BIOL 151 Lecture: Metaphase to Anaphase Transition and Cell Signaling

Flashcards covering key terms and definitions related to the Metaphase to Anaphase Transition, Mitosis, Kinetochore function, cell cycle regulation, mutations, stem cell biology, and fundamental concepts of cell signaling from BIOL 151 Lecture notes.

Metaphase to Anaphase Transition

The regulated process of moving from metaphase to anaphase, involving the destruction of Securin and Cohesin to allow sister chromatid separation.

MAD (Mitotic Arrest Deficient)

A protein that binds CDC20 in response to signals from unattached kinetochores, preventing premature anaphase. It releases CDC20 when all kinetochores are attached.

CDC20

A protein that, once released by MAD, combines with APC to form a complex that ubiquinates Securin.

APC (Anaphase-Promoting Complex)

An E3 ubiquitin ligase that, when combined with CDC20, ubiquinates Securin, marking it for destruction.

Ubiquitin

A small protein attached to Securin by the APC/CDC20 complex, targeting Securin for destruction by the proteasome.

Securin

A protein that binds to and inactivates Separase. Its destruction by ubiquitination is essential for anaphase to begin.

Separase

An enzyme that destroys Cohesin, leading to the separation of sister chromatids and progression into anaphase. It is inactivated when bound to Securin.

Cohesin

A protein complex that holds sister chromatids together from the S phase until anaphase. Its destruction by Separase initiates anaphase.

Kinetochore

A complex protein structure on chromatids where spindle fiber microtubules attach, acting as a source of the 'not attached' signal and containing molecular motors.

Mitosis

The process of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus.

Prophase

The initial stage of mitosis where chromosomes condense and the spindle fiber system begins to form.

Metaphase

The stage of mitosis where spindle fibers align the chromatids in the middle of the cell; the cell remains in this stage until all kinetochores are attached.

Anaphase

The stage of mitosis where sister chromatids separate and are pulled to opposite poles of the cell.

Telophase

The final stage of mitosis where new nuclei reform around the separated chromosomes.

Cytokinesis

The process following telophase where the cell's cytoplasm divides, pinching the cell into two distinct daughter cells.

Loss of Function Mutation

A type of mutation that causes a protein to cease having some or all of its normal biological function.

Gain of Function Mutation

A type of mutation that causes a protein to acquire an enhanced or new activity, or to be produced in excessive amounts.

Premature Anaphase

Entry into the anaphase stage of mitosis before all kinetochores are properly attached to spindle fibers, often leading to aneuploidy.

Stuck in Metaphase

A condition where a cell fails to progress from metaphase to anaphase, often due to unresolved kinetochore attachments or persistent inhibition of Separase.

Hematopoietic Stem Cells

Stem cells located in the bone marrow that are responsible for the production of all blood cell types, including red and white blood cells.

Intestinal Villi

Multicellular, finger-like projections within the small intestine that increase surface area for nutrient absorption.

Stem Cells

Undifferentiated cells capable of self-renewal and differentiating into one or more specialized cell types.

Self-renewal Cell Division

An asymmetrical division where a stem cell produces one daughter cell identical to itself (another stem cell) and one transit amplifying cell or differentiating cell.

Transit Amplifying Cells

Cells produced from stem cell division that undergo rapid proliferation before differentiating into mature cell types.

Differentiation

The process by which a less specialized cell becomes a more specialized cell type, guided by internal and external signals.

Adult Stem Cells

Pluripotent stem cells found in various mature tissues that can differentiate into a limited set of specialized cell types within that tissue.

Pluripotent (Adult Stem Cells)

Describes adult stem cells capable of differentiating into a limited range of cell types, often within a specific lineage.

Cell Signaling

The process by which cells communicate with each other, involving the release of signaling molecules that bind to and activate receptors on target cells.

Signaling Molecules (Ligands)

Molecules released by cells that act as chemical messages, binding to specific receptors to initiate a cellular response.

Receptor

A protein, usually located on the cell surface or inside the cell, that binds to specific signaling molecules, leading to activation and a cellular response.

Signal Transduction

The process by which an extracellular signal is converted into an intracellular response, often involving a cascade of molecular events.