Chapter5 Flashcards
briefly describe the reactions that occur within cells
thousands of chemical reactions happen in the microscopic space of cells, and different reactions have different purposes. Life requires energy and cells use energy to manufacture and move things.
what is energy
the capacity to perform work and move an object against an opposing force
name and describe the types of energy
kinetic energy is the energy of motion. potential energy is stored energy that an object possesses as a result o its location or structure
how does potential energy work in molecules
chemical energy is potential energy in molecules that is released to power the work of the cell. if we couldn’t convert energy from one form to another we couldn’t survive
what is the first law of thermodynamics?
the total amount of energy in this world is constant; energy can be transferred and transformed but not destroyed. This is also known as the law of energy conservation
what is the second law of thermodynamics
energy conversions reduce the order of the universe and increase its ntropy (disorder). basically means energy tends to go towards transformations that aren’t very useful
what are the two main types of chemical reactions
endergomic and exergonic reactions. endergomic- products are rich in PE. energy is absorbed from surroundings as the reaction occurs, so the products store (typically in covalnt bonds) more energy than the reactants did. exergonic- a chemical reaction that releases energy. it begins with reactants whose covalent bonds contain more enrgy than those in the products
what are examples of exergonic and endergomic reactions
endergonic: energy-poor reactants like CO2 and H2O, using energy from sunlight, produce energy-rich sugar molecules (ex C6H12)6) exergonic- when burning wood, PE o lucose in cellulose molecules is released as heat and light producing carbon dioxide and water. In cellular respiration, oxygen is used to convert chemical energy stored in fuel molecules like glucose to form chemical energy cell can use to perform work.
what is cellular metabolism and energy coupling?
cellular metabolism is the sum of all endergonic and exergonic reactions carried out by the cell. energy coupling is the use of energy released from exergonic reactions to drive essential endergonic reactions, is critical for cells, ATP is key for this
what is ATP
adenosine triphosphate. adenosine is adenine, a nitrogenous base and ribose. triphosphate is three negatively charged phosphate groups. these bonds are unstable and can be easily broken down by hydrolysis
how does the structue of ATP correlate to its energy-storage abilities
the triphosphate, because it has like charges crowded together contributes to the potential energy stored in ATP. Most cellular work depends on ATP energizing molecules by phosphorylating them.
what type of reaction is the hydrolysis of ATP, what kind of reaction is it coupled to, and how?
the hydrolysis of ATP is an exergonic reaction or one that releases energy (ATP —-> ADP + P) they hydrolysis of ATP is coupled to an endergonic reaction by a phosphate group from ATP being transferred to some other molecule. thiis called phosphorylation
what is the ceullular work driven by ATP?
there is chemical work, or the phosphorylation of reactant molecules drives the endergonic synthesis of protein molecules. then there is mechanical work. An example would be the transfer of phosphate group to special motot proteins in muscle cells causes the proteins to change and pull on actin filaments causing cells to contract
how does the dephosphorylation of ATP work?
energy is released in exergonic reactions, such as glucose breaking down during cellular respiration is used to regenerate ATP form ADP. When ADP is phosphorylated, ATP is formed. (an endergonic or energy-storing reaction)
what is activation energy?
most of cell’s molecules are rich in PE but will not spontantously break down into simpler molecules bc there is an energy barrier that must be overcome for reaction to begin. activation energy is the energy barrier, or the amount of energy that must be absorbed by reactants to become activated and start chemical reactions
what is an enzyme
a protein molecules that functions as a biological catalyst, increasing the rate of reaction without itself being changed into a different molecule
what is the shape and parts of an enzyme
enzymes have a unique 3D shape that determines which chemical reaction it can catalyze. it has a substrate, which is the specific reactant that an enzyme acts on. It aso has an active sire, which is a region of the enzyme, typically a pocket or groove, where it fits.
how is the enzyme specific?
an active site only fits one kind of substrate molecule, so the cell has many different kinds of enzymes to catalyze all its reactions
what happens as the enzyme is working and what happens after a reaction is catalyzed
the active site changes shape slightly when a substrate binds to an enzyme so that it embraces the substrate more snugly. this induced fit may strain substrate bonds or place chemical groups of the active site in position to catalyze the reaction. After catalysis, the enzyme releases the products and emerges unchanged from the reaction; the active site can now be used for another substrate.
what are some examples of ideal enzyme conditions
few enzymes can tolerate extremely salty ocnditions, few enzymes can tolerate pHs out of range 6-8, higher temperatures denature enzyme
what are enzyme helpers?
many enzymes will not functions without nonprotein helpers called cofacters ex ions of zinc, iron, or copper. a coenzyme is a cofacter, that’s an organic molecule, ex: vitamins
what are inhibitors
chemicals that attach to enzymes by covalent bonds and interfere with enzyme’s activity. they are sometimes irreversible (ex toxins and poisons) The main two types are competitive and noncompetitive.
