Chapter Seven. A View of the Cell

Transcription

1 Chapter Seven A View of the Cell

2 Cellular Organization Cell Tissue group of cells functioning together. Organ group of tissues functioning together. Organ System group of organs functioning together. Organism group of organ systems functioning together.

3 The History of the Cell The Cell The basic unit of an organism Discovery made possible by the invention of the microscope

4 Microscopes and Cells 1600 s. Anton van Leeuwenhoek first described living cells as seen through a simple microscope.

5 Microscopes and Cells Robert Hooke used the first compound microscope to view thinly sliced cork cells. Compound scopes use a series of lenses to magnify in steps. Hooke was the first to use the term cell.

6 Microscopes and Cells 1830 s. Mathias Schleiden identified the first plant cells and concluded that all plants made of cells. - Theodor Schwann made the same conclusion about animal cells.

7 Cell Theory: All organisms are made up of one or more cells. The cell is the basic unit of organization of all organisms. All cells come from other cells all ready in existence.

8 Two Basic Cell Types 1) Prokaryote Lacks internal compartments. No true nucleus. Most are single-celled (unicellular) organisms. Examples: bacteria

9 Two Basic Cell Types 2) Eukaryote Has several internal structures (organelles). True nucleus. Either unicellular or multicellular. unicellular example: yeast multicellular examples: plants and animals

10 Cell Rap Types of cells bacteria cells Eukaryotes -organelles Prokaryote - no organelles animal cells plant cells

11 Cell size comparison Animal cell Bacterial cell most bacteria 1-10 microns eukaryotic cells microns micron = micrometer = 1/1,000,000 meter diameter of human hair = ~20 microns

12 The Functions of Eukaryotic Cell Parts 1. Boundaries 2. Controls 3. Assembly 4. Transport 5. Storage 6. Energy Transformers 7. Support 8. Locomotion 9. Cell Division Cell video clip Cell Song

13 Plasma Membrane Serves as a boundary between the cell and its external environment. Boundaries Allows materials to pass in and out of the cell. Fluid mosaic model

14 Boundaries Cell Wall Surrounds the plasma membrane of the cells of plants, bacteria, and fungi. Plant cell walls contain cellulose while fungi cell walls contain chitin.

15 Controls Nucleus Regulates cell function. Surrounded by a double-layered membrane (nuclear enveloped) with large pores that allow materials to pass in and out of the nucleus. Contains chromatin long tangles of DNA.

16 Controls Nucleolus Found in the nucleus and responsible for ribosome production. (Ribosomes are the sites of protein production.)

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18 Assembly Cytoplasm The jelly-like material that surrounds the organelles.

19 Transport Endoplasmic reticulum Folded membrane that acts as the cell s delivery system. Smooth E.R. contains enzymes for lipid synthesis. Rough E.R. is studded with ribosomes for protein synthesis.

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21 Transport Golgi apparatus (or Golgi body) A series of flattened sacs where newly made lipids and proteins from the E.R. are repackaged and shipped to the plasma membrane.

22 : Storage Vacuoles and Vessicles A sac of fluid surrounded by a membrane used to store food, fluid, or waste products.

23 Storage Lysosomes Contain a digestive enzyme. Can fuse with vacuoles to digest food, or can digest worn cell parts. Also known as suicide sacs because they can also destroy the whole cell.

24 Energy Transformers Mitochondria Produce the energy for the cell. Also known as the powerhouse of the cell. Has a highly folded inner membrane (cristae).

25 Energy Transformers Chloroplasts Found in plant cells and some protists. Transforms light energy into chemical energy which is stored in food molecules. Contain chlorophyll a green pigment that traps light energy and gives plants their green color.

26 Support Cytoskeleton A network of thin, fibrous materials that act as a scaffold and support the organelles. Microtubules hollow filaments of protein. Microfilaments solid filaments of protein.

27 Locomotion Cilia Short, numerous, hairlike projections from the plasma membrane. Move with a coordinated beating action.

28 Locomotion Flagella Longer, less numerous projections from the plasma membrane. Move with a whiplike action.

29 Cell Division Centrioles made of protein. play a role in the splitting of the cell into two cells. found in animal and fungi cells.

30 Composite Animal Cell

31 Composite Animal Cell

32 Movement Across the Membrane Establishes Homeostasis Occurs through channel proteins Can be active or passive Passive does not require energy Active does require energy

33 Passive Transport: Diffusion Particles in a solution move constantly Particles tend to move from an area of high concentration to low concentration When concentration is equal everywhere, it has reached equilibrium Substances diffuse across membranes without requiring the cell to use energy (passive transport)

34 Diffusion HIGH concentration LOW concentration

35 Passive Transport: Osmosis If a substance can diffuse across a membrane, the membrane is said to be permeable to it and impermeable if it can't diffuse across it Water diffuses easily Osmosis is the diffusion of water across a selectively permeable membrane from an area of high concentration to low concentration

36 Osmosis The direction of osmosis is determined by comparing total solute concentrations HYPERTONIC - more solute, less water ISOTONIC - equal solute, equal water HYPOTONIC - less solute, more water hypotonic hypertonic

37 Managing water balance Cell survival depends on balancing water uptake & loss freshwater balanced saltwater

38 The Phospholipid Bilayer is a Semipermeable Membrane The phospholipid bilayer is Nonpolar Has hydrophilic edges and hydrophobic center What molecules can get through directly? Nonpolar molecules: fats & other lipids

39 Diffusion through phospholipid bilayer inside cell lipid NH salt 3 sugar aa outside cell Semipermeable H 2 O What molecules can NOT get through directly? polar molecules H 2 O ions (charged) salts, ammonia large molecules starches, proteins

40 Passive Transport- Facilitated Diffusion Cell membranes have protein channels that act like carriers, making it easier for certain molecules to cross. They "facilitate" the diffusion of molecules. There are hundreds of different channels that only allow certain molecules to come through.

41 Passive Transport- Facilitated Diffusion It will only occur if there is a higher concentration on one side of the membrane. It doesn't require energy. It's passive transport.

42 Active Transport Cells may need to move molecules against concentration gradient conformational shape change transports solute from one side of membrane to other protein pump costs energy = ATP LOW Change in Shape of Protein ATP HIGH The Doorman

43 How about large molecules? Moving large molecules into & out of cell through vesicles & vacuoles

44 How about large molecules? ENDOCYTOSIS: into the cell 2 types 1. phagocytosis = cellular eating 2. pinocytosis = cellular drinking EXOCYTOSIS: out of the cell exocytosis

45 Endocytosis phagocytosis pinocytosis fuse with lysosome for digestion non-specific process receptor-mediated endocytosis triggered by molecular signal

46 Getting through cell membrane summary Passive Transport Simple diffusion diffusion of nonpolar, hydrophobic molecules lipids HIGH LOW concentration gradient Facilitated transport diffusion of polar, hydrophilic molecules through a protein channel HIGH LOW concentration gradient Active transport diffusion against concentration gradient LOW HIGH uses a protein pump requires ATP ATP

47 Cell Membrane Cell membrane establishes homeostasis for the cell by controlling what passes in and out of the cell. HOW? 1. PHOSPHOLIPID BILAYER creates a barrier 2. Protein channels that allow polar substances through 3. Glyco-proteins are name tags

48 Phospholipid Bilayer Glycoprotein Integral Proteins Peripheral Proteins