Cell Biology: Basic Unit of Life

Cell Biology

Basic Unit of Life

• Cells are the fundamental units of life.
• All living organisms are composed of cells, which are classified into two main types: prokaryotic and eukaryotic.

Prokaryotic Cells

• Lack a nucleus and membrane-bound organelles.
• Generally smaller and simpler than eukaryotic cells.
• Examples include bacteria and archaea.
• Genetic material is usually a single circular DNA molecule.

Eukaryotic Cells

• Contain a nucleus and membrane-bound organelles.
• Larger and more complex than prokaryotic cells.
• Examples include plant cells, animal cells, fungi, and protists.
• Genetic material is organized into multiple linear chromosomes.

Cell Organelles

• Nucleus: Contains genetic material (DNA) and controls cellular activities.
• Mitochondria: Powerhouse of the cell; site of ATP production through respiration.
• Ribosomes: Site of protein synthesis; can be free-floating or attached to the endoplasmic reticulum.
• Endoplasmic Reticulum (ER):
  • Rough ER: Studded with ribosomes; synthesizes proteins.
  • Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or for use within the cell.
• Lysosomes: Contain digestive enzymes to break down waste and cellular debris.
• Chloroplasts (in plant cells): Site of photosynthesis; contain chlorophyll.
• Cell Membrane: Semi-permeable barrier that regulates the movement of substances in and out of the cell.

Cell Division

• Mitosis: Process by which a eukaryotic cell divides to produce two identical daughter cells.
  • Phases: Prophase, Metaphase, Anaphase, Telophase.
• Meiosis: Specialized form of cell division that produces gametes (sperm and eggs) with half the chromosome number.

Cellular Processes

• Cellular Respiration: Process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.
• Photosynthesis: Process by which plants convert light energy into chemical energy in the form of glucose, using carbon dioxide and water.
• Protein Synthesis: Involves transcription (DNA to mRNA) and translation (mRNA to protein).

Cell Communication

• Cells communicate through signaling molecules and receptors.
• Types of signaling include autocrine, paracrine, endocrine, and synaptic signaling.

Cell Theory

• All living organisms are made of cells.
• The cell is the basic unit of life.
• All cells arise from pre-existing cells.

Basic Unit of Life

• Cells serve as the essential building blocks of all living organisms.
• Two primary cell types exist: prokaryotic and eukaryotic.

Prokaryotic Cells

• Characterized by the absence of a nucleus and membrane-bound organelles.
• Typically smaller and less complex compared to eukaryotic cells.
• Include organisms like bacteria and archaea.
• Possess genetic material primarily in the form of a single circular DNA molecule.

Eukaryotic Cells

• Defined by the presence of a nucleus and membrane-bound organelles.
• Generally larger and more intricate than prokaryotic cells.
• Examples encompass plant cells, animal cells, fungi, and protists.
• Genetic material is organized into multiple linear chromosomes.

Cell Organelles

• Nucleus: Houses DNA, directing cellular functions and activities.
• Mitochondria: Known as the powerhouse of the cell; responsible for ATP production through cellular respiration.
• Ribosomes: Sites for protein synthesis, found freely in the cytoplasm or bound to the endoplasmic reticulum.
• Endoplasmic Reticulum (ER):
  • Rough ER: Contains ribosomes; involved in protein synthesis.
  • Smooth ER: Lacks ribosomes; functions in lipid synthesis and detoxification processes.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for export or internal use.
• Lysosomes: Contain enzymes for digesting waste materials and cellular debris.
• Chloroplasts: Present in plant cells; the site for photosynthesis, containing chlorophyll.
• Cell Membrane: A semi-permeable structure that regulates substance movement in and out of the cell.

Cell Division

• Mitosis: A process that enables eukaryotic cells to divide, resulting in two identical daughter cells.
  • Key phases include Prophase, Metaphase, Anaphase, and Telophase.
• Meiosis: A specialized cell division leading to the formation of gametes (sperm and eggs) with half the chromosome count.

Cellular Processes

• Cellular Respiration: Converts glucose and oxygen into energy (ATP), carbon dioxide, and water.
• Photosynthesis: Utilized by plants to transform light energy into chemical energy (glucose), using carbon dioxide and water.
• Protein Synthesis: Comprises two main stages—transcription (DNA to mRNA) and translation (mRNA to protein).

Cell Communication

• Involves signaling through molecules and corresponding receptors.
• Signaling types include autocrine, paracrine, endocrine, and synaptic signaling.

Cell Theory

• Establishes that all living organisms are cellular in nature.
• Affirms that the cell is the fundamental unit of life.
• States that all cells originate from pre-existing cells.