Biology Chapter: Cell Structure and Function

Basic Unit of Life: Cells are the fundamental building blocks of all living organisms.
Components:
- Plasma Membrane: Semi-permeable barrier that surrounds the cell.
- Cytoplasm: Gel-like substance within the cell where organelles are suspended.
- Nucleus: Control center containing genetic material (DNA).
- Cytoskeleton: Network of fibers providing structure and shape.

Metabolism: Cells carry out chemical reactions to maintain life, including energy production.
Protein Synthesis: Cells produce proteins through transcription and translation processes.
Homeostasis: Regulation of internal conditions for optimal functioning.
Response to Stimuli: Ability to react to environmental changes.

Mitosis: Process of cell division resulting in two identical daughter cells; involves stages: prophase, metaphase, anaphase, and telophase.
Meiosis: Specialized cell division for gamete production; results in four genetically diverse cells.
Importance: Essential for growth, repair, and reproduction.

Signal Transduction: Mechanism by which cells respond to external signals (hormones, neurotransmitters).
Cell Surface Receptors: Proteins on the cell membrane that bind to signaling molecules.
Communication Types:
- Autocrine: Cell signals itself.
- Paracrine: Signals neighboring cells.
- Endocrine: Hormonal signals traveling through the bloodstream.

Prokaryotic Cells: Simple, unicellular organisms (e.g., bacteria) without a nucleus.
Eukaryotic Cells: Complex cells with a nucleus; can be unicellular (e.g., yeast) or multicellular (e.g., plants, animals).
Stem Cells: Undifferentiated cells with the potential to develop into different cell types.

Mitochondria: Powerhouse of the cell; produces ATP through cellular respiration.
Ribosomes: Sites of protein synthesis; can be free in the cytoplasm or attached to the endoplasmic reticulum.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes; involved in protein synthesis and processing.
- Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
Golgi Apparatus: Modifies, sorts, and packages proteins for secretion or delivery to other organelles.
Lysosomes: Contain digestive enzymes for breaking down waste materials and cellular debris.
Chloroplasts: Found in plant cells; site of photosynthesis, converting light energy to chemical energy.
Cell Wall: Rigid outer layer found in plant cells, providing support and protection.

Cells are the fundamental unit of life for all organisms.
Plasma membrane acts as a semi-permeable barrier, controlling entry and exit of substances.
Cytoplasm is a gel-like matrix where organelles are suspended, allowing for chemical reactions.
Nucleus serves as the control center, housing genetic material (DNA) that dictates cellular functions.
Cytoskeleton comprises a network of fibers that maintain cell shape and provide structural support.

Metabolism encompasses all chemical reactions within a cell, crucial for energy production.
Protein synthesis occurs through transcription (DNA to mRNA) and translation (mRNA to protein).
Homeostasis is the cell's ability to maintain stable internal conditions despite external changes.
Cells can respond to environmental stimuli, showcasing adaptability and interaction with surroundings.

Mitosis produces two identical daughter cells, involving stages: prophase, metaphase, anaphase, and telophase.
Meiosis creates four genetically diverse gametes, facilitating sexual reproduction.
Cell division is vital for organism growth, tissue repair, and reproduction processes.

Signal transduction refers to the processes by which cells interpret and respond to external signals, such as hormones and neurotransmitters.
Cell surface receptors are proteins that specifically bind to signaling molecules to initiate a cellular response.
Communication strategies include:
- Autocrine signaling where a cell responds to its own signals.
- Paracrine signaling involving communication with neighboring cells.
- Endocrine signaling that uses hormones traveling through the bloodstream for long-distance communication.

Prokaryotic cells are simple, unicellular organisms (e.g., bacteria) characterized by the absence of a nucleus.
Eukaryotic cells are more complex entities with a defined nucleus; they can be unicellular (like yeast) or multicellular (like plants and animals).
Stem cells are undifferentiated cells with the ability to transform into various cell types, playing a key role in development and regeneration.

Mitochondria, known as the powerhouse of the cell, generate ATP through cellular respiration processes.
Ribosomes are the sites of protein synthesis, found free in the cytoplasm or attached to the endoplasmic reticulum (ER).
Endoplasmic Reticulum (ER) is divided into:
- Rough ER, which is ribosome-studded and is critical for protein synthesis and modification.
- Smooth ER, which is free of ribosomes and is involved in lipid synthesis and detoxification processes.
Golgi apparatus modifies, sorts, and packages proteins for secretion or distribution to other organelles.
Lysosomes contain digestive enzymes to break down waste materials and cellular debris.
Chloroplasts are unique to plant cells, facilitating photosynthesis by converting light energy into chemical energy.
The cell wall is a rigid structure found in plant cells, providing additional support and protection.