homework ch. 6 Flashcards
Which of the following is the branch of chemistry concerned with energy changes?
thermodynamics
What is the term for the ability to do work?
energy
With very few exceptions, all energy that enters biological systems ultimately comes from the ____
sun
Which of the following describe how energy is used in chemical reactions?
Energy stored in certain chemical bonds can be used to make new bonds.
All activities of living organisms involve changes in ______ which is the ability to do work.
energy
The branch of chemistry that studies _____ changes is called thermodynamics.
energy
Work in the cell or in the physical world can only be done with expenditure of _____ it is defined as the capacity to do work.
energy
Heat is a measure of the random ___ of molecules.
motion
The energy that flows through most biological systems on Earth ultimately comes from which source?
sun
According to the second law of thermodynamics, increases when energy is transferred from one form to another and some energy is lost as heat in the process.
entropy or disorder
__ stored in the chemical bonds of a molecule can be used to make new bonds in a different molecule.
energy
All living things require which of the following, in order to carry out chemical reactions and thereby survive?
energy
What is the term used to describe the energy of a system that is available to do work?
free energy
Which of the following is the branch of chemistry concerned with energy changes?
thermodynamics
Any agent that speeds up the rate of a chemical reaction without being permanently changed or consumed by it is known as a(n) _____
catalyst
Heat is a form of ____ energy, because it reflects the random motion of molecules.
kinetic
What molecule is a common energy source for living organisms?
ATP
Which of the following is another way to state the second law of thermodynamics?
Entropy increases.
The hydrolysis of ATP has Blank______.
a negative ΔG
The energy available to do work in a system is called ____ energy.
free
Cells use ___ hydrolysis to drive endergonic reactions.
ATP
The process of influencing chemical bonds to lower the activation energy of a reaction is called Blank______.
catalysis
Select the steps in the ATP cycle.
Hydrolysis of ATP to release energy that can be used to drive endergonic reactions
Synthesis of ATP using energy released from exergonic reactions
All cells use a molecule called to carry and release energy cyclically.
ATP
What are enzymes?
Proteins or RNA molecules that act as catalysts.
______ or reactants, are molecules that bind to an enzyme and are converted to products in chemical reactions.
substrates
Hydrolysis of which covalent bonds in ATP releases a considerable amount of energy?
Phosphate-phosphate bond
Where does a substrate bind on an enzyme in order for a chemical reaction to take place?
active site
Certain reactions in cells are endergonic. How do cells make those reactions proceed?
They couple them with ATP hydrolysis.
When several enzymes that catalyze different steps of a sequence of reactions are associated with one another in a noncovalently bonded assembly, they form a(n) _____ complex
multienzyme or multi-enzyme
The two main steps in the ATP cycle are the synthesis of ATP from _______ and Pi, and the subsequent hydrolysis of ATP, which releases _______ that drives endergonic reactions.
ADP, energy
The optimum pH of most enzymes is
6-8
usually around 7
What is a substrate?
A reactant molecule that forms a temporary association with an enzyme before being converted to a product
Which of the following describes the active site of an enzyme?
It is the part of the enzyme where the substrate fits.
Which of the following are included in metabolism?
Both the synthesis and breakdown of organic molecules
The bacterial enzyme pyruvate dehydrogenase contains multiple copies of each of three enzymes for a total of 60 protein subunits. This is an example of Blank______.
a multienzyme complex
A _____ ______ is a sequence of reactions occurring in an individual cell that are organized so that the product of one reaction becomes the substrate of the next.
biochemical pathway
In order to function efficiently and to conserve energy and raw materials, a cell Blank______.
maintains biochemical pathways active only when their products are needed
What statement describes metabolism?
Metabolism refers to the sum of all chemical reactions that occur within an organism.
Each _____ in a biochemical pathway acts on the products of the previous reaction.
enzyme
Select reasons why metabolic pathways are regulated.
By regulating metabolic pathways, cells conserve raw materials.
By regulating metabolic pathways, cells waste less energy.
Regulation allows cells to operate efficiently.
