Cell Structure and Function

Cell Structure and Function

• Cell: Basic unit of structure and function in living things
• Multicellular Organisms: Composed of more than one cell
• Unicellular Organism: Single-celled organism (e.g., bacteria)
• Prokaryotic Cell: Lacks a nucleus and membrane-bound organelles (e.g., bacteria)
• Eukaryotic Cell: Contains a nucleus and membrane-bound organelles (e.g., plant & animal cells)
• Asexual Reproduction: Single-celled organisms reproduce by dividing into two identical cells
• Organelle: Specialized structure performing specific functions within a cell
• Cell Membrane: Controls entry and exit of substances
• Cytoskeleton: Network of protein filaments maintaining cell shape and movement
• Cytoplasm: Jelly-like fluid suspending organelles
• Nucleolus: Structure inside the nucleus producing ribosomes
• Endoplasmic Reticulum (Rough ER): Modifies, finishes, and transports proteins
• Endoplasmic Reticulum (Smooth ER): Modifies, finishes, and transports lipids
• Golgi Apparatus: Modifies, sorts, and packages proteins
• Lysosome: Breaks down food and worn-out cell parts
• Vacuole: Stores food, water, wastes, and other materials
• Centrioles: Appear during cell division; help separate chromosomes
• Cilia/Flagella: Hairlike structures assisting in movement
• Mitochondria: Site of cellular respiration, producing ATP energy
• Chloroplast: Captures sunlight to produce glucose (photosynthesis)
• Cell Wall: Rigid carbohydrate layer surrounding plant cells
• Homeostasis: Maintaining a stable internal environment
• Equilibrium: Balance between continuing processes
• Stimulus: Signal triggering a response
• Positive Feedback: Enhances response
• Negative Feedback: Lowers or stops response

Cell Membrane and Transport

• Selective Permeability: Cell membrane allows some substances to pass while blocking others
• Concentration Gradient: Difference in concentration of a substance between locations
• Passive Transport: Movement of substances across the membrane down the concentration gradient without energy
• Diffusion: Movement of a substance from high to low concentration
• Facilitated Diffusion: Diffusion through a protein channel
• Osmosis: Diffusion of water across a membrane
• Active Transport: Movement of substances against the concentration gradient using energy
• Protein Pumps: Use energy to transport charged atoms or large particles
• Endocytosis: Cell membrane engulfs material to create a vesicle (entering cell)
• Exocytosis: Vesicle releases contents outside the cell (exiting cell)

Cell Reproduction and Development

• Fertilization: Fusion of egg and sperm to create a new organism
• Mitosis: Cell division where the nucleus divides
• Cell Differentiation: Cells become specialized in structure and function
• Stem Cell: Unspecialized cell able to develop into any cell type
• Tissue: Group of similar cells performing the same function
• Organ: Group of tissues working together
• Organ System: Group of organs working together
• Cell Cycle: Repeated pattern of growth, DNA replication, and cell division
• Interphase: Longest phase of the cell cycle
• Prophase: Chromosomes become visible, nuclear envelope dissolves, spindle forms
• Metaphase: Chromosomes line up in the middle of the cell
• Anaphase: Chromosomes move to opposite sides of the cell
• Telophase: Nuclei reform and the cell begins to split
• Cytokinesis: Division of the cytoplasm
• Chromosome: Thread-like structure of DNA containing genes
• Chromatid: One of two identical sister parts of a duplicated chromosome
• Centromere: Region connecting sister chromatids
• Cancer: Uncontrolled cell division leading to tumors