Membranes and Transport Study Notes

Chapter 5: Membranes and Transport - Cell Structure and Function Notes

Essential Knowledge Objectives

• Reviewing Essential Knowledge objectives on Schoology is crucial for exam preparation as they outline exact AP exam expectations.

Science Practice Review

Science Practice 1: Explaining Biological Concepts and Processes

• Concept: Explain biological concepts and processes presented in written format.

• Skills:

  • 1.A: Describe biological concepts and processes.

  • 1.B: Explain biological concepts and processes.

  • 1.C: Explain biological concepts and processes in applied contexts.

Science Practice 2: Analyzing Visual Representations

• Concept: Analyze visual representations of biological concepts and processes.

• Skills:

  • 2.A: Describe characteristics of visual representations of biological concepts and processes.

  • 2.B: Explain relationships between characteristics of biological models in both theoretical and applied contexts.

  • 2.C: Explain how biological models relate to larger principles, concepts, processes, systems, or theories.

  • 2.D: Represent relationships within biological models, including mathematical models, diagrams, flowcharts, and systems.

Free-Response Question (FRQ) Test Tips

• Always look for the bold-faced task verb in FRQs to understand what is required for your response.

• Identify simply requires listing something.

• Describe or Explain demand more detail.

Common FRQ Task Verbs

• Calculate: Perform mathematical steps to reach a final answer, including algebraic expressions, properly substituted numbers, and correct units and significant figures.

• Construct/Draw: Create a diagram, graph, representation, or model to illustrate or explain relationships/phenomena (labels may be required).

• Describe: Provide relevant characteristic(s) of a specified topic.

• Determine: Decide or conclude after reasoning, observation, or applying mathematical routines.

• Evaluate: Judge or determine the significance/importance of information, or the quality/accuracy of a claim.

• Explain: Provide information on how or why a relationship, process, pattern, position, situation, or outcome occurs, using evidence and/or reasoning.

  • Explain "how": Typically requires analyzing the relationship, process, pattern, position, situation, or outcome.

  • Explain "why": Typically requires analysis of motivations or reasons.

• Identify: Indicate or provide information about a specified topic, without elaboration.

• Justify: Provide evidence to support, qualify, or defend a claim, and reasoning to explain how that evidence supports or qualifies the claim.

• Make a claim: Assert something based on evidence or knowledge.

• Predict/Make a prediction: Predict causes or effects of a change in, or disruption to, components in a relationship, pattern, process, or system.

• Represent: Use appropriate graphs, symbols, words, illustrations, and tables of numerical values to describe biological concepts, characteristics, and/or relationships.

• State (the null hypothesis): Provide a hypothesis to support or defend a claim about a scientifically testable question related to experimental variables.

• Support a claim: Provide reasoning to explain how evidence supports or qualifies a claim.

Science Practice 5: Statistical Tests and Data Analysis

• Concept: Perform statistical tests and mathematical calculations to analyze and interpret data.

• Skills:

  • 5.A: Perform mathematical calculations, including mathematical equations in the curriculum, means, rates, ratios, percentages, and percent changes.

  • 5.B: Use confidence intervals and error bars to estimate whether sample means are statistically different.

  • 5.C: Perform chi-square hypothesis testing.

  • 5.D: Use data to evaluate a hypothesis or prediction, including rejecting or failing to reject the null hypothesis.

• Assumed Mathematical Skills:

  • Mean (Average): ext{Mean} = rac{ ext{Sum of All Data Points}}{ ext{Number of Data Points}}

  • Rates: Determined by finding the slope of a graph or calculating the change in y values divided by the change in x values.

  • Ratios: Comparison of two quantities (e.g., surface area to volume ratio of cells).

  • Percentages: ext{Percentage} = rac{ ext{part}}{ ext{whole}} imes 100 ext{%}

  • Percentage Change: ext{Percentage Change} = rac{ ext{Final value} - ext{Initial value}}{ ext{Initial value}} imes 100 ext{%}

• Common Mistake: Failing to include units for numerical answers. All numbers in science require proper units.

Overview of Membranes

• Focus on Eukaryotic Cells; specifically, the cell membrane.

• Barrier Function:

  • Membranes form a barrier between the inside and outside of the cell, enabling the cell to regulate what enters and exits, allowing it to be different from its surroundings.

  • Membranes form a barrier between organelles and the cytosol, allowing for the compartmentalization of functions within the cell.

• Study Approach: First, examine the structure of membranes, then how they regulate what enters and exits cells.

Membrane Structure: Major Components

Phospholipids

• Core Structure: Amphipathic molecules with both hydrophilic and hydrophobic regions.

  • "Phospho" part: The phosphate group. This part is polar (hydrophilic) and forms the