Biology Review for the GHSGT The Cell Membrane and Cellular Transport

Solutions A solution is a liquid mixture of solute dissolved in solvent Example: Salt water is a solution. Salt (the solute) Is dissolved in water (the solvent)

Maintaining Homeostasis Keeping an ideal balance of solutes within the cell Cytoplasm must keep it’s watery-jelly like substance (solvent) in the right balance with solutes such as salt and other minerals

Hormones Chemical messengers that regulate body functions Maintain homeostasis Movement of oxygen/carbon dioxide Maintain internal temperature Regulation of fluids across cell membrane

Cell Membrane Main Purpose: regulate the movement of materials into and out of the cell Is semi-permeable (selectively permeable)- only certain substances can go through Has a phospholipid bilayer

Passive Transport Molecules move spontaneously through the cell membrane from areas of higher concentration to areas of lower concentration. Moves “with the concentration gradient” Automatic, doesn’t not require energy Three types: diffusion, facilitated diffusion, osmosis

Diffusion Diffusion - process by which substances move directly through the cell membrane Facilitated diffusion- involves the help of carrier proteins For molecules too large to fit between the phospholipids

Osmosis The movement of water from an area of high concentration to an area of low concentration through a semi-permeable membrane Essentially, osmosis is the diffusion of water Can occur in either direction, depending on solution concentrations Could be hypertonic, hypotonic, or isotonic

Types of Solutions Hypertonic- particle concentration is higher in the solution than in the cell. Water goes out Cell shrinks

Types of Solutions Hypotonic – particle concentration is lower in solution than in the cell Water goes into cell Cell swells

Types of Solutions Isotonic- particle concentration is the same outside and inside the cell Same amount of water goes in as goes out

Types of Solutions

Activity – What will be the effect on the cell? 1. Internal cellular solution concentration of 11.4 mg/L placed in a solution with 9.9 mg/L. 2. Internal cellular solution concentration of 1.1 mg/L placed in a solution with 4.4 mg/L.

Activity – What will be the effect on the cell? 3. Internal cellular solution concentration of 0.01 mg/L placed in a solution with 0.1 mg/L. 4. Internal cellular solution concentration of 6.81 mg/L placed in a solution with 6.69 mg/L. 5. Internal cellular solution of 8.03 mg/L placed in a solution with 2.21 mg/L.

Active Transport For movement against the concentration gradient (low to high) Requires energy Movement is characterized by it’s direction exocytosis or endocytosis

Exocytosis Removes materials from the cell Waste materials, proteins, and fats Uses a storage sac to move materials toward membrane, membrane opens up, and materials are expelled out from the cell

Endocytosis Brings materials into the cell without passing through the cell membrane The membrane folds itself around the substance, creating a vesicle, and brings the substance into the cell How Amoebas eat

Fill in the Blank 1. A cell which has no net gain or loss of water is in a(n) __________ solution. 2. The process of expending energy to move molecules across a membrane is __________ transport. 3. A plant cell that has swelled to its limits is referred to as a ________ solution; a shrunken plant cell is a __________solution.

Choose the best answer 1. the movement of substance into and out of a cell without the use of energy is called: A. active transport B. passive transport C. exocytosis D. endocytosis

Choose the best answer 2. The movement of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration is called: A. active transport B. diffusion C. osmosis D. hypotonic

Choose the best answer 3. A type of membrane which allows only certain molecules to pass through is called: A. permeable B. semi-permeable C. active D. porous

Choose the best answer 4. A cell placed in a solution shrinks by the process of osmosis. What kind of solution is outside the cell? A. hypotonic B. hypertonic C. active D. isotonic

Choose the best answer 5. If the solution surrounding a cell has a lower concentration of solutes than inside the cell, water will move into the cell through osmosis, causing it to expand. What kind of solution is surrounding the cell? A. active B. passive C. hypertonic D. hypotonic

Short Answer 6. How does active transport differ from diffusion? 7. Dried beans are soaked overnight in preparation for cooking. Explain the process affecting the beans. What will happen to the dried beans? 8. Describe the difference between exocytosis and endocytosis. 9. A celery stalk is placed in a solution. It begins to wilt. What is a likely component of that solution?

From American Book Company’s Passing the High School Graduation Test in Science by Liz Thompson and Michelle Gunter