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Cells: Function

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  • Often in biology, structure determines function and vice versa. clockwise: muscle tissue, red blood cells, bacteria on smoked salmon, nerve cells,
  • This is an actual microscopic image. Colors are added digitally to enhance the different parts.
  • This is an actual microscopic image. Colors are added digitally to enhance the different parts.
  • Transcript

    • 1. Cells: FunctionThe Inner Workings of Life Heartlife 2012-2013 Teacher: Julie Pen Harvard Cell Video
    • 2. Plasma Membrane• Made of a phospholipid bilayer• Semi-permeable: like a screen - some things pass while others cannot
    • 3. Selectively Permeable Membrane
    • 4. Transport Across Membranes• Passive Transport: small, uncharged molecules move freely across the plasma membrane• Active Transport: Larger, charged molecules need help to get across – requires energy
    • 5. Passive Transport• Passive Transport: – Small, uncharged molecules move in and out of a cell • water, carbon dioxide, ammonia, oxygen, fatty acids – Molecules move both directions across the plasma membrane – Net movement is down the concentration gradient • Simple Diffusion – directly through the phospholipid bilayer • Facilitated Diffusion – with the help of channel or carrier proteins – proteins only let certain molecules through
    • 6. Active TransportActive Transport• Larger, charged molecules need the help of transport proteins to get across• Can go against concentration gradient• Requires energy Transport Animations
    • 7. Exocytosis
    • 8. Endocytosis EndocytosisExocytosis
    • 9. Nucleus• Surrounded by a double membrane – called the nuclear envelope• Contains chromatin – loose DNA strands that form chromosomes – DNA & RNA hold "blueprints" that build/regulate proteins • direct all cell functions• Pores in membrane allow material to enter and leave the nucleus
    • 10. Nucleolus• Dense mass of RNA and proteins inside the nucleus• NOT bound by membrane• Ribosomes are made here• Sometimes more than one
    • 11. Ribosomes• Ribosomes build proteins in a process called translation – Two subunits (parts) work together – mRNA feeds through, directing the sequence of amino acids – amino acid are joined to form a polypeptide chain Protein Synthesis Video
    • 12. Ribosomes• Build proteins by connecting amino acid chains• mRNA gives instructions for specific amino acid sequences• tRNA pieces hold amino acids and match up with mRNA to build the protein chain
    • 13. Rough Endoplasmic ReticulumRough ER• studded with ribosomes• Sorts & transports proteins• connected to nuclear envelope• Vesicles are pinched off to transport contents to Golgi or outside of cell
    • 14. Smooth Endoplasmic ReticulumSmooth ER• Makes lipids – steroids, hormones• Breaks down carbohydrates, lipids and toxins• Vesicles pinch off – transport contents to Golgi or outside cell• Liver, ovaries & testes have LOTS of smooth ER
    • 15. Golgi Apparatus• Looks like a stack of pancakes• Stores, sorts, modifies and packages proteins• Molecules transported to and from the Golgi by means of vesicles
    • 16. Lysosomes• Garbage disposal of the cell• Contain hydrolytic enzymes that break down wastes (old cell parts as well as invaders)
    • 17. Mitochondria• Site of Cellular Respiration (O2 is used, CO2 is given off)• Food molecules (fats, protein, carbs) are converted into ATP • Folds called cristae increase surface area & efficiency of chemical reactions • Inner fluid is called the matrix • Has its own DNA and ribosomes
    • 18. Cell Wall• Found in bacterial and plant (as well as algae) cells• Located outside of the cell membrane
    • 19. Cell Wall• Rigid, protective barrier composed of strong cellulose fibers (polysaccharides) and proteins• Outermost lamella is a gluey layer between adjacent cells
    • 20. Chloroplasts• Contain chlorophyll (green pigment)• Inside the double membrane, granum are formed from stacks of thylakoids (membrane-bound disks) – this is where photosynthesis occurs (solar energy converted into carbs) • Contains own DNA and replicates independently from the rest of the cell
    • 21. Week 7 Lab ReviewMicroscope Lab: plant vs. animal cells
    • 22. Intercellular Junctions• Tight junctions bind cells together and prevent certain fluids and molecules from crossing the membrane.• Desmosomes (plasmodesmata) are strong anchors between cells. – made from folds of both cells’ intertwined membranes• Gap junctions are formed from proteins embedded in the cell membrane. – allow substances (and electrical charges) to flow in and out between cell.
    • 23. PlasmodesmataGaps in a plant/bacterial cell wall that allow for transportation of substances between cells
    • 24. Peroxisomes• Small sacks enclosed in a single membrane• Contains enzymes that break down alcohol & fatty acids• Formed from pinching off from the ER• Found mostly in kidney and liver cells
    • 25. Cytoskeleton• Microfilaments – thin, contractile (stretchy) filaments – help muscles cells contract – pinches cells in two during cytokinesis – provide strength, elasticity and support to the cell’s cytoskeleton• Microtubules – tiny, tube-like structures – form centrioles – give rise to cilia and flagella – limited transport capabilities – give shape and support to cell’s cytoskeleton
    • 26. Centrioles• Only in animal cells• Hang out near the nucleus• Made from microtubules• Help divide chromosomes during cell division.
    • 27. Cilia & Flagella• Hair or tail-like structures that provide motility• Formed from microtubules that arrange themselves into a cylindrical shape• Centrioles form basal bodies that provide the framework for each cilium or flagellum• Generally occur only in animal cells
    • 28. Flagellum

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