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AP Biology: The plasma Membrane is a structure conserved across domains (Big Idea 1) yet highly specialized to species and their internal and external environments (Big Idea 2). Greater than the sum of its parts, it possess emergent properties (Big Idea 3) that regulate the complex interactions of cells (Big Idea 4).

GSE Biology: SB1. Obtain, evaluate, and communicate information to analyze the nature of the relationships between structures and functions in living cells.d. Plan and carry out investigations to determine the role of cellular transport (e.g., active, passive, and osmosis) in maintaining homeostasis.

Chapter 5 - Membrane Transport and Cell Signaling

Guided Reading

Define: selective permeability, amphipathic, and fluid mosaic model

Concept 5.1 (old 7.1): Cellular membranes are fluid mosaics of lipids and proteins

  1. What is meant by membrane fluidity? Describe the movements seen in the membrane.
  2. What three factors can affect membrane fluidity?
  3. Explain how cholesterol affects the fluidity of membranes at different temperatures?
  4. How have plants, such as winter wheat, adapted to colder temperatures?
  5. Membrane function is determined by different sets of proteins. Define the two main groups of membrane proteins.
  6. Integral proteins-
  7. Peripheral proteins-
  8. Complete the table using figure 7.9 regarding functions performed by membrane proteins.

Function of membrane proteins / Description
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and ECM
  1. What role do carbohydrates play in the cell membrane?
  2. Define glycolipids and glycoproteins.
  3. What are some examples of why cell to cell recognition important?
  4. Explain the importance of variation among carbohydrate chains within the cell membrane.
  5. Summarize how the structure of the membrane is created by the ER and golgi apparatus.

Concept 5.2 (old 7.2): Membrane structure results in selective permeability

  1. Compare and contrast the permeability of the cell membrane in terms of polar molecules vs. nonpolar molecules.
  2. Distinguish between channel proteins and carrier proteins.
  3. Are transport proteins specific? Cite an example that supports your response (hint- aquaporins).

Concept 5.3 (old 7.3): Passive transport is diffusion of a substance across a membrane with no energy investment

  1. Vocabulary review – define the following terms in your own words

  • Diffusion
  • Facilitated diffusion
  • Concentration gradient
  • Passive transport
  • Osmosis
  • Tonicity
  • Isotonic
  • Hypertonic
  • Hypotonic
  • Solute
  • Solvent
  • Active transport
  • osmoregulation

  1. Briefly describe one important example of diffusion.
  2. Compare the balance of water in cells with and without cell walls?
  3. Explain how organisms without cell walls have adapted to live in hyper or hypotonic environments.

*Complete the Scientific Skills Exercise on page 109.

Concept 5.4 (old 7.4): Active transport uses energy to move solutes against their gradients

  1. Explain active transport in terms of how it works and why it is important.
  2. Explain how the sodium-potassium pump works to transport ions across the cell membrane against the concentration gradient (use figure 7.16 to help).
  3. Explain how proton pumps work.
  4. How has knowledge of these concepts helped dehydration issues as a result of diarrhea in people living in developing countries?

Concept 5.5 (old 7.5): Bulk transport across the plasma membrane occurs by exocytosis and endocytosis

  1. Complete the following table to compare exocytosis and endocytosis.

Endocytosis / Both Endo and Exocytosis / Exocytosis
Definition- / Definition-
Examples- / Examples-
  1. Summarize the three kinds of endocytosis using the table below.

Type of Endocytosis / Explanation
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis

Research the Following:

Cystic Fibrosis (CF) is the result of a mutated gene on chromosome seven and is inherited by offspring from their parents. CF is a recessive trait resulting in cells that cannot regulate sodium, chloride and bicarbonate transport. Using your knowledge of active transport and the sodium-potassium pump, explain where in the process you would expect the problem to occur in individuals with CF.

Concept 5.6 (old chapter 11): The plasma membrane plays a key role in most cell signaling

  1. Compare local and long distance signaling.
  2. What is a signal transduction pathway?
  3. What is a ligand?
  4. Complete the table below by summarizing the three stages of cell signaling (as seen above).

Summary of Reception - / Summary of Transduction- / Summary of Response-
  1. There are two main types of membrane receptors. Use the table below to summarize these receptors.

Membrane Receptor / Description of signaling process / Examples of their uses in living organisms
G Protein –
Coupled Receptors
Ion Channel Receptors
  1. Explain how intracellular receptor proteins function using aldosterone as the example.
  2. Explain the role of the following two categories of enzymes in the process of transduction.
  3. Protein kinase
  4. Protein phophatase
  5. Explain the role of a second messenger during transduction.
  6. How is cAMP formed?
  7. Cellular activities are regulated by signal transduction pathways.When cell signaling causes a response in the nucleus, what normally happens (figure 5.26)? When cell signaling causes a response in the cytoplasm, what normally happens (figure 5.25)?
  8. How are signals terminated?
  9. Explain what apoptosis is and what signals can trigger them (use at least two specific examples). – not in book

Test Your Understanding Questions and a Practice Test QR code are found on page 121.

Space for notes take from the videos on the website: