Lecture 15 Review
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What is the outcome of lateral inhibition in cell groups?

  • Cells communicate equally with all neighbors.
  • Cells stop dividing altogether.
  • Some cells predominate over their neighbors. (correct)
  • All cells achieve the same fate.

    • Which of the following is NOT a mechanism by which cells become different?

  • Inductive signaling
  • Lateral inhibition
  • Uniform cell division (correct)
  • Asymmetric cell division

    • Which cell signaling pathway is NOT mentioned as a conserved mechanism in animal development?

  • Fibroblast growth factor (FGF) (correct)
  • Transforming growth factor-ß (TGFß)
  • Hedgehog (Hh)
  • Notch

    • What can result from the same inductive signal applied to different cells?

    <p>Diversity in cell responses may occur.</p> Signup and view all the answers

    What type of signaling involves communication between neighboring cells for differentiation?

    <p>Cell non-autonomous</p> Signup and view all the answers

    What are the two phases involved in cell fate commitment?

    <p>Specification and determination</p> Signup and view all the answers

    Which of the following correctly distinguishes between specification and determination?

    <p>Specification does not establish a fixed fate; determination does.</p> Signup and view all the answers

    What does the differential gene expression theory explain?

    <p>How cells express genes differently to adopt various fates.</p> Signup and view all the answers

    Which mechanism can specify cell fate autonomously?

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

    What role does cell-cell communication play in cell fate determination?

    <p>It allows cells to acquire different fates non-autonomously.</p> Signup and view all the answers

    Which of the following describes induction in the context of cell differentiation?

    <p>The method where one cell influences the fate of neighboring cells.</p> Signup and view all the answers

    What is the term used for the phenomenon where a group of cells restricts the fate of their neighbors?

    <p>Lateral inhibition</p> Signup and view all the answers

    Which of the following is NOT a characteristic of totipotent cells?

    <p>They are limited to specific fates in differentiation.</p> Signup and view all the answers

    What is the initial phase of commitment where cells are reversible in fate determination?

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

    What does cell fate typically refer to in developmental biology?

    <p>The ultimate identity of a cell</p> Signup and view all the answers

    Which of the following correctly describes the term 'differential gene expression'?

    <p>It dictates cell differentiation.</p> Signup and view all the answers

    In an isolation experiment, if a cell expresses a different fate than it would normally, what conclusion can be drawn?

    <p>The cell is not specified nor determined.</p> Signup and view all the answers

    What does the term 'terminally differentiated' refer to?

    <p>A specialized state of a cell</p> Signup and view all the answers

    What type of experiment is conducted to test determination by placing cells in a new environment?

    <p>In vitro transplantation experiment</p> Signup and view all the answers

    What would it indicate if a specified muscle cell changes to muscle despite being placed in a new environment?

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

    What characterizes the cell fate potential according to the concept of step-wise restriction?

    <p>Both intrinsic and extrinsic factors influence cell fate.</p> Signup and view all the answers

    What defines a cell as determined in developmental biology?

    <p>Transplantation does not alter their normal fate.</p> Signup and view all the answers

    What is meant by cell fate becoming progressively restricted during development?

    <p>Cells lose their ability to become any cell type.</p> Signup and view all the answers

    Who demonstrated that a nucleus from a differentiated cell can direct normal development?

    <p>John Gurdon</p> Signup and view all the answers

    What significant achievement is attributed to Shinya Yamanaka?

    <p>Creating induced pluripotent stem cells.</p> Signup and view all the answers

    What does the differential gene expression theory suggest regarding somatic cells?

    <p>Only a fraction of the genome is expressed in any cell type.</p> Signup and view all the answers

    What is the main factor that allows different cell types to exhibit unique characteristics?

    <p>Differential gene expression</p> Signup and view all the answers

    What was a significant finding from cloning experiments like those conducted with Dolly the sheep?

    <p>Adult cells can be used to produce genetically identical organisms.</p> Signup and view all the answers

    What happens to genes that are not transcribed in a cell?

    <p>They retain potential to be expressed</p> Signup and view all the answers

    Which of the following describes an enucleated egg in the context of nuclear transplantation?

    <p>An egg cell that has had its nucleus removed.</p> Signup and view all the answers

    Which mechanism involves sister cells being born different due to inheritance of cytoplasmic determinants?

    <p>Cell autonomous mechanism</p> Signup and view all the answers

    What is the role of cell signaling in the context of sister cells becoming different?

    <p>It involves non-cell autonomous mechanisms</p> Signup and view all the answers

    What type of cell was used by Ian Wilmut to successfully clone Dolly the sheep?

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

    In asymmetric cell division, where are cytoplasmic determinants localized?

    <p>Asymmetrically in one daughter cell</p> Signup and view all the answers

    What type of mechanism does asymmetric cell division represent?

    <p>Cell autonomous mechanism</p> Signup and view all the answers

    Which of the following is NOT a way sister cells become different?

    <p>Random mutation events</p> Signup and view all the answers

    What is the significance of differential gene expression in cellular biology?

    <p>It allows for specialization of cell types</p> Signup and view all the answers

    What is one mechanism through which sister cells can become different?

    <p>Asymmetric division</p> Signup and view all the answers

    Which of the following describes a cell nonautonomous mechanism of differentiation?

    <p>Inductive signaling</p> Signup and view all the answers

    What role do signaling molecules play in cell differentiation?

    <p>They relay, amplify, and integrate signals.</p> Signup and view all the answers

    Which type of inductive signal results in a consistent outcome, regardless of concentration?

    <p>All-or-none signals</p> Signup and view all the answers

    How can inductive signals affect cell fate?

    <p>They can direct cells to new developmental fates.</p> Signup and view all the answers

    Which of the following is an example of a mechanism that involves extracellular signaling?

    <p>Lateral inhibition</p> Signup and view all the answers

    Which concept best describes how a signaling molecule operates in the extracellular space?

    <p>It may alter gene expression in target cells.</p> Signup and view all the answers

    What differentiates morphogens from other types of inductive signals?

    <p>Morphogens operate in a concentration-dependent manner.</p> Signup and view all the answers

    What are the primary functions of signaling molecules during cell development?

    <p>Survival, migration, secretion, and metabolism.</p> Signup and view all the answers

    Which mechanism is not categorized as cell extrinsic?

    <p>Asymmetric division</p> Signup and view all the answers

    Study Notes

    Cell Fate Commitment

    • Cell fate commitment involves two phases: specification and determination.
    • Specification is a reversible commitment to a particular fate.
    • Determination is an irreversible commitment to a particular fate.

    Testing Specification

    • An isolation experiment can test for cell specification.
    • If a cell expresses a different fate than normal in isolation, it is not specified.
    • If a cell expresses its normal fate, it is specified.

    Testing Determination

    • In vitro transplantation experiments can test for cell determination.
    • If a cell expresses its normal fate in a new environment, it is determined.
    • If a cell does not express its normal fate in a new environment, it is not determined.

    In Vivo Test for Determination

    • Cells are determined if their fate does not change when transplanted to a new position in the embryo.

    Commitment to a Particular Fate is Progressive

    • Each step of commitment is irreversible.
    • Cell fate becomes increasingly restricted during development.

    Differential Gene Expression Theory

    • The genome remains constant in all somatic cells.
    • Only a small portion of the genome is expressed in any given cell type.
    • Different cell types express different gene groups, resulting in unique cellular characteristics.
    • Unused genes that are not transcribed are retained.

    Differential Gene Expression Makes Cells Different

    • Specific transcription regulators control the expression of certain genes.
    • Regulatory modules determine gene expression patterns, leading to cell differentiation.

    Two Ways of Making Sister Cells Different

    • Cell autonomous: Asymmetric division causes sister cells to be different due to cytoplasmic determinants.
    • Cell nonautonomous: Cell signalling or inductive signalling leads to sister cells becoming different from differences acting on and/or between them.

    Asymmetric Cell Division

    • Cytoplasmic determinants become asymmetrically localized.
    • Cytoplasmic determinants are inherited by one daughter cell.

    Examples of Asymmetric Cell Division

    • The first division in C. elegans produces different cells.

    Cell Non-Autonomous Mechanisms

    • Inductive signaling and lateral inhibition.

    Inductive Signaling

    • Some inductive signals function in an all-or-none manner.
    • Other signals function in a concentration-dependent manner.
    • Morphogens are diffusible molecules with varying concentrations that produce specific cellular responses.

    Morphogen Gradients

    • Morphogens are secreted from a source.
    • They form concentration gradients with the highest concentration near the source.
    • Cells respond to morphogen concentrations, leading to a reproducible pattern of differentiation.
    • Example Shh (Sonic Hedgehog) in the chick limb bud.
    • Inappropriate morphogen expression can lead to extra digit formation.

    Cellular Differentiation and Tissue Asymmetries

    • Equivalent cells can adopt different fates due to cell-cell interactions and lateral inhibition.

    Lateral Inhibition

    • Equivalent cells can adopt different fates.
    • Cells compete by inhibiting neighbors and one cell predominates. This mechanism directs the development of a set pattern (e.g. fly bristles).

    Cell-Cell Communication in Animal Development

    • Cell-cell signaling involves a small number of conserved pathways.
    • Important pathways include TGFβ, Wnt, Hedgehog, Notch, and RTKs.
    • Sequential inductions can direct and control the differentiation hierarchy.
    • Combinations of signals can result in diverse cellular responses.

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    Description

    Test your knowledge on cell fate commitment, which includes the phases of specification and determination. This quiz covers the characteristics of each phase, methods for testing specification and determination, and the progressive nature of commitment. Dive into the fascinating world of cellular biology with engaging questions!

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