Cell Biology Overview

Cell Biology

• Cells are the basic units of life, exhibiting a wide range of structures and functions.
• Prokaryotic cells lack a nucleus and membrane-bound organelles. Examples include bacteria and archaea.
• Eukaryotic cells have a nucleus and membrane-bound organelles like mitochondria and chloroplasts. Examples include plant and animal cells.
• Cellular structures perform specific functions: e.g., the nucleus contains DNA, ribosomes synthesize proteins, mitochondria generate ATP.
• Cell membranes are selectively permeable, controlling the movement of substances in and out of the cell.
• Diffusion, osmosis, and active transport are mechanisms for substance movement across cell membranes.
• Specialized cells are adapted for specific functions through structural and functional differences. e.g., nerve cells have long extensions for rapid signaling.

Organisation

• Organisms are organized into levels, from cells to organisms, with each level exhibiting emergent properties that arise from the interaction of components at the lower levels.
• Tissues are groups of similar cells performing a similar function.
• Organs are groups of tissues working together to perform specific functions to achieve a particular result within an organism.
• Organ systems are groups of organs working together to perform specific functions, e.g., the circulatory system.
• Organisms exhibit different levels of complexity, from unicellular to multicellular, with different modes of cellular organization depending on their complexity.
• Organisms have specific organelles and functions that achieve a particular end-result, e.g., plants utilize chloroplasts for photosynthesis.

Infection and Response

• Pathogens are disease-causing microorganisms like bacteria, viruses, fungi, and protists.
• Immune systems defend against pathogens through various mechanisms.
• Non-specific defenses, like skin and phagocytosis, provide a general defense against pathogens.
• Specific defenses, involving antibodies, lymphocytes (B and T cells) and the immune response, eliminate pathogens and provide lasting immunity.
• Vaccination stimulates the immune system to produce antibodies without causing the disease.
• Antigens are molecules that trigger an immune response. Antibodies bind to specific antigens.
• The inflammatory response is a localized response to tissue damage or infection, characterized by redness, swelling, heat, and pain.
• Understanding the immune response is crucial for developing effective treatments and preventive measures against infectious diseases.

Bioenergetics

• Organisms need energy for life processes like growth, reproduction, and movement.
• Photosynthesis is the process by which plants capture light energy and convert it to chemical energy in the form of glucose (a sugar).
• Respiration is the process by which organisms break down glucose to release energy in the form of ATP.
• Aerobic respiration requires oxygen and produces more ATP than anaerobic respiration (which doesn't require oxygen).
• Metabolic pathways involve multiple enzyme-catalysed reactions that either build up (anabolism) or break down (catabolism) molecules.
• Energy transfer occurs in cells in the form of ATP, a molecule that provides energy for various cellular processes.
• Energy transformations during photosynthesis and respiration illustrate the flow of energy through ecosystems.
• Organisms need a continuous supply of energy to maintain their bodies and to carry out their life processes.