Cell Structure and Function Quiz

Cell Membrane

• Defines the boundary of the cell, separating the internal environment from the external environment.
• Composed primarily of a phospholipid bilayer, with embedded proteins.
• Regulates the passage of substances into and out of the cell through various mechanisms like diffusion, osmosis, facilitated diffusion, and active transport.
• Provides structural support for the cell.
• Contains receptor proteins that allow the cell to communicate with its environment.

Nucleus

• Typically the largest organelle in eukaryotic cells.
• Encloses the cell's genetic material (DNA) organized into chromosomes.
• Controls cellular activities by directing protein synthesis.
• Contains the nucleolus, a region involved in ribosome production.
• Separates DNA from the rest of the cell's activities, maintaining its integrity.

Cytoplasm

• The jelly-like substance filling the cell, excluding the nucleus.
• Site of many metabolic reactions (e.g., glycolysis, protein synthesis).
• Contains various organelles suspended in it.
• Provides a medium for the movement of molecules and organelles within the cell.

Ribosomes

• Small, granular organelles responsible for protein synthesis.
• Found free in the cytoplasm or attached to the endoplasmic reticulum.
• Consist of ribosomal RNA and proteins.
• Translate mRNA into proteins following instructions from the DNA.

Endoplasmic Reticulum (ER)

• Network of membranes extending throughout the cytoplasm.
• Two types: smooth ER and rough ER.
• Smooth ER synthesizes lipids, detoxifies substances, and stores calcium.
• Rough ER is studded with ribosomes, involved in protein synthesis and modification.

Golgi Apparatus

• Stacks of flattened membrane-bound sacs.
• Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
• Involved in the creation of lysosomes.

Mitochondria

• Often referred to as the "powerhouse" of the cell.
• Site of cellular respiration, where energy (ATP) is generated from glucose.
• Possess their own DNA and ribosomes, indicating an evolutionary connection to bacteria.
• Have a double membrane structure: a smooth outer membrane and a highly folded inner membrane (cristae) to maximize surface area for processes like the electron transport chain.

Lysosomes

• Membrane-bound sacs containing enzymes capable of breaking down cellular waste products and other molecules.
• Responsible for intracellular digestion, recycling material within the cell.
• Help remove cellular debris.
• Importance in defense against foreign material, such as bacteria.

Vacuoles

• Membrane-bound sacs that store water, nutrients, and waste products.
• More prominent in plant cells; important for turgor pressure.

Cytoskeleton

• Network of protein filaments (microtubules, microfilaments, intermediate filaments) extending throughout the cytoplasm.
• Provides structural support for the cell, keeps organelles in place, facilitates intracellular transport, and enables movement.
• Plays a crucial role in cell division and maintaining cell shape.

Chloroplasts (Plant Cells Only)

• Double-membrane organelles containing chlorophyll.
• Site of photosynthesis, capturing light energy for converting carbon dioxide and water into glucose.
• Important for food production and oxygen release.