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Transcript
A Tour of the Cell Read pg.98-99 ~ Create a double bubble to compare and contrast prokaryotic and eukaryotic cells Prok aryo tic DIFFERENCES Eukaryotic SIMILARITIES DIFFERENCES Chp.6: Tour of the Cell How big is a cell? • Cells Alive! How Big is a Cell? • Most cells are between 1 and 100 μm (10-6 or 1/ 1,000,000 m) • Eukaryotic Cells are larger than prokaryotic cells Types of cells Prokaryote bacteria cells - no organelles - organelles Eukaryote animal cells Eukaryote plant cells Prokaryotic Cells • No nucleus, no membrane-bound organelles • But, they do have a cell membrane and they do have an organelle – Ribosomes! • Also have Nucleoid region, Cell Wall, and Cytosol (fluid) Eukaryotic Cells • Eukaryotic Cells contain a nucleus and membrane-bound organelles • The membrane is key! Limits to Cell Size • As a cell grows, its surface area to volume ratio decreases • This means the cell has more volume that needs to get oxygen, food, get rid of waste but less SA to do it over (in proportion) Why organelles? • Specialized structures – specialized functions mitochondria • cilia or flagella for locomotion • Containers – partition cell into compartments – create different local environments chloroplast • separate pH, or concentration of materials – distinct & incompatible functions • lysosome & its digestive enzymes • Membranes as sites for chemical reactions Golgi – unique combinations of lipids & proteins – embedded enzymes & reaction centers • chloroplasts & mitochondria ER Cells gotta work to live! • What jobs do cells have to do? – Make proteins • proteins control every cell function – Store energy • for daily life • for growth – Make more cells • growth • repair • renewal Proteins do all the work! proteins cells DNA organism Repeat after me… Proteins do all the work! Cell functions • Building proteins 1. read DNA instructions 2. build proteins 3. process proteins • folding • modifying – removing amino acids – adding other molecules » e.g, making glycoproteins for cell membrane 4. address & transport proteins Building Proteins • Organelles involved – nucleus – ribosomes – endoplasmic reticulum (ER) – Golgi apparatus – vesicles The Protein Assembly Line nucleus ribosome ER Golgi apparatus vesicles Nucleus DNA • Function chromosome – protects DNA histone protein • Structure – nuclear envelope • double membrane • membrane fused in spots to create pores – allows large macromolecules to pass through nuclear pores nuclear pore nucleolus nuclear envelope 1 nuclear membrane production of mRNA from DNA in nucleus DNA Nucleus mRNA 2 nuclear pore mRNA travels from nucleus to ribosome in cytoplasm through nuclear pore small ribosomal subunit mRNA large ribosomal subunit cytoplasm Nucleolus • Function – ribosome production • build ribosome subunits from rRNA & proteins • exit through nuclear pores to cytoplasm & combine to form functional ribosomes large subunit small subunit rRNA & proteins ribosome nucleolus Ribosomes large subunit • Function – protein production small subunit • Structure – rRNA & protein – 2 subunits combine 0.08mm Ribosomes Rough ER Smooth ER Types of Ribosomes • Free ribosomes – suspended in cytosol – synthesize proteins that function in cytosol • Bound ribosomes – attached to endoplasmic reticulum – synthesize proteins for export or for membranes membrane proteins Endoplasmic Reticulum • Function – processes proteins – manufactures membranes – synthesis & hydrolysis of many compounds • Structure – membrane connected to nuclear envelope & extends throughout cell Types of ER rough smooth Smooth ER function • Membrane production • Many metabolic processes – synthesis • synthesize lipids – oils, phospholipids, steroids & sex hormones – hydrolysis • hydrolyze glycogen into glucose – in liver • detoxify drugs & poisons – in liver – ex. alcohol & barbiturates Membrane Factory • Build new membrane – synthesize phospholipids • builds membranes – ER membrane expands • bud off & transfer to other parts of cell that need membranes Rough ER function • Produce proteins for export out of cell – protein secreting cells – packaged into transport vesicles for export Synthesizing proteins cisternal space polypeptide signal sequence ribosome ribosome mRNA membrane of endoplasmic reticulum cytoplasm Golgi Apparatus • Function – finishes, sorts, tags & ships cell products • like “UPS shipping department” – ships products in vesicles • membrane sacs • “UPS trucks” secretory vesicles transport vesicles Golgi Apparatus Vesicle transport protein vesicle budding from rough ER ribosome migrating transport vesicle fusion of vesicle with Golgi apparatus protein on its way! endoplasmic reticulum nucleus DNA TO: RNA vesicle TO: TO: vesicle ribosomes TO: finished protein protein Making Proteins Golgi apparatus Putting it together… nucleus nuclear pore Making proteins cell membrane protein secreted rough ER ribosome vesicle proteins smooth ER transport vesicle cytoplasm Golgi apparatus Lysosomes •Sac of hydrolytic enzymes; intracellular digestion of macromolecules • Phagocytosis • Autophagy: recycle cell’s own organic material • Apoptosis: programmed cell death Vacuoles • Membrane-bound sacs – digestion & release of cellular waste – Food (phagocytosis) – Contractile (pump excess water) – Central (storage in plants) Mitochondria • Quantity in cell correlated with metabolic activity – cellular respiration • double membrane (phospholipid); – Outer membrane is smooth – Inner membrane is highly convoluted forming folds called cristae • Contains enzymes used for ATP production •contain own DNA Chloroplast • Contains chlorophyll, captures energy from Sun and converts it to chemical bond energy via photosynthesis • Structure: double membrane, contains thylakoids (flattened disks), grana (stacked thylakoids), stroma. • own DNA Microscope Review Types of Microscopes • Compound Light Microscopes (like what we use in class)-uses 2 or more lenses to magnify objects. – Max magnification 1500X. • Electron Microscopes-uses a beam of electrons to image a specimen. Scanning EM(SEM) – Surface – Magnification 60,000X Transmission EM(TEM) – Inside – Magnification 100,000 X + Body Tube Eyepiece Revolving Nosepiece Low Power Objective Arm Medium Power Objective Stage Clip High Power Objective Course Adjustment Knob Stage Fine Adjustment Knob Diaphragm Light Source Base Using a Microscope • Always carry the microscope by the arm and the base. • To calculate magnification, multiply the eyepiece magnification by the objective magnification. • Always make sure the stage is all the way up when focusing and slowly bring the stage down. • When on low power, use the course adjustment knob (the big knob) • When on medium and high power, use the fine adjustment knob (the little knob) ONLY!!! • NEVER use the course adjustment knob on medium or high power!!! Why? You are so close to the slide that you will run into it with the objective!! • When you are finished with the microscope, wrap the cord around the base and put the lowest objective down. Make sure the stage is all the way down. How to Draw a Diagram from a Microscope Drawing the Diagram 1. If it is not already provided, draw your “field of view” • 2. • 3. This is the circle that you see when you look through the microscope Draw exactly what you see make sure it’s not a water spot or air bubble!!! Add color exactly like the colors you observe in the specimen. 4. Mark the diagram with the specimen name and magnification. Labels 5. Printed neatly 6. Horizontal to the upper edge of the paper 7. Lines connecting labels to the diagram should be straight. Pseudopod Food vacuole Ameoba 400X Assignment • Cell Observations: Prokaryotic vs. Eukaryotic Cells – Examine at least one of each of the following types of cells • • • • Bacteria Protist Plant Animal – Draw your observations under high power – Complete analysis questions on the back