Transcript Chapter 4
Chapter 4 Section 1 Exchange within the Environment Exchange with the Environment A cell must be able to take in energy and get rid of wastes The exchange of materials between a cell and its environment takes place at the cell membrane Diffusion Movement of particles from an area of high concentration to low concentration Naturally spreading out Diffusion Can occur across cell membranes or outside the cell No energy is needed Examples Tea in cup of hot water Fragrance from a candle Diffusion Demonstrations Osmosis The diffusion of water through the cell membrane Pure water has the highest concentration (100%) To lower concentration, something must be added to the water Summarize the difference between diffusion and osmosis. Diffusion is anything, Osmosis is water In diffusion or osmosis, particles move from areas of _High__ concentration to areas of _Low_ concentration. Thirsty for sea water? Salt water has a low concentration of water and high concentration of salt. The cells of your body have high concentration of water and low salt. Which way will the water move? Water from your cells will move from high to low concentration, leaving your cells and dehydrating you Passive Transport Occurs through the proteins embedded throughout the membrane No energy used Still moving high to low Includes sugars and amino acids Active Transport Occurs through the proteins embedded throughout the membrane Uses energy (ATP) Occurs from LOW to HIGH Example – nutrients brought into the roots of a plant Endocytosis Bringing large particles into the cell Means “within the cell” The cell membrane surrounds a particle and encloses it in a vesicle Exocytosis Taking things out of the cell Means “outside the cell” Vesicles are formed at the ER or Golgi and brought to the membrane to be released out of the cell Cell Energy Nearly all of the energy that fuels life comes from the sun Photosynthesis The process by which plants capture light energy from the sun and convert it into sugar 6CO2 + 6H2O + light energy C6H12O6 + 6O2 Pigments Molecules in plant cells that absorb light energy Chlorophyll is the main pigment for photosynthesis 2 ways to release stored energy from food molecules Cellular respiration Fermentation Cellular respiration The process of releasing ATP in the cell from oxygen and glucose: producing carbon dioxide and water Like the lungs but not quite Relates to breathing in that both use oxygen and release carbon dioxide Cellular respiration takes place in the mitochondria C6H12O6 + 6O2 6CO2 + 6H2O + energy Fermentation The breakdown of sugars to make ATP in the absence of oxygen 2 types of fermentation In the muscles, producing lactic acid as a product In bacteria and yeast, used in baking bread. The CO2 produced makes bread light and fluffy