facilitated diffusion. The movement of molecules by facilitated diffusion does not require any of the cell ’ s energy. Example: Osmosis

32. Osmosis: is the diffusion of water through a selectively permeable membrane. Osmosis involves the movement of water molecules from an area of higher concentration to an area of lower concentration. Many cells contain water channel proteins, known as aquaporins that allow water to pass right through them. Without aquaporins, water would diffuse in and out of cells very slowly.

33. When the concentration is the same on both sides of the membrane, the two solutions will be isotonic. The more concentrated sugar solution is hypertonic, compared to the dilute sugar solution. The dilute sugar solution is hypotonic.

34. The net movement of water out of or into a cell exerts a force known as osmotic pressure.

35. Active Transport The movement of material against a concentration difference is known as active transport. Active transport requires energy. Small molecules and ions are carried across membranes by proteins in the membrane that act like pumps. Many cells use such proteins to move calcium, potassium, and sodium ions across cell membranes. The use of energy in these systems enables cells to concentrate substances in a cell, even when the forces of diffusion tend to move these substances out of the cell.

36. Endocytosis: Endocytosis is the process of taking large particles into the cell by means of infoldings, or pockets, of the cell membrane, forming a vesicle or vacuole in the cytoplasm. Two examples of endocytosis are Phagocytosis (food) and Pinocytosis (liquid).

37. Many cells also release material from the cell, a process known as exocytosis. During exocytosis, the membrane of the vacuole fuses with the cell membrane, forcing the contents out of the cell. Exocytosis:

38. Chapter 7.4 Homeostasis and Cells To maintain homeostasis, unicellular organisms grow, respond to the environment, transform energy, and reproduce. Unicellular Organisms: Whether a prokaryote or a eukaryote, homeostasis is an issue for each unicellular organism. Every unicellular organism needs to find sources of energy or food, to keep concentrations of water and minerals within certain levels, and to respond quickly to changes in its environment.

39. Multicellular Organisms: The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis.

40. A tissue is a group of similar cells that performs a particular function. Many groups of tissues working together is an organ. A group of organs that work together to perform a specific function is called an organ system.

41. Communication between Cells: Cells in a large organism communicate by means of chemical signals that are passed from one cell to another. To respond to one of these chemical signals, a cell must have a receptor to which the signaling molecule can bind. Sometimes these receptors are on the cell membrane, others are inside the cytoplasm.

42. Animal Cell