Biochemistry Chapter 17 - Introduction to Metabolism

ATP is the universal carrier of chemical energy in biological systems.

ATP consists of adenine, a nitrogenous base, bound to a ribose sugar. This unit is then attached to three phosphate groups in a chain, creating a triphosphate structure.

The hydrolysis of ATP produces ADP (adenosine diphosphate) and inorganic phosphate (Pi).

<p>The hydrolysis of ATP releases energy, making it an exergonic reaction. This energy can then be used to drive endergonic reactions, which require energy input.</p> Signup and view all the answers

<p>NADP+ is a phosphorylated version of NAD+, possessing an additional phosphate group compared to NAD+.</p> Signup and view all the answers

<p>The essential portion of both NAD+ and NADP+ is the nicotinamide fragment, responsible for electron transfer.</p> Signup and view all the answers

<p>'High-energy chemical bond' in ATP refers to the bonds between the phosphate groups.</p> Signup and view all the answers

<p>ATP can be directly hydrolyzed into AMP by removing pyrophosphate (PPi), a cluster of two phosphate groups.</p> Signup and view all the answers

<p>Metabolic pathways are a series of biochemical reactions catalyzed by specific enzymes. These reactions work sequentially, with the product of one reaction serving as the substrate for the next.</p> Signup and view all the answers

<p>Enzymes in metabolic pathways can be loosely organized, meaning they function independently but collaboratively, or they can be complexed together in a multi-enzyme complex, facilitating a more coordinated and efficient process. They can also be located in specific cellular compartments like the cytosol, mitochondria, or embedded within membranes.</p> Signup and view all the answers

<p>Cofactors, including coenzymes and metal ions, are essential for the activity of many enzymes. They provide the necessary chemical environment or participate directly in the catalytic process.</p> Signup and view all the answers

<p>Anabolic reactions are building processes, consuming energy to synthesize complex molecules from simpler ones. Catabolic reactions break down complex molecules into simpler ones, releasing energy in the process.</p> Signup and view all the answers

<p>Many essential cofactors that are required for specific enzymatic reactions are organic molecules that humans cannot synthesize. These cofactors, or their building blocks, are often derived from our diet and are classified as vitamins.</p> Signup and view all the answers

<p>Lipids (or triglycerides)</p> Signup and view all the answers

<p>Glycolysis is a central metabolic pathway that breaks down glucose into pyruvate, generating ATP (energy). It occurs in the cytosol and is a crucial pathway for energy production.</p> Signup and view all the answers

<p>Both types of pathways involve sequential enzymatic reactions. In loosely organized pathways, enzymes function independently, allowing for more flexibility and potential branching. In multi-enzyme complexes, enzymes are tightly linked, facilitating a more directed and efficient process.</p> Signup and view all the answers

<p>All of these nutrient classes can be broken down to acetyl-CoA (AcCoA).</p> Signup and view all the answers

<p>Aerobes require oxygen for survival, while anaerobes cannot tolerate oxygen.</p> Signup and view all the answers

<p>Metal ions like Fe2+ and Cu2+ serve as essential cofactors for many enzymes, particularly those involved in redox reactions. These ions facilitate electron transfer and other chemical transformations required for enzymatic activity.</p> Signup and view all the answers

<p>Facultative anaerobes can switch between aerobic and anaerobic metabolism depending on the presence or absence of oxygen.</p> Signup and view all the answers

<p>Phototrophs utilize sunlight, while chemotrophs use redox reactions for energy.</p> Signup and view all the answers

<p>Autotrophs obtain carbon from CO2, while heterotrophs obtain carbon from organic molecules like carbohydrates.</p> Signup and view all the answers

<p>Humans are chemoheterotrophs, relying on organic molecules from other organisms for both their carbon and energy sources.</p> Signup and view all the answers

<p>Excess carbohydrates can be converted into fats in our bodies.</p> Signup and view all the answers

<p>NAD+ or NADP+ acts as electron carriers, capturing a pair of electrons released during catabolic reactions and converting them into ATP or making them available for anabolic reactions.</p> Signup and view all the answers

<p>NAD+ or NADP+ is reduced to NADH or NADPH. The nicotinamide portion of the molecule accepts a hydride anion (a hydrogen ion with two electrons: H:-), gaining the electrons and becoming reduced.</p> Signup and view all the answers

<p>While both are reduced forms of NAD+, NADH is primarily involved in ATP production through the electron transport chain. NADPH plays a vital role in reductive biosynthesis reactions, supplying electrons for building molecules like fatty acids and steroids.</p> Signup and view all the answers

<p>FAD (flavin adenine dinucleotide) is another important electron carrier in metabolic pathways. It captures a pair of electrons in a two-step process, ultimately becoming FADH2, which carries chemical energy that can be used for ATP production.</p> Signup and view all the answers

<p>Oxidation in organic compounds can be recognized by an increase in oxygen atoms in the structure or a decrease in hydrogen atoms in the structure.</p> Signup and view all the answers

<p>The energy of a chemical bond is directly linked to the electrons shared between the atoms. The pair of electrons, through their interactions and energy levels, determine the bond's strength and the energy stored within it.</p> Signup and view all the answers

<p>Redox reactions are fundamental to biochemical processes because they drive energy transfers and allow for the construction and breakdown of molecules essential for life.</p> Signup and view all the answers

<p>Metabolic pathways are likened to a system of interstates, with biochemical molecules like cars traversing them, moving through different biochemical pathways that may intersect and redirect traffic depending on the cell's needs.</p> Signup and view all the answers

<p>ATP is the universal carrier of chemical energy, used by all organisms to drive biosynthesis, cellular processes, and replication.</p> Signup and view all the answers

<p>Aerobic life forms utilize oxygen as a final electron acceptor, reducing it to water. Anaerobic life forms use different electron acceptors, such as sulfate (SO42-) reduced to sulfide (S2-) in their metabolic endpoints.</p> Signup and view all the answers

<p>The citric acid or Krebs cycle is the central hub of metabolism, where the breakdown products of all nutrients converge. It facilitates complete oxidation of carbons to CO2 and generates important cofactors like NADH and FADH2.</p> Signup and view all the answers

<p>NADH and FADH2 act as electron carriers that initiate ATP synthesis in the electron transport process. They collect electrons from the Krebs cycle and deliver them to the electron transport chain.</p> Signup and view all the answers

<p>Metabolic pathways are interconnected and flexible. They redirect biomolecule traffic based on the cell's requirements, ensuring efficient utilization of resources and synthesis of essential molecules.</p> Signup and view all the answers

<p>The main source of chemical energy for all organisms is ATP.</p> Signup and view all the answers

<p>The text implies that metabolic pathways are complex and interconnected, requiring a detailed understanding of individual biochemical reactions and their interconnectedness.</p> Signup and view all the answers