Developing Standards Cells Cell Membrane

Wirkus H

Cells: Cell MembranesTextbook Sections: 2.11-2.14, 3.8-3.9, 5.10-5.19

Big Ideas: Cells are the basic units of life. Their structures are specifically adapted to their function and the overall goal of maintaining homeostasis. Every cell is covered by a membrane that controls what enters and leaves the cell. Properties of Water Exam Standards What I need to Know1. A cell is essentially a membrane surrounding a solution of water with molecules and organelles dissolved inside. 2. Define polar vs. nonpolar.3. Define hydrogen bonding.4. Differentiate between hydrogen bonding and polar covalent bonding. 5. Describe the unique properties of water: surface tension

specific heat

universal solvent (ability to dissolve many substances) cohesion & adhesion6. Explain how water travels up (against gravity) through a plant, from its roots to its leaves. 7. Define pH.8. Differentiate between acids and bases. 9. Explain what a buffer is. Lipids (and other macromolecules) Exam Standards What I need to Know1. Lipids contain very few polar bonds; they have many C-H bonds.2. Chemical energy is stored in chemical bonds, and C-H bonds store lots of energy compared to other bonds. 3. Define hydrophilic and hydrophobic.4. Explain why lipids are hydrophobic.5. Explain why proteins, nucleic acids, and carbohydrates are hydrophilic.6. Be able to use the structural formula of a molecule to determine if it is hydrophobic or hydrophillicMembrane Structure Exam Standards What I need to Know1. Every cell is covered by a membrane that controls what can enter and leave the cell.2. The cell membrane separates life from non-life. 3. Organelle membranes are structurally similar to cell membranes. 4. The cell membrane regulates what enters and leaves the cell.5. Cells are enclosed within semi permeable membranes that regulate their interaction with their surroundings.6. Define semi permeable. 7. The cell membrane is the boundary that separates the controlled internal environment of the cell from the external environment, allowing the cell to maintain homeostasis.8. Homeostasis is the process by which organisms maintain a relatively stable internal environment. H9. The cell membrane is made of lipids embedded with proteins and other molecules.10. The phospholipid bilayer prevents hydrophilic substances from crossing without the assistance of proteins. 11. Describe the fluid mosaic model of the cell membrane. 12. Describe the structure and properties of a phospholipid.13. Draw, label, and explain the formation of the phospholipid bilayer.14. Explain how the bilayer separates the internal and external environment (i.e. how it prevents substances from crossing it)15. Describe the types of membrane proteins and their functions: transport proteins

receptor proteins

enzymes

ID proteins16. Distinguish between peripheral and integral membrane proteins. 17. Short carbohydrate chains attached to phospholipids or membrane proteins often serve as ID tags for the cell, so it can be identified by other cells. 18. How does cholesterol contribute to the fluidity of the cell membrane?19. What are the functions of the cell membrane?Membrane Transport Exam Standards What I need to Know1. The cell membrane regulates transport of materials into and out of the cell, facilitates chemical reactions, and aids communication with its environment.2. These functions are carried out by cell membrane proteins.3. Facilitated Diffusion is when a cell membrane protein is said to facilitate, or help, the diffusion of a solute across the membrane. 4. Explain how transport proteins facilitate diffusion. 5. Diffusion is when particles tend to move from an area where they are more concentrated to an area where they are less concentrated. 6. Explain why diffusion is a spontaneous process. 7. Explain why a concentration gradient of a substance across a membrane represents potential energy.8. Osmosis is the diffusion of water through a selectively permeable membrane. 9. Equilibrium is when the concentration of the solute is the same throughout the system. 10. Identify the solute and solvent in a particular solution (e.g. salt water or coffee)11. If the solute concentration on either side of the membrane is unequal, water will diffuse by osmosis. 12. Predict the direction of water movement based on differences in solute concentration. 13. Isotonic is when the concentration of solutes is the same inside and outside the cell.14. Hypertonic is when a solution has a higher solute concentration than the cell (more solute outside the cell)15. Hypotonic is when a solution has a lower solute concentration than the cell (less solute outside the cell)16. Differentiate between passive transport, facilitated diffusion, and active transport.17. Compare exocytosis and endocytosis.18. Be able to use the properties of a molecule and its concentration gradient to determine which mode of membrane transportation will be required for a particular molecule to cross a membrane.19. Determine the direction water will diffuse across a membrane by osmosis.20. Explain the effects of osmosis on plants vs. animal cells.21. Describe how the cell controls which molecules cross the cell membrane.22. Explain how hydrophobic molecules cross cell membranes.23. Explain how large molecules are transported across cell membranes. 24. Distinguish between channel proteins and carrier proteins.25. Distinguish between endocytosis, exocytosis, and phagocytosis. 26. Explain how active transport relates to the sodium-potassium pump. Surface Area to Volume Ratio (limits to cell size) Exam Standards What I need to Know1. Materials needed for cell growth and activity enter the cell through the cell membrane. Waste products leave the cell through the cell membrane.2. As cell size increases, surface area to volume decreases.3. Be able to calculate the surface area to volume ratio (SA:V) of an object.4. Explain why a cell is limited by SA:V.5. Explain how increasing SA:V increases the efficiency of an object, such as the shape of the particular organelles or organ. Root Words to Know:

aqua water

-pori a small opening

endo- inner, within -cyto cell exo- outer, external

hyper- over, exceeding

-tonus tension hypo- under, lower

iso- same, equal

phago- eat, devour

pino- drink

-plasm molded

-lyso loosening, decomposition Unit 2: Cells