Biochem Recit PDF

Cell Membrane communication, and structural support. - The cell membrane, also known as the - The membrane proteins plasma membrane, is the outer...

Cell Membrane communication, and structural support. - The cell membrane, also known as the - The membrane proteins plasma membrane, is the outermost function as membrane layer of a cell. It serves as a crucial channels, carrier molecules, boundary that separates the internal receptor molecules, enzymes, environment of the cell from its or structural supports in the external surroundings. membrane. - Cell membranes are selectively permeable, meaning that they allow Membrane channels - and carrier molecules some substances, but not others, to are involved with the movement of substances pass into or out of the cells. through the cell membrane. - Extracellular: Refers to substances located Receptor molecules - are part of an outside the cell. intercellular communication system that - Intracellular: Also known as cytoplasmic, enables cell recognition and coordination of refers to substances inside the cell. the activities of cells. Functions of the Cell Membrane Additionally, the cell membrane contains other molecules: 1. Encloses the cytoplasm - The cell membrane surrounds and contains the 1. Cholesterol - Cholesterol within the cytoplasm, providing a distinct phospholipid membrane gives it added boundary for the cell. strength and stability by limiting how 2. Acts as a selective barrier - It much the phospholipids can move. regulates what enters and exits the 2. Carbohydrates - Often attached to cell, maintaining a stable internal proteins or lipids on the extracellular environment. surface of the membrane, contributing 3. Supports cell contents - The to cell recognition and signaling. membrane provides structural support, helping maintain the cell's shape and Fluid-Mosaic Model integrity. 4. Cell communication - It facilitates The fluid-mosaic model describes the cell communication between cells, playing membrane's structure as a dynamic and a role in cellular signaling and flexible arrangement of phospholipids, interaction. proteins, cholesterol, and carbohydrates. It also highlights the fluid nature of the membrane, Composition of the Cell Membrane allowing lateral movement of molecules within the layer, contributing to the The cell membrane is primarily composed of membrane's functionality and adaptability. two major types of molecules: According to this model: 1. Phospholipids - These molecules Phospholipids form a double layer (bilayer) of form a bilayer, which is fundamental molecules where: to the membrane's structure. 2. Proteins - These are embedded within Polar - phosphate-containing ends of the phospholipid bilayer and play the phospholipids are hydrophilic various roles, including transport, (water-loving) and therefore face the  extracellular fluid and cytoplasm of Krebs cycle, and oxidative the cell. phosphorylation. Nonpolar - fatty acid ends of the - Have unequal sharing of electrons phospholipids are hydrophobic among atoms (water-fearing) and therefore face away from the fluid on either side of the membrane, toward the center of 3. Photosynthesis the double layer of phospholipids. - The process by which green plants, algae, and some bacteria convert light The double layer of phospholipids forms a energy, water, and carbon dioxide into lipid barrier between the inside and outside glucose and oxygen. This is a key of the cell. process for the production of energy-rich molecules and the release Biochemical Processes of oxygen into the atmosphere. - are the chemical reactions and pathways 4. Protein Synthesis that occur within living organisms to sustain - The process by which cells generate life. These processes involve the new proteins. This includes transformation of molecules through transcription (the synthesis of RNA enzymatic actions, leading to the production of from DNA) and translation (the energy, the synthesis of necessary assembly of proteins based on the biomolecules, and the regulation of cellular sequence of the RNA). activities. - are fundamental to all aspects of physiology 5. Enzyme Action and metabolism, allowing cells and organisms - Enzymes are biological catalysts that to grow, reproduce, respond to their speed up chemical reactions without environment, and maintain homeostasis. being consumed in the process. Enzyme activity is crucial for Types of Biochemical Processes regulating the speed and specificity of biochemical processes. 1. Metabolism Catabolism - The breakdown of 6. Signal Transduction complex molecules into simpler ones, - The process by which cells respond to releasing energy. Examples include the external signals, such as hormones or breakdown of glucose during growth factors, through a series of glycolysis and the citric acid cycle. biochemical reactions that lead to a Anabolism - The synthesis of specific cellular response. complex molecules from simpler ones, requiring energy. Examples include 7. DNA Replication and Repair protein synthesis and DNA - The processes involved in copying the replication. DNA of a cell before it divides, and in correcting errors in DNA to maintain 2. Cellular Respiration genetic integrity. - A series of metabolic processes that convert biochemical energy from 8. Detoxification nutrients into adenosine triphosphate - The process by which cells convert (ATP), which cells use as a source of toxic substances into less harmful energy. This includes glycolysis, the  ones, often through enzymatic action, Understanding these processes is essential for to protect the organism from damage. fields such as medicine, biotechnology, and environmental science, as it allows for the ATP - consists of adenosine and three development of treatments, innovations, and phosphate groups. solutions for various biological challenges. - ATP is synthesized when adenosine diphosphate (ADP), which has two (di-) phosphate groups, combines with Water a phosphate group to form the larger - is an essential molecule for all known ATP molecule. forms of life, playing a crucial role in many biological, chemical, and Example of Biochemical Process in Cellular physical processes. Its unique Respiration properties are due to its molecular structure and the hydrogen bonds that form between water molecules. - 70% of the planet is covered in water, as well as our bodies Properties of Water 1. Polarity - Water is a polar molecule, meaning it has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity allows water to form hydrogen bonds with other polar molecules and ions, making it an excellent solvent. 2. Cohesion - Cohesion is the attraction between Importance of Biochemical Processes molecules of the same substance. In water, cohesion is the result of Biochemical processes are vital because they hydrogen bonds between water enable organisms to: molecules. This property contributes Generate and store energy for cellular to water's high surface tension, functions. allowing it to form droplets and Build and repair cellular structures enabling small insects to walk on its such as membranes, proteins, and surface. nucleic acids. 3. Adhesion Regulate physiological functions such - Adhesion is the attraction between as digestion, respiration, and immune water molecules and other substances. response. Water’s adhesion to other materials, Communicate and adapt to such as glass, is due to its polarity. environmental changes through This property is essential for processes signaling pathways. like capillary action, where water moves up thin tubes or through porous  materials, which is crucial for water move across its surface without transport in plants. sinking. 4. High Specific Heat Capacity 9. Capillary Action - Water has a high specific heat - Capillary action occurs when water capacity, meaning it can absorb or rises against gravity in a narrow space, release a large amount of heat with such as a thin tube or plant xylem. only a slight change in its temperature. This property results from both This property helps stabilize cohesion and adhesion, enabling water temperatures in the environment and to move through small spaces and is within living organisms, providing a vital for the movement of water and buffer against extreme temperature nutrients in plants. changes. 5. High Heat of Vaporization Biological Significance of Water's Properties - Water requires a significant amount of Temperature Regulation - Water's energy to change from a liquid to a gas high specific heat helps organisms due to the strength of hydrogen bonds. maintain a stable internal temperature. This high heat of vaporization allows Transport Medium - Its solvent water to effectively cool surfaces properties make water an ideal through evaporation, which is vital for medium for transporting substances processes like sweating and like nutrients, gases, and waste transpiration in plants. products within organisms and 6. Density and Expansion upon ecosystems. Freezing Chemical Reactions - Water is - Unlike most substances, water involved in many chemical reactions, expands and becomes less dense when including hydrolysis and condensation it freezes. Ice forms a crystalline reactions critical for metabolism. structure that is less dense than liquid Support and Structure - The water, which is why ice floats. This cohesive and adhesive properties of property insulates aquatic ecosystems water contribute to the structural in cold climates, allowing life to integrity of cells and tissues, survive under the ice layer. especially in plants. 7. Universal Solvent - Due to its polarity and ability to form hydrogen bonds, water is known as a universal solvent. It can dissolve a wide range of substances, including salts, sugars, acids, bases, and gases, making it essential for chemical reactions and transport of nutrients and waste products in biological systems. 8. High Surface Tension - Water has a high surface tension due to the cohesive forces between water molecules at the surface. This allows water to form droplets and provides the ability for some organisms to