Week 3 - Cell Structure and Function Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of transport proteins in the plasma membrane?

Serve as identity markers

Facilitate cell-adhesion

Regulate movement of substances across the membrane (correct)

Catalyze chemical reactions

Which type of protein is involved in binding ligands to initiate cellular responses?

Cell surface receptors (correct)

Transport proteins

Anchoring proteins

Identity markers

What role do identity markers play in the plasma membrane?

They secure the cytoskeleton to the membrane.

They regulate the internal chemical environment of the cell.

They facilitate enzymatic reactions on the membrane.

They differentiate healthy cells from diseased ones. (correct)

Which of the following best describes the structure of integral membrane proteins?

They penetrate the entire lipid bilayer. Signup and view all the answers

Which functional category includes proteins that catalyze chemical reactions on a cell's surface?

Enzymes Signup and view all the answers

What is the primary function of the plasma membrane?

To regulate movement of substances in and out of the cell Signup and view all the answers

What distinguishes membrane-bound organelles from non-membrane-bound organelles?

Membrane-bound organelles are enclosed by a membrane. Signup and view all the answers

Which structure is considered the largest within the cell?

Nucleus Signup and view all the answers

What component of the plasma membrane is essential for maintaining its structure and fluidity?

Cholesterol Signup and view all the answers

Which of the following statements accurately describes phospholipids?

They contain a hydrophilic head and two hydrophobic tails. Signup and view all the answers

What is included in the cytoplasm of a cell?

Cellular organelles Signup and view all the answers

Which function is NOT typically performed by cells?

Store genetic information Signup and view all the answers

What do ribosomes and proteasomes have in common?

Both are non-membrane-bound organelles. Signup and view all the answers

Which of the following describes the cytosol?

It is the viscous fluid of the cytoplasm. Signup and view all the answers

Which of the following is a function of the cell's plasma membrane?

To separate internal and external environments Signup and view all the answers

What type of solution maintains cell volume without any net movement of water?

Isotonic solution Signup and view all the answers

What occurs when erythrocytes are placed in a hypotonic solution?

Water moves into the cell and causes lysis Signup and view all the answers

Which term describes a solution with a higher concentration of solutes than cytosol?

Hypertonic Signup and view all the answers

Which of the following describes the effect of a hypertonic solution on erythrocytes?

Cell shrinking and possible crenation Signup and view all the answers

What causes hemolysis in erythrocytes when exposed to a hypotonic solution?

Excessive water intake and sudden rupture Signup and view all the answers

What is a common characteristic of isotonic solutions?

No net movement of water between cell and solution Signup and view all the answers

What happens when erythrocytes are immersed in pure water?

They swell and may undergo lysis Signup and view all the answers

Which of the following is a correct definition of tonicity?

The ability of a solution to alter a cell's volume by osmosis Signup and view all the answers

What is the main function of the plasma membrane in relation to cell communication?

It establishes and maintains an electrochemical gradient necessary for communication. Signup and view all the answers

Which of the following best describes passive processes of membrane transport?

They occur without the requirement of energy and rely on concentration gradients. Signup and view all the answers

What primarily influences the rate of diffusion?

The steepness of the concentration gradient. Signup and view all the answers

What occurs during active transport?

Energy is required to move substances against their concentration gradient. Signup and view all the answers

What happens to solutes during the process of diffusion?

They eventually become evenly distributed throughout the area. Signup and view all the answers

Which type of membrane transport requires the formation of membrane-bound vesicles?

Vesicular transport Signup and view all the answers

Which statement correctly describes osmosis?

It is the diffusion of water across a selectively permeable membrane. Signup and view all the answers

What ultimately happens if a substance continues to diffuse unopposed?

It will reach an equilibrium when evenly distributed. Signup and view all the answers

What is the primary role of Na/K pumps in cells?

To establish K+ and Na+ gradients Signup and view all the answers

What are glycolipids and glycoproteins primarily involved in?

Cell recognition and communication Signup and view all the answers

Which of the following best describes ligands?

Substances that bind to macromolecules Signup and view all the answers

What function do channel-linked receptors primarily serve?

Allowing ion passage into or out of cells Signup and view all the answers

Which organelle is characterized by having ribosomes attached to it?

Rough Endoplasmic Reticulum Signup and view all the answers

What is the primary function of the Smooth Endoplasmic Reticulum?

Synthesis and storage of lipids Signup and view all the answers

Which of the following describes a characteristic of membrane-bound organelles?

Isolated environments for cellular activities Signup and view all the answers

Cell communication primarily utilizes which of the following?

Ligands Signup and view all the answers

Study Notes

Plasma Membrane

Forms the outer boundary, separating the cell's internal environment from the external environment.
Composed of a fluid mixture with equal parts lipid and protein by weight.
Regulates the movement of most substances in and out of the cell.
Contains phospholipids, cholesterol, and glycolipids.

Nucleus

The largest structure within the cell.
Enclosed by a nuclear envelope.
Contains genetic material (DNA) and a nucleolus.
The inner fluid is called nucleoplasm.

Cytoplasm

Cellular contents between the plasma membrane and nucleus.
Includes cytosol, organelles, and inclusions.

Cytosol

The viscous fluid of the cytoplasm.
Composed primarily of water.
Contains dissolved macromolecules and ions.

Organelles

Complex, organized structures within the cell.
Have unique shapes and functions.
Classified into two categories: membrane-bound and non-membrane-bound.

Membrane-Bound Organelles

Enclosed by a membrane.
Separates their contents from the cytosol.
Includes endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and mitochondria.

Non-Membrane-Bound Organelles

Not enclosed within a membrane.
Primarily composed of proteins
Includes ribosomes, cytoskeleton, centrosomes, and proteasomes.

Common Cellular Functions

Maintain the cell's integrity and shape, relying on the plasma membrane and internal contents.
Obtain nutrients, form chemical building blocks, and harvest energy for survival.
Dispose of waste to avoid accumulation that could disrupt cellular activities.
Some cells are capable of cell division, creating more cells of the same type for new growth and replacement.

Phospholipid Bilayer

The basic structure of the plasma membrane framework.
Composed of phospholipids, which have a polar, hydrophilic "head" and two nonpolar, hydrophobic "tails."
Forms two parallel sheets of molecules with the hydrophobic tails facing inward and the hydrophilic heads directed outward.
Ensures the separation of the cell's internal environment (cytosol) from the external environment (interstitial fluid).

Membrane Proteins

Half of the plasma membrane by weight.
Float and move within the fluid bilayer.
Perform most of the membrane's functions.
Classified into two structural types: integral and peripheral.

Integral Proteins

Embedded within the phospholipid bilayer.
Have both hydrophobic and hydrophilic regions, allowing them to interact with both the lipid tails and the aqueous environments.

Peripheral Proteins

Attached to the inner or outer surface of the membrane.
Can be anchored to integral proteins or phospholipids.

Protein Function Categories (Transport Proteins)

Regulate the movement of substances across the membrane.
Examples: channels, carrier proteins, pumps, symporters, and antiporters.

Protein Function Categories (Cell Surface Receptors)

Bind to molecules called ligands, initiating cellular responses.
Examples: neurotransmitters released from nerve cells that bind to muscle cells to initiate contraction.

Protein Function Categories (Identity Markers)

Communicate to other cells that they belong to the body.
Used to distinguish healthy cells from those that should be destroyed.

Protein Function Categories (Enzymes)

Catalyze chemical reactions on either the internal or external surface of the cell.

Protein Function Categories (Anchoring Sites)

Secure the cytoskeleton to the plasma membrane, providing structural support and stability.

Protein Function Categories (Cell-Adhesion Proteins)

Perform cell-to-cell attachments, holding cells together in tissues and organs.

Membrane Transport

The process of obtaining and eliminating substances across the plasma membrane.
Classified into two categories: passive processes and active processes.

Passive Processes

Do not require energy.
Depend on substances moving down their concentration gradient, from areas of higher concentration to areas of lower concentration.
Two types: diffusion and osmosis.

Active Processes

Require energy to move substances across the membrane.
Move substances up their concentration gradient or against their natural tendency to move from high to low concentration.
Two types: active transport and vesicular transport.

Diffusion

The net movement of ions or molecules from an area of greater concentration to an area of lesser concentration.
Driven by the concentration gradient.
The steeper the gradient, the faster the rate of diffusion.
Continues until the substance reaches equilibrium, where molecules are evenly distributed.

Osmosis

The passive movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration.
Driven by differences in solute concentration.
Water moves to dilute the higher concentration of solutes.

Tonicity

The ability of a solution to change the volume or pressure of a cell by osmosis.
Describes the relative concentration of solutions: isotonic, hypotonic, and hypertonic.

Isotonic Solution

The cytosol and the solution have the same relative concentration of solutes.
No net movement of water occurs.

Hypotonic Solution

The solution has a lower concentration of solutes and a higher concentration of water than the cytosol.
Water moves into the cell, increasing its volume and pressure.
Lysis (rupturing) or hemolysis (rupturing of erythrocytes) can occur if the difference is significant.

Hypertonic Solution

The solution has a higher concentration of solutes than the cytosol.
Water moves out of the cell, decreasing its volume and pressure.
Crenation (cell shrinkage) can occur.

Resting Membrane Potential (RMP)

The electrical potential difference across the plasma membrane of a cell at rest.
Typically, the inside of the cell is negatively charged relative to the outside.
Important in the function of nerve and muscle cells.

Maintaining the RMP

Depends mainly on the Na+/K+ pumps, which maintain concentration gradients for Na+ and K+ ions.

Cell Communication

The plasma membrane plays a crucial role in cell communication.
Structures like glycolipids and glycoproteins facilitate direct interactions between cells and recognition of and responses to external signals.

Ligand-Receptor Signaling

Most cell communication occurs through ligands, which bind to macromolecules (receptors) on the cell surface.
Neurotransmitters and hormones are examples of ligands.
Important for controlling growth, reproduction, and other cellular processes.

Channel-Linked Receptors

Allow the passage of ions into or out of the cell in response to ligand binding.
Initiate electrical changes in the RMP of nerve and muscle cells.

Endoplasmic Reticulum (ER)

An extensive interconnected membrane network.
Classified into two types: rough ER (with ribosomes) and smooth ER (without ribosomes).
Rough ER synthesizes proteins, which are then transported and processed by Golgi apparatus.
Smooth ER plays a role in lipid synthesis, transport, and storage.

Ribosomes

Small, non-membrane bound organelles responsible for protein synthesis.
Found either free-floating in the cytosol or attached to the ER (rough ER).

Golgi Apparatus

A stack of flattened, membranous discs called cisternae.
Modifies, sorts, and packs proteins synthesized by the ER.
Produces secretory vesicles that transport proteins to other organelles or for secretion outside the cell.

Lysosomes

Membrane-bound sacs containing enzymes that digest and break down substances that enter the cell or waste products.
Involved in autophagy, the process of breaking down damaged or worn-out organelles within the cell.

Peroxisomes

Small, membrane-bound organelles containing enzymes that break down fatty acids and harmful substances such as hydrogen peroxide (H2O2).
Play a role in detoxification, breaking down toxins and harmful chemicals.

Mitochondria

The "powerhouses" of the cell.
Responsible for producing ATP (adenosine triphosphate), the primary energy currency of the cell, through aerobic respiration.
Have their own DNA separate from the nuclear DNA.
Thought to have originated from prokaryotic organisms that were engulfed by eukaryotic cells.

Vesicles

Small, membrane-bound sacs that transport substances within the cell.
Examples: secretory vesicles, transport vesicles, lysosomes, and peroxisomes.

Cytoskeleton

A network of protein filaments that provide structural support, maintains cell shape, allows for movement within the cell, and assists with cell division.
Composed of three types of filaments: microfilaments, intermediate filaments, and microtubules.

Centrosome

A region near the nucleus that contains two centrioles, which are small, cylindrical structures involved in cell division.
During cell division, the centrioles help to form spindle fibers, which are responsible for separating the chromosomes into daughter cells.

Proteasomes

Large, protein complexes that degrade or break down unneeded proteins.
Involved in quality control within the cell, ensuring that only properly folded and functional proteins remain.

Cilia

Short, hair-like projections on the cell surface.
Move fluid or particles past the cell, such as in the respiratory tract to move mucus.

Flagellum

Long, whip-like projection on the cell surface.
Propels the cell, such as in sperm cells for movement.

Microvilli

Finger-like projections on the cell surface.
Increase the surface area of the cell, allowing for more efficient absorption of nutrients, such as in the small intestine.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers key concepts of cell structure and function, including the plasma membrane, nucleus, cytoplasm, and organelles. Test your knowledge on the components and roles of these essential cell structures. Ideal for biology students looking to solidify their understanding of cellular components.