Transcript cell
Cellular Processes THE CELL IN ITS ENVIRONMENT 1. How do small substances move into and out of the cell? Diffusion Osmosis Active Transport 2. What is diffusion? Main method by which small molecules move across the cell. Molecules move from areas of higher concentration to an area of lower concentration. 3. What causes diffusion? Molecules will spread out and bump into one another until they are spread evenly throughout the environment. 4. How do single celled organisms get oxygen from water? More oxygen molecules are outside the cell (higher concentration of oxygen) in the water. Oxygen diffuses from areas of higher concentration (water) to areas of lower concentration (inside 5. Predicting . . .What would happen if the concentration of oxygen were higher inside the cell than outside? 6. What is osmosis? Diffusion of water molecules through a selectively permeable membrane. NORMAL High Conc of H2O outside (H2O enters) & cell swells High Conc of H2O inside (H2O exits) & cell shrinks 7. What are the Effects of Osmosis on Cells? 8. What is passive transport? For a cell, moving materials through the cell membrane by diffusion and osmosis is like cycling down hill. It does not require much energy. 9. What is active transport? Using cellular energy to move materials through a cell membrane. –Ex: Cell would use when they need to take in nutrients that has a higher concentration inside the cell. 10. What are transport proteins? Used in active transport – proteins “pick up” molecules outside the cell and carry them in, using energy. 11. What happens when the particles are too big? Diffusion, passive transport, and active transport do not work as well. The cell membrane relies on endocytosis and exocytosis. 12. What is endocytosis? 1. Cell comes in contact with a particle 2. Cell membrane wraps around particle. 3. Once totally surrounded a vesicle pinches off. 13. What is exocytosis? 1. Large particles leaving cell are packaged in vesicles. 2. Vesicle travels to the membrane and fuses with it. 3. Cell releases particles into the environment. SOURCES OF ENERGY 1. How is the sun related to a cell’s energy? The sun supplies energy for most living things directly or indirectly. –Plants use energy from the sun to make food. –A giraffe obtains energy by eating the grass. –The lion obtains energy by feeding on the giraffe. 2. What is photosynthesis? Photosynthesis – process by which a cell captures energy in sunlight and uses it to make food. –Autotrophs – organism that makes its own food –Heterotroph – organism that cannot make its own food (usually get food by eating other organisms.) Autotroph Heterotroph 3. What happens during photosynthesis? Plants use energy from the sun to convert carbon dioxide and water into oxygen and sugars. 4. What are the two stages of photosynthesis? As related to baking a cake: 1.) Capturing the sun’s energy (combine ingredients to make the batter) 2.) Using energy to make food (bake the batter) 5. What is the first stage? Capturing the energy in sunlight: 1. ) Occurs mostly in the leaves 2.) Involves the chlorophyll in the chloroplasts 3.) Chlorophyll captures light energy and uses it to power the second stage. Using 6. What is stage 2? energy to make food – –Cell needs water and carbon dioxide –Carbon dioxide enters cell through small openings under the leaves (stomata) –Water travels through plant’s stems to leaves –Once in the leaves – carbon dioxide and water move into the chloroplasts. 6. Stage 2 continued . . . Inside the chloroplasts – water and carbon dioxide undergo a chemical reactions –One product is a sugar (carb) – cell can use energy for various functions –The other product is oxygen which exists the leaf through the stomata. PHOTOSYNTHESIS EQUATION LIGHT Carbon Dioxide Water Glucose (sugar) oxygen 7. How do you get energy from respiration? This is the process by which cells obtain energy from glucose (sugar). During respiration, cells break down stored sugar and release the energy it contains. 8. What are the two stages of respiration? Stage 1– Happens in cytoplasm –Glucose broken down into smaller molecules –Releases small amount of energy Stage 2– –Happens in the mitochondria –Small molecules broken into smaller molecules –Requires oxygen and releases lots of energy 9. What are the products of respiration? Energy is released Carbon dioxide and water diffuse out of cell –* When you breathe in you get oxygen (needed for respiration) when you breathe you release carbon dioxide and water (products of respiration) Respiration Equation C6H12O6 + 6O2 6CO2 + 6H2O + energy CELL DIVISION 1. What is the cell cycle? Begins when cell is formed and ends when the cell divides and forms new cells. Before division, the cell must make a copy of its DNA. DNA of cell is organized in chromosomes – copying them helps ensures cell survival. 2. How do you make more prokaryotic cells? Not complex Binary Division – “splitting into two parts” Each of the resulting cells contains one copy of DNA. 3. How many chromosomes do humans have? Humans have 46 23 pairs of homologous chromosomes – (similar chromosomes) 3. How do you make more eukaryotic cells? 3 main stages STAGE 1 (Interphase) –1. Cell grows and copies (DNA) organelles and chromosomes. Chromosomes are duplicated – known as chromatids – held together by a centromere. Chromatids Centromere Second Stage –1. Chromatids separate through mitosis. –2. Mitosis ensures that each new cell receives a copy of each chromosome. Third Stage –Cell divides and produces two cells that are identical to the original cell.