Cell Structure and Cell Membrane

The cell is the basic unit of life, consisting of:
- Plasma membrane (cell membrane)
- Cytoplasm ( jelly-like substance inside the cell membrane)
- Genetic material (DNA or RNA)

Also known as the plasma membrane
Semi-permeable membrane that surrounds the cell
Functions:
- Regulates what enters and leaves the cell
- Maintains cell shape
- Protects the cell from its environment
- Allows cell signaling and communication
Composed of:
- Phospholipid bilayer (hydrophobic tails and hydrophilic heads)
- Proteins (integral and peripheral)
- Cholesterol (helps maintain fluidity)

Process by which a cell becomes two daughter cells:
1. Interphase:
  - Cell grows, replicates its DNA, and prepares for cell division
2. Mitosis:
  - Division of the replicated DNA into two identical sets of chromosomes
  - Four stages: Prophase, Metaphase, Anaphase, and Telophase
3. Cytokinesis:
  - Division of the cytoplasm and formation of two daughter cells
Types of cell division:
- Mitosis: Results in two diploid daughter cells (same number of chromosomes as the parent cell)
- Meiosis: Results in four haploid daughter cells (half the number of chromosomes as the parent cell)

Movement of molecules across the cell membrane:
1. Passive Transport:
  - No energy required
  - Types: Diffusion, Osmosis, and Facilitated Diffusion
2. Active Transport:
  - Energy required
  - Types: Pumping, Vesicular Transport, and Receptor-Mediated Endocytosis
Mechanisms of cell transport:
- Diffusion: Random movement of molecules from high to low concentration
- Osmosis: Movement of water molecules from high to low concentration
- Facilitated Diffusion: Assisted movement of molecules with the help of transport proteins
- Pumping: Movement of molecules against their concentration gradient using energy

The cell is the basic unit of life, consisting of plasma membrane, cytoplasm, and genetic material.
Plasma membrane is semi-permeable, regulating what enters and leaves the cell, maintaining cell shape, protecting the cell, and allowing cell signaling and communication.
Genetic material can be DNA or RNA.

Composed of phospholipid bilayer with hydrophobic tails and hydrophilic heads, proteins (integral and peripheral), and cholesterol.
Cholesterol helps maintain fluidity in the membrane.

Contains digestive enzymes that break down and recycle cellular waste and foreign substances.

Mitosis: Results in two diploid daughter cells (same number of chromosomes as the parent cell).
Meiosis: Results in four haploid daughter cells (half the number of chromosomes as the parent cell).

Diffusion: Random movement of molecules from high to low concentration.
Osmosis: Movement of water molecules from high to low concentration.
Facilitated Diffusion: Assisted movement of molecules with the help of transport proteins.
Pumping: Movement of molecules against their concentration gradient using energy.