Cell Biology Quiz

Cell Biology

Cell Theory
- All living organisms are composed of one or more cells.
- Cells are the basic unit of structure and organization in organisms.
- All cells arise from pre-existing cells.
Cell Types
- Prokaryotic Cells
  - Lack a nucleus and membrane-bound organelles.
  - Smaller and simpler (e.g., bacteria).
- Eukaryotic Cells
  - Contain a nucleus and membrane-bound organelles.
  - Larger and more complex (e.g., plants, animals, fungi).
Cell Structure
- Plasma Membrane
  - Semi-permeable barrier that controls movement of substances in and out.
  - Composed of a phospholipid bilayer with embedded proteins.
- Cytoplasm
  - Jelly-like substance where cellular processes occur.
  - Contains organelles and cytosol.
- Nucleus
  - Contains genetic material (DNA).
  - Controls cellular activities and gene expression.
- Organelles
  - Mitochondria: Powerhouse of the cell; produces ATP.
  - Ribosomes: Site of protein synthesis.
  - Endoplasmic Reticulum (ER):
    - Rough ER: Studded with ribosomes; synthesizes proteins.
    - Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies.
  - Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
  - Lysosomes: Contains digestive enzymes for waste breakdown.
  - Chloroplasts (in plants): Site of photosynthesis; contains chlorophyll.
  - Cell Wall (in plants, fungi, bacteria): Provides structural support and protection.
Cell Membrane Transport
- Passive Transport: Movement of substances without energy (e.g., diffusion, osmosis).
- Active Transport: Movement of substances against a concentration gradient, requiring energy (e.g., protein pumps).
- Endocytosis and Exocytosis: Processes for transporting large molecules into (endocytosis) and out of (exocytosis) the cell.
Cell Cycle
- Phases:
  - Interphase: Cell prepares for division (G1, S, G2 phases).
  - Mitosis: Division of the nucleus (prophase, metaphase, anaphase, telophase).
  - Cytokinesis: Division of the cytoplasm, resulting in two daughter cells.
Cell Communication
- Cells communicate via signaling molecules (e.g., hormones).
- Signal transduction pathways convert external signals into cellular responses.
Cell Division
- Mitosis: Produces two identical daughter cells for growth and repair.
- Meiosis: Produces gametes (sperm and eggs) with half the chromosome number for sexual reproduction.
Apoptosis
- Programmed cell death; crucial for development and maintenance of healthy tissues.
- Involves a cascade of biochemical events leading to cell death.
Stem Cells
- Undifferentiated cells with the potential to develop into various cell types.
- Types:
  - Embryonic Stem Cells: Pluripotent; can become any cell type.
  - Adult Stem Cells: Multipotent; limited to specific lineages.

Cell Theory

Composed of one or more cells, all living organisms share this fundamental characteristic.
Cells serve as the basic unit of structure and organization in living things.
All cells originate from pre-existing cells, emphasizing continuity in life.

Cell Types

Prokaryotic Cells
- Characterized by the absence of a nucleus and membrane-bound organelles.
- Generally smaller and simpler compared to eukaryotic cells (e.g., bacteria).
Eukaryotic Cells
- Feature a defined nucleus and membrane-bound organelles.
- Typically larger and more complex; examples include plants, animals, and fungi.

Cell Structure

Plasma Membrane
- Acts as a semi-permeable barrier, regulating substance movement in and out of the cell.
- Composed of a phospholipid bilayer with embedded proteins.
Cytoplasm
- Jelly-like matrix where cellular processes take place.
- Contains organelles and cytosol, the fluid component.
Nucleus
- Houses genetic material (DNA) and controls cellular activities and gene expression.
Organelles
- Mitochondria: Function as the cell's powerhouses, generating ATP.
- Ribosomes: Sites for protein synthesis.
- Endoplasmic Reticulum (ER):
  - Rough ER is ribosome-studded for protein synthesis.
  - Smooth ER synthesizes lipids and detoxifies harmful substances.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
- Lysosomes: Contain enzymes to digest waste materials.
- Chloroplasts (in plants): Conducts photosynthesis, containing chlorophyll.
- Cell Wall (in plants, fungi, bacteria): Provides structural support and protection.

Cell Membrane Transport

Passive Transport: Involves movement of substances without energy input (e.g., diffusion, osmosis).
Active Transport: Requires energy to move substances against a concentration gradient (e.g., protein pumps).
Endocytosis and Exocytosis: Mechanisms for transporting large molecules into (endocytosis) and out of (exocytosis) the cell.

Cell Cycle

Phases:
- Interphase: Preparation phase for cell division, including G1, S, and G2 phases.
- Mitosis: Encompasses nucleus division (includes prophase, metaphase, anaphase, and telophase).
- Cytokinesis: Finalizes cell division by splitting the cytoplasm into two daughter cells.

Cell Communication

Communication among cells occurs through signaling molecules, including hormones.
Signal transduction pathways convert external signals into appropriate cellular responses.

Cell Division

Mitosis: Produces two identical daughter cells, essential for growth and tissue repair.
Meiosis: Generates gametes (sperm and eggs) with half the chromosome number for sexual reproduction.

Apoptosis

Programmed cell death vital for development and maintenance of healthy tissues.
Involves a series of biochemical events leading to cell elimination.

Stem Cells

Undifferentiated cells capable of developing into various specialized cell types.
Embryonic Stem Cells: Pluripotent, able to differentiate into any cell type.
Adult Stem Cells: Multipotent, with differentiation potential limited to specific cellular lineages.