Inleiding tot Biologie en Celbiologie

Introduction to Biology

• Biology is the scientific study of life.
• It encompasses a diverse range of organisms, from microscopic bacteria to large mammals.
• Key themes in biology include evolution, genetics, and ecology.

Cell Biology

• Cell biology is the study of the basic structural and functional units of life, the cells.
• All living organisms are composed of cells, either as single-celled organisms or complex multicellular organisms.
• Cells are highly organized structures, containing various organelles with specialized functions.

Cell Structure

• Plasma Membrane: The outer boundary of the cell, regulating the passage of substances in and out. It is selectively permeable.
• Cytoplasm: The jelly-like substance filling the cell, containing organelles.
• Nucleus (Eukaryotic cells): The control center of the cell, containing DNA, which stores genetic information.
• Ribosomes: Involved in protein synthesis. Found in both prokaryotic and eukaryotic cells.
• Endoplasmic Reticulum (ER): A network of membranes involved in protein and lipid synthesis. Rough ER has ribosomes, smooth ER does not.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
• Mitochondria: The powerhouses of the cell, responsible for cellular respiration and energy production. Double membrane structure.
• Lysosomes: Membrane-bound sacs containing digestive enzymes, breaking down waste materials and cellular debris.
• Vacuoles: Storage sacs, playing different roles in different cell types. Often much larger in plant cells.
• Chloroplasts (Plant cells only): Contain chlorophyll, enabling photosynthesis. Double membrane structure.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic: Smaller, simpler cells lacking membrane-bound organelles. Examples include bacteria and archaea.
• Eukaryotic: Larger, more complex cells containing membrane-bound organelles. Examples include animals, plants, fungi, and protists.

Cellular Processes

• Metabolism: The sum of all chemical reactions that occur within a cell.
• Respiration: The process by which cells break down glucose to release energy in the form of ATP.
• Photosynthesis: The process by which plants and other organisms convert light energy into chemical energy.
• Cell Division: The process by which cells reproduce, essential for growth, repair, and reproduction. Types include mitosis (somatic cells) and meiosis (gametes).
• Transcription & Translation: The processes by which genetic information in DNA is used to synthesize proteins.

Cell Communication

• Cellular communication is crucial to coordinating cell activities in multicellular organisms.
• Signals can be transmitted through direct contact, through the use of local mediators, or via long-distance signaling.
• Signal transduction pathways are involved in the cellular response to these signals.

Cell Function

• Maintaining homeostasis: regulating internal conditions.
• Responding to stimuli: adjusting to changes in the environment.
• Transporting substances: moving materials across the cell membrane.
• Utilizing energy for cellular processes: Respiration and Biosynthesis.
• Synthesizing proteins necessary for vital cellular functions.
• Cell division and differentiation in development (especially important in multicellular organisms).