Cell Structure and Function

Semi-permeable membrane that separates cell from environment
Composed of phospholipid bilayer with embedded proteins
Functions:
- Regulates what enters and leaves the cell
- Maintains cell shape and structure
- Provides mechanical support and protection

Passive Transport:
- Diffusion: movement of molecules from high to low concentration
- Osmosis: movement of water molecules through a selectively permeable membrane
- Facilitated Diffusion: assisted diffusion through transport proteins
Active Transport:
- Requires energy (ATP) to move molecules against concentration gradient
- Examples: pumping ions, transporting molecules into/out of cell

Types:
- Mitosis: division of somatic cells (body cells) resulting in 2 identical daughter cells
- Meiosis: division of sex cells (gametes) resulting in 4 non-identical daughter cells
Stages of Cell Division:
1. Interphase: cell growth and preparation for division
2. Prophase: condensation of chromosomes and breakdown of nuclear envelope
3. Metaphase: alignment of chromosomes at cell center
4. Anaphase: separation of sister chromatids
5. Telophase: reconstruction of nuclear envelope and chromosomes uncoil
6. Cytokinesis: division of cytoplasm and separation of daughter cells

Nucleus: contains genetic material (DNA) and regulates gene expression
Mitochondria: generates energy for the cell through cellular respiration
Endoplasmic Reticulum (ER):
- Rough ER: involved in protein synthesis and transport
- Smooth ER: involved in lipid synthesis and detoxification
Ribosomes: site of protein synthesis
Lysosomes: contains digestive enzymes for breaking down cellular waste and foreign substances
Golgi Apparatus: involved in protein modification, sorting, and packaging for transport
Cytoskeleton: provides structural support, shape, and movement to the cell

Eukaryotic cells have a true nucleus, which contains genetic material, and membrane-bound organelles that perform specific functions.
Prokaryotic cells lack a true nucleus and membrane-bound organelles, making them smaller and simpler in structure.
Cell shape and size vary depending on the function they perform and the environment they inhabit.

The cell membrane is a semi-permeable membrane that separates the cell from its environment.
It is composed of a phospholipid bilayer with embedded proteins that help regulate the movement of molecules.
The cell membrane has three main functions: regulating what enters and leaves the cell, maintaining cell shape and structure, and providing mechanical support and protection.

Passive transport is the movement of molecules from an area of high concentration to an area of low concentration without the use of energy.
Diffusion is the movement of molecules from high to low concentration until equilibrium is reached.
Osmosis is the movement of water molecules through a selectively permeable membrane from an area of high concentration to an area of low concentration.
Facilitated diffusion is the assisted diffusion of molecules through transport proteins, which helps to speed up the process.
Active transport is the movement of molecules against their concentration gradient using energy from ATP.
Active transport is used to pump ions, transport molecules into or out of the cell, and maintain proper ion balance.

Mitosis is the division of somatic cells (body cells) resulting in two identical daughter cells.
Meiosis is the division of sex cells (gametes) resulting in four non-identical daughter cells.
Interphase is the stage of cell division where the cell grows and prepares for division.
Prophase is the stage of cell division where the chromosomes condense and the nuclear envelope breaks down.
Metaphase is the stage of cell division where the chromosomes align at the cell center.
Anaphase is the stage of cell division where the sister chromatids separate.
Telophase is the stage of cell division where the nuclear envelope reforms and the chromosomes uncoil.
Cytokinesis is the stage of cell division where the cytoplasm divides and the daughter cells separate.

The nucleus is the organelle that contains genetic material (DNA) and regulates gene expression.
Mitochondria are the organelles responsible for generating energy for the cell through cellular respiration.
Rough ER is involved in protein synthesis and transport, while smooth ER is involved in lipid synthesis and detoxification.
Ribosomes are the site of protein synthesis.
Lysosomes contain digestive enzymes for breaking down cellular waste and foreign substances.
The Golgi apparatus is involved in protein modification, sorting, and packaging for transport.
The cytoskeleton provides structural support, shape, and movement to the cell.