Cellular Organization and Nucleus Structure
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Questions and Answers

What is the primary function of endocytosis in a cell?

  • Releases substances from the cell
  • Promotes cell differentiation
  • Brings substances into the cell (correct)
  • Regulates the cell's membrane potential

    • Which phase of interphase is primarily responsible for DNA replication?

  • G2 phase
  • S phase (correct)
  • M phase
  • G0 phase

    • What is the role of MPF (M-phase promoting factor) in the cell cycle?

  • Promotes cell differentiation
  • Inhibits cell division
  • Stimulates mitosis and the cell cycle transition (correct)
  • Triggers the transition from prophase to metaphase

    • What distinguishes a malignant tumor from a benign tumor?

    <p>Malignant tumors can metastasize to other parts of the body (A)</p> Signup and view all the answers

    What happens to a cell when a gene is 'turned off'?

    <p>The specific protein coded by the gene is not produced (C)</p> Signup and view all the answers

    What is the name of the DNA strand that provides a template for mRNA synthesis?

    <p>Template strand (C)</p> Signup and view all the answers

    Which enzyme is essential for the transcription of DNA into RNA?

    <p>RNA polymerase (D)</p> Signup and view all the answers

    What RNA nucleotide replaces thymine in the synthesized RNA strand?

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

    During translation, which molecule functions to bring amino acids to the ribosome?

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

    What happens when a cell is placed in a hypertonic solution?

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

    What distinguishes facilitated diffusion from simple diffusion?

    <p>It involves carrier proteins (D)</p> Signup and view all the answers

    What is the primary difference between pinocytosis and phagocytosis?

    <p>Phagocytosis involves large particles, pinocytosis involves fluids (C)</p> Signup and view all the answers

    What is the role of a selectively permeable membrane?

    <p>To enable only specific molecules to enter or exit (A)</p> Signup and view all the answers

    What are the two general classes of cells?

    <p>Somatic and Germ (A), Prokaryotic and Eukaryotic (B)</p> Signup and view all the answers

    How are the two layers of phospholipids arranged in the plasma membrane?

    <p>Hydrophilic heads facing outward, hydrophobic tails inward (C)</p> Signup and view all the answers

    What body system utilizes recognition proteins to assess cell conditions?

    <p>Immune system (D)</p> Signup and view all the answers

    What is the main function of cell membrane carrier proteins?

    <p>They facilitate the movement of substances across the membrane. (A)</p> Signup and view all the answers

    Which of the following distinguishes cytosol from cytoplasm?

    <p>Cytoplasm includes organelles and cytosol, cytosol is only the liquid part. (A)</p> Signup and view all the answers

    What is the primary role of a nucleosome?

    <p>To package and regulate the accessibility of DNA (D)</p> Signup and view all the answers

    Which structure would you find in non-dividing cells?

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

    What occurs during the process of transcription?

    <p>RNA is synthesized from a DNA template (B)</p> Signup and view all the answers

    Flashcards

    Endocytosis

    The process of bringing substances into a cell.

    Exocytosis

    The process of releasing substances from a cell.

    MPF (M-phase promoting factor)

    A factor that promotes the transition into mitosis.

    Benign vs Malignant Tumors

    Benign tumors are non-cancerous; malignant tumors are cancerous.

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    Cellular Differentiation

    The process by which cells become specialized in structure and function.

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    Phospholipid bilayer

    A double layer of phospholipids forming the plasma membrane, with hydrophobic and hydrophilic regions.

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    Membrane proteins

    Proteins embedded in the plasma membrane that perform specific functions such as transport and recognition.

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    Cytosol vs Cytoplasm

    Cytosol is the fluid part of the cytoplasm; cytoplasm includes organelles within that fluid.

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    Nucleosome

    A structural unit of DNA wrapped around histone proteins, playing a key role in packaging DNA.

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    Chromatin vs Chromosomes

    Chromatin is DNA in a loosely packed form; chromosomes are tightly coiled during cell division.

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    Template DNA

    The strand of DNA that serves as a template for mRNA synthesis.

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    Triplets

    Sets of three consecutive nitrogen bases in DNA that code for specific amino acids.

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    RNA polymerase

    The enzyme that synthesizes RNA from a DNA template.

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    Codon

    A sequence of three nucleotides in mRNA that codes for one amino acid.

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    Gene

    A segment of DNA that contains the instructions to make proteins and determine traits.

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    Transcription

    The process by which DNA is copied to produce mRNA, which carries genetic information to the ribosomes.

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    Intron vs Exon

    Introns are non-coding regions, while exons are coding regions of genes.

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    Diffusion

    The passive movement of molecules from high to low concentration.

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    Osmosis

    The passive movement of water across a selectively permeable membrane.

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    Facilitated diffusion

    A type of passive transport that uses carrier proteins to move substances.

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    Endocytosis vs Exocytosis

    Endocytosis is the intake of substances, while exocytosis is the expulsion of substances from the cell.

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    Study Notes

    Cellular Level of Organization

    • Cells: Two general types exist.
    • Plasma membrane: Separates the cell from its environment, composed of a phospholipid bilayer.
    • Membrane proteins: Various types have specific functions, including recognition of abnormal cells.
    • Carrier proteins: Facilitate specific molecule movement across the membrane.
    • Cytoplasm: Contains cytosol and organelles.
    • Organelles: Perform specific functions, with examples like microvilli, centrioles, cilia, flagella, ribosomes, rough endoplasmic reticulum (RER), smooth ER, Golgi apparatus, lysosomes, peroxisomes, mitochondria, proteosomes, nucleus, and nucleolus.

    Nucleus

    • Nucleosomes: DNA-protein structures.
    • Chromatin: DNA in non-dividing cells.
    • Chromosomes: DNA in dividing cells.
    • Triplets: Three consecutive nitrogenous bases that code for specific amino acids.
    • Genes: Functional units of heredity, Sequences of nucleotides for protein production.

    DNA and Protein Synthesis

    • Transcription: DNA into RNA.
    • RNA polymerase: Enzyme for transcription.
    • RNA nucleotides: Thymine replaced by Uracil.
    • Codons: Three-base sequence on mRNA.
    • Translation: mRNA into protein.
    • tRNA: Transfer RNA with anticodons.
    • Anticodons: Complementary to codons.
    • mRNA start codon: AUG.

    Cellular Transport

    • Diffusion: Movement of substances from high to low concentration.
    • Osmosis: Water movement across a membrane.
    • Isotonic solution: No net water movement.
    • Hypotonic solution: Water moves into the cell.
    • Hypertonic solution: Water moves out of the cell.
    • Passive transport: Movement without energy (diffusion and osmosis).
    • Active transport: Requires energy (like sodium-potassium exchange pump).
    • Facilitated diffusion: Substances move down their concentrations gradient through protein channels.
    • Symport (cotransport): Substances move in the same direction.
    • Antiport (countertransport): Substances move in opposite directions.
    • Endocytosis: Cell takes in substances (pinocytosis, phagocytosis).
    • Exocytosis: Cell releases substances (secretory vesicles).

    Cell Cycle and Cell Division

    • Cell cycle phases: Interphase, mitosis, cytokinesis.
    • Interphase: Cell growth and DNA replication; contains S phase.
    • DNA replication enzyme: Enzyme binds the nucelotides together covalently.
    • Cytokinesis: Cytoplasmic division.
    • M-phase promoting factor (MPF): Regulates cell cycle progression.

    Cellular Differentiation

    • Cellular specialization: Cellular differentiation due to gene activation/repression.

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    Related Documents

    Chapter 3: The Cellular Level of Organization Study Guide Spring 2025 PDF

    Description

    Explore the fundamentals of cellular organization, including the types of cells, components of the plasma membrane, and the functions of organelles. Delve into the structure and function of the nucleus, including nucleosomes, chromatin, and genes. Test your understanding of these crucial biological concepts.

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