Bio-Chapters 6 & 7 Review
Heat
A calorie is the commonly used unit of chemical energy. It is also the unit of:
These mutations most likely change the shape of the active site of the enzyme
A current problem in modern medicine is the development of drug resistance mutations. This occurs when a mutation arises in a patient making him/her resistant to a drug and thus rendering the drug useless in treating a specific disease. Many useful drugs are competitive inhibitors of specific enzymes, and the drug-resistance mutations prevent the binding of the drug. These types of mutations, in addition to preventing competitive inhibitor binding, can also sometimes reduce the activity of the enzyme. Why is that the case?
Competitive inhibiter
A drug binds to the active site of an enzyme. If it is bound to the active site of the enzyme, it prevents substrate binding. This drug would be considered a:
Aerobic respiration
A human cell has a mutation in the gene that encodes the enzyme that generates lactate from pyruvate, rendering that enzyme completely non-functional. Assuming that there is ample glucose present, how would this cell generate energy in the presence of oxygen?
Competitive inhibitor
A molecule that closely resembles the shape of a substrate for an enzyme would most likely serve as a:
Oxygen cannot accept electrons, and thus an electron carrier like NAD+ is needed.
Aerobic respiration involves the transfer of many electrons from glucose to electron carriers such as NAD+ over a series of multiple steps. Ultimately though, it is the reaction of glucose with oxygen to generate carbon dioxide, water and energy. Why doesn't glucose react directly with oxygen in cells?
The formation of water from oxygen
As a forensic pathologist, you have just completed an autopsy of a poisoning victim. After a thorough examination, you conclude that the victim died of cyanide poisoning. You know that cyanide binds to the cytochrome oxidase complex, and therefore list the official cause of death as suffocation due to cyanide exposure. However, if you wanted to provide a more technical explanation as to the cause of death, what process was specifically inhibited directly by cyanide?
The electron transport chain
Cytochromes contain a heme group similar to that in hemoglobin. The iron atom (Fe) in the center of the group can be oxidized and reduced. If someone was suffering from iron deficiency anemia, what stage of cellular respiration would be most affected?
Glucose priming
During what step of glycolysis are two ATP molecules required?
The capacity to do work
Energy is defined as:
No. This only describes one chemical reaction. A metabolic pathway includes multiple chemical reactions
Enzyme 1 converts substrate A into product B. Is this an example of a metabolic pathway?
It is lost as heat
Glucose is broken down through cellular respiration, which involves a large number of chemical reactions. At the end of the cellular respiration process, a large number of ATP molecules are generated, but yet, not all of the possible energy that is contained in a molecule of glucose can be harnessed through these chemical reactions to generate ATP. In other words, during cellular respiration, not all of the energy that is contained in a molecule of glucose is converted into the energy stored in ATP. What happened to the remaining energy?
Feedback inhibition
Hexokinase is an enzyme that binds specifically to glucose and converts it into glucose 6-phosphate. The activity of hexokinase is suppressed by glucose 6-phosphate, which binds to hexokinase at a location that is distinct from the active site. This is an example of what?
ATP can be made by direct phosphorylation of ADP in the cytoplasm, and by an enzyme complex that uses the energy from a proton gradient to drive ATP synthesis in the mitochondria. It can also be made in other locations in the cell, depending on the cell type.
How and where is ATP made in a eukaryotic cell?
Glycolysis will be inhibited, but the Krebs cycle will be functional, allowing it to be utilized to breakdown acetyl-CoA generated from beta-oxidation.
If citrate levels are high in the cell, but ATP levels are low, what do you think will happen in the cell?
The reaction is spontaneous
If the Delta G of a reaction was -31.45 k Joules, you would know that:
It would increase
If you were able to increase the kinetic energy of the molecules inside your body, how would this affect your body temperature?
It was reduced to form NADH
In a chemical reaction, glyceraldehyde-3-phosphate + NAD+ yields 1, 3-bisphosphoglycerate + NADH. In this reaction, what happened to NAD+?
A difference in H+ concentration on the two sides of the inner mitochondrial membrane.
In aerobic respiration, chemiosmosis generation of ATP is driven by:
Substrate
In an enzyme-catalyzed reaction, the reactant is called the:
Chemical A has lost electrons to chemical B
In an experiment described in a chemistry lab book, the directions state that after mixing two chemicals (A and B) and waiting 5 minutes that A will be oxidized. This means that:
Aerobic respiration
In animals that take in oxygen from their environment, glucose is broken down into carbon dioxide and water in a process called:
Pyruvate
In glycolysis, a major portion of the energy remains in the final product, which is called:
It is a bad idea, because if ATP levels are high in cells, excess acetyl-CoA from the metabolism of carbohydrates can be used for fatty acid synthesis.
In order to lose weight and reduce body fat, a friend of yours has decided to eliminate all fat from his diet, while consuming unrestricted amounts of carbohydrates. What do you think of this idea?
The enzyme has to seperate itself from the product
In order to reuse an enzyme after the conclusion of an enzyme catalyzed reaction, what must occur?
Yes, in the case that a cell can use a terminal electron acceptor other than oxygen, it can make use of the electron transport chain.
In the absence of oxygen, can cells utilize the electron transport chain?
Waiting at the top of the stairs for the roller coaster to pull into the station
It is summer, and you are excited about going to your local amusement park, and specifically about riding the new roller coaster that was just built. You imagine waiting at the top of the stairs for the roller coaster to pull into the station, climbing into the car, strapping yourself into the seatbelt, and pulling down the harness. You can imagine the cars slowly chugging up to the top of the first hill, coming down on the other side, and the excitement you expect to feel as you go along for the ride. Of all of the things that you have imagined, which is an example of potential energy?
Glycolysis
It is thought that the oldest stage of cellular respiration from an evolutionary perspective is
Protien X
Kinases are enzymes that can phosphorylate (transfer phosphate groups onto) macromolecules such as proteins. A particular kinase, Kinase 1 is known to promote cell division. It promotes cell division by phosphorylating Protein X. Phosphorylation of Protein X activates Protein X. Once activated, Protein X stimulates the production of other proteins such as Protein Y and Z that directly promote cell division. In order to function, Kinase 1 requires the presence of Metal A. However, in the presence of Protein A, Kinase 1 is nonfunctional. From the description, what is considered the substrate of Kinase 1?
The phosphate groups of ATP are held together by unstable bonds that can be broken to release energy
Many metabolic pathways are ultimately concerned with ATP; either with the generation of ATP, or with the requirement of ATP for that pathway to function. Why is ATP so important to metabolism?
An increase in lactic acid levels
Many of the antiviral drugs currently used to treat HIV/AIDS also interfere with an enzyme that helps mitochondria multiply. Treatment can therefore result in a decrease in the number of mitochondria found in certain tissues. Given this information, what might you expect to see in patients treated with antiviral drugs
Decarboxylation
One way to generate acetyl-CoA is to convert pyruvate into acetyl-CoA by stripping off a CO2 molecule. The removal of CO2 is referred to as what type of reaction?
Autotrophs
Organisms that can manufacture their own chemical energy are called ____________.
Heterotrophs
Organisms that depend on the energy stored in chemical bonds by other organisms for their food energy are called ____________.
Electrons
Oxidation and reduction reactions are chemical processes that result in a gain or loss of:
Allosteric activator
Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group. This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated. AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1, 6-bisphosphate. ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1, 6-bisphosphate. There are other regulators of this enzyme as well. What is the role of AMP in this example?
If ATP levels are high, it is important to directly inhibit the reaction that commits the substrate to glycolysis to allow the substrate to be available for other reactions, since the cell has ample energy.
Phosphofructokinase is regulated by a number of factors, including high levels of ATP. Why is this enzyme regulated by ATP levels?
Ribozymes
RNA molecules that also act as enzymes are given the name:
NAD+
Regardless of the electron or hydrogen acceptor used, one of the products of fermentation is always:
acetyl-CoA joins the Kreb cycle and unites with oxaloacetate -> forming citrate -> which forms alpha-ketoglutarate -> which forms succinyl-CoA -> which forms succinate -> which forms fumarate -> which forms malate -> which forms oxaloacetate
The Krebs cycle occurs in the mitochondria. There are nine biochemical reactions involved in the Krebs cycle, and they are highly ordered. Select the correct order from the following choices. (Note: These are abbreviated and do not show NAD, ADP, ATP, or FAD.)
The First Law of Thermodynamics
The Law of Thermodynamics that states that energy cannot be created or destroyed is:
The Second Law of Thermodynamics
The Law of Thermodynamics that states that increases in entropy are favored is:
Metabolism
The chemistry of living systems representing all chemical reactions is called:
Activation Energy
The energy needed to destabilize existing chemical bonds and start a chemical reaction is called:
Into the intermembrane space of the mitochondria
The energy released in the mitochondrial electron transport chain is used to transport protons where?
Cofactors
The inorganic non-protein components that participate in enzyme catalysis are known as:
Endergonic
The synthesis of sugar molecules through the process of photosynthesis requires energy absorbed from sunlight. Bearing this in mind, what kind of reaction is photosynthesis?
the sun
The ultimate source of energy for humans comes from what source?
Dehydrogenation
To form NADH from NAD+, two electrons and a proton are removed from an organic molecule. What term best describes the reaction in which electrons and a proton are removed from an organic molecule?
The optimal temperature for the human enzyme is 40 degrees C. The optimal temperature for the hot springs prokaryote enzyme is 72 degrees C.
What are the optimal temperatures for the human enzyme and hot springs prokaryote enzyme?
2 CO2, 3 NADH, 1 FADH2, 1 ATP
What are the products of one turn of the Krebs cycle?
Glycolysis
What cellular respiration process is common to all living cells:
It is reduced to form water
What happens to the oxygen that is used in cellular respiration?
Acetyl-CoA
What important metabolic intermediate does not cross the inner membrane of the mitochondria?
Pyruvate
What is an end-product of glycolysis?
NADH contributes its electrons to the first transmembrane complex in the electron transport chain and FADH2 contributes its electrons after the first transmembrane complex.
What is different about the way that NADH and FADH2 donate electrons to the electron transport chain?
2
What is the net number of ATP generated directly during glycolysis per molecule of glucose?
They must be deaminated
What must happen to amino acids before they can be used in catabolic reactions
Reduced
When an atom or molecule gains one or more electrons, it is said to be:
Glycolysis coupled with lactate fermentation
When oxygen is unavailable during heavy exercise what process do muscle cells use for energy generation?
ADP is converted into ATP by the addition of a phosphate group.
When substrate-level phosphorylation occurs, it means that:
An induced name
When the substrate is bound to the enzyme, the shape of the enzyme may change slightly, leading to:
In the mitochondria
Where does pyruvate oxidation occur in eukaryotic cells?
0 Joules
While standing at the top of the stairs, you have a potential energy of 40 Joules. If you walk all the way down the stairs, what would your potential energy be at the bottom of the stairs?
To generate and maintain the proton gradient essential for ATP production.
Why are the components of the electron transport chain embedded in the inner mitochondrial membrane rather than floating freely in the cytoplasm of mitochondrial matrix?
We can break down these macromolecules to provide energy for the endergonic reactions in our bodies.
Why do we have storage macromolecules, such as fats, in our bodies?
ATP can be used by cells to drive endergonic reactions
Why is the energy generated from the catabolism of sugars and other macromolecules ultimately harnessed to generate ATP?
No. The energy contained within these macromolecules is converted into other forms of chemical energy and kinetic energy, though some is lost as heat.
You eat a bowl of beans as part of your dinner. As you digest the beans, the proteins that are present get broken down to their component amino acids. As your body destroys the macromolecules that were present in the beans, is the energy present in those molecules destroyed?
The Second Law of Thermodynamics
You return home to find that your baby brother has scattered his toy trains and trucks all over the floor of your room. As you begin to pick up the toys and put them away, you realize that even though he is just a baby, he has clearly mastered
