Mastering Biology CH. 5
Isotonic
1. The ideal osmotic environment for an animal cell is a(n)___________ environment.
Increase the negative charge of each phosphate group.
In a theoretical world where all things are possible, how could you increase the amount of energy that could be stored in a molecule of ATP?
Molecules move across the plasma membrane against their concentration gradient.
In active transport,
Would stay together but in a reverse orientation, with their tails projecting outward
In an oil-based, nonpolar environment, phospholipids would arrange themselves so that they __________.
High-energy electrons "fall" to lower energy levels
In cellular respiration, most energy is released and transferred to ATP when _____.
Increases the rate of LDL receptor-mediated endocytosis
New drugs are being developed to lower levels of circulating cholesterol. A successful drug would be one that _____.
Succinylcholine must be a competitive inhibitor of acetylcholine
Succinylcholine is structurally almost identical to acetylcholine, but if combined with the enzyme that normally hydrolyzes acetylcholine, the enzyme is no longer able to hydrolyze acetylcholine. This suggests that _____.
The activation energy required to initiate this reaction is seldom reached.
The hydrolysis of DNA into nucleotides constitutes an exergonic reaction. Yet, DNA is quite stable. Why is this the case?
Excessive salt ions can cause an enzyme to denature.
Which statement regarding enzyme function is true?
Nine
You're on the pilot episode of a new reality show called "The Transport Factor." The host hands you three different amino acids, four different sugars, and two different ions. Then the host shouts, "How many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport?" Quickly, you correctly respond: _____.
Bacteria can't survive in a hypertonic solution because they lose water.
Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?
Facilitated diffusion.
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
Endocytosis
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____.
Understanding the enzyme's structure would help pharmaceutical companies design molecules that fit to the binding site and alter activity.
A pharmaceutical company wishes to focus on an enzyme to develop new medications. What type of study would be of the greatest benefit?
Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.
Frequently, transplanted organs are rejected by the recipient's body. How is this reaction related to plasma membranes?
Enzyme
3. A specific__________speeds up each of a cell's chemical reactions.
Active site
3. An enzyme is specific because the shape of its_________ matches only particular reactants.
Hypertonic
3. There is a net diffusion of water out of an animal cell when it is placed in a(n)__________ solution.
Activation energy
4. An enzyme speeds up reactions by lowering the_________.
Feedback inhibition, metabolism
4. Mechanisms such as_________enable precise control over a cell's_________-- all of its chemical reactions.
Hypotonic
4. The ideal osmotic environment for a plant cell is a(n)__________ environment
Hypertonic
5. A plant cell placed in a(n)__________ solution will lose water and plasmolyze.
Induced fit
5. The_________ between an active site and its substrate often strains bonds and helps the reaction proceed.
Isotonic
6. A plant cell surrounded by a(n)_________ solution will be flaccid (limp).
Coenzyme
6. A(n)__________, which is often a vitamin, binds to an enzyme and plays a role in catalysis.
Total energy input equals total energy output
Energy is conserved. This means that in any system, _____.
Denature
7. High temperatures or changes in pH can__________ an enzyme, causing it to lose its shape and biological activity.
Catalyst
1. An enzyme is considered a(n)_________ because it speeds up a chemical reaction without being used up.
Phosphorylation
1. There are three main types of cellular work: chemical, transport, and movement. Most of this work is powered by the transfer of a phosphate group from one molecule to another in a process known as___________.
Hypotonic
2. An animal cell placed in a(n)___________ solution will gain water, swell, and possibly burst.
Substrate
2. In a catalyzed reaction, a reactant is often called a(n)________.
Exergonic, endergonic, ATP
2. Through energy coupling, cells use__________, or energy-releasing, reactions to drive__________ , or energy-requiring, reactions. The molecule___________is the energy shuttle between these two types of reactions.
B ... the diffusion gradient there is steeper
Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.
Cells couple energy-releasing reactions to energy-requiring reactions.
In plant cells, carbon dioxide and water are joined to form carbohydrates. Plant cells can also break down carbohydrates such as glucose, releasing carbon dioxide, water, and energy. No one has ever observed such reactions between water and carbon dioxide outside of living cells. What allows simple molecules to assemble into more complex molecules, and also disassemble, in cells but not in other, nonbiological environments?
Stored
Kinetic energy is energy in motion. Potential energy is _____ energy.
Microbes are engulfed into the macrophage via phagocytosis.
Macrophages are white blood cells that roam the body searching for invading microbes. Inside macrophage vacuoles these invaders are destroyed. How do the microbes get inside the macrophages?
The difference in water concentration across a selectively permeable membrane
Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?
The temperature should be raised.
Taq polymerase is an enzyme isolated from the organism Thermus aquaticus. This organism has been found living in the hot springs of Yellowstone National Park. This enzyme is used to copy human DNA from crime scenes. Most reactions are performed at ranges similar to those of the human body; however, what considerations should be made for optimum use of this enzyme?
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
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
Actively pump water back into their cells to counter its loss due to osmosis
Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.
Through facilitated diffusion or diffusion.
Water crosses the plasma membrane
Fluid retention in pregnant women
What condition might result from an excess of aquaporins?
The direction of the oxygen concentration gradient
What controls the direction of a molecule, such as oxygen, involved in passive transport?
Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
Which of the following is a difference between active transport and facilitated diffusion?
Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.
Which of the following is an accurate comparison of active transport and facilitated diffusion?
One molecule of glucose
Which of the following is highest in chemical energy?
