Outcomes: Gradients 2Identify whether a chemical or energy gradient exists in new situations, Gradients 3Indicate the direction of energy or material movement under different conditions such as: A) Chemical concentrations B) Temperature C) Permeability of membranes, Gradients 4Indicate the relative rate of energy or material movement under different conditions including: A) chemical concentrations B) temperature C) permeability of membranes D) varied shape (surface-to-volume ratio); Membrane Transport 2Explain how processes of transport work including: A) Diffusion i) Passive ii) Facilitated B) Osmosis i) Passive ii) Facilitated C) Active transport, Membrane Transport 3Define the following terms, and explain how they relate to the movement of materials across a membrane: A) Isotonic B) Hypotonic C) Hypertonic, Membrane Transport 4Explain how larger objects/molecules cross membranes by exocytosis, endocytosis, and phagocytosis, and predict when each of these transport mechanisms is used., Membrane Transport 5Predict how the following conditions affect membrane transport: A) gradient conditions B) temperature C) ATP availability D) changes in permeability E) molecule size, charge, or polarity; Thermoregulation 7Explain why organisms thermoregulate.
Prerequisite objective: Membrane Transport 1Identify the components of cell membranes, and explain how the arrangement of components makes the membrane semi-permeable.
- Ask students to work in groups to complete a table to compare and contrast modes of transport. (Membrane Transport 2Explain how processes of transport work including: A) Diffusion i) Passive ii) Facilitated B) Osmosis i) Passive ii) Facilitated C) Active transport)
| Diffusion | Facilitated diffusion | Active transport | |
| Description | Passive movement of… | Passive movement of… | Active movement of… |
| Are proteins involved? (yes/no) | No |
Follow up with clicker questions on how gradients relate to membrane transport. (Gradients 3Indicate the direction of energy or material movement under different conditions such as: A) Chemical concentrations B) Temperature C) Permeability of membranes, Gradients 4Indicate the relative rate of energy or material movement under different conditions including: A) chemical concentrations B) temperature C) permeability of membranes D) varied shape (surface-to-volume ratio), Membrane Transport 3Define the following terms, and explain how they relate to the movement of materials across a membrane: A) Isotonic B) Hypotonic C) Hypertonic, Membrane Transport 5Predict how the following conditions affect membrane transport: A) gradient conditions B) temperature C) ATP availability D) changes in permeability E) molecule size, charge, or polarity)
- (Gradients 4Indicate the relative rate of energy or material movement under different conditions including: A) chemical concentrations B) temperature C) permeability of membranes D) varied shape (surface-to-volume ratio), Membrane Transport 5Predict how the following conditions affect membrane transport: A) gradient conditions B) temperature C) ATP availability D) changes in permeability E) molecule size, charge, or polarity) Show an image of the activity at a cell membrane, that demonstrates that there are lots of materials moving in and out of cells (see example below). Ask students to brainstorm for 3 minutes about factors that can affect how quickly this transport occurs. In our experience, the list often contains factors such as: temperature, membrane permeability, size of chemical gradient, and sometimes cell shape. Formalize the role of cell shape with the concept of surface area-to-volume ratio. Most cells are very small to maintain high SA/V, facilitating an optimal rate of material movement. Learn.Genetics has a great demonstration of cell size and scale here. Students may or may not have identified temperature as a factor with enzymes in mind. This is also a good opportunity to address Thermoregulation 7Explain why organisms thermoregulate.: enzymes work best at a narrow temperature range.
- After introducing students to gradients and membrane transport, you may want to engage them in one of the following case studies:
- Osmosis – Agony and Ecstasy – This case follows Susan, an intern at a local hospital, who has admitted a patient she discovers has used the drug Ecstasy. The girl becomes delirious, and Susan begins to suspect that she may be suffering from water intoxication. (Membrane Transport 2Explain how processes of transport work including: A) Diffusion i) Passive ii) Facilitated B) Osmosis i) Passive ii) Facilitated C) Active transport, Membrane Transport 3Define the following terms, and explain how they relate to the movement of materials across a membrane: A) Isotonic B) Hypotonic C) Hypertonic)
- Osmosis – Osmosis is Serious Business! – This directed case study involves two “stories,” each one concerned with some aspect of osmosis in living cells. Part I is centered around the effects of a hypertonic environment on plant cells, while Part II focuses on the effects of a hypotonic environment on human cells. (Membrane Transport 2Explain how processes of transport work including: A) Diffusion i) Passive ii) Facilitated B) Osmosis i) Passive ii) Facilitated C) Active transport, Membrane Transport 3Define the following terms, and explain how they relate to the movement of materials across a membrane: A) Isotonic B) Hypotonic C) Hypertonic)
- Membrane Structure and Transport – Newsflash! Transport Proteins on Strike! – This role-play case study teaches students about plasma membrane transport and the functions of transport proteins in the phospholipid bilayer. Students act out the parts of molecules and structures in a fantastical cellular world where the unionized transport proteins have called for a work stoppage. (Membrane Transport 1Identify the components of cell membranes, and explain how the arrangement of components makes the membrane semi-permeable., Membrane Transport 2Explain how processes of transport work including: A) Diffusion i) Passive ii) Facilitated B) Osmosis i) Passive ii) Facilitated C) Active transport, Membrane Transport 4Explain how larger objects/molecules cross membranes by exocytosis, endocytosis, and phagocytosis, and predict when each of these transport mechanisms is used.)