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Transcript
Unit 2: More on Matter & Energy in Ecosystems Macromolecules to Organelles to Cells Where are cells on the biological scale? • • • • • • • • • • • • • • • • • Sub-Atomic Particles Atoms Molecules Macromolecules (proteins, lipids, nucleic acids, carbohydrates) Organelles Let’s scale up! Cells Tissue Organs Atom Tissue Population Organ System Molecule Organ Community Organism Macromolecule System Ecosystem Population Community Organelle Organism Biome Ecosystems Cell Biosphere Biome Biosphere Solar System Universe A sense of scale between living cells and atoms. Each diagram shows an image magnified by a factor of 10 in a progression from a thumb, to skin cells, to a ribosome, to a cluster of atoms forming part of one of the many protein molecules in our bodies. HYPERLINK!!! • http://learn.genetics.utah.edu/content/cells/scale/ I. Macromolecules Make up the Organelles of a Cell A. B. C. D. Proteins Carbohydrates Lipids Nucleic acids Cell Organelles II. Cell Organelles A.Nucleus a. Has a nuclear envelope and a nucleolus b.Contains DNA c. Controls all cell activities B. Mitochondria a. Double membrane; football shape b. “Power House” of the cell 1. Food converted into ATP energy (adenosine triphosphate=“gasoline of cells”) 2. Uses Oxygen, produces CO2 C. Endoplasmic Reticulum a. Site where cell membrane and proteins are made b. Two types of ER membrane: Rough (ribosomes attached) and Smooth c. “Highways” of the cell D. Golgi Apparatus Receives and modifies proteins E. Lysosomes a. Cellular digestion b. Breakdown of waste F. Cytoplasm (cytosol) - Water based, gel-like material where chemical reactions occur G. Cytoskeleton Filaments Move organelles and the cell H. Vesicles Sacs of material from the cell membrane, ER, and Golgi I. Chloroplast (plant cells only) a. Bean-shaped; with numerous membranes b. Contains chlorophyll c. Where photosynthesis takes place J. Ribosomes a. tiny molecular machine made of two subunits b. the site of protein synthesis K. Cell Membrane (plasma membrane) a. Encloses cell and organelles b. Membrane is fluid-like and is constantly in motion c. Made of a “phospholipid bilayer” d. Phospholipids have non-polar, hydrophobic (water hating) ends that stick together and polar, hydrophilic (water loving) ends II. Importance of the Cell Membrane a. Proteins on the surface and embedded in the cell membrane interact with “lipid bilayer” b. Membrane and proteins control what goes in and out of cell c. Proteins act like pores, channels, pumps and carriers d. Many enzymes in the cell membrane speed up chemical reactions e. Carbohydrate “antenna” embedded in membrane allows cells to communicate carbohydrates III. Crossing the Cell Membrane A. The membrane is selectively permeable which means some things can get through and some cannot. B. Small, polar molecules pass through the membrane with ease Ex: Water, carbon dioxide, and oxygen C. Large, non-polar molecules and ions do not pass through without help Ex: glucose IV. Cells Respond to their Environment A. Homeostasis – cells maintain a constant internal environment in response to environmental changes B. Assures balance and equilibrium to keep cells healthy V. Maintaining Cell Homeostasis with and without Energy A. Passive Transport (Requires no Energy) a. Diffusion – Molecules move from an area of higher concentration to an area of lower concentration b. Simple Diffusion –Molecules move directly through the membrane. Molecules move with the concentration gradient (a difference in the concentration of molecules across a distance.) c. Facilitated Diffusion – carrier proteins help transport larger molecules and ions WITH their concentration gradient (from HIGH to LOW concentration) d. Osmosis – water molecules diffuse • Solute – molecule being dissolved across a cell membrane • Solvent – the 1. Water moves from an area of higher substance that (water) concentration to an area of dissolves the solute; usually water. lower (water) concentration. 2. Water always moves in the directionAdd to your notebook! of high solute. 3. Osmosis affects cells. Types of Solutions: • Hypotonic – Solute concentration is lower outside the cell compared to inside the cell. (water moves in) • Hypertonic – Solute concentration is higher outside the cell compared to inside the cell. (water moves out) • Isotonic – Solute concentration is equal inside and outside the cell. B. Active Transport (Requires Energy) a. Carrier proteins move molecules against concentration gradient b. From LOW to HIGH b. Movement in Vesicles - Some molecules are too large to transport through carrier proteins. 1. Endocytosis – cell membrane pinches in and creates a vesicle enclosing macromolecules and large particles Ex: food and bacteria 2. Exocytosis - membrane vesicle fuses with cell membrane and releases material outside cell Ex: proteins, waste, and toxins Need Energy