Cell Structure and Function Quiz

Cell Structure and Function

• Cells are the basic structural and functional units of all living organisms.
• Cells exhibit a wide range of shapes and sizes, reflecting their diverse functions.
• The basic components of a cell include the plasma membrane, cytoplasm, and the nucleus.

Plasma Membrane

• The plasma membrane is a selectively permeable barrier that separates the intracellular environment from the extracellular environment.
• Composed primarily of a phospholipid bilayer and embedded proteins.
• Regulates the passage of substances into and out of the cell.
• Contains channels and pumps that actively transport molecules across the membrane.

Cytoplasm

• The cytoplasm is the region of the cell outside the nucleus and within the plasma membrane.
• Contains cytosol, a jelly-like fluid.
• Houses various organelles like mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes.
• Involved in many metabolic processes.

Nucleus

• The nucleus is the control center of the cell, containing the cell's genetic material (DNA).
• Typically a single, membrane-bound organelle.
• Contains chromatin (DNA + proteins) which condenses into chromosomes during cell division.
• Contains a nucleolus, where ribosomes are assembled.

Organelles

• Mitochondria: Powerhouses of the cell, responsible for cellular respiration and ATP production.
• Ribosomes: Involved in protein synthesis. Found free in the cytoplasm or attached to the rough endoplasmic reticulum.
• Endoplasmic Reticulum (ER): Network of membranes extending throughout the cytoplasm.
  • Rough ER: studded with ribosomes; involved in protein synthesis and modification.
  • Smooth ER: lacks ribosomes; involved in lipid synthesis, detoxification, and calcium storage.
• Golgi apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
• Lysosomes: Contain enzymes that break down waste materials and cellular debris.
• Peroxisomes: Involved in detoxification processes, particularly the breakdown of hydrogen peroxide.

Cell Types

• Prokaryotic cells: Lack a nucleus and membrane-bound organelles (bacteria, archaea).
• Eukaryotic cells: Possess a nucleus and membrane-bound organelles (plants, animals, fungi, protists). More complex and larger than prokaryotic cells.

Cell Processes

• Diffusion: Passive movement of molecules from an area of high concentration to an area of low concentration.
• Osmosis: Passive movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.
• Active transport: Movement of molecules against their concentration gradient, requiring energy (ATP).
• Endocytosis: Process by which cells take in materials by engulfing them in vesicles.
• Exocytosis: Process by which cells release materials by fusing vesicles with the plasma membrane.

Tissues

• Specialized cells combine to form tissues.
• Tissues are organized groups of cells that perform specific functions.

Cell Cycle

• The cell cycle is a series of events that leads to cell growth and division. Consists of interphase and mitotic phase.
• Cell division occurs via mitosis (somatic cells) or meiosis (germ cells).

Cell Communication

• Cells communicate with each other through various mechanisms, including signaling molecules and receptors.
  • Allows coordination of activities within an organism.
• Different types of signaling like paracrine, endocrine, and synaptic.