Cell Structure and Function Quiz

Cell Structure and Function

• Cells are the fundamental units of life, found in all living organisms.
• Cells take in nutrients and release waste products.
• Cells can reproduce by dividing.
• Organelles within cells perform essential life processes like nutrient intake, gas exchange, movement, waste removal, growth, reproduction, and responding to stimuli.

Cell Components and Their Roles

• Cell Membrane: A protective, lipid bilayer barrier. Semi-permeable, allowing selective substance passage; diffusion occurs across it.
• Cytoplasm: A jelly-like substance filling the cell; holds organelles, nutrients, allowing internal movement.
• Nucleus: The control center, containing DNA (stored as chromatin, or chromosomes during division). Enclosed by a nuclear envelope with pores.
• Vacuoles: Storage compartments for nutrients, wastes, and other substances. Plant cells have a large central vacuole for support.
• Mitochondria: The "powerhouse" of the cell; site of cellular respiration (glucose + oxygen → carbon dioxide + water + energy).
• Lysosomes: Contain enzymes for digesting cellular waste, bacteria, and damaged organelles.
• Ribosomes: Synthesize proteins based on DNA instructions; can be free-floating or bound to the ER.
• Endoplasmic Reticulum (ER): A network of interconnected tubes for transport within cells; Rough ER has ribosomes for protein synthesis; Smooth ER makes fats and oils.
• Golgi Apparatus: Processes, modifies, and packages proteins for delivery.
• Cytoskeleton: Provides structural support and maintains cell shape.

Plant Cell Specifics

• Cell Wall: A rigid outer layer providing support, protection and strength only found in plants, bacteria, fungi, and some algae.
• Chloroplasts: Sites of photosynthesis (carbon dioxide + water + sunlight → glucose + oxygen). Containing chlorophyll, they are only in plant cells and some algae.
• Thylakoids are stacks of compartments within a Chloroplast and are surrounded by stroma.

Animal vs. Plant Cells

• Plant cells have cell walls, chloroplasts, and a large central vacuole; animal cells lack these.
• Animal cells contain centrioles (important for cell division).

Cell Cycle and Mitosis

• The cell cycle is a repeating series of events; cell division involves mitosis forming two daughter cells for growth and repair.
• Chromosomes: Long DNA strands, visible during division. Humans have 46.
• Chromosomes consist of identical chromatids joined by a centromere.
• Mitosis stages: Prophase, Metaphase, Anaphase, Telophase.
  • Prophase: Chromatin condenses, nuclear envelope breaks down, spindle fibers form.
  • Metaphase: Chromosomes line up at the cell's equator.
  • Anaphase: Chromatids separate to opposite poles.
  • Telophase: Chromosomes uncoil, nuclear envelope reforms, nucleolus reappears.

Cytokinesis

• Cytoplasm division after nucleus division, resulting in two separate daughter cells.
• Animals pinch at the cell membrane; plants form a cell plate.

Factors Affecting Mitosis

• Factors like altitude, light and chemicals (e.g., antibiotics, chemotherapy drugs) affect mitosis rates.

Cell Longevity and Death

• Cells can die due to damage (necrosis) or programmed cell death (apoptosis).

Key Vocabulary

• Mitosis: Cell division for growth and repair
• Chromosomes: Structures made up of DNA and proteins
• Chromatids: Identical pieces of a chromosome
• Cytokinesis: Cytoplasm Division.
• Apoptosis: Programmed cell death.