Cell Biology: Basic Unit of Life

Prokaryotic Cells
- No nucleus; DNA is in the nucleoid region.
- Generally smaller and simpler.
- Example: Bacteria and Archaea.
Eukaryotic Cells
- Have a defined nucleus containing DNA.
- Larger and more complex.
- Examples: Plant cells, animal cells, fungi, protists.

Plasma Membrane
- Semi-permeable barrier that regulates entry and exit of substances.
Cytoplasm
- Jelly-like substance where cellular processes occur.
Organelles
- Specialized structures within cells:
  - Nucleus: Contains genetic material (DNA).
  - Mitochondria: Powerhouse of the cell; energy (ATP) production.
  - Endoplasmic Reticulum (ER):
    - Rough ER: Studded with ribosomes; synthesizes proteins.
    - Smooth ER: Involved in lipid synthesis and detoxification.
  - Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
  - Lysosomes: Contains digestive enzymes; breaks down waste.
  - Ribosomes: Sites of protein synthesis.
  - Chloroplasts (in plants): Site of photosynthesis.

Mitosis: Process of cell division resulting in two identical daughter cells.
- Phases: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis: Specialized cell division for producing gametes (sex cells).
- Results in four non-identical daughter cells with half the chromosome number.

Metabolism: All chemical reactions within a cell.
- Anabolism: Builds complex molecules.
- Catabolism: Breaks down molecules for energy.
Cellular Respiration: Conversion of glucose and oxygen to energy (ATP), producing carbon dioxide and water.
- Stages: Glycolysis, Krebs cycle, Electron transport chain.
Photosynthesis (in plants):
- Converts light energy into chemical energy.
- Takes place in chloroplasts; uses carbon dioxide and water to produce glucose and oxygen.

Communication between cells via signaling molecules.
Types:
- Autocrine: Affects the same cell that releases the signal.
- Paracrine: Affects nearby cells.
- Endocrine: Hormonal signaling affecting distant cells.

Understanding cell structure and function is crucial for fields like medicine, genetics, biotechnology, and ecology.

Prokaryotic Cells:
- Lack a nucleus; DNA is located in the nucleoid region.
- Smaller and simpler in structure.
- Examples include Bacteria and Archaea.
Eukaryotic Cells:
- Possess a defined nucleus that houses DNA.
- Generally larger and more complex than prokaryotic cells.
- Examples include plant cells, animal cells, fungi, and protists.

Plasma Membrane:
- Acts as a semi-permeable barrier to control substance movement in and out of the cell.
Cytoplasm:
- A jelly-like fluid where metabolic processes take place.
Organelles: Specialized cellular structures include:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Functions as the powerhouse of the cell, producing energy (ATP).
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; involved in protein synthesis.
  - Smooth ER: Engaged in lipid synthesis and detoxification processes.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
- Lysosomes: Contain digestive enzymes for breaking down waste materials.
- Ribosomes: The sites of protein synthesis in cells.
- Chloroplasts (in plant cells): Where photosynthesis occurs.

Mitosis: A process of cell division that produces two identical daughter cells.
- Key phases include Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis: A specialized division producing gametes, resulting in four non-identical cells with half the chromosome count.

Metabolism: Encompasses all chemical reactions occurring within a cell.
- Anabolism: Involves building complex molecules.
- Catabolism: The breakdown of molecules to release energy.
Cellular Respiration: Converts glucose and oxygen into energy (ATP), yielding carbon dioxide and water.
- Includes stages such as Glycolysis, Krebs cycle, and Electron transport chain.
Photosynthesis (in plants):
- Transforms light energy into chemical energy, occurring in chloroplasts.
- Utilizes carbon dioxide and water to produce glucose and oxygen.

Involves communication between cells through signaling molecules.
Types of signaling include:
- Autocrine: Affects the same cell that releases the signal.
- Paracrine: Affects adjacent cells.
- Endocrine: Hormones affecting distant cells.