Cell Biology: Cell Structure

Cell Membrane: Semi-permeable membrane that separates the cell from its environment
- Composed of phospholipid bilayer, proteins, and cholesterol
- Regulates what enters and leaves the cell
Cytoplasm: Jelly-like substance inside the cell membrane
- Composed of water, salts, sugars, and various organelles
- Site of metabolic reactions
Nucleus: Control center of the cell
- Contains DNA, the genetic material
- Surrounded by a double membrane called the nuclear envelope
Organelles: Specialized structures within the cell
- Examples: mitochondria, ribosomes, lysosomes, Golgi apparatus, endoplasmic reticulum

Metabolism: Chemical reactions that occur within the cell
- Involves energy conversion, synthesis, and breakdown of molecules
- Examples: photosynthesis, respiration, glycolysis
Cell Division: Process of cell growth and reproduction
- Mitosis: Division of somatic cells (body cells)
- Meiosis: Division of gametes (sex cells)
Cell Signaling: Communication between cells
- Involves reception, transmission, and response to signals
- Examples: hormone signaling, neurotransmission

Passive Transport: Movement of molecules without energy input
- Diffusion: Random movement of molecules from high to low concentration
- Osmosis: Movement of water molecules through a selectively permeable membrane
- Facilitated Diffusion: Assisted transport of molecules through a transport protein
Active Transport: Movement of molecules against their concentration gradient
- Requires energy input (e.g., ATP)
- Examples: pumping ions against their concentration gradient

Interphase: Period of cell growth and preparation for cell division
- G1 phase: Cell growth and DNA replication
- G2 phase: Preparation for cell division
M phase: Cell division (mitosis and cytokinesis)
Checkpoint: Regulation points in the cell cycle to ensure proper progression
- Examples: G1/S checkpoint, G2/M checkpoint

Cell Membrane: A semi-permeable membrane that separates the cell from its environment, composed of phospholipid bilayer, proteins, and cholesterol, regulating what enters and leaves the cell.
Cytoplasm: A jelly-like substance inside the cell membrane, composed of water, salts, sugars, and various organelles, serving as the site of metabolic reactions.
Nucleus: The control center of the cell, containing DNA, the genetic material, surrounded by a double membrane called the nuclear envelope.
Organelles: Specialized structures within the cell, including mitochondria, ribosomes, lysosomes, Golgi apparatus, and endoplasmic reticulum.

Metabolism: Chemical reactions that occur within the cell, involving energy conversion, synthesis, and breakdown of molecules, including photosynthesis, respiration, and glycolysis.
Cell Division: The process of cell growth and reproduction, involving mitosis (division of somatic cells) and meiosis (division of gametes).
Cell Signaling: Communication between cells, involving reception, transmission, and response to signals, including hormone signaling and neurotransmission.

Passive Transport: The movement of molecules without energy input, including diffusion (random movement of molecules from high to low concentration), osmosis (movement of water molecules through a selectively permeable membrane), and facilitated diffusion (assisted transport of molecules through a transport protein).
Active Transport: The movement of molecules against their concentration gradient, requiring energy input (e.g., ATP), such as pumping ions against their concentration gradient.

Interphase: The period of cell growth and preparation for cell division, consisting of G1 phase (cell growth and DNA replication) and G2 phase (preparation for cell division).
M phase: The stage of cell division, including mitosis and cytokinesis.
Checkpoint: Regulation points in the cell cycle to ensure proper progression, including G1/S checkpoint and G2/M checkpoint.