Results for "Hydrogen Atoms"

1.14 Contrast the energy change that occurs when two helium atoms or two hydrogen atoms combine.

Here are the answers to your biology questions: 1. Definitions: * Metabolism: The sum total of all chemical reactions that occur within a living organism. * Catabolism: The breakdown of complex molecules into simpler ones, releasing energy. * Anabolism: The synthesis of complex molecules from simpler ones, requiring energy input. * Endergonic Reaction: A reaction that requires an input of energy to proceed. * Exergonic Reaction: A reaction that releases energy. 2. Role of Enzymes in Metabolism: Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy. They bind to specific substrates, forming an enzyme-substrate complex, and catalyze the reaction. This allows metabolic processes to occur at rates compatible with life. 3. Enzyme Activity: * Activation Energy: The minimum amount of energy required for a reaction to occur. * Catalyst: A substance that speeds up a chemical reaction without being consumed in the process. * Active Site: The specific region on an enzyme where the substrate binds. * Denaturation: The loss of an enzyme's shape and function, often due to extreme temperature or pH. * Substrate: The molecule upon which an enzyme acts. * Enzyme-Substrate Complex: A temporary complex formed when an enzyme binds to its substrate. * Suffix -ase: Commonly used to denote enzymes, such as sucrase, protease, and lipase. 4. Oxidation-Reduction Reactions in Cellular Respiration: In cellular respiration, oxidation-reduction reactions involve the transfer of electrons and hydrogen ions. Oxidation is the loss of electrons (and often hydrogen atoms), while reduction is the gain of electrons (and often hydrogen atoms). Energy is released during these reactions and is used to produce ATP. 5. Balanced Equation for Cellular Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP) 6. Structure of a Mitochondrion: * Outer Membrane: Encloses the mitochondrion. * Inner Membrane: Folded into cristae, increasing surface area for ATP production. * Intermembrane Space: The space between the outer and inner membranes. * Matrix: The fluid-filled space inside the inner membrane, containing enzymes for the citric acid cycle. 7. Glycolysis: Glycolysis is the breakdown of glucose into pyruvate. It occurs in the cytoplasm and produces 2 ATP, 2 NADH, and 2 pyruvate molecules. 8. Citric Acid Cycle: The citric acid cycle, also known as the Krebs cycle, occurs in the mitochondrial matrix. It completely oxidizes pyruvate, producing 2 ATP, 6 NADH, and 2 FADH₂ molecules per glucose molecule. 9. Electron Transport Chain and Oxidative Phosphorylation: The electron transport chain is a series of protein complexes embedded in the inner mitochondrial membrane. Electrons from NADH and FADH₂ are transferred through the chain, releasing energy that is used to pump protons into the intermembrane space. The resulting proton gradient drives ATP synthesis through ATP synthase. 10. ATP and NADH Production: * Glycolysis: 2 ATP, 2 NADH * Citric Acid Cycle: 2 ATP, 6 NADH, 2 FADH₂ * Electron Transport Chain: ~32 ATP (from NADH and FADH₂) 11. Structure and Function of a Dicot Leaf: Dicot leaves are typically broad and flat, with a network of veins. They have a waxy cuticle to prevent water loss, stomata for gas exchange, and mesophyll cells containing chloroplasts for photosynthesis. 12. Structure of a Chloroplast: * Thylakoid: A flattened, disc-shaped sac. * Thylakoid Membrane: The membrane surrounding the thylakoid. * Thylakoid Space: The interior of the thylakoid. * Stroma: The fluid-filled space outside the thylakoids. * Grana: Stacks of thylakoids. 13. Site of Light-Dependent and Light-Independent Reactions: * Light-Dependent Reactions: Thylakoid membrane * Light-Independent Reactions (Calvin Cycle): Stroma 14. Balanced Equation for Photosynthesis: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ * Carbon (C) from CO₂ is incorporated into glucose. * Hydrogen (H) from water (H₂O) is incorporated into glucose. * Oxygen (O) from water is released as O₂. 15. Dual Nature of Light: Light exhibits both wave-like and particle-like properties. As a wave, it has a wavelength and frequency. As a particle, it consists of photons, discrete packets of energy. 16. Light Reactions: Light energy is absorbed by pigments in photosystems I and II, exciting electrons. These electrons are transferred through a series of electron carriers, generating ATP and NADPH. Water is split, releasing oxygen as a byproduct. 17. Calvin Cycle: The Calvin cycle uses ATP and NADPH from the light reactions to fix CO₂ from the atmosphere. CO₂ is incorporated into RuBP, forming 3-PGA. 3-PGA is reduced to G3P, which can be used to synthesize glucose or regenerate RuBP. 18. Role of Photosynthetic Pigments: Photosynthetic pigments, such as chlorophyll a, chlorophyll b, and carotenoids, absorb light energy and transfer it to the reaction center of photosystems. 19. Role of Photosystems: Photosystems I and II are protein complexes containing pigments and electron carriers. They absorb light energy and use it to excite electrons, initiating the electron transport chain. 20. Phases of the Calvin Cycle: * Carbon Fixation: CO₂ is fixed to RuBP, forming 3-PGA. * Reduction: 3-PGA is reduced to G3P using ATP and NADPH. * Regeneration of RuBP: G3P is used to regenerate RuBP, allowing the cycle to continue. 21. ATP, NADPH, and CO₂ Requirements: * To produce 1 G3P molecule: 9 ATP, 6 NADPH, and 3 CO₂ * To produce 1 glucose molecule: 18 ATP, 12 NADPH, and 6 CO₂ I

Chapter Summary 2.1 The Importance of Chemistry in Anatomy and Physiology Chemicals are all around us. Household products such as soap and shampoo as well as food and medicine are comprised of chemicals. The human body is also made of chemicals. We begin our examination of anatomy and physiology with a study of basic chemistry. 2.2 Fundamentals of Chemistry Matter is anything that has mass and takes up space. 1. Elements and atoms a. Naturally occurring matter on Earth is composed of ninety-two elements. b. Elements usually combine to form compounds. c. Elements are composed of atoms. d. Atoms of different elements vary in size, weight, and ways of interacting. 2. Atomic structure a. An atom consists of electrons surrounding a nucleus, which has protons and neutrons. The exception is hydrogen, which has only a proton in its nucleus. b. Electrons are negatively charged, protons positively charged, and neutrons uncharged. c. A complete atom is electrically neutral. d. The atomic number of an element is equal to the number of protons in each atom. 3. Isotopes a. Isotopes are atoms with the same atomic number but different mass numbers (due to differing numbers of neutrons). The atomic weight of an element is the average of the mass numbers of its various isotopes. b. All the isotopes of an element react chemically in the same manner. c. Some isotopes are radioactive and release atomic radiation. 4. Molecules and compounds a. Two or more atoms may combine to form a molecule. b. A molecular formula represents the numbers and types of atoms in a molecule. c. If atoms of the same element combine, they produce molecules of that element. d. If atoms of different elements combine, they form molecules called compounds. 2.3 Bonding of Atoms When atoms form links called bonds, they gain, lose, or share electrons. Electrons occupy space in areas called electron shells that encircle an atomic nucleus. Atoms with completely filled outer shells are inert, whereas atoms with incompletely filled outer shells gain, lose, or share electrons and thus become stable. 1. Ionic bonds a. Atoms that lose electrons become positively charged (cations); atoms that gain electrons become negatively charged (anions). b. Ions with opposite charges attract and join by ionic bonds. 2. Atoms that share electrons join by covalent bonds. a. Nonpolar molecules result from an equal sharing of electrons. b. Polar molecules result from an unequal sharing of electrons. c. Hydrogen bonds may form within and between polar molecules. 3. Chemical reactions a. In a chemical reaction, bonds between atoms, ions, or molecules break or form. Starting materials are called reactants; the resulting atoms or molecules are called products. b. Three types of chemical reactions are synthesis, in which large molecules build up from smaller ones; decomposition, in which molecules break down; and exchange reactions, in which parts of two different molecules trade positions. c. Many reactions are reversible. The direction of a reaction depends upon the proportion of reactants and products and the energy available. d. Catalysts (enzymes) influence the rate (not the direction) of the reaction. 2.4 Electrolytes, Acids and Bases, and Salts Compounds that ionize in water are electrolytes. 1. Electrolytes that release hydrogen ions are acids, and those that release hydroxide or other ions that react with hydrogen ions are bases. a. Acids and bases react to form water and electrolytes called salts. 2. Acid and base concentrations a. pH represents the concentration of hydrogen ions (H+) and hydroxide ions (OH−) in a solution. b. A solution with equal numbers of H+ and OH− is neutral and has a pH of 7.0; a solution with more H+ than OH− is acidic (pH less than 7.0); a solution with fewer H+ than OH− is basic (pH greater than 7.0). c. A tenfold difference in hydrogen ion concentration separates each whole number in the pH scale. d. Buffers are chemicals that resist pH change. 2.5 Chemical Constituents of Cells Molecules containing carbon and hydrogen atoms are organic and are usually nonelectrolytes; other molecules are inorganic and are usually electrolytes. 1. Inorganic substances a. Water is the most abundant compound in the body. Many chemical reactions take place in water. Water transports chemicals and heat and helps release excess body heat. b. Oxygen releases energy for metabolic activities from glucose and other molecules. c. Carbon dioxide is produced when certain metabolic processes release energy. d. Inorganic salts provide ions needed in a variety of metabolic processes. e. Electrolytes must be present in certain concentrations inside and outside of cells. 2. Organic substances a. Carbohydrates provide much of the energy cells require and are built of simple sugar molecules. b. Lipids, such as triglycerides (fats), phospholipids, and steroids, supply energy and are used to build cell parts. 1) The building blocks of triglycerides are glycerol and three fatty acids. 2) The building blocks of phospholipids are glycerol, two fatty acids, and a phosphate group. 3) Steroids include rings of carbon atoms and are synthesized in the body from cholesterol. c. Proteins serve as structural materials, energy sources, hormones, cell surface receptors, antibodies, and enzymes that speed chemical reactions without being consumed. 1) The building blocks of proteins are amino acids. 2) Proteins vary in the numbers and types of their constituent amino acids; the sequences of these amino acids; and their three-dimensional structures, or conformations. 3) Primary structure is the amino acid sequence. Secondary structure comes from attractions between amino acids that are close together in the primary structure. Tertiary structure reflects attractions of far-apart amino acids and folds the molecule. The amino acid sequence determines the protein’s conformation. 4) The protein’s conformation determines its function. 5) Exposure to excessive heat, radiation, electricity, or certain chemicals can denature proteins. d. Nucleic acids constitute genes, the instructions that control cell activities, and direct protein synthesis. 1) The two types are RNA and DNA. 2) Nucleic acid building blocks are nucleotides. 3) DNA molecules store information that cell parts use to construct specific proteins. 4) RNA molecules help synthesize proteins. 5) DNA molecules are replicated, and an exact copy of the original cell’s DNA is passed to each of the newly formed cells resulting from cell division.

The concept of moles in chemistry is famously difficult to explain and understand. A mole is an amount of something, such as a mole of carbon dioxide or a mole of glucose. By definition, a mole is 6.02214076 × 10^23 particles or things. The problem that the mole solves for chemists Chemists want to react things together in such a way that there's nothing left over, for example, when reacting hydrogen and fluorine to make hydrogen fluoride. They need the exact same number of hydrogens and fluorines to achieve this. Counting out individual atoms for this purpose is impractical. Using the relative masses of atoms to solve the problem Hydrogen atoms are lighter than fluorine atoms, so a specific mass ratio is needed to ensure the same number of atoms in each pile. The mass ratio for hydrogen and fluorine atoms in a chemical reaction is 1:1. The mass ratio can be used to determine the required amounts of each substance for a reaction. Understanding atomic masses and isotopes The mass of an atom is mainly in its nucleus, and isotopes can affect the atomic mass of an element. Hydrogen and oxygen atoms have slightly different atomic masses due to isotopes. The formal definition of atomic mass units is based on the mass of the carbon isotope. The simplification of using moles Chemists can simplify the process by using moles, where 1 mole of an element represents its atomic mass in grams. This simplifies the calculations and ensures the perfect ratio of chemicals for a reaction. Conclusion The concept of moles in chemistry simplifies the process of determining the amounts of substances needed for a chemical reaction, based on the atomic masses of the elements involved. Moles provide a convenient way to express the amounts of substances in chemical equations.

Physics Concept #20: Quantum Physics (2) (Algebra Based)