Cell Biology Quiz
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Questions and Answers

Which type of membrane protein spans across the entire membrane?

  • Peripheral membrane protein
  • Cholesterol
  • Glycoprotein
  • Integral membrane protein (correct)

Passive transport requires the use of ATP to move substances across the membrane.

False (B)

What are the main functions of plasma membrane proteins?

Transport, signaling, cell recognition, and structural support.

Phospholipids are considered ______ molecules because they contain both hydrophilic and hydrophobic regions.

<p>amphipathic</p> Signup and view all the answers

The Frye and Edidin experiment of 1970 provided evidence for what aspect of cell membranes?

<p>Fluid mosaic model (A)</p> Signup and view all the answers

Match the following cell structures to their primary functions:

<p>Nucleus = Contains genetic material Ribosomes = Protein synthesis Mitochondrion = Energy production Chloroplasts = Photosynthesis</p> Signup and view all the answers

Cholesterol maintains membrane fluidity at both high and low temperatures.

<p>True (A)</p> Signup and view all the answers

What is the endomembrane system?

<p>A network of membranes that include the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles.</p> Signup and view all the answers

Cells are generally classified into two main types: ______ and eukaryotes.

<p>prokaryotes</p> Signup and view all the answers

How many cells approximately comprise an adult human body?

<p>About 37 trillion cells.</p> Signup and view all the answers

What phase of the cell cycle involves DNA synthesis?

<p>S phase (B)</p> Signup and view all the answers

Somatic cells are haploid and germ cells are diploid.

<p>False (B)</p> Signup and view all the answers

What are the main components of a duplicated chromosome?

<p>sister chromatids and a centromere</p> Signup and view all the answers

During metaphase, chromosomes are aligned at the __________.

<p>metaphase plate</p> Signup and view all the answers

Match the following terms with their correct definitions:

<p>Centrosome = Microtubule organizing center Cleavage furrow = Indicates where the cell will divide Cohesin = Protein that holds sister chromatids together Binary fission = Cell division in bacteria</p> Signup and view all the answers

Which of the following is NOT a major checkpoint in cell division?

<p>S checkpoint (B)</p> Signup and view all the answers

Metastasis refers to the spread of cancer cells to other parts of the body.

<p>True (A)</p> Signup and view all the answers

What is the diploid number of chromosomes in a human somatic cell?

<p>46</p> Signup and view all the answers

Crossing over occurs during __________ of meiosis.

<p>prophase I</p> Signup and view all the answers

What are the products of oogenesis?

<p>One functional ovum and three polar bodies (B)</p> Signup and view all the answers

Which of the following processes requires ATP?

<p>Active transport (C)</p> Signup and view all the answers

Glycoproteins and glycolipids both consist of carbohydrates attached to proteins or lipids, respectively.

<p>True (A)</p> Signup and view all the answers

What is the primary role of cholesterol in the plasma membrane?

<p>To maintain membrane fluidity.</p> Signup and view all the answers

The ________ hypothesis proposes that eukaryotic cells originated from a symbiotic relationship between prokaryotic organisms.

<p>endosymbiont</p> Signup and view all the answers

Match the following types of membrane proteins to their functions:

<p>Integral membrane proteins = Transport molecules across the membrane Peripheral membrane proteins = Attach to other proteins but do not span the membrane Transmembrane proteins = Span the entire membrane and can facilitate transport Glycoproteins = Involved in cell recognition and signaling</p> Signup and view all the answers

What feature of phospholipids makes them amphipathic molecules?

<p>They have a hydrophobic tail and a hydrophilic head. (D)</p> Signup and view all the answers

Endocytosis involves the expulsion of materials from the cell.

<p>False (B)</p> Signup and view all the answers

Name one factor that controls plasma membrane fluidity.

<p>Temperature or the proportion of saturated vs unsaturated fatty acids.</p> Signup and view all the answers

The ________ is the site within the cell where ribosomes are synthesized.

<p>nucleolus</p> Signup and view all the answers

What is the primary function of cohesin protein during cell division?

<p>To hold sister chromatids together (B)</p> Signup and view all the answers

Somatic cells contain half the number of chromosomes compared to germ cells.

<p>False (B)</p> Signup and view all the answers

What happens during the S (synthesis) phase of interphase?

<p>DNA replication occurs.</p> Signup and view all the answers

In humans, the haploid number of chromosomes is ______.

<p>23</p> Signup and view all the answers

Match the following phases of the cell cycle with their descriptions:

<p>G1 = Cell growth and normal functions S = DNA synthesis and replication G2 = Preparation for mitosis M = Mitosis and cytokinesis</p> Signup and view all the answers

At which checkpoint is DNA damage typically assessed?

<p>G1 checkpoint (D)</p> Signup and view all the answers

Tumors can be classified as either benign or malignant based solely on their size.

<p>False (B)</p> Signup and view all the answers

What is the role of the mitotic spindle during mitosis?

<p>To separate sister chromatids.</p> Signup and view all the answers

In meiosis, crossing over occurs during ______.

<p>prophase I</p> Signup and view all the answers

What is the primary distinguishing feature of malignant tumors compared to benign tumors?

<p>Malignant tumors invade surrounding tissues. (C)</p> Signup and view all the answers

What phase of the cell cycle is characterized by the duplication of chromosomes?

<p>S phase (C)</p> Signup and view all the answers

Somatic cells are haploid while gametes are diploid.

<p>False (B)</p> Signup and view all the answers

What is the role of cohesin protein during cell division?

<p>Cohesin holds sister chromatids together until they are ready to separate during mitosis.</p> Signup and view all the answers

The _____ is the region where sister chromatids are held together.

<p>centromere</p> Signup and view all the answers

Match the following cell cycle phases with their descriptions:

<p>G1 phase = Cell growth and preparation for DNA replication S phase = DNA synthesis and chromosome duplication G2 phase = Preparation for mitosis M phase = Mitosis and cytokinesis</p> Signup and view all the answers

During which phase do chromosomes line up at the metaphase plate?

<p>Metaphase (B)</p> Signup and view all the answers

Malignant tumors do not invade neighboring tissues.

<p>False (B)</p> Signup and view all the answers

What happens during the G1 phase of the cell cycle?

<p>Cells grow and prepare for DNA replication.</p> Signup and view all the answers

The process of _____ produces gametes in humans.

<p>meiosis</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Diploid = Cells with two complete sets of chromosomes Haploid = Cells with one complete set of chromosomes Autosomes = Non-sex chromosomes Sex chromosomes = Chromosomes that determine the sex of an organism</p> Signup and view all the answers

What distinguishes glycolipids from glycoproteins?

<p>Glycolipids have lipid tails, while glycoproteins have amino acid chains. (C)</p> Signup and view all the answers

Passive transport requires ATP to move substances across the cell membrane.

<p>False (B)</p> Signup and view all the answers

What is the function of active transport in cellular processes?

<p>To move substances against their concentration gradient using ATP.</p> Signup and view all the answers

The fluid mosaic model describes the structure of the __________ membrane.

<p>plasma</p> Signup and view all the answers

Match the following membrane transport processes with their descriptions:

<p>Endocytosis = Intake of materials into the cell Exocytosis = Expulsion of materials from the cell Active Transport = Movement against a concentration gradient using ATP Passive Transport = Movement along a concentration gradient without ATP</p> Signup and view all the answers

Which of the following factors can influence membrane fluidity?

<p>All of the above (D)</p> Signup and view all the answers

The Endosymbiont Hypothesis suggests that eukaryotic cells evolved from symbiotic relationships with prokaryotic cells.

<p>True (A)</p> Signup and view all the answers

Where in the cell are membranes primarily synthesized?

<p>In the endoplasmic reticulum.</p> Signup and view all the answers

Cholesterol helps maintain __________ of the plasma membrane at varying temperatures.

<p>fluidity</p> Signup and view all the answers

Which organelle is responsible for modifying, sorting, and packaging proteins?

<p>Golgi apparatus (D)</p> Signup and view all the answers

Flashcards

Cell Cycle

The series of events that take place in a cell leading to its duplication (division) and the production of two daughter cells.

Mitosis

A type of cell division that produces two daughter cells genetically identical to the parent cell. It involves the division of the nucleus and cytoplasm.

Interphase

The longest stage of the cell cycle where the cell grows, replicates its DNA, and prepares for cell division. It consists of the G1, S, and G2 phases.

Chromosomes

Thread-like structures made of DNA and proteins that carry genetic information. During cell division, they condense and become visible.

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Sister Chromatids

Two identical copies of a chromosome that are joined together at the centromere. They result from DNA replication during the S phase.

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Centromere

A specialized region on a chromosome that holds sister chromatids together. It serves as an attachment point for microtubules during cell division.

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Mitosis Phases

The four distinct stages of mitosis: Prophase, Metaphase, Anaphase, and Telophase. Each stage involves specific events related to chromosome movement and cell division.

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Cytokinesis

The division of the cytoplasm during cell division, following nuclear division (mitosis). It results in the formation of two daughter cells.

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Haploid vs. Diploid

Haploid cells have one set of chromosomes (n), whereas diploid cells have two sets (2n). Gametes are haploid, while somatic cells are diploid.

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Meiosis

A type of cell division that produces gametes (sex cells) with half the number of chromosomes as the parent cell. It involves two rounds of division (meiosis I and meiosis II).

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Fluid Mosaic Model

Describes the structure of the plasma membrane as a flexible and constantly moving layer of phospholipids with embedded proteins. It allows for fluidity and selective permeability.

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Glycoprotein vs. Glycolipid

Glycoproteins are proteins with attached carbohydrate chains, while glycolipids are lipids with attached carbohydrate chains. Both are important for cell recognition and signaling.

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Integral Membrane Protein

A protein that is permanently embedded within the phospholipid bilayer of the cell membrane. These proteins play a crucial role in transport, communication, and other functions.

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Peripheral Membrane Protein

A protein that is loosely bound to the surface of the cell membrane. They can be easily removed without disrupting the membrane structure.

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Active Transport

The movement of molecules across a cell membrane against their concentration gradient, requiring energy (ATP). This allows cells to concentrate specific molecules inside or outside.

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Passive Transport

The movement of molecules across a cell membrane down their concentration gradient, without requiring energy (ATP). This is driven by the natural tendency of molecules to spread out.

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Endocytosis

A process where the cell membrane engulfs material from the outside, forming a vesicle to bring it inside. This allows cells to take in large molecules or even entire cells.

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Exocytosis

A process where a vesicle inside the cell fuses with the cell membrane and releases its contents outside. This allows cells to secrete substances like hormones or waste products.

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Cholesterol's Effect on Membrane Fluidity

Cholesterol acts as a fluidity buffer. At high temperatures, cholesterol reduces fluidity, providing stability. At low temperatures, cholesterol increases fluidity by preventing phospholipids from packing too tightly.

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Selective Permeability

The plasma membrane only allows certain molecules to pass through, while blocking others. This is essential for maintaining cell integrity and controlling the cell's environment.

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Phospholipid Bilayer

The structural foundation of cell membranes, composed of two layers of phospholipid molecules. The hydrophilic heads face outward, while the hydrophobic tails face inward.

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Somatic Cells

Body cells that make up an organism; they are diploid (2n), meaning they have two sets of chromosomes.

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Gametes

Sex cells (sperm and egg) responsible for reproduction; they are haploid (n), meaning they have one set of chromosomes.

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Chromatin

The loose, uncoiled form of DNA found in the nucleus during interphase; it allows for easy access to genetic information for transcription.

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M (Mitotic) Phase

The shortest stage of the cell cycle where the cell undergoes nuclear division (mitosis) and cytoplasmic division (cytokinesis).

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Cholesterol's Effect on Fluidity

Cholesterol acts like a membrane fluidity buffer. At high temps, it reduces fluidity, providing stability. At low temps, it prevents phospholipids from packing too tightly, increasing fluidity.

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Phospholipids (Amphipathic)

Phospholipids have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. This dual nature makes them amphipathic, allowing them to form bilayers.

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What are the major phases of the cell cycle?

The cell cycle is a series of events that take place in a cell leading to its duplication and the production of two daughter cells. It is divided into two main phases: Interphase and M (Mitotic) phase. Interphase is further divided into three subphases: G1, S, and G2 phases while M phase includes Mitosis and Cytokinesis.

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What is the difference between somatic cells and gametes?

Somatic cells are body cells that make up an organism; they are diploid (2n), meaning they have two sets of chromosomes. Gametes are sex cells (sperm and egg) responsible for reproduction; they are haploid (n), meaning they have one set of chromosomes.

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What is the role of cohesin protein?

Cohesin is a protein that holds sister chromatids together during mitosis. It ensures that the replicated chromosomes are properly separated during anaphase.

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What are the differences between centrosome, centriole, and centromere?

A centrosome is a microtubule organizing center (MTOC) that contains two centrioles, which are small, cylindrical structures. The centromere is a specialized region on a chromosome that holds sister chromatids together.

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What happens during the S phase of interphase?

The S phase of interphase is the stage when DNA replication occurs. This is crucial for ensuring that each daughter cell receives a complete copy of the genome. During S phase, the amount of DNA in the cell doubles.

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Why are the numbers 0, 23, 46, and 92 important for mitosis in human somatic cells?

Human somatic cells are diploid (2n) with 46 chromosomes (23 pairs). During S phase, the DNA replicates, resulting in 92 chromatids. During mitosis, the 92 chromatids are separated, resulting in two daughter cells with 46 chromosomes (23 pairs) each.

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What is the G0 phase?

The G0 phase is a state where cells are not actively dividing but are still metabolically active. Cells in the G0 phase can exit the cell cycle and remain quiescent for extended periods.

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Explain the concept of checkpoints in the cell cycle.

Checkpoints are control mechanisms that act as surveillance points to ensure that the cell cycle progresses correctly. There are three major checkpoints: G1, G2, and M. These checkpoints monitor the integrity of DNA, the completion of DNA replication, and the proper attachment of chromosomes to the spindle, respectively.

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What is the difference between a benign and malignant tumor?

A benign tumor is a non-cancerous growth that is contained and does not spread to other parts of the body. A malignant tumor is cancerous and can invade surrounding tissues and spread to other parts of the body.

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What is metastasis?

Metastasis is the spread of cancer cells from the primary tumor to other parts of the body. The process involves cancer cells breaking away from the primary tumor, entering the bloodstream or lymphatic system, and forming new tumors in other tissues.

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Study Notes

Cell Membranes

  • Fluid Mosaic Model: The plasma membrane is a fluid structure with diverse components embedded in a phospholipid bilayer.

  • Phospholipids (Amphipathic): Phospholipids have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails, arranging themselves in a bilayer. These amphipathic properties result from the polar head and nonpolar tails.

  • Integral Membrane Proteins: Proteins embedded within the phospholipid bilayer; some span the entire membrane (transmembrane proteins). Transmembrane proteins are a type of integral membrane protein.

  • Peripheral Membrane Proteins: Proteins loosely bound to the membrane surface; often involved in signaling or structural support.

  • Glycoproteins & Glycolipids: Proteins or lipids with carbohydrate chains attached, important for cell recognition and communication. Glycoproteins have carbohydrates attached to proteins, while glycolipids have carbohydrates attached to lipids.

  • Cholesterol: Regulates membrane fluidity; affects fluidity at high and low temperatures; Cholesterol influences membrane fluidity by altering the packing of phospholipids.

  • Selective Permeability: The plasma membrane controls what enters and exits the cell based on size, charge, and other factors.

  • Active Transport: Requires energy (ATP) to move molecules against their concentration gradient.

  • Passive Transport: Does not require energy, molecules move with their concentration gradient.

  • Endocytosis & Exocytosis: Processes for transporting large molecules or particles into or out of the cell.

  • Frye & Edidin Experiment (1970): Demonstrated the fluid nature of the plasma membrane via cell fusion experiments.

  • Saturated vs Unsaturated Fatty Acids: Saturated fatty acids lead to a more rigid membrane, while unsaturated ones provide greater fluidity; the degree of saturation of fatty acids affects membrane fluidity.

  • Plasma Membrane Synthesis & Sidedness: Synthesized in the endoplasmic reticulum; "sidedness" refers to the asymmetrical placement of proteins and lipids on each side of the membrane.

  • Major Functions of Plasma Membrane Proteins: Transport, cell recognition, enzymatic activity, signal transduction. These are crucial for various cellular processes.

Cell Organelles & Structures

  • Eukaryotic Cell Organization: Eukaryotic cells have membrane-bound organelles.
    • Cytoplasm & Cytosol: Cytoplasm is internal cellular material.  Cytosol is the jelly-like part of the cytoplasm surrounding organelles.
    • Nucleus: Contains genetic material (DNA); the nucleolus is a region within the nucleus that synthesizes ribosomes.
  • Ribosomes: Synthesize proteins; can be free-floating or attached to the endoplasmic reticulum.
  • Endoplasmic Reticulum: Involved in protein and lipid synthesis.
    • Rough ER: Ribosomes attached to the outer surface; functions in protein synthesis.
    • Smooth ER: Lacks ribosomes; functions in lipid synthesis, detoxification, and calcium storage.
    • Mitochondria: Generate ATP (energy); powerhouse of the cell.
    • Golgi Complex (Apparatus): Processes, packages, and sorts proteins and lipids for secretion or use within the cell.
    • Lysosomes: Contain digestive enzymes for breaking down waste materials.
  • Vacuoles: Fluid-filled sacs that store water, nutrients, and waste. 
  • Cytoskeleton: A network of fibers that supports and shapes the cell.
    • Microtubules, Microfilaments, Intermediate Filaments: Structural proteins maintaining cell shape and enabling movement.
    • Centrioles: Involved in cell division, located in centrosomes.
  • Microscopes: Used to visualize cells.
    • Scanning Electron Microscope (SEM): Produces 3-D images of cell surface features.
    • Transmission Electron Microscope (TEM): Provides high-resolution images of internal cell structures.
  • Prokaryotic Cells: Bacteria and Archaea; do not contain membrane-bound organelles.
    • Nucleoid: Region where DNA is located in a prokaryotic cell.
  • Endomembrane System: A group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins (includes many organelles).

Cell Cycle & Cell Division

  • Cell Cycle: A series of events that leads to cell duplication.
    • Interphase: G1, S, G2 phases involve cell growth, DNA replication, and preparation for cell division.
    • M Phase: Mitosis and cytokinesis, involving nuclear division and cytoplasmic division.
    • G0 Phase: Non-dividing state.
  • Chromosome Structure:
    • Chromosomes: Consist of DNA and protein.
    • Chromatid: One of the two identical DNA copies of a chromosome after replication.
    • Centromere: Region where chromatids are joined together.
  • Mitosis Phases: Prophase, Metaphase, Anaphase, Telophase.
  • Cytokinesis: Division of the cytoplasm to form two separate daughter cells.
  • Cell Cycle Control and Checkpoints: Ensure proper DNA replication and cell division.
  • Tumors: Abnormal cell growth.
    • Benign Tumors: Non-cancerous.
    • Malignant Tumors: Cancerous.
    • Metastasis: Spread of cancer cells.

Meiosis & Gamete Formation

  • Gametes: Sex cells (sperm and egg).
    • Somatic Cells: Non-sex cells.
  • Karyotype: Chromosome arrangement.
    • Homologous Chromosomes (Homologs): Similar chromosomes, one inherited from each parent.
  • Diploid (2n) & Haploid (n): Number of chromosomes.
    • Haploid Number (n): Half the diploid number.
  • Meiosis: Cell division resulting in haploid gametes.
    • Crossing Over/Recombination: Exchange of genetic material between homologous chromosomes.
    • Chiasmata: Points where homologous chromosomes cross over during meiosis.
    • Spermatogenesis & Oogenesis: Different gamete formation processes in males and females.
    • Fertilization: Fusion of sperm and egg.
    • Zygote: Fertilized egg.

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Test your knowledge of cell membrane structures and functions, including membrane proteins, transport mechanisms, and the cell cycle. This quiz covers essential concepts in cell biology, such as the endomembrane system and chromosome duplication.

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