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Transcript
Discovery of the Cell • Robert Hooke (1635-1703) – invented the term cell; studied dead plant cells such as cork. • Anton van Leeuwenhoek (1632-1723) - 1st to observe living cells. 1 Discovery of the Cell • Matthias Schleidan (1804-1881) – concluded that all plants are composed of cells. • Theodor Schwann (1810-1882) - concluded all animals were composed of cells. • Rudolf Virchow (1821 – 1902) - reasoned that cell come only from other cells. 2 Protocells: One theory of the origins of cells states that the first life on earth consisted of several types of tiny protocells, celllike organisms. These organisms were able to survive and reproduce in a very limited environment because of their simplicity. Over time, some of these protocells came together and shared their specialization in a symbiotic relationship. These colonies of protocells eventually became the cells we know today. 3 Basic Structure of a Cell 4 Introduction to Cell Theory 1. Cells are the basic units of organisms 2. Cells come only from other cells 3. All living things are made of cells Basic types of cells: Animal Cell Plant Cell Bacterial Cell 5 Number of Cells Organisms may be: • Unicellular – composed of one cell • Multicellularcomposed of many cells that may organize 6 Cells May be Prokaryotic or Eukaryotic Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles Ex: blue-green algae Eukaryotes include most other cells & have a nucleus and membranebound organelles (plants, fungi, & animals) 7 Prokaryotes Nucleoid region contains the DNA •Cell membrane & cell wall • Contain ribosomes (no membrane) to make proteins in their cytoplasm •Evolved 3.5 billion years ago 8 Eukaryotic Cell Contain 3 basic cell structures: • Nucleus • Cell Membrane • Cytoplasm with organelles • Evolved 1.5 billion years ago 9 Two Main Types of Eukaryotic Cells Plant Cell Animal Cell 10 Organelles Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm 11 Organelles Found in Cells Examples of Organelles include: Endoplasmic reticulum (ER) (rough & smooth) – canals for movement Golgi Bodies – wrap & export proteins Nucleolus – makes ribosomes Lysosomes – digests & gets rid of wastes Ribosomes – makes proteins 12 Golgi Bodies • Stacks of flattened sacs • Have a shipping side & a receiving side • Receive & modify proteins made by ER • Transport vesicles with modified proteins pinch off the ends Transport vesicle 13 Lysosome • Contain digestive enzymes • Break down food and worn out cell parts for cells • Programmed for cell death (lyse & release enzymes to break down & recycle cell parts) 14 Nucleolus • Cell may have 1 to 3 nucleoli • Inside nucleus • Disappears when cell divides • Makes ribosomes that make proteins 15 Smooth & Rough Endoplasmic Reticulum Rough ER has ribosomes on its surface & makes proteins to EXPORT Smooth ER lacks ribosomes & makes proteins USED In the cell 16 Cell Powerhouse Mitochondrion ( mitochondria ) Rod shape Site of Cellular respiration 17 In Animal Cells: Mitochondria Active cells like muscles have more mitochondria Burn sugars to produce energy ATP 18 Surrounding the Cell Cell (Plasma) membrane Lies immediately against the cell wall in plant cells Made of protein and phospholipids “Selectively permeable” 19 Cell or Plasma Membrane Cell membrane Living layer Controls the movement of materials into and out of the cell Selectively permeable 20 Cytoplasm of a Cell Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place 21 More on Cytoplasm Cytoplasm Contains organelles to carry out specific jobs Examples: chloroplast & mitochondrion 22 Control Organelle Nucleus Controls the normal activities of the cell Bounded by a nuclear membrane (envelope) Contains chromosomes 23 More on the Nucleus Nucleus Each cell has fixed number of chromosomes that carry genes Genes control cell characteristics 24 Plant Cell Organelles Chloroplast Contain the green pigment chlorophyll Traps sunlight to make to make sugars (food) Process called photosynthesis 25 Plant Cell Cell wall Dead layer Large empty spaces present between cellulose fibers Freely permeable 26 Plant Cell Cell wall Made of cellulose which forms very thin fibers Strong and rigid Found in plant cells 27 Plant Cell Cell wall Protect and support the enclosed substances (protoplasm) Resist entry of excess water into the cell Give shape to the cell 28 Plant Cell Organelles Vacuole Have a large central vacuole Surrounded by tonoplast Contains cell sap Sugars, proteins, minerals, wastes, & pigments 29 Different kinds of plant cells Onion Epidermal Cells Guard Cells root hair Root Hair Cell 30 vacuole cytoplasm nucleus mitochondrion glycogen granule Animal cell No cell wall or chloroplast Stores glycogen in the cytoplasm for food energy cell membrane 31 Animal Cell Organelles • Near the nucleus • Paired structures • Help cell divide 32 Different kinds of animal cells white blood cell Amoeba red blood cell muscle cell cheek cells sperm nerve cell Paramecium 33 Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria 34 Differences between plant cells and animal cells Animal cells Plant cells Relatively smaller in size Relatively larger in size Irregular shape Regular shape No cell wall Cell wall present 35 Differences between Plant Cells and Animal Cells Animal cells Plant cells Vacuole small or absent Large central vacuole Glycogen as food storage Starch as food storage Nucleus at the center Nucleus near cell wall 36 Compound Microscope • Instrument for observing small objects • Magnify images up to 2000X their size 37 Different parts of a microscope 38 Revolving nosepiece Eyepiece Clip Body tube Coarse adjustment Fine adjustment Condenser Arm Iris diaphragm Stage Objective Mirror Condenser control knob Base 39 Observing an Object: Because the light rays from an object cross before reaching your eye, the image you see through most microscopes will be inverted and upside down. Magnification: the increase of an object's apparent size. Resolution: the power to show details clearly. Resolution allows the viewer to see two objects that are very close together as two objects rather than as one. Resolution is controlled by the quality of the lenses being used - the better the lenses, the better the resolution. 40 Care and handling: A microscope is a delicate piece of equipment and should be treated gently. Always use two hands when moving the microscope. Place one hand around the arm of the microscope and the other under the base for support. Always carry the microscope upright and close to the body when moving any distance. Place the microscope flat on the table, but not too near the edge where it might be knocked off. If it becomes necessary to clean the lenses on the microscope, ask your facilitator for a piece of "lens paper". Other materials, such as paper towel, can scratch the surface of the lens. 41 Preparing Specimens for Viewing: • In most instances, light must pass through any object to be viewed with a light microscope. For this reason, the object must be fairly thin. Thick objects must be sliced into thin sections for viewing. • Many objects do not have distinct, contrasting colors. This makes it difficult to see details. To improve the viewing of these objects, they are stained. Staining is the use of a biological to make the details visible. 42 Making a Slide: • Place a clean slide on the table. • For liquid samples, place one or two drops in the center of the slide. For solid samples, place the sample in the center of the slide and add one drop of water or staining solution. • Hold the plastic cover slip by the edges. Do not get fingerprints on the cover slip. Set one edge against the slide and lower it until it contacts the liquid. The liquid should spread across the whole area of the cover slip. • Never use a slide under the microscope without a cover slip. Its major purpose is to protect the objective lens for the liquid on the slide. • Unless otherwise instructed, wipe the sample and cover slip off the slide with a paper towel when finished. Throw the paper towel and its contents away. Return the microscope slide to its container. 43 The cell is the Basic Unit of Life • Cell is the smallest unit of living organisms • Unicellular organisms are made of one cell only • The cells of multicellular organisms are specialized to perform different functions – e.g. mesophyll cells for photosynthesis and root hair cells for water absorption 44 Levels of organization • Cells are grouped together and work as a whole to perform special functions 45 Tissue • A group of similar cells to perform a particular function – Animals : epithelial tissue, muscular tissue – Plants : vascular tissue, mesophyll 46 Organ • Different tissues group together to carry out specialized functions – Heart : consists of muscles, nervous tissue and blood vessels – Leaf : consists of epidermis, mesophyll and vascular tissue 47 The Structures of a Leaf (Plant Organ) Chloroplast Palisade Mesophyll Cell Spongy Mesophyll Cell Air Space Stoma 48 The Structures of a Heart (Animal Organ) 49 System • Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way – Human : digestive, respiratory, excretory, circulatory and reproductive systems – Plant : root and shoot systems 50 Human Body Systems Examples of systems : Digestive System Respiratory System Circulatory System Nervous System Reproductive System 51 Examples of a Human Body System 52 Examples of a Human Body System The Respiratory System 53 Examples of a Human Body System Circulatory System 54 Examples of a Human Body System Nervous System 55 Levels of Organization CELLS (muscle cells,nerve cells) TISSUES (muscle, epithelium) ORGANS (heart, lungs, stomach) SYSTEMS (circulatory system) ORGANISM (human) 56 It’s You! 57