BIO CH5
The induced fit model of enzyme catalysis states that __________.
the active site of the enzyme changes shape after substrate binds to it
Which is the best definition of energy?
the capacity to cause change
Entropy means that __________.
the quantity of usable energy declines with each energy transformation
Heat is defined as ____________.
the total amount of energy associated with the movement of atoms and molecules in a substance
Water crosses the plasma membrane
through facilitated diffusion or diffusion.
ATP drives work in cells by __________.
transferring its phosphate group to other cell molecules
Structure A in the figure is a(n) _____.
transport protein
An animal cell placed in a hypertonic solution will __________.
lose water by osmosis and shrivel
Which curve shows the course of the reaction in the presence of an enzyme--the black curve or the red curve? Which line represents the activation energy for that reaction--a, b, or c?
red curve; line b
Enzymes work by _____.
reducing activation energy
If you are shipwrecked, it is not a good idea to drink seawater because .
seawater is hypertonic to the body's cells and tissues; therefore, the cells will lose water through osmosis, making you even more thirsty
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
During an enzymatic reaction, a molecule of _____ binds to the enzyme and is broken down into one or more molecules of ____, which are released.
substrate, product
The combination of sucrose, sucrase, and water produces sucrase, glucose, and fructose. Which component of the reaction is the enzyme?
sucrase
Why are enzymes so critical to cell functioning?
Enzymes enable and regulate cellular reactions.
How do enzymes affect activation energy?
Enzymes lower the amount of energy required to activate a chemical reaction.
Use the graph and your knowledge of enzymes to identify the three true statements about enzymes.
Enzymes lower the overall energy input needed for a reaction to occur. By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart. Reactants cannot convert to products without an initial input of energy to start the reaction.
Which type of passive diffusion is involved in ion transport across cell membranes?
Facilitated diffusion
____________ molecules generally can pass directly through the plasma membrane more readily than _____________ molecules.
Hydrophobic; hydrophilic
In the figure below, how does the molecule labeled A affect enzyme function?
It is an inhibitor that changes the enzyme's active site.
You are riding on your bike and stop pedaling, coasting along the road. Eventually, your bike slows down and stops. What happened to the energy of your motion when your bike stopped?
It was released as heat.
Imagine that you synthesize a molecule that resembles the substrate of a particular enzyme but has a different chemical composition. You discover that this "substrate imposter" can bind to the enzyme's active site. What effect will the "substrate imposter" have on the reaction that is normally catalyzed by the enzyme?
It will inhibit the reaction.
Which of the following best describes the process of facilitated diffusion?
Passive movement of solutes across a membrane down their concentration gradients with the involvement of membrane proteins
Which of the following features explains why plant cells do not explode as a result of osmosis?
Plant cells have a cell wall that prevents the cell from absorbing too much water.
Both animal and plant cells accumulate water through osmosis when placed in hypotonic solutions. This causes the cells to swell. Why can plant cells better tolerate this?
Plant cells, but not animal cells, have rigid cell walls that limit how far cells can expand and prevent them from bursting.
A(n) ___ is a molecule that can bind to an enzyme and prevent the enzyme from working.
inhibitor
An enzyme _____.
is an organic catalyst
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
A plant cell surrounded by a(n) ___ solution will be flaccid (limp).
isotonic
The ideal osmotic environment for an animal cell is a(n) ____ environment.
isotonic
Which of these is hydrophobic like the interior of the plasma membrane?
A) Lipid soluble molecules
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
You decide to try your hand at canning pickles. You immerse freshly picked cucumbers in a solution that has a solute concentration twice that found in the cucumber cells. You allow your preparation to cure for several months in a sealed jar. When you later open the jar, you find that the fluid surrounding the pickles is more dilute than when you started. This change in concentration is due to ____________.
pickles in a hypertonic solution losing water through osmosis
Chemical energy is a form of _____ energy.
potential
Most enzymes are _____.
proteins
The region on an enzyme where a substrate binds is called the .
active site
The specific location within an enzyme molecule where the substrate binds is called the ____.
active site
"The use of energy to move molecules across a membrane" is the definition of __________.
active transport
Requires energy from the cell. Molecules move against their concentration gradient.
active transport
The concentration of calcium in a cell is 0.3%. The concentration of calcium in the surrounding fluid is 0.1%. How could the cell obtain more calcium?
active transport
The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of
active transport.
An enzyme is considered a(n) ____ because it speeds up a chemical reaction without being used up.
catalyst
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
An enzyme is a protein that __________.
changes the rate of a metabolic reaction without being consumed by the reaction
High temperatures or changes in pH can ___ an enzyme, causing it to lose its shape and biological activity.
denature
A form of passive transport. Molecules move across the plasma membrane by crossing the lipid bilayer.
diffusion
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.
endocytosis
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of
endocytosis
"Conservation of energy" refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
Activation energy can be described as __________.
energy that must be invested to start a reaction
Lactose takes years to break down on its own. But if exposed to the protein lactase, the reaction proceeds very quickly, while lactase itself remains unchanged. Lactase is an example of a(n) ____.
enzyme
A vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.
exocytosis
A form of passive transport. Molecules move across the plasma membrane using a transport protein.
facilitated diffusion
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
facilitated diffusion
Which of these are by-products of cellular respiration?
heat and water
A plant cell placed in a(n) ___ solution will lose water and plasmolyze.
hypertonic
There is a net diffusion of water out of an animal cell when it is placed in a(n) ___ solution.
hypertonic
This cell is in a(n) _____ solution.
hypertonic
In osmosis, water moves across a selectively permeable membrane toward the __________ solution; that is, toward the solution with the __________ solute concentration.
hypertonic ... greater
You know that this cell is in a(n) _____ solution because it _____.
hypertonic solution ... lost water
An animal cell placed in a(n) ___ solution will gain water, swell, and possibly burst.
hypotonic
The ideal osmotic environment for a plant cell is a(n) ___ environment.
hypotonic
How does the figure below represent the relationship between energy and ATP?
ATP can perform cellular work when it releases a phosphate group.
Which of the following is a true statement about ATP and cellular work?
ATP consists of adenosine and three phosphate groups.
You know that this cell is in a(n) _____ solution because the cell _____.
hypotonic ... swelled
The ____ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
Which of the following conditions represent(s) stored (potential) energy: (1) table sugar ready to be ingested, (2) a diver about to dive off the ten-meter platform at the Olympics, or (3) a gerbil running on its exercise wheel in its cage?
1 and 2
Which of the following situations represents released energy: (1) a dart shot out of a dart gun, (2), a compressed spring in a dart gun, or (3) active transport of a substance across a cellular membrane?
1 and 3
Put the following steps of ATP phosphate transfer in the correct order: 1. ATP transfers a phosphate group to a protein 2. ATP energizes a molecule in a cell 3. A protein changes shape 4. ATP enables transport of ions across cell membrane
1, 2, 3, 4
Ten kilocalories are equivalent to ________ calories.
10,000
A Calorie displayed on the nutritional label of a candy bar is equal to __________.
1000 calories
BioFlix Activity: Membrane Transport -- Exocytosis and Endocytosis
A) exocytosis B) endocytosis
Can you complete this concept map that reviews the basic concepts of energy?
A) kinetic B) potential C) motion D) chemical energy E) entropy F) heat G) 1st law H) 2nd law
BioFlix Activity: Membrane Transport -- Facilitated Diffusion
A) plasma membrane B) side with higher concentration molecules C) side with lower concentration of molecules D) facilitated diffusion causes net movement of molecules down their concentration gradient E) transport protein
BioFlix Activity: Membrane Transport -- DIffusion
A) side with higher concentration molecules B) plasma membrane C) side with lower concentration of molecules D) diffusion causes net movement of molecules down their concentration gradient
BioFlix Activity: Membrane Transport -- Active Transport
A) side with lower concentration of square molecules B) transport protein C) energy input from cell D) plasma membrane E) side with higher concentration square molecules
Cells use this molecule to store the chemical energy released by the breakdown of food molecules during cellular respiration.
ATP
The photos below show a plant before watering (left) and after it was watered (right). What causes the change in plant appearance?
Cells that were in an isotonic environment are restored to a hypotonic environment.
What best explains the observation that enzymes are selective in the reactions they catalyze?
There is a precise compatibility between an enzyme's active site and the substrate molecule.
How do enzyme inhibitors work?
They bind to an enzyme, which alters the active site so a substrate cannot bind.
For what purpose(s) might a cell transport materials across its plasma membrane?
To import nutrients, to get rid of wastes, or to secrete proteins
The energy stored in ATP (adenosine triphosphate) can drive cellular work by energizing other molecules. This process occurs when .
a phosphate group is transferred from ATP to another molecule
Which of these is exhibiting kinetic energy?
a space station orbiting Earth
Enzymes speed up chemical reactions by lowering the ____, which allows the reaction to proceed much more quickly.
activation energy
Molecules of food have a form of potential energy called __________.
chemical energy
In active transport,
molecules move across the plasma membrane against their concentration gradient.