Anatomy & Physiology 1 – Exam 2 Review: Step-by-Step Study Guidance

Q1. Compare and contrast Passive vs. Active Transport across a plasma membrane. Give an example of each!

Background

Topic: Membrane Transport Mechanisms

This question tests your understanding of how substances move across the cell membrane, specifically distinguishing between passive and active transport, and recognizing examples of each.

Key Terms and Concepts:

• Passive Transport: Movement of substances across the membrane without energy input (ATP).

• Active Transport: Movement of substances against their concentration gradient, requiring energy (usually ATP).

• Examples: Simple diffusion, facilitated diffusion, osmosis (passive); sodium-potassium pump, proton pump (active).

Step-by-Step Guidance

1. Define passive transport and describe how it relies on the concentration gradient (from high to low concentration) and does not require cellular energy.

2. List and briefly describe types of passive transport (e.g., simple diffusion, facilitated diffusion, osmosis).

3. Define active transport and explain how it moves substances against their concentration gradient (from low to high concentration), requiring energy input (usually ATP).

4. List and briefly describe types of active transport (e.g., primary active transport like the sodium-potassium pump, secondary active transport).

5. Provide one specific example of each type of transport, describing the molecule moved and the mechanism involved.

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Q2. Describe 3 possible pathways (destinations) in a cell that the Golgi apparatus sends products of the rough ER. Include the type of vesicle used, the final destination of these proteins and a specific protein example of each.

Background

Topic: Protein Processing and Trafficking

This question assesses your understanding of how proteins synthesized in the rough endoplasmic reticulum (rER) are processed, packaged, and sent to various destinations by the Golgi apparatus.

Key Terms and Concepts:

• Golgi Apparatus: Organelle responsible for modifying, sorting, and packaging proteins.

• Vesicles: Membrane-bound sacs that transport proteins (e.g., secretory vesicles, lysosomal vesicles, membrane vesicles).

• Destinations: Secretion outside the cell, incorporation into the plasma membrane, delivery to lysosomes.

Step-by-Step Guidance

1. Identify three main destinations for proteins processed by the Golgi apparatus (e.g., secretion, plasma membrane, lysosomes).

2. For each pathway, specify the type of vesicle involved (e.g., secretory vesicle, membrane-bound vesicle, lysosomal vesicle).

3. Describe the final destination and function of the protein in each pathway.

4. Give a specific protein example for each pathway (e.g., insulin for secretion, membrane receptor for plasma membrane, digestive enzyme for lysosome).

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Q3. Briefly explain genetic Transcription and Translation. Include the location in a cell each takes place, any enzymes/organelles/molecules important in these processes and what each synthesizes.

Background

Topic: Protein Synthesis (Central Dogma of Molecular Biology)

This question tests your understanding of the two main steps in protein synthesis: transcription (DNA to RNA) and translation (RNA to protein), including where they occur and the molecules involved.

Key Terms and Concepts:

• Transcription: Synthesis of mRNA from a DNA template (occurs in the nucleus).

• Translation: Synthesis of a polypeptide (protein) from mRNA (occurs in the cytoplasm at ribosomes).

• Key molecules: DNA, mRNA, tRNA, rRNA, RNA polymerase, ribosome.

Step-by-Step Guidance

1. Define transcription and state where in the cell it occurs.

2. Identify the main enzyme involved in transcription (RNA polymerase) and the product (mRNA).

3. Define translation and state where in the cell it occurs.

4. Identify the organelle (ribosome) and molecules (mRNA, tRNA, rRNA) involved in translation, and the product (polypeptide/protein).

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Q4. Describe the mechanism by which the Casein gene is turned on during late pregnancy in women. Begin with the proper hormone and end with exocytosis of the Casein protein into milk!

Background

Topic: Gene Regulation and Protein Secretion

This question examines your understanding of hormone-regulated gene expression, specifically how the Casein gene is activated and its protein product secreted during lactation.

Key Terms and Concepts:

• Hormone: Prolactin (stimulates milk protein gene expression).

• Gene Activation: Hormone-receptor interaction, transcription factors, initiation of transcription.

• Protein Synthesis and Secretion: Transcription, translation, processing in rER and Golgi, exocytosis.

Step-by-Step Guidance

1. Identify the hormone responsible for activating the Casein gene (prolactin) and describe how it signals the cell.

2. Explain how the hormone-receptor complex leads to activation of transcription factors that bind to the Casein gene promoter.

3. Describe the process of transcription of the Casein gene and subsequent translation of mRNA into protein.

4. Outline how the Casein protein is processed and packaged for secretion (rER, Golgi apparatus).

5. Describe the final step of exocytosis, where the Casein protein is released into milk.

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Q5. Why are people with Cystic Fibrosis vulnerable to respiratory infections and digestive problems? Include what occurs structurally at the cellular level of these organs!

Background

Topic: Cell Membrane Structure and Disease

This question tests your understanding of how a genetic mutation affects cell membrane proteins, leading to clinical symptoms in cystic fibrosis.

Key Terms and Concepts:

• Cystic Fibrosis Transmembrane Conductance Regulator (CFTR): A chloride channel protein in epithelial cell membranes.

• Effects: Thick, sticky mucus in lungs and digestive tract due to defective chloride transport.

• Consequences: Impaired mucociliary clearance, increased infection risk, blocked pancreatic ducts.

Step-by-Step Guidance

1. Describe the normal function of the CFTR protein in epithelial cells of the respiratory and digestive tracts.

2. Explain how a mutation in the CFTR gene alters the structure and function of the protein.

3. Discuss how this leads to abnormal chloride and water transport across cell membranes.

4. Describe the resulting changes in mucus consistency and how this affects respiratory and digestive function.

5. Connect these cellular changes to increased vulnerability to infections and digestive problems.

Try solving on your own before revealing the answer!