Cell and Tissue Structure Quiz

Cell and Tissue Form

• Cells come together to form tissues, which are collections of cells with specific structures that allow them to work together and perform a specific function.
• The shape of cells and organs reflects their function.

Organizing Cells into Tissues

• The cytoskeleton helps organize cells internally and connects cells to external structures.
• Cells connect and communicate through cell junctions.
• The extracellular matrix (ECM) provides structural support and helps with cell communication.
• The ECM can include the basal lamina, a structure that provides support for layers of cells, particularly epithelial tissues.

Tissues Form Organs

• Two or more tissues combine and function together to make up an organ.
• Organs perform major functions, such as those within the respiratory organ system.

The Cytoskeleton

• The cytoskeleton provides internal structural support and enables movement of substances within the cell.
• It is made up of long chains of protein subunits called polymers.

Types of Cytoskeletal Elements

• Microfilaments are made of actin monomers, are short, thin double helixes, and are extensively branched just beneath the cell membrane.
  • They support cell shape, transport materials inside cells, contract muscle cells, participate in cell division, and enable cell movement.
• Intermediate Filaments are made up of different proteins depending on the cell type, and provide mechanical strength to the cell.
  • They contribute to cell and tissue shape and support.
  • Genetic defects in the genes for intermediate filaments can lead to diseases like fragile skin that blisters easily.
• Microtubules are hollow tubes of tubulin dimers.
  • They contribute to cell shape and support, hold organelles in place, transport materials within the cell, enable cell movement using cilia and flagella, move chromosomes during cell division, and are dynamic structures that undergo polymerization and depolymerization.

Motor Proteins and Cell Movement

• Motor proteins use microtubules and microfilaments as tracks to transport materials within a cell.
• Kinesin and dynein move materials to and from different regions of the cell.
• Myosin is a motor protein involved in muscle contraction.

Cell Adhesion Molecules and Cell Junctions

• Cell adhesion molecules allow cells to attach to other cells and to the extracellular matrix (ECM).
  • Cadherins bind adjacent cells and are used in adherens junctions and desmosomes.
  • Integrins allow cells to attach to the ECM and are used in hemidesmosomes.
• Cell junctions connect cells to other cells or tissues and are reinforced by the cytoskeleton.

Types of Cell Junctions

• Anchoring Junctions
  • Adherens Junctions attach cells to cells and involve cadherins.
  • Desmosomes attach cells to cells and involve cadherins in a button-like arrangement.
  • Hemidesmosomes attach cells to the basal lamina and involve integrins in a button-like arrangement.
• Barrier Junctions
  • Tight Junctions create a seal between cells, preventing substances from moving between them.
• Communicating Junctions
  • Gap Junctions (animals) and Plasmodesmata (plants) allow for communication between cells.

The Extracellular Matrix (ECM)

• The ECM is the material outside of the cellular membrane and provides structural support and informational cues for cells.
• Plant ECM consists mainly of cellulose and provides structural support to the cell.
• Animal ECM is an insoluble meshwork of proteins and polysaccharides, abundant in connective tissue, and contains a significant amount of collagen.
• Collagen is a protein that provides strength and flexibility.
• Basal Lamina is a specialized layer of ECM underneath epithelial tissue and provides flexible support.

The Extracellular Matrix and Cancer

• Cancer cells can escape tumors and move to other parts of the body by crossing the ECM and basal lamina.
• Integrins help cancer cells cross the basal lamina, and drugs targeting integrins are being studied for cancer treatment.

The Extracellular Matrix and Cell Shape

• The surface where cells grow and attach can significantly affect their shape.
• Cells grown on a glass surface are more likely to be flat, while cells grown in liquid are more likely to be rounded.

Test your knowledge on the organization of cells and tissues. This quiz covers the role of the cytoskeleton, extracellular matrix, and how tissues form organs with specific functions. Understand how cell shapes contribute to their roles in the body.