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Transcript
Microscopes provide windows to the world of the cell The light microscope enables us to see the overall shape and structure of a cell Electron microscopes~ can view ultrastructures of cells They use a beam of electrons instead of light The greater resolving power of electron microscopes The Cell Theory • Robert Hooke (1600’s/ English)) used a compound light microscope to study cork, the dead cells of oak bark. • Cells are the basic building blocks of all living things. • Schleiden & Schwann (1830;s, German) their observations & conclusions are summarized as the cell theory The cell theory is made up of three main ideas: 1.All organisms are composed of one or more cells. 2. The cell is the basic unit of organization of organisms. 3. All cells come from preexisting cells. Why study cells? Cells Tissues Organs Bodies bodies are made up of cells cells do all the work of life! The Jobs of Cells Cells have 3 main jobs make energy • need energy for all activities • need to clean up waste produced while making energy make proteins • proteins do all the work in a cell, so we need lots of them make more cells • for growth • to replace damaged or diseased cells Our organelles do all these jobs! 2 Types of cells bacteria cells Prokaryote - no organelles Eukaryotes - organelles animal cells plant cells Prokaryotic cells-Bacteria small, relatively simple cells oThey do not have a nucleus o enclosed by a plasma membrane and is usually encased in a rigid cell wall o Inside the cell are its DNA and other parts Eukaryotic cells are partitioned into functional compartments All other life forms are made up of one or more eukaryotic cells These are larger and more complex than prokaryotic cells Eukaryotes are distinguished by the presence of a true nucleus The cytoplasm contains organelles Many organelles have membranes as boundaries These compartmentalize the interior of the cell This allows the cell to carry out a variety of activities simultaneously Animal Cell Plant Cell Cell sizes vary with their function Cell size and shape relate to function Cell size comparison most bacteria Animal cell Bacterial cell 1-10 microns eukaryotic cells 10-100 microns micron = micrometer = 1/1,000,000 meter diameter of human hair = ~20 microns Natural laws limit cell size a cell must be large enough to house the parts it needs to survive and reproduce The maximum size of a cell is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes A small cell has a greater ratio of surface area to volume than a large cell of the same shape 30 µm Surface area of one large cube = 5,400 µm2 10 µm Organelles Organelles do the work of cells each structure has a job to do • keeps the cell alive; keeps you alive They’re like mini-organs! Model Animal Cell 1. Cells need power! Making energy to fuel daily life & growth, the cell must… • • • • ATP take in food & digest it take in oxygen (O2) make ATP remove waste organelles that do this work… • • • • cell membrane lysosomes vacuoles & vesicles mitochondria Cell membrane phosphate “head” Function separates cell from outside controls what enters or leaves cell • O2, CO2, food, H2O, nutrients, waste recognizes signals from other cells • allows communication between cells Structure double layer of fat • phospholipid bilayer receptor molecules • proteins lipid “tail” cytoplasm jelly-like material holding organelles in place cell membrane cell boundary controls movement of materials in & out recognizes signals Vacuoles & vesicles Function small food particle moving material around cell storage Structure membrane sac vacuole filled w/ digestive enzymes vesicle vesicle filled w/ digested nutrients Vacuoles have diverse functions in cell maintenance membrane-bound sacs with varied functions. Food vacuoles, from phagocytosis, fuse with lysosomes. Contractile vacuoles, found in freshwater protists, pump excess water out of the cell. Central vacuoles are found in many mature plant cells. Food & water storage food vacuole plant cells central vacuole animal cells contractile vacuole cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage cell membrane cell boundary controls movement of materials in & out recognizes signals Lysosomes Function digest food • used to make energy clean up & recycle • digest broken organelles lysosomes Structure membrane sac of digestive enzymes digesting broken organelles small food particle vacuole digesting food A Job for Lysosomes 6 weeks 15 weeks Connection: Abnormal lysosomes can cause fatal diseases Lysosomal storage diseases are hereditary They interfere with other cellular functions Examples: Pompe’s disease, TaySachs disease ENERGY-CONVERTING ORGANELLES Mitochondria Function make ATP energy from cellular respiration • sugar + O2 ATP • fuels the work of life Structure double membrane in both animal & plant cells ATP cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals lysosome food digestion garbage disposal & recycling Plants make energy two ways! Mitochondria make energy from sugar + O2 • cellular respiration • sugar + O2 ATP ATP Chloroplasts make energy + sugar from sunlight • photosynthesis • sunlight + CO2 ATP & sugar • ATP = active energy • sugar = stored energy • build leaves & roots & fruit out of the sugars sugar ATP Chloroplasts found in plants and some protists convert solar energy to chemical energy in sugars Mitochondria are in both cells!! animal cells plant cells mitochondria chloroplast cytoplasm jelly-like material around organelles central vacuole storage: food, water or waste cell wall support mitochondria make ATP in cellular respiration cell membrane cell boundary controls movement of materials in & out recognizes signals chloroplast make ATP & sugars in photosynthesis lysosome digestion & clean up 2. Cells need workers = proteins! Making proteins to run daily life & growth, the cell must… • read genes (DNA) • build proteins • structural proteins (muscle fibers, hair, skin, claws) • enzymes (speed up chemical reactions) • signals (hormones) & receptors organelles that do this work… • • • • nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus Proteins do all the work! one of the major job of cells is to make proteins, because… proteins do all the work! structural enzymes signals receptors DNA proteins cells Nucleus Function control center of cell protects DNA • instructions for building proteins Structure nuclear membrane nucleolus • ribosome factory chromosomes • DNA cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage lysosome food digestion garbage disposal & recycling nucleolus produces ribosomes nucleus protects DNA controls cell chromosomes DNA mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals Ribosomes Function protein factories read instructions to build proteins from DNA Structure some free in cytoplasm some attached to ER Ribosomes on ER cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals lysosome food digestion garbage disposal & recycling nucleolus produces ribosomes nucleus protects DNA controls cell ribosomes build proteins Endoplasmic Reticulum Function works on proteins • helps complete the proteins after ribosome builds them makes membranes Structure rough ER • ribosomes attached • Make membranes smooth ER • Synthesizes lipids cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage lysosome food digestion garbage disposal & recycling ribosomes builds proteins mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals nucleus protects DNA controls cell ER works on proteins makes membranes Golgi Apparatus Function finishes, sorts, labels & ships proteins • like UPS headquarters • shipping & receiving department ships proteins in vesicles • “UPS trucks” vesicles carrying proteins Structure membrane sacs transport vesicles cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage lysosome food digestion garbage disposal & recycling ribosomes builds proteins mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals nucleus protects DNA controls cell ER helps finish proteins makes membranes Golgi apparatus finishes, packages & ships proteins nucleus control cell protects DNA nucleolus make ribosomes endoplasmic reticulum processes proteins makes membranes ribosomes make proteins cytoplasm jelly-like material around organelles central vacuole storage: food, water or waste Golgi apparatus finish & ship proteins cell wall support mitochondria make ATP in cellular respiration cell membrane cell boundary controls movement of materials in & out recognizes signals chloroplast make ATP & sugars in photosynthesis lysosome digestion & clean up 3. Cells need to make more cells! Making more cells to replace, repair & grow, the cell must… • copy their DNA • make extra organelles • divide the new DNA & new organelles between 2 new “daughter” cells organelles that do this work… • nucleus • centrioles Centrioles Function help coordinate cell division • only in animal cells Structure one pair in each cell cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage lysosome food digestion garbage disposal & recycling nucleus protects DNA controls cell centrioles cell division ribosomes builds proteins mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals ER helps finish proteins makes membranes Golgi apparatus finishes, packages & ships proteins THE CYTOSKELETON The cell’s internal skeleton that functions in cell structural support and motility A network of protein fibers makes up the cytoskeleton three main types of fibers in the cytoskeleton: microtubules, microfilaments, and intermediate filaments. Microfilaments enable cells to change shape and move Intermediate filaments reinforce the cell and anchor certain organelles Microtubules give the cell rigidity provide anchors for organelles act as tracks for organelle movement MICROFILAMENT INTERMEDIATE FILAMENT MICROTUBULE Cilia and flagella locomotor appendages that protrude from certain cells Clusters of microtubules drive the whipping action of these organelles Cell Summary Cells have 3 main jobs make energy • need food + O2 • cellular respiration & photosynthesis • need to remove wastes make proteins Our organelles do all those jobs! • need instructions from DNA • need to chain together amino acids & “finish” & “ship” the protein make more cells • need to copy DNA & divide it up to daughter cells