Cell Biology Overview - Lecture 2
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Questions and Answers

What is the primary function of microtubules within a cell?

  • Provide shape and movement
  • Act as tracks for intracellular transport (correct)
  • Give mechanical support
  • Facilitate transcription

    • Which process occurs in the cytosol?

  • Translation (correct)
  • DNA synthesis
  • Transcription
  • DNA replication

    • What is the role of telomerase in DNA replication?

  • Extends the 3’ end of the lagging strand (correct)
  • Catalyzes the formation of hydrogen bonds
  • Synthetizes RNA primers
  • Replaces RNA primers with DNA

    • What type of bonds connect adenine and thymine in DNA?

    <p>Hydrogen bonds (2)</p> Signup and view all the answers

    What is the correct order of the flow of genetic information in the central dogma of molecular biology?

    <p>DNA → RNA → Protein</p> Signup and view all the answers

    What problem arises during the replication of the lagging strand?

    <p>Loss of DNA with each division</p> Signup and view all the answers

    What component of DNA provides its structural integrity?

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

    How are the two DNA strands oriented relative to one another?

    <p>Antiparallel to each other</p> Signup and view all the answers

    What role do cohesins play during cell division?

    <p>They hold sister chromatids together.</p> Signup and view all the answers

    Which stage of mitosis is characterized by the alignment of chromosomes at the metaphase plate?

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

    What is the primary function of the kinetochores during cell division?

    <p>They attach microtubules to chromosomes.</p> Signup and view all the answers

    What triggers the separation of chromatids during anaphase?

    <p>APC/C activation</p> Signup and view all the answers

    In which phase do the centrosomes migrate to opposite sides of the nucleus?

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

    How does cytokinesis differ between animal and plant cells?

    <p>Animal cells split through a contractile ring; plant cells form a new cell wall.</p> Signup and view all the answers

    Which of the following microtubules provides structural integrity to the mitotic spindle?

    <p>Interpolar microtubules</p> Signup and view all the answers

    What happens during telophase in mitosis?

    <p>Chromosomes decondense and nuclear envelopes reform.</p> Signup and view all the answers

    What is the primary function of a promoter in gene expression?

    <p>To provide a binding site for RNA polymerase</p> Signup and view all the answers

    Which component is part of eukaryotic gene regulation but not prokaryotic?

    <p>RNA Polymerase II</p> Signup and view all the answers

    In the context of the Lac Operon, what role does glucose play?

    <p>It represses transcription of the operon</p> Signup and view all the answers

    What is the role of enhancers in eukaryotic gene regulation?

    <p>They regulate gene expression from a distance</p> Signup and view all the answers

    How do repressors function in prokaryotic gene regulation?

    <p>They block RNA polymerase from binding to promoters</p> Signup and view all the answers

    What is the significance of enhancers in the evolution of vertebrate body plans?

    <p>They allow for the tweaking of gene expression patterns</p> Signup and view all the answers

    Which of the following accurately describes the Mediator complex in eukaryotic gene expression?

    <p>It is essential for transcription initiation</p> Signup and view all the answers

    What happens to transcription when lactose is present in the environment of a bacterium using the Lac Operon?

    <p>Lactose binds to the Lac repressor and releases it</p> Signup and view all the answers

    What is the primary significance of Hox genes across bilaterally symmetric animals?

    <p>They demonstrate shared molecular principles in animal development.</p> Signup and view all the answers

    What role do maternal inputs play in zygotic gene expression?

    <p>They establish gradients that direct zygotic gene expression.</p> Signup and view all the answers

    Which of the following represents the role of VegT in embryonic development?

    <p>It activates Nodal to induce mesoderm formation.</p> Signup and view all the answers

    How does fertilization influence the development in Xenopus laevis?

    <p>It triggers cortical rotation leading to the gray crescent formation.</p> Signup and view all the answers

    What happens at the animal pole of Xenopus laevis during development?

    <p>It differentiates into the ectoderm, which includes skin and nervous system.</p> Signup and view all the answers

    What is the primary function of the Spemann-Mangold Organizer (SMO) in vertebrate body plan establishment?

    <p>To regulate signaling events that establish body axes.</p> Signup and view all the answers

    Which mechanism assists in moving Wnt11 to the future dorsal side during cortical rotation?

    <p>Kinesin movement along microtubules.</p> Signup and view all the answers

    What does the marginal zone, or equatorial region, become during development?

    <p>Mesoderm.</p> Signup and view all the answers

    What is the primary role of tight junctions in epithelial cells?

    <p>Preventing solute diffusion between cells.</p> Signup and view all the answers

    What type of junction connects actin filaments of adjacent cells?

    <p>Adherens Junctions</p> Signup and view all the answers

    What property do cadherins depend on for their cell-cell adhesion function?

    <p>Calcium ions (Ca²⁺)</p> Signup and view all the answers

    Which of the following components do integrins connect to the cytoskeleton?

    <p>Extracellular matrix components</p> Signup and view all the answers

    What occurs during the epithelial-mesenchymal transition (EMT)?

    <p>Epithelial cells lose adhesion and become migratory.</p> Signup and view all the answers

    Which of the following best describes the role of cadherins in neural tube formation?

    <p>They maintain cohesion within the neural tube.</p> Signup and view all the answers

    What is NOT a function of the extracellular matrix (ECM)?

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

    Which type of junction is primarily responsible for cell communication?

    <p>Gap Junctions</p> Signup and view all the answers

    What role does Wnt11 play in the formation of the Spemann-Mangold Organizer?

    <p>It specifies the dorsal fate via the Wnt signaling pathway.</p> Signup and view all the answers

    What happens when the Spemann-Mangold Organizer is transplanted?

    <p>It can induce a secondary body axis.</p> Signup and view all the answers

    How do inhibitors like Chordin and Noggin function in the context of the organizer?

    <p>They diffuse to the ventral side creating a BMP activity gradient.</p> Signup and view all the answers

    What does high BMP activity generally lead to in terms of tissue structure?

    <p>Induction of ventral structures.</p> Signup and view all the answers

    Which of the following statements is accurate regarding the evolutionary conservation in vertebrates?

    <p>Similar developmental mechanisms are shared among vertebrates.</p> Signup and view all the answers

    Which cellular behaviors are essential for morphogenesis?

    <p>Movement, adhesion, and shape changes.</p> Signup and view all the answers

    What characterizes epithelial cells compared to mesenchymal cells?

    <p>They have a polarized structure with distinct apical and basal sides.</p> Signup and view all the answers

    What is one of the main roles of the organizer during development?

    <p>To create a balance between dorsal and ventral characteristics.</p> Signup and view all the answers

    Study Notes

    Cell Biology Overview

    • Lecture 2 provides a detailed overview of cell biology fundamentals, including the discovery of cells, cell theory, microscopy, and organelles.

    Discovery of Cells and Cell Theory

    • Invention of the microscope in the 17th century led to the discovery of cells.
    • All living organisms are made of cells.
    • Cells are the basic unit of life.
    • Cells arise from pre-existing cells.
    • Hereditary information passes from cell to cell.
    • All cells have the same basic chemical composition.
    • Energy flow occurs within cells.

    Cell Sizes and Microscopy

    • Small bacteria: ~1 µm.
    • Typical vertebrate cells: ~10 μm.
    • Organelles: 1-2 μm.
    • Ribosomes: ~25 nm.
    • Light Microscope: Resolution ~0.2 µm; used for observing cells and larger organelles.
    • Transmission Electron Microscopy (TEM): Resolution ~nm; reveals fine cellular details like ribosomes.
    • Immunofluorescence Microscopy: Detects specific proteins in cells.
    • GFP Tagging: Revolutionized cell biology by allowing protein localization in living cells.

    Prokaryotes vs. Eukaryotes

    • Prokaryotes: Include bacteria and archaea.
    • Eukaryotes: Include fungi, animals, and plants.
    • Genetic material in prokaryotes is in the cytoplasm, while eukaryotes enclose genetic material in a nucleus with a double membrane.
    • Eukaryotes have membrane-bound organelles for specialized functions.

    Organelles and Their Functions

    • Nucleus: Double membrane with nuclear pores for molecular exchange; encloses DNA.
    • Mitochondria: Double membrane organelles producing ATP; evolved from engulfed bacteria, contain their own DNA.
    • Chloroplasts: Found in plants and algae; use light energy to produce energy-rich molecules while consuming CO2 and releasing O2, evolved from photosynthetic bacteria.
    • Endoplasmic Reticulum (ER): Synthesizes lipids and proteins for secretion.
    • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
    • Cytosol: Surrounds organelles, accounting for ~50% of cell volume; site of many biochemical reactions, including protein synthesis.
    • Cytoskeleton: Cellular framework made of microfilaments (actin filaments), microtubules, and intermediate filaments; essential for cell shape, structural integrity, and internal organization.

    Central Dogma of Molecular Biology

    • DNA --> RNA --> Protein
    • Replication, transcription, and translation occur in the cell
    • Replication and Transcription: Occur in the nucleus.
    • Translation: Occurs in the cytosol.

    Cellular Composition

    • Cells are ~70% water.
    • Major macromolecules include proteins (~15%), RNA (~6%), and DNA (~1%).
    • Other components: Polysaccharides and phospholipids (~4%).
    • Small molecules (~4%).

    DNA Structure and Synthesis

    • DNA is made of deoxynucleotides (bases + deoxyribose + phosphate).
    • Bases: Pyrimidines (Cytosine, Thymine) – single rings; Purines (Adenine, Guanine) – double rings.
    • DNA strands have polarity: 5' End: Phosphate group; 3' End: Free hydroxyl (-OH) group.

    Other key concept summaries

    • Additional lectures cover RNA, transcription, protein folding and structure, protein synthesis, and the role of organelles in these cellular processes

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