BioCh5_5.2 Cytology PDF

5 Cytology  5.2 THE CELL ENVIRONMENT  5.2 Objectives Describe how cells in a particular environment maintain homeostasis. Compare how different solutions affect cells. Explain how molecules are transported across the cell membrane. ESSENTIAL QUESTION ? C...

5 Cytology  5.2 THE CELL ENVIRONMENT  5.2 Objectives Describe how cells in a particular environment maintain homeostasis. Compare how different solutions affect cells. Explain how molecules are transported across the cell membrane. ESSENTIAL QUESTION ? Could my goldfish survive in the ocean?  homeostasis the internal balance within the systems of living organisms that must be kept stable in order to maintain life  dynamic equilibrium the balance of changes and motions in a system Getting Feedback - Feedback is how cells regulate. Positive feedback happens when a substance involved in a cellular process causes the process to speed up.  Positive Oxygen enters red blood cell. Feedback Breathe air. Oxygen binds to one site on hemoglobin. Oxygen carried Oxygen binds to to cells. remaining three sites on hemoglobin. Getting Feedback Negative feedback happens when a substance produced by a cellular process causes the process to slow down or stop.  Negative ATP is ATP is Feedback too low. too high. PFK is ATP binds produced. to PFK. homeostasis osmosis  osmosis the diffusion of water molecules through a semipermeable membrane  semipermeable membrane a membrane that allows certain substances to pass through but not others. cells have a semipermeable membrane. Hypertonic Solution a solution whose solute concentration is greater than the solute concentration of the cytoplasm in a cell ocean water Hypotonic Solution a solution whose solute concentration is less than the solute concentration of the cytoplasm in a cell pure water Isotonic Solution a solution whose solute concentration is equal to the solute concentration of the cytoplasm in a cell red blood cells and plasma  Solutions and the Cell outside the cell outside the cell outside the cell hypertonic isotonic hypotonic hypotonic hypertonic isotonic inside the cell inside the cell inside the cell Passive and Active Transport passive transport: the active transport: the movement of movement of molecules across a molecules across a membrane without membrane using using chemical energy chemical energy Passive and Active Transport passive transport: active transport: move from high to move from low to low concentration high concentration Passive Transport Four factors determine whether a particle can be passively transported across a cell membrane. 1. particle size 2. particle shape 3. particle polarity 4. membrane composition Passive Transport diffusion osmosis facilitated diffusion  facilitated diffusion a type of passive transport in which substances can move across a cell membrane through special protein channels embedded in the membrane (transport proteins) Active Transport Active Transport endocytosis exocytosis Active Transport endocytosis: a cell exocytosis: a vesicle engulfs a particle, releases its contents forming a vesicle outside the cell 1. Which kind of transport requires energy? ? 2. What do we call kinds of transport that don’t require energy? 3. Which type of transport typically involves only very small solute particles? 4. Which type of transport doesn’t require energy but does require special ? transport proteins? 5. What is the difference between endocytosis and exocytosis? case study Passive Transport and Kidney Stones  ESSENTIAL QUESTION Could my goldfish survive in the ocean? ? No. My goldfish could not survive in the ocean because it does not have the necessary structures to survive in a hypertonic environment like seawater.