DOC 2 Week 6 1. Define passive transport and explain diffusion and osmosis. 2. Explain active transport and explain endocytosis and exocytosis. - Describe how enzymes affect speed of chemical reactions. List three enzymes and the reactions they facilitate. - 4. Write and explain the summary equation for Cell Respiration. 5. Write and explain the summary equation for Photosynthesis.

1. **Passive Transport** Passive transport is the movement of molecules across a cell membrane without the use of cellular energy. - **Diffusion:** This is the movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached. - **Osmosis:** This is a specific type of diffusion that involves the movement of water molecules through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration. 2. **Active Transport** Active transport is the movement of substances across a cell membrane against their concentration gradient, which requires energy, usually in the form of ATP. - **Endocytosis:** The process by which cells engulf external materials by forming vesicles from the plasma membrane that encase the substance. - **Exocytosis:** The process of expelling materials from the cell by fusing vesicles containing the material with the plasma membrane, releasing their contents outside the cell. 3. **Enzymes and Chemical Reaction Speed** Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur. They bind to reactants (substrates) and convert them into products without being consumed in the process. - **Examples of Enzymes:** - **Amylase:** Catalyzes the breakdown of starch into sugars. - **Catalase:** Facilitates the decomposition of hydrogen peroxide into water and oxygen. - **DNA Polymerase:** Enables the synthesis of new DNA strands during replication by adding nucleotides to a DNA template. 4. **Summary Equation for Cell Respiration** The summary equation for cell respiration is: \[ \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP} \] This equation represents the process by which cells convert glucose and oxygen into carbon dioxide, water, and energy (ATP). Glucose (\(\text{C}_6\text{H}_{12}\text{O}_6\)) is oxidized to produce energy that is stored as ATP, while carbon dioxide and water are released as byproducts. 5. **Summary Equation for Photosynthesis** The summary equation for photosynthesis is: \[ 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \] In this process, carbon dioxide and water, in the presence of light energy, are converted into glucose and oxygen. Photosynthesis occurs in chloroplasts, where the light energy is captured and used to drive the production of organic molecules, releasing oxygen as a byproduct.