Chapter 8
1. Explain the role of catabolic and anabolic pathways in cellular metabolism.
Catabolic pathways release energy by breaking down complex molecules to simpler compounds. Anabolic pathways consume energy to build complicated molecules from simpler ones.
2. Distinguish between kinetic and potential energy.
Kinetic energy is associated with the relative motion of objects. Potential energy is the energy that matter possesses because of its location or structure.
3. Explain the first and second laws of thermodynamics in your own words.
1st Law of Thermodynamics: conservation of energy; energy is transferred and transformed, not created or destroyed.
2nd Law of Thermodynamics: transformation increases entropy (randomness/disorder)
4. List the three main kinds of cellular work. Explain in general terms how cells obtain the energy to do cellular work.
- Chemical work: the pushing of endergonic reactions
- Transport work: the pumping of substances across membranes against the direction of spontaneous movement.
- Mechanical work: the contraction of muscle cells and the movement of chromosomes during cellular reproduction.
Cells manage their energy resources to do this work through energy coupling, the use of an exergonic process to drive an endergonic one.
5. Describe the structure of ATP and identify the major class of macromolecules to which ATP belongs.
ATP contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it. ATP is also one of the nucleoside triphosphates used to make RNA.
6. Explain how ATP performs cellular work.
When ATP hydrolyzes there is a release of energy and this energy is used to perform the three types of cellular work.
7. Describe the function of enzymes in biological systems.
An enzyme catalyzes a reaction by lowering the activation energy barrier, enabling the reactant molecules to absorb enough energy to reach the transition state, even at moderate temperatures. This eliminates the need to use heat to speed up the reaction because high temperatures can also denature proteins and kill cells.
8. Explain how enzyme structure determines enzyme specificity.
9. Explain the induced-fit model of enzyme functions.
Enzyme changes shape to bond with the substrate
10. Explain how temperature, pH, cofactors, and enzyme inhibitors can affect enzyme activity.
The rate of an enzyme reaction increases with increasing temperature up to a point. After that point, the rate of the reaction will drop. The same thing occurs with pH. The cofactors can be bound tightly or loosely to the enzyme. Coenzymes act as organic helpers and perform a crucial function in catalysis. Competitive inhibitors mimic the substrate. Noncompetitive inhibitors bind to another part of the enzyme altering its shape.
12. Describe the function of enzymes in biological systems.
An enzyme acts as a catalyst, which speeds up reactions. Enzymes are proteins in biological systems used to regulate the metabolism.
Key Terms
Metabolism: The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.
Metabolic Pathway: A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway)
Catabolic Pathways: A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.
Anabolic Pathways: A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.
Bioenergetic: (1) The overall flow and transformation of energy in an organism. (2) The study of how energy flows through organisms.
Energy: The capacity to cause change, especially to do work (to move matter against an opposing force).
Kinetic Energy: The energy associated with the relative motion of objects. Moving matter can preform work by imparting motion to other matter.
Heat/Thermal Energy: The total amount of kinetic energy due to the random motion of atoms or molecules in a bond of matter; also called thermal energy. Heat is energy in its most random form.
Potential Energy: The energy that matter possesses as a result of its location or spatial arrangement (structure).
Chemical Energy: Energy available in molecule's for release in a chemical reaction; a form of potential energy.
Thermodynamics: The study of energy transformations that occur in a collection of matter.
First Law of Thermodynamics: The principle of conservation of energy: energy can be transferred and transformed, but it cannot be created or destroyed.
Entropy: A measure of randomness or disorder.
Seconds Law of Thermodynamics: The principle stating that every energy transfer or transformation increases the entropy of the universe, Ordered forms of energy are at least partly converted to heat.
Free Energy: The portion of a biological system's energy that can perform work when temperature and pressure are uniform throughout the system. *the change in free energy of a system is calculated by the equation G=H-TS, where H is enthalpy [in biological systems, equivalent to total energy] T is also temperature, and S is entropy.
Exergonic Reaction: A spontaneous chemical reaction, in which there is a net realise of free energy.
Endergonic Reaction: A non-spontaneous chemical reaction, in which free energy is absorbed from the surroundings.
Energy Coupling: In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.
ATP (Adenosine Triphosphate): An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells.
Phosphorylated: Referring to a molecule that is covalently bonded to a phosphate group.
Enzyme: A macromolecule serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction.
Catalyst: A chemical agent that increases the rate of a reaction without being consumed by the reaction.
Activation Energy/Free Energy of Activation: The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation.
Substrate: The reactant on which an enzyme works.
Enzyme-Substrate Complex: A temporary complex formed when an enzyme binds to its substrate molecule.
Active Site: The specific portion of an enzyme that binds the substrate by means of multiple weak interactions and that forms the pocket in which catalysis occurs.
Induced Fit: Induced by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.
Cofactors: Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis.
Coenzyme: An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions.
Competitive Inhibitors: A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.
Noncompetitive Inhibitors: A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme's shape so that the active site no longer functions effectively.
Allosteric Regulation: The binding of a regulatory molecule to a protein at one site that affects the functions of the protein at a different site.
Cooperativity: A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the others, facilitation binding of subsequent substrate molecules.
Feedback Inhibition: A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
| 208206537 | List the four major classes of macromolecules. | Carbohydrates, lipids, proteins, amino acids | |
| 208206538 | Distinguish between monomers and polymers. | A monomer is a single building block of a substance while a polymer is a long chain of monomers. | |
| 208206539 | Distinguish among monosaccharides, disaccharides, and polysaccharides. | Monosaccharides are the simples sugars, can be used for fuel, can be converted into other organic molecules, can be combined into polymers. Disaccharides: consist of two monosaccharides and are joined by a glycosidic linkage (covalent bond) Polysaccharides are polymers of sugar and serve many roles in organisms. | |
| 208206540 | Describe the formation of a glycosidic linkage. | Maltose is a glucose bonded through glycosidic linkage to bond together with another glucose. Carbohydrates use glycosidic linkage. | |
| 208206541 | Distinguish between the glycosidic linkage found in starch and cellulose. Explain why the difference is biologically important. | Starches use glycosidic linkages only. Cellulose uses glycosidic linkages. | |
| 208206542 | Describe the role of symbiosis in cellulose digestion. | Symbiosis are two organisms living together (or inside of one another) in which they depend on each other for survival. Bacteria can break down cellulose and they live in the intestines. Host will benefit from bacteria. | |
| 208206543 | Describe the building-block molecules, structure, and biological importance of fats, phospholipids, and steroids. | Fats consist of glycerol plus 3 fatty acids, 16-20 carbons in fat chains, some double bonds. Used for energy storage. Phospholipids consist of a phosphate plus 2 fatty acids and are found in cell membranes. Steroids consist of 4 fused rings and are found in hormones and cholesterol. | |
| 208206544 | Identify an ester linkage and describe how it is formed. | Ester linkage consists of 3 fatty acids linked with glycerol | |
| 208206545 | Distinguish between saturated and unsaturated fats. | Saturated fats have the max number of hydrogen atoms possible and do not have double bonds, they come from animal sources and are solid at room temperature. Unsaturated fats have one or more double bonds, are typically found in plants and are liquid at room temperature. | |
| 208206546 | Name the principal energy storage molecules of plants and animals. | Carbohydrates | |
| 208206547 | Distinguish between a protein and a polypeptide. | A protein is a polymer made of many amino acid monomers. It may have many polypeptides folded and coiled into a specific shape. A polypeptide is a polymer chain of amino acids linked together by peptide bonds. | |
| 208206548 | Explain how a peptide bond forms between two amino acids. | When 2 amino acids are positioned so the carboxyl group of one is adjacent to the amino group of another, they join by dehydration reaction through the removal of a water molecule, this is called a peptide bond. | |
| 208206549 | List and describe the four major components of an amino acid. Explain how amino acids may be grouped according to the physical and chemical properties of the R group. | Amino group, carboxly group, hydrogen atom and R group (rest) and some of the groups of amino acids are polar, nonpolar, or electrically charged. | |
| 208206550 | Explain what determines protein conformation and why it is important. | Protein conformation depends on the physical and chemical conditions of the protein's environment. If things in the protein's environment are altered it goes through a process called denaturation in which the protein unravels and loses it's native shape. When this happens, it becomes biologically inactive. | |
| 208206551 | Explain how the primary structure of a protein is determined. | By its specific conformation (shape), determines how it functions, composed of unique sequence of amino acids | |
| 208206552 | Name two types of secondary protein structures. Explain the role of hydrogen bonds in maintaining secondary structure. | Alphahelix and Beta pleated sheets Hydrogen bonding is between the carboxyl oxygen of one amino acid and the amino hydrogen of another.large number of hydrogen bonds makes them highly stable. As a result, they increase the stability of the molecule as a whole and help define its shape. Supports a particular shape for that part of the protein. | |
| 208206553 | Explain how weak interactions and disulfide bridges contribute to tertiary protein structure. | Tertiary structure is the overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids. A hydrophobic interaction is one type of interaction that contributes to tertiary structure. As a polypeptide folds into its functional shape, amino acids with hydrophobic (nonpolar) side chains usually end up in clusters at the core of the protein, out of contact with water. Once nonpolar amino acid side chains are close together, Van Der Waals interactions help hold them together. Meanwhile, hydrogen bonds between polar side chains and ionic bonds between positively and negatively charged side chains also help stabilize tertiary structure. The shape of a protein may be reinforced further by covalent bonds called disulfide bridges. Disulfide bridges form where two cysteine monomers, amino acids with sulfhydrul groups (--SH) on their side chains, are brought close together by the folding of the protein. | |
| 208206554 | List four conditions under which proteins may be denatured. | Temperature Acid (pH) Salt content Other aspects of the environment | |
| 208206555 | List the major components of a nucleotide, and describe how these monomers are linked to form a nucleic acid. | Pentose sugar, a phosphate group, and a nitrogenous base. The phosphate group of one nucleotide bonds with the pentose sugar of another nucleotide to form nucleic acids. | |
| 208206556 | pyrimidine and purine | - Pyrimidine has a six-membered ring of carbon and nitrogen atoms. The members are cytosine (C) thymine (T) and uracil (U). - Purines are larger with a six-membered ring fused to a five-membered ring. Purine members are adenine (A) and guanine (G) | |
| 208206557 | nucleotide and nucleoside | - A nucleotide is composed of three parts: nitrogenous base, five-carbon sugar (pentose), and phosphate group. - A nucleoside is he portion of this unit without the phosphate group. | |
| 208206558 | ribose and deoxyribose | - Ribose is the sugar connected to the nitrogenous base in the nucleotides of RNA. - Deoxyribose is the sugar connected to the nitrogenous base in the nucleotides of DNA. | |
| 208206559 | 5' end and 3' end of a nucleotide | Adjacent nucleotides are joined by a phosphodiester linkage, which consists of a phosphate group that links the sugars of two nucleotides. The two free ends of the polymer are different in which one ends has a phosphate attached to a 5' carbon and the other end has a hydroxyl group on a 3' carbon. | |
| 208206560 | Briefly describe the three-dimensional structure of DNA. | Cellular DNA molecules have two polynucleotides that spiral around an imaginary axis, this forms a double helix. The double helix consists of two antiparallel nucleotide strands. The nitrogenous bases in DNA for hydrogen bonds in a complementary fashion (A → U, C → G) | |
| 208206561 | Explain the role of catabolic and anabolic pathways in cellular metabolism. | Catabolic pathways release energy by breaking down complex molecules to simpler compounds. Anabolic pathways consume energy to build complicated molecules from simpler ones. | |
| 208206562 | Distinguish between kinetic and potential energy. | Kinetic energy is associated with the relative motion of objects. Potential energy is the energy that matter possesses because of its location or structure. | |
| 208206563 | Explain the first and second laws of thermodynamics in your own words. | 1st Law of Thermodynamics: conservation of energy; energy is transferred and transformed, not created or destroyed. 2nd Law of Thermodynamics: transformation increases entropy (randomness/disorder) | |
| 208206564 | List the three main kinds of cellular work. Explain in general terms how cells obtain the energy to do cellular work. | - Chemical work: the pushing of endergonic reactions - Transport work: the pumping of substances across membranes against the direction of spontaneous movement. - Mechanical work: the contraction of muscle cells and the movement of chromosomes during cellular reproduction. Cells manage their energy resources to do this work through energy coupling, the use of an exergonic process to drive an endergonic one. | |
| 208206565 | Describe the structure of ATP and identify the major class of macromolecules to which ATP belongs. | ATP contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it. ATP is also one of the nucleoside triphosphates used to make RNA. | |
| 208206566 | Metabolism | The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism. | |
| 208206567 | Explain how ATP performs cellular work. | When ATP hydrolyzes there is a release of energy and this energy is used to perform the three types of cellular work. | |
| 208206568 | Describe the function of enzymes in biological systems. | An enzyme catalyzes a reaction by lowering the activation energy barrier, enabling the reactant molecules to absorb enough energy to reach the transition state, even at moderate temperatures. This eliminates the need to use heat to speed up the reaction because high temperatures can also denature proteins and kill cells. | |
| 208206569 | Explain how enzyme structure determines enzyme specificity. | ... | |
| 208206570 | Explain the induced-fit model of enzyme functions. Enzyme changes shape to bond with the substrate | ... | |
| 208206571 | Explain how temperature, pH, cofactors, and enzyme inhibitors can affect enzyme activity. | The rate of an enzyme reaction increases with increasing temperature up to a point. After that point, the rate of the reaction will drop. The same thing occurs with pH. The cofactors can be bound tightly or loosely to the enzyme. Coenzymes act as organic helpers and perform a crucial function in catalysis. Competitive inhibitors mimic the substrate. Noncompetitive inhibitors bind to another part of the enzyme altering its shape. | |
| 208206572 | Describe the function of enzymes in biological systems. | An enzyme acts as a catalyst, which speeds up reactions. Enzymes are proteins in biological systems used to regulate the metabolism. |
