Cell Biology: Cell Structure

Plasma Membrane: semi-permeable membrane that separates cell from environment
Cytoplasm: jelly-like substance inside cell where metabolic processes occur
Nucleus: contains genetic material (DNA) and controls cell growth and reproduction
Mitochondria: generates energy for cell through cellular respiration
Endoplasmic Reticulum (ER): involved in protein synthesis and transport
Ribosomes: site of protein synthesis
Lysosomes: contains digestive enzymes and breaks down waste
Golgi Apparatus: involved in protein modification and transport

Passive Transport: movement of molecules from high to low concentration without energy input
- Diffusion: random movement of molecules
- Osmosis: movement of water molecules through selectively permeable membrane
- Facilitated Diffusion: assisted transport of molecules through protein channels
Active Transport: movement of molecules from low to high concentration with energy input
- Pumps: energy-driven transport of molecules
- Vesicular Transport: transport of molecules through vesicles

Mitosis: process of cell division that results in two identical daughter cells
- Interphase: cell growth and preparation for cell division
- Prophase: chromatin condenses and nuclear envelope breaks down
- Metaphase: chromosomes align at center of cell
- Anaphase: sister chromatids separate
- Telophase: nuclear envelope reforms and chromatin uncoils
- Cytokinesis: cytoplasm divides and cell splits
Meiosis: process of cell division that results in four non-identical daughter cells with half the number of chromosomes

Signaling Molecules: molecules that transmit information between cells
- Hormones: signaling molecules that act over long distances
- Neurotransmitters: signaling molecules that act over short distances
Signal Transduction Pathways: series of molecular interactions that transmit signals from cell surface to target molecule
- Receptor Proteins: proteins that bind signaling molecules
- Second Messengers: molecules that transmit signals from receptor proteins to target molecules

Plasma Membrane: semi-permeable, separating cell from environment, controlling what enters and leaves
Cytoplasm: jelly-like substance inside cell, site of metabolic processes, maintaining cell shape
Nucleus: contains genetic material (DNA), controlling cell growth and reproduction, surrounded by double membrane
Mitochondria: generates energy for cell through cellular respiration, converting glucose into ATP
Endoplasmic Reticulum (ER): involved in protein synthesis, transport, and folding
Ribosomes: site of protein synthesis, reads mRNA, and builds polypeptide chains
Lysosomes: contains digestive enzymes, breaks down waste, and recycles cellular materials
Golgi Apparatus: involved in protein modification, transport, and packaging, receives proteins from ER

Passive Transport: no energy input, movement from high to low concentration
- Diffusion: random movement of molecules, equalizing concentration
- Osmosis: water movement through selectively permeable membrane, equalizing concentration
- Facilitated Diffusion: assisted transport of molecules through protein channels
Active Transport: energy input, movement from low to high concentration
- Pumps: energy-driven transport of molecules, against concentration gradient
- Vesicular Transport: transport of molecules through vesicles, exocytosis, and endocytosis

Mitosis: cell division, resulting in two identical daughter cells, with same number of chromosomes
- Interphase: cell growth, preparation for cell division, replication of DNA
- Prophase: chromatin condenses, nuclear envelope breaks down, microtubules form
- Metaphase: chromosomes align at center of cell, attached to microtubules
- Anaphase: sister chromatids separate, moving to opposite poles
- Telophase: nuclear envelope reforms, chromatin uncoils, and nucleolus reappears
- Cytokinesis: cytoplasm divides, cell splits, and cleavage furrow forms
Meiosis: cell division, resulting in four non-identical daughter cells, with half the number of chromosomes

Signaling Molecules: molecules transmitting information between cells
- Hormones: signaling molecules, acting over long distances, regulating growth and development
- Neurotransmitters: signaling molecules, acting over short distances, transmitting neural signals
Signal Transduction Pathways: series of molecular interactions, transmitting signals from cell surface to target molecule
- Receptor Proteins: proteins binding signaling molecules, initiating signal transduction
- Second Messengers: molecules transmitting signals from receptor proteins to target molecules