Cell Structure and Function Quiz
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Questions and Answers

What is the primary function of microfilaments in a cell?

  • Regulate exchange of materials
  • Anchor organelles like the nucleus
  • Segregate chromosomes during cell division
  • Aid in cell movement and support cell structure (correct)

    • All cell types in the human body possess membranous organelles.

    False

    What term describes the structure of the plasma membrane?

    Fluid mosaic

    The __________ is the basic unit of life and the human body.

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

    Match the structures to their functions:

    <p>Mitochondrion = Energy production Ribosome = Protein synthesis Microtubules = Cell movement and chromosome segregation Cilia and flagella = Motility of cells</p> Signup and view all the answers

    What is the main function of mitochondria?

    <p>Energy processing</p> Signup and view all the answers

    Mitochondria contain their own DNA and replicate independently of the nuclear genome.

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

    What is the term for the process which produces ATP in the presence of oxygen?

    <p>Aerobic cellular respiration</p> Signup and view all the answers

    The inner mitochondrial membrane is extensively folded to form cristae__.

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

    Which phase of the cell cycle involves DNA replication?

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

    Meiosis results in two identical daughter cells.

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

    What type of cell division occurs in somatic cells?

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

    During prophase, chromatin condenses into chromosomes___.

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

    What is a key characteristic of telomeres?

    <p>They shorten with each cell division.</p> Signup and view all the answers

    Cytokinesis follows mitosis in cell division.

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

    Match the following phases of mitosis with their descriptions:

    <p>Prophase = Condensation of chromatin into chromosomes Metaphase = Alignment of chromosomes at the equatorial plate Anaphase = Separation and pulling of chromosomes to opposite poles Telophase = Partitioning of the cell into two daughter cells</p> Signup and view all the answers

    What is the role of DNA polymerase during DNA replication?

    <p>To add nucleotides to the growing daughter strand using a template</p> Signup and view all the answers

    The two halves of a replicated chromosome are called sister chromatids.

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

    Which term describes the sequence of events in somatic cell division?

    <p>Cell cycle</p> Signup and view all the answers

    Aerobic cellular respiration can occur without oxygen.

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

    How does water move through aquaporins?

    <p>Facilitated diffusion</p> Signup and view all the answers

    Isotonic solutions cause no net movement of water across the cell membrane.

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

    What term describes solutions with a relatively lower solute concentration than the cell?

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

    In a __________ solution, a red blood cell would crenate.

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

    Match the following types of solutions with their effects on cells:

    <p>Hypotonic = Causes cell to swell Hypertonic = Causes cell to shrink Isotonic = No net movement Osmolarity = Total concentration of a solution</p> Signup and view all the answers

    Why are intravenous (IV) fluids usually isotonic to blood?

    <p>To maintain osmotic balance</p> Signup and view all the answers

    If you are severely dehydrated, which type of solution would be best to drink?

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

    Aquaporins are channel proteins that facilitate the movement of solutes across the cell membrane.

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

    What structure is responsible for organizing microtubules in animal cells?

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

    Cilia are long structures that propel cells while flagella are short and assist in movement.

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

    What are the small holes in the nuclear envelope called that allow materials to exit?

    <p>nuclear pores</p> Signup and view all the answers

    The dense region in the nucleus responsible for making ribosomal subunits is called the __________.

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

    Match the organelles with their primary functions:

    <p>Centrioles = Organize microtubules Golgi complex = Modify and sort proteins Smooth ER = Synthesize lipids Ribosomes = Translate mRNA into proteins</p> Signup and view all the answers

    What is the function of ribosomes?

    <p>Translate mRNA into proteins</p> Signup and view all the answers

    The rough endoplasmic reticulum is involved in the synthesis of proteins destined for the cytoplasm.

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

    Where do ribosomes assemble their subunits?

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

    The __________ is all of the DNA in an organism.

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

    Which organelle is involved in detoxifying alcohols and metabolizing fatty acids?

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

    Tay-Sachs disease results from dysfunctional peroxisomes.

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

    What do tRNA molecules carry that matches the mRNA sequence?

    <p>amino acids</p> Signup and view all the answers

    The ________ modifies and packages proteins for export from the cell.

    <p>Golgi complex</p> Signup and view all the answers

    What is the pH of the interior of lysosomes?

    <p>Acidic (pH 5)</p> Signup and view all the answers

    Match the diseases to their associated organelle dysfunction:

    <p>Tay-Sachs disease = Lysosomes Parkinson's disease = Proteasomes Alzheimer's disease = Proteasomes</p> Signup and view all the answers

    What is the primary function of the sodium-potassium (Na+-K+) pump in animal cells?

    <p>To create a higher concentration of Na+ outside and K+ inside the cell</p> Signup and view all the answers

    Secondary active transport requires direct use of ATP to move solutes across the membrane.

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

    What is the process called when a cell engulfs large particles or cells?

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

    Water moves through a semi-permeable membrane during _________.

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

    Match the following transport processes with their descriptions:

    <p>Endocytosis = Movement of substances into the cell via vesicles Exocytosis = Movement of substances out of the cell via vesicles Transcytosis = Movement through a cell by endocytosis followed by exocytosis Phagocytosis = Engulfing and digesting large particles or invaders</p> Signup and view all the answers

    Which type of active transporter moves substances against their concentration gradients using energy from ATP hydrolysis?

    <p>Primary active transporters</p> Signup and view all the answers

    Cyanide inhibits active transport by blocking vesicular transport only.

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

    What is the chemical formula of water?

    <p>H2O</p> Signup and view all the answers

    The process of moving solutes when one solute flows down its concentration gradient and helps move another solute up its gradient is called ________.

    <p>secondary active transport</p> Signup and view all the answers

    Match the following membrane transport processes with their specific characteristics:

    <p>Symporters = Transport two solutes in the same direction Antiporters = Transport two solutes in opposite directions Pinocytosis = Cell drinking of dissolved solutes Receptor-mediated endocytosis = Import of specific molecules into the cell</p> Signup and view all the answers

    Which component makes up the majority of biological membranes?

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

    Membrane fluidity is essential for biological function.

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

    What is the role of cholesterol in biological membranes?

    <p>Cholesterol serves as a fluidity buffer in membranes.</p> Signup and view all the answers

    Membrane is permeable to __________ molecules like O2 and CO2.

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

    Match the membrane proteins with their functions:

    <p>Integral proteins = Span the entire membrane Peripheral proteins = Bound by electrostatic interactions Receptors = Bind specific molecules and send signals Enzymes = Catalyze chemical reactions</p> Signup and view all the answers

    Which statement best describes the fluid mosaic model?

    <p>It consists of phospholipids, proteins, carbohydrates, and cholesterol.</p> Signup and view all the answers

    Saturated fatty acids lead to a more fluid membrane than unsaturated fatty acids.

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

    What is simple diffusion?

    <p>The tendency of solutes to move from high to low concentration without the need for energy.</p> Signup and view all the answers

    The __________ of the lipid bilayer allows for the lateral movement of proteins and lipids.

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

    What happens to membrane fluidity at higher temperatures?

    <p>It increases.</p> Signup and view all the answers

    Facilitated diffusion requires energy input to transport solutes across membranes.

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

    What is meant by 'selective permeability' of membranes?

    <p>It refers to the property of membranes to allow only certain substances to enter or exit the cell.</p> Signup and view all the answers

    The __________ gradient is important in the process of facilitated diffusion.

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

    What type of proteins are likely to serve as cell identity markers?

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

    Study Notes

    Cell Structure and Function

    • Cells are the basic unit of life and are highly diverse with ~200 different cell types in the human body.
    • Each cell has a unique structure that reflects its function.
    • Organelles are small subunits within cells that perform specific functions.
    • Membranous organelles are surrounded by a membrane, while non-membranous organelles are not.
    • Only eukaryotic cells possess membranous organelles.

    Plasma Membrane

    • The plasma membrane is a flexible barrier that surrounds the cell, separating the internal and external environments.
    • It regulates the exchange of materials between the cell and its surroundings.
    • The plasma membrane is also involved in cell communication.

    Cytoplasm

    • The cytoplasm is the region between the plasma membrane and the nucleus.
    • It contains a jelly-like fluid called cytosol and various organelles.
    • The cytosol provides an aqueous environment for cellular chemical reactions.

    Cytoskeleton

    • The cytoskeleton is a network of protein filaments that shapes, stabilizes, and moves cells and their internal structures.

    Microfilaments

    • Made of actin and myosin.
    • Aid in cell movement, support cell structure, and form microvilli.

    Intermediate Filaments

    • Made of various protein subunits.
    • Provide tensile strength and anchor organelles like the nucleus.

    Microtubules

    • Made of tubulin.
    • Dynamic structures that rapidly assemble and disassemble.
    • Segregate chromosomes during cell division.
    • Form cilia and flagella, aiding in cellular movement.

    Centrosome

    • The microtubule-organizing center in animal cells.
    • Contains short microtubules called centrioles.
    • Plays a crucial role in the formation of the mitotic spindle during mitosis.

    Cilia and Flagella

    • Made of microtubules.
    • Cilia are short bundles of microtubules that move like oars, found in the respiratory tract and oviduct.
    • Flagella are long bundles of microtubules that whip through fluids, found in human sperm.

    Nucleus

    • The nucleus is a membranous organelle that contains DNA.
    • It is surrounded by a nuclear envelope with nuclear pores which allow the passage of RNA and ribosomal subunits.
    • The nucleolus is a dense region where ribosomal subunits are made.

    DNA Packaging

    • DNA must be tightly packaged for efficient storage and movement during cell division.
    • Uncoiled DNA is called chromatin, where genes are accessible for transcription.
    • Tightly wound DNA forms chromosomes, where genes are inactive.
    • The genome comprises all the DNA in an organism.

    Ribosomes

    • Ribosomes are composed of ribosomal RNA (rRNA) and protein.
    • Assembles in the cytoplasm as a large and small subunit.
    • Some ribosomes attach to the rough endoplasmic reticulum (rER).
    • Ribosomes translate mRNA into proteins.

    Central Dogma of Biology

    • DNA sequences called genes encode information to make proteins.
    • Genes are transcribed into mRNA.
    • mRNA is translated by ribosomes into proteins.

    Endoplasmic Reticulum (ER)

    • A network of membranes involved in protein translation, modification, and lipid synthesis.

    Rough ER (rER)

    • Dotted with ribosomes.
    • Synthesizes proteins destined for organelles.
    • Exports membranes to other organelles.

    Smooth ER (sER)

    • Synthesizes lipids, including fatty acids and steroids.
    • Inactivates drugs in liver cells.
    • Participates in carbohydrate metabolism.
    • Stores calcium ions.

    Golgi Complex

    • Modifies, sorts, finishes, and sends proteins to their destinations.
    • Two distinct faces:
      • Entry face receives proteins from the rER.
      • Exit face exports cellular proteins.
    • Proteins are modified within the Golgi and packaged into vesicles for export.

    Lysosomes

    • Spherical, membrane-bound sacs containing digestive enzymes.
    • Maintain an acidic pH (pH 5).
    • Break down and recycle cellular molecules.
    • Defects in lysosomes can lead to lysosomal storage disorders, such as Tay-Sachs disease.

    Peroxisomes

    • Spherical, membrane-bound sacs with a crystalline core.
    • Contain oxidases that metabolize fatty acids and detoxify alcohol.
    • Contain catalase, which breaks down hydrogen peroxide.

    Proteasomes

    • Large cellular machines that break large polypeptides into smaller peptides.
    • Other peptidases further break the peptides into amino acids.
    • Dysfunction of proteasomes can contribute to diseases like Parkinson's or Alzheimer's.

    Mitochondria

    • Bounded by two membranes: outer and inner mitochondrial membranes.
    • The space between the membranes is called the intermembrane space.
    • The inner membrane is folded into cristae.
    • The inner membrane encloses the mitochondrial matrix.
    • Aerobic cellular respiration occurs primarily in the mitochondria, converting glucose into ATP.
    • Mitochondria are maternally inherited and contain their own DNA.
    • Mitochondrial dysfunction can trigger cell death (apoptosis).

    Somatic Cell Division

    • Somatic cells divide by mitosis and cytokinesis.
    • The cell cycle consists of interphase and M phase.

    Interphase

    • A period of cell growth with three stages:
      • G1: Cell growth and preparation for DNA replication.
      • S phase: DNA replication.
      • G2: Replication of cytoplasmic components.

    M phase (Mitosis)

    • Division of nuclear components.
    • Four stages:
      • Prophase: Dissolution of the nuclear envelope and condensation of chromatin into chromosomes.
      • Metaphase: Alignment of chromosomes at the equatorial plate and attachment of the mitotic spindle.
      • Anaphase: Separation of chromosomes to opposite poles of the cell by the mitotic spindle.
      • Telophase: Partitioning of the two components into two forming daughter cells.

    Cytokinesis

    • Division of the rest of the cellular components.

    Chromosome Anatomy

    • An unreplicated chromosome is a single structure.
    • A replicated chromosome is composed of two sister chromatids joined at the centromere.
    • The kinetochore is a protein complex around the centromere that serves as the attachment site for the mitotic spindle.

    Telomeres

    • DNA sequences at the ends of chromosomes that protect against degradation.
    • Telomere length decreases with age.
    • Cancer cells have overactive telomerase, which elongates telomeres, allowing for rapid cell division.

    Reproductive Cell Division (Meiosis)

    • Meiosis is the division of reproductive cells into gametes, which are haploid cells.
    • Meiosis consists of two rounds of division.

    Meiosis I

    • The cell divides replicated chromosomes into daughter cells.
    • Crossing over occurs, exchanging genetic information between homologous chromosomes.
    • Results in two daughter cells with haploid sets of chromosomes.

    Meiosis II

    • Separates sister chromatids into two separate gametes.
    • Results in four non-identical daughter cells (gametes) with haploid chromosomes.

    Membrane Structure and Function

    • The plasma membrane is a fluid mosaic, with lipids and proteins floating freely in a bilayer.
    • The lipid bilayer is composed of phospholipids, cholesterol, and glycolipids.

    Membrane Fluidity

    • Essential for membrane function.
    • Regulated by:
      • Saturation of fatty acid tails: Saturated fatty acids lead to less fluidity.
      • Cholesterol: Influences membrane fluidity by increasing space between lipids and restricting movement.
      • Temperature: Higher temperatures increase fluidity.

    Selective Permeability

    • Membranes are selectively permeable, allowing only certain substances to cross.
    • Nonpolar molecules can readily diffuse across the lipid bilayer.
    • Polar molecules require transport proteins to cross.

    Membrane Proteins

    • Integral membrane proteins are anchored to the hydrophobic core of the lipid bilayer.
    • Peripheral membrane proteins are bound to the membrane by electrostatic interactions.
    • Glycoproteins are membrane proteins with attached saccharides.
    • Membrane proteins serve various functions:
      • Receptors: Bind specific molecules and trigger intracellular signaling.
      • Enzymes: Catalyze chemical reactions.
      • Linker proteins: Connect cells and facilitate movement.
      • Cell identity markers: Help distinguish cell types.

    Membrane Transport

    • Solutes can cross membranes through various mechanisms.

    Simple Diffusion

    • Passive transport of nonpolar solutes down their concentration gradient.
    • No metabolic energy required.

    Facilitated Diffusion

    • Passive transport of charged or polar solutes down their concentration gradient with the help of transport proteins (ion channels or carrier proteins).
    • No metabolic energy required.

    Active Transport

    • Movement of solutes against their concentration gradient.
    • Requires metabolic energy (usually ATP).

    Electrochemical Gradient

    • The combined influence of the concentration gradient and electrical gradient of a charged substance.
    • Substances move from an area of high concentration to low concentration and from an area of one charge to an area of opposite charge.

    Active Transport

    • Moves solutes against their concentration gradients across membranes.
    • Requires energy, often from ATP hydrolysis.
    • Sodium-potassium (Na+-K+) pump:
      • Keeps Na+ concentration higher outside the cell.
      • Keeps K+ concentration higher inside the cell.
      • A carrier protein that changes shape using energy from ATP hydrolysis.
    • Primary active transporters:
      • Move solutes up their concentration gradients using ATP hydrolysis.
    • Secondary active transporters:
      • Use electrochemical gradients set up by primary active transporters for energy.
      • Move two solutes simultaneously.
      • One solute moves down its concentration gradient, releasing free energy that moves the other solute up its gradient.
      • Symporters: Both solutes move in the same direction.
      • Antiporters: Solutes move in opposite directions.
    • Cyanide inhibits ATP production in the mitochondrion, impacting all active transport.

    Vesicular Transport

    • An active transport process that uses membrane sacs called vesicles to move products between organelles.
    • Endocytosis: Movement into cells via vesicles.
    • Exocytosis: Movement of substances out of cells.
    • Transcytosis: Movement of substances through cells by endocytosis followed by exocytosis.
    • Receptor-mediated endocytosis: Imports specific molecules into cells.
    • Phagocytosis: "Eating" of molecules or invaders by phagocytic cells.
      • Substances/cells are engulfed and internalized into a vesicle.
      • Vesicle fuses with lysosome, and contents are digested.
      • Important for immune cells (e.g., macrophages, neutrophils).
    • Pinocytosis: Cell "drinking" of dissolved solutes.
      • Also called bulk-phase endocytosis.
      • Large volumes of molecules imported into a vesicle, then fuse with lysosome.
      • Important for immune cells that surveil the body for invaders.

    Osmosis

    • The movement of water from low solute concentration to high solute concentration across a semi-permeable membrane.
    • Water can move across the lipid bilayer, but it is very inefficient.
    • Aquaporins: Channel proteins that facilitate the efficient diffusion of water across biological membranes.
    • Cells behave differently in different solutions based on tonicity, which is determined by the osmolarity of the solution.

    Tonicity

    • Hypertonic solutions: Have a higher solute concentration than inside the cell.
      • Water moves out of the cell.
      • Cell shrinks.
    • Hypotonic solutions: Have a lower solute concentration than inside the cell.
      • Water moves into the cell.
      • Cell swells.
    • Isotonic solutions: Have the same solute concentration as inside the cell.
      • No net water movement.

    Cell Function

    • Cells are organized by organelles.
    • Membranous organelles compartmentalize cell function within membranes/membrane folds.
    • Nonmembranous organelles perform specific functions in the cytoplasm.
    • Somatic cells divide by mitosis, producing two identical daughter cells.
    • Reproductive cells divide by meiosis, producing four nonidentical gametes.

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    Description

    Test your knowledge on the fundamental concepts of cell structure and function. This quiz covers key topics such as organelles, the plasma membrane, cytoplasm, and the cytoskeleton. Prepare to explore the diverse and intricate world of cells.

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