Anatomy & Physiology: Cell Structure and Membrane Transport Study Guide

Study Guide - Smart Notes

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Q1. Complete the following table: List the function of each organelle (Nucleus, Rough Endoplasmic Reticulum, Smooth Endoplasmic Reticulum, Golgi Apparatus, Mitochondria, Lysosome, Ribosome, Centrioles, Microvilli, Cilia, Cytoskeleton).

Background

Topic: Cell Organelles and Their Functions

This question tests your understanding of the structure and function of various cellular organelles, which is fundamental to cell biology in Anatomy & Physiology.

Key Terms:

Organelle: Specialized structure within a cell that performs a specific function.
Nucleus: Contains genetic material (DNA) and controls cell activities.
Endoplasmic Reticulum (Rough/Smooth): Involved in protein and lipid synthesis.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
Mitochondria: Site of ATP (energy) production.
Lysosome: Contains digestive enzymes to break down waste.
Ribosome: Site of protein synthesis.
Centrioles: Involved in cell division.
Microvilli: Increase surface area for absorption.
Cilia: Move substances across cell surfaces.
Cytoskeleton: Provides structural support and shape to the cell.

Step-by-Step Guidance

Review the definition and function of each organelle listed in your textbook (pages 72-74).
For each organelle, write a brief description of its main function in the cell.
Pay attention to how some organelles work together (e.g., ribosomes on rough ER, Golgi apparatus packaging proteins).
Make sure to distinguish between similar-sounding organelles (e.g., rough vs. smooth ER).
Fill in the table with concise, accurate functions for each organelle, using your own words for better understanding.

Try solving on your own before revealing the answer!

Final Answer:

Nucleus: Stores genetic material (DNA); controls cell activities.
Rough Endoplasmic Reticulum: Synthesizes and transports proteins (has ribosomes attached).
Smooth Endoplasmic Reticulum: Synthesizes lipids and detoxifies substances; no ribosomes.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
Mitochondria: Produces ATP through cellular respiration; the "powerhouse" of the cell.
Lysosome: Contains digestive enzymes to break down waste and cellular debris.
Ribosome: Site of protein synthesis.
Centrioles: Help organize cell division (mitosis/meiosis).
Microvilli: Increase surface area for absorption (especially in intestines).
Cilia: Move substances across the cell surface (e.g., mucus in respiratory tract).
Cytoskeleton: Provides structural support, shape, and aids in movement within the cell.

Each organelle has a unique and essential role in maintaining cell function and homeostasis.

Q2. List the general functions of the cell (plasma) membrane.

Background

Topic: Plasma Membrane Structure and Function

This question assesses your knowledge of the roles played by the cell membrane in maintaining cellular integrity and function.

Key Terms:

Plasma Membrane: The outer boundary of the cell, composed mainly of a phospholipid bilayer with embedded proteins.
Selective Permeability: The ability of the membrane to allow some substances to pass while blocking others.
Homeostasis: Maintenance of a stable internal environment.

Step-by-Step Guidance

Recall the main structural components of the plasma membrane (phospholipids, proteins, cholesterol).
Think about how the membrane acts as a barrier between the cell's interior and its environment.
List the ways the membrane controls what enters and exits the cell (selective permeability, transport proteins).
Consider additional functions such as cell communication, recognition, and structural support.

Try solving on your own before revealing the answer!

Final Answer:

Acts as a physical barrier separating the cell from its environment.
Regulates the movement of substances into and out of the cell (selective permeability).
Facilitates communication with other cells via receptors and signaling molecules.
Provides structural support and helps maintain cell shape.
Allows for cell recognition and interaction with other cells.

The plasma membrane is essential for maintaining homeostasis and proper cell function.

Q3. Draw the cell membrane and label the following structures: phospholipid (head and tail regions/hydrophobic and hydrophilic regions), extracellular fluid, cytoplasm, transmembrane (integral) protein.

Background

Topic: Cell Membrane Structure

This question tests your ability to visualize and label the key components of the plasma membrane, which is crucial for understanding membrane function.

Key Terms:

Phospholipid Bilayer: Double layer of phospholipids with hydrophilic heads and hydrophobic tails.
Hydrophilic: Water-attracting (polar) region.
Hydrophobic: Water-repelling (nonpolar) region.
Transmembrane (Integral) Protein: Protein that spans the membrane and assists in transport or signaling.
Extracellular Fluid: Fluid outside the cell.
Cytoplasm: Fluid inside the cell.

Step-by-Step Guidance

Draw two parallel lines to represent the phospholipid bilayer.
Label the outer and inner surfaces as hydrophilic (phospholipid heads) and the interior as hydrophobic (tails).
Indicate the extracellular fluid above the top layer and the cytoplasm below the bottom layer.
Draw and label a transmembrane (integral) protein spanning the bilayer.
Make sure to clearly mark the head and tail regions of the phospholipids.

Try solving on your own before revealing the answer!

Final Answer:

Your drawing should include:

Phospholipid bilayer with hydrophilic heads facing outward (toward extracellular fluid and cytoplasm) and hydrophobic tails facing inward.
Label the extracellular fluid (outside) and cytoplasm (inside).
Transmembrane (integral) protein spanning the bilayer.
Clearly indicate hydrophilic (polar) and hydrophobic (nonpolar) regions.

This diagram helps visualize how the membrane's structure relates to its function.

Q4. Passive Transport Mechanisms: What are passive transport mechanisms, and what do they move across the cell membrane without using?

Background

Topic: Membrane Transport

This question focuses on the types of transport that do not require cellular energy (ATP) to move substances across the cell membrane.

Key Terms:

Passive Transport: Movement of substances across the membrane without energy input.
ATP: Adenosine triphosphate, the cell's energy currency.

Step-by-Step Guidance

Recall the definition of passive transport and how it differs from active transport.
Think about what is NOT required for passive transport (hint: energy/ATP).
List examples of passive transport mechanisms (diffusion, osmosis, facilitated diffusion).
Consider what drives passive transport (concentration gradients).

Try solving on your own before revealing the answer!

Final Answer:

Passive transport mechanisms move ions or molecules across the cell membrane without using cellular energy (ATP). They rely on concentration gradients to drive movement.

Q5. Diffusion: a) What is diffusion? b) How can a molecule or ion diffuse across the membrane?

Background

Topic: Diffusion Across Cell Membranes

This question tests your understanding of the process of diffusion and the different ways substances can cross the cell membrane.

Key Terms:

Diffusion: Movement of molecules from high to low concentration.
Simple Diffusion: Direct movement through the lipid bilayer.
Facilitated Diffusion: Movement via a membrane protein.

Step-by-Step Guidance

Define diffusion in terms of concentration gradients.
Identify the direction of movement (from high to low concentration).
Explain the two main pathways: simple diffusion (through lipid bilayer) and facilitated diffusion (via protein channels/carriers).
Think of examples of molecules that use each pathway (e.g., oxygen for simple, glucose for facilitated).

Try solving on your own before revealing the answer!

Final Answer:

a) Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.
b) Molecules or ions can diffuse across the membrane either by moving directly through the lipid portion (simple diffusion) or by using a membrane protein (facilitated diffusion).

Q6. Osmosis: a) What is osmosis? b) In which direction do water molecules move? c) What is osmotic pressure? d) What is tonicity, and how do isotonic, hypertonic, and hypotonic solutions affect a cell?

Background

Topic: Osmosis and Tonicity

This question explores the movement of water across membranes and how different solutions affect cell volume and pressure.

Key Terms:

Osmosis: Diffusion of water across a selectively permeable membrane.
Osmotic Pressure: The pressure required to stop the movement of water.
Tonicity: The ability of a solution to cause a cell to gain or lose water.
Isotonic: Equal solute concentration inside and outside the cell.
Hypertonic: Higher solute concentration outside the cell.
Hypotonic: Lower solute concentration outside the cell.

Step-by-Step Guidance

Define osmosis and specify what is moving (water molecules).
Describe the direction of water movement (toward higher solute concentration).
Explain osmotic pressure and what causes it to increase.
Define tonicity and describe the effects of isotonic, hypertonic, and hypotonic solutions on a cell (draw or visualize if needed).
Think about what happens to a cell in each type of solution (shrinks, swells, or stays the same).

Try solving on your own before revealing the answer!

Final Answer:

a) Osmosis is the movement of water across a selectively permeable membrane.
b) Water moves toward the area with higher solute concentration.
c) Osmotic pressure is the pressure needed to stop the movement of water due to osmosis; it increases with higher solute concentration.
d) Tonicity describes how a solution affects cell volume:
- Isotonic: No net movement of water; cell stays the same size.
- Hypertonic: Water leaves the cell; cell shrinks (crenates).
- Hypotonic: Water enters the cell; cell swells (may burst).

Q7. Active Transport Mechanisms: What are active transport mechanisms, and what do they use to move substances across the cell membrane?

Background

Topic: Active Transport

This question tests your understanding of how cells move substances against concentration gradients using energy.

Key Terms:

Active Transport: Movement of substances across the membrane using cellular energy (ATP).
ATP: The energy molecule used by cells.

Step-by-Step Guidance

Recall the difference between active and passive transport.
Identify the source of energy used in active transport (ATP).
List examples of active transport mechanisms (e.g., Na+/K+ pump, vesicular transport).
Think about why cells need to use energy to move some substances (against concentration gradients).

Try solving on your own before revealing the answer!

Final Answer:

Active transport mechanisms move ions or molecules across the cell membrane using cellular energy (ATP), often against their concentration gradient.

Q8. Active Transport: a) What can active transport do with solutes, and in which direction does it move them?

Background

Topic: Active Transport Directionality

This question focuses on the ability of active transport to move substances against their natural flow.

Key Terms:

Active Transport: Uses energy to move substances against their concentration gradient.
Concentration Gradient: Difference in concentration across a membrane.

Step-by-Step Guidance

Recall that active transport can import (bring in) or export (send out) solutes.
Identify the direction: from low to high concentration (against the gradient).
Think of examples, such as the sodium-potassium pump moving Na+ out and K+ in.
Consider why this process requires energy.

Try solving on your own before revealing the answer!

Final Answer:

Active transport can import or export solutes and moves them against their concentration gradient (from low to high concentration), which requires energy.

Q9. Vesicular Transport: a) What is vesicular transport? b) What are the two main types?

Background

Topic: Bulk Transport Across Membranes

This question examines how cells move large particles or volumes of material using vesicles.

Key Terms:

Vesicular Transport: Movement of materials into or out of the cell using vesicles.
Vesicle: Small, membrane-bound sac.
Endocytosis: Bringing materials into the cell.
Exocytosis: Expelling materials from the cell.

Step-by-Step Guidance

Define vesicular transport and the role of vesicles.
Identify the two main types: endocytosis and exocytosis.
Think about the direction of movement for each type (into or out of the cell).
Recall examples of substances moved by each process.

Try solving on your own before revealing the answer!

Final Answer:

a) Vesicular transport is the movement of materials into or out of the cell in small, membrane-bound sacs called vesicles.
b) The two main types are endocytosis (into the cell) and exocytosis (out of the cell).

Q10. Endocytosis: a) What is endocytosis? b) What are the three types of endocytosis, and what do they involve?

Background

Topic: Endocytosis Types

This question tests your knowledge of the different ways cells can take in materials using vesicles.

Key Terms:

Endocytosis: Process by which cells engulf external substances.
Receptor-mediated Endocytosis: Specific uptake using receptors.
Pinocytosis: "Cell drinking"; uptake of fluids.
Phagocytosis: "Cell eating"; uptake of large particles.

Step-by-Step Guidance

Define endocytosis and its general purpose.
List the three types: receptor-mediated, pinocytosis, and phagocytosis.
Describe what each type involves (specific molecules, fluids, or large particles).
Think of examples for each type (e.g., immune cells using phagocytosis).

Try solving on your own before revealing the answer!

Final Answer:

a) Endocytosis is a process in which a cell engulfs extracellular material by forming a vesicle around it.
b) The three types are:
- Receptor-mediated endocytosis: Uptake of specific molecules using cell surface receptors.
- Pinocytosis: Uptake of extracellular fluid and dissolved substances ("cell drinking").
- Phagocytosis: Uptake of large particles or cells ("cell eating").

Q11. Exocytosis: What is exocytosis?

Background

Topic: Exocytosis

This question focuses on how cells expel materials using vesicles.

Key Terms:

Exocytosis: Process of releasing substances from the cell by vesicle fusion with the plasma membrane.

Step-by-Step Guidance

Define exocytosis and its role in the cell.
Describe the process: vesicle fuses with the plasma membrane, releasing contents outside.
Think of examples (e.g., secretion of hormones, neurotransmitters).

Try solving on your own before revealing the answer!

Final Answer:

Exocytosis is a process in which a cell releases intracellular material by fusing a vesicle with the plasma membrane, expelling its contents to the outside of the cell.