Cell Structure Basics

Plasma Membrane: Semi-permeable membrane that separates cell from environment, regulates what enters/leaves cell
Cytoplasm: Jelly-like substance inside cell membrane, site of metabolic reactions
Nucleus: Control center of cell, contains genetic material (DNA)
Mitochondria: Powerhouses of cell, generate energy through cellular respiration
Endoplasmic Reticulum (ER): Network of membranous tubules and sacs, involved in protein synthesis and transport
Ribosomes: Small organelles found throughout cytoplasm, site of protein synthesis
Lysosomes: Membrane-bound sacs containing digestive enzymes, break down and recycle cellular waste
Golgi Apparatus: Complex of flattened sacs and tubules, involved in protein modification and secretion

Passive Transport: Movement of molecules from high to low concentration, no energy required
- Diffusion: Movement of molecules from high to low concentration until equilibrium
- Osmosis: Movement of water molecules through selectively permeable membrane
Active Transport: Movement of molecules from low to high concentration, energy required
- Pump: Uses energy to move molecules against concentration gradient
- Carrier Proteins: Bind to molecules and transport them across membrane

Mitosis: Process of cell division resulting in two daughter cells with same number of chromosomes as parent cell
- Interphase: Cell growth and preparation for cell division
- Prophase: Chromatin condenses, nuclear envelope breaks down
- Metaphase: Chromosomes line up at center of cell
- Anaphase: Sister chromatids separate
- Telophase: Nuclear envelope reforms, chromatin uncoils
Meiosis: Process of cell division resulting in four daughter cells with half the number of chromosomes as parent cell

Signal Transduction Pathways: Series of molecular events that transmit signal from receptor to response
Receptors: Proteins that bind to signaling molecules (ligands)
Signaling Molecules: Hormones, neurotransmitters, growth factors, etc.
Response: Cellular response to signal, e.g. gene expression, protein activation

Plasma membrane is semi-permeable, regulating what enters and leaves the cell
Cytoplasm is a jelly-like substance inside the cell membrane, site of metabolic reactions
Nucleus is the control center of the cell, containing genetic material (DNA)
Mitochondria are the powerhouses of the cell, generating energy through cellular respiration
Endoplasmic Reticulum (ER) is a network of membranous tubules and sacs, involved in protein synthesis and transport
Ribosomes are small organelles found throughout the cytoplasm, site of protein synthesis
Lysosomes are membrane-bound sacs containing digestive enzymes, breaking down and recycling cellular waste
Golgi Apparatus is a complex of flattened sacs and tubules, involved in protein modification and secretion

Passive transport involves the movement of molecules from high to low concentration, requiring no energy
Diffusion is the movement of molecules from high to low concentration until equilibrium
Osmosis is the movement of water molecules through a selectively permeable membrane
Active transport involves the movement of molecules from low to high concentration, requiring energy
Pumps use energy to move molecules against the concentration gradient
Carrier proteins bind to molecules and transport them across the membrane

Mitosis is the process of cell division resulting in two daughter cells with the same number of chromosomes as the parent cell
Interphase involves cell growth and preparation for cell division
Prophase involves chromatin condensing and the nuclear envelope breaking down
Metaphase involves chromosomes lining up at the center of the cell
Anaphase involves sister chromatids separating
Telophase involves the nuclear envelope reforming and chromatin uncoiling
Meiosis is the process of cell division resulting in four daughter cells with half the number of chromosomes as the parent cell

Signal transduction pathways are a series of molecular events that transmit signals from receptors to responses
Receptors are proteins that bind to signaling molecules (ligands)
Signaling molecules include hormones, neurotransmitters, growth factors, etc.
Response is the cellular response to the signal, e.g. gene expression, protein activation