Cell Biology Basics

Cells are the fundamental building blocks of all living organisms.
Two main types of cells: prokaryotic (no nucleus) and eukaryotic (nucleus present).

Complex structure, larger than prokaryotic cells.
Contains membrane-bound organelles (e.g., nucleus, mitochondria, endoplasmic reticulum).
DNA is linear and organized into chromosomes within the nucleus.
Examples: Animal cells, plant cells, fungal cells, and protists.

Nucleus: Control center containing genetic material (DNA).
Mitochondria: Powerhouse, site of ATP production (cellular respiration).
Chloroplasts: Site of photosynthesis in plant cells.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes, involved in protein synthesis.
- 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; break down waste materials and cellular debris.
Cell Membrane: Semi-permeable barrier that regulates the entry and exit of substances.

Consists of interphase (G1, S, G2) and mitotic phase (mitosis and cytokinesis).
Interphase: The cell grows and DNA is replicated.
Mitosis: Division of the nucleus; phases include prophase, metaphase, anaphase, and telophase.
Cytokinesis: Division of the cytoplasm, resulting in two daughter cells.

Cells communicate through signaling molecules (e.g., hormones, neurotransmitters).
Receptors on cell membranes receive signals and initiate responses.
Types of signaling: autocrine, paracrine, endocrine, and synaptic.

Passive Transport: Movement of substances across the cell membrane without energy (e.g., diffusion, osmosis).
Active Transport: Movement of substances against their concentration gradient, requiring energy (e.g., sodium-potassium pump).

Catabolism: Breakdown of molecules to release energy (e.g., glycolysis).
Anabolism: Synthesis of complex molecules from simpler ones, requiring energy (e.g., protein synthesis).

Programmed cell death, a crucial process for maintaining health by eliminating damaged cells.

Different cells have specialized functions (e.g., muscle cells, nerve cells, epithelial cells) based on their structure and organelle composition.

These notes provide a concise overview of key concepts in cell biology, essential for understanding the functions and structures of cells.

Cells are the essential units that make up all living organisms.
Two primary classifications of cells: prokaryotic cells (lack a nucleus) and eukaryotic cells (contain a nucleus).

Characterized by a simple structure and generally smaller than eukaryotic cells.
Do not possess membrane-bound organelles.
DNA is circular and situated in the nucleoid region.
Common examples include Bacteria and Archaea.

More complex in structure and larger compared to prokaryotic cells.
Contain membrane-bound organelles such as nucleus, mitochondria, and endoplasmic reticulum.
DNA is linear and organized into chromosomes located within the nucleus.
Examples include animal cells, plant cells, fungal cells, and protists.

Nucleus: Functions as the control center housing genetic material (DNA).
Mitochondria: Known as the powerhouse of the cell, responsible for ATP production via cellular respiration.
Chloroplasts: Specialized organelles in plant cells where photosynthesis occurs.
Endoplasmic Reticulum (ER):
- Rough ER is involved in protein synthesis and is studded with ribosomes.
- Smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification processes.
Golgi Apparatus: Organizes, modifies, and packages proteins for export or delivery to different organelles.
Lysosomes: Contain digestive enzymes that break down waste materials and cellular debris.
Cell Membrane: Semi-permeable barrier that controls the entry and exit of substances.

Comprises interphase (G1, S, G2) and the mitotic phase (mitosis and cytokinesis).
Interphase: Involves cell growth and DNA replication.
Mitosis: The process of nuclear division, featuring four key phases: prophase, metaphase, anaphase, and telophase.
Cytokinesis: The cytoplasmic division resulting in the formation of two daughter cells.

Cells use signaling molecules such as hormones and neurotransmitters for communication.
Receptors on cell membranes detect signals and initiate cellular responses.
Communication can occur via autocrine, paracrine, endocrine, and synaptic signaling.

Passive Transport: Involves the movement of substances across the cell membrane without the use of energy, including processes like diffusion and osmosis.
Active Transport: Requires energy to move substances against their concentration gradient, exemplified by the sodium-potassium pump.

Catabolism: Refers to the breakdown of molecules for energy release (e.g., glycolysis).
Anabolism: The process of synthesizing complex molecules from simpler ones, which requires energy (e.g., protein synthesis).

Programmed cell death crucial for maintaining overall health by removing damaged cells.

Cells differentiate and acquire specialized functions (such as muscle cells, nerve cells, epithelial cells) based on their structural and organelle variations.