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Biochem Exam 2
Terms in this set (127)
Histones are usually modified by:
Is formed following adrenal secretion
Is involved in signaling from G protein to PKA
Involves reaction with ribosome positions 3&5
Tyrosine kinases tend to be involved in:
If the concentration of CTP increases, what is the effect upon ATCase activity?
It induces inhibitor which can be overcome by the substrate.
Why does ATP stimulate ATCase?
Because if ATP is able to stimulate it must be in concentration excess over CTP. It is in the interest of the cell to keep these two molecules in general equilibrium. Because both are used in near equal proportions during nucleotide symbiosis.
cooperativity in an enzyme indicates?
That separate enzyme subunits in a complex influence one another.
In ATCase, there are multiple catalytic subunits. How do they associate together?
They form two separate trimmers.
In the ATCase enzyme complex, CTP binds:
To the regulatory subunit only.
The ATCase enzyme is designed to:
Increase in activity within a narrow range of substrate concentrations.
How is a G-protein normally inactivated?
By hydrolysis of GTP.
How does cAMP overcome competitive inhibition?
By inactivating the inhibitory subunit.
What is the nature of inhibition of protein kinase A by its regulatory subunit?
What is an isoenzyme?
Distinct enzymes that have the same catalytic functions.
The regulatory subunit of PKA?
Binds as a pseudo substrate to the active site.
You have isolated the inhibitory subunit of ATCase. What would the activity be?
It would bind ATP.
In the T state, ATCase:
Binds substrate which promotes transition to the R state.
If you were to find a molecule that could mimic the binding of CTP to the ATCase enzyme in an irreversible way, what would the result be?
ATP would no longer be an inducer.
The regulatory subunits of ATCase:
Link two catalytic subunits
Contain no catalytic activity
How is cooperatively different from allosteric substrate stimulation?
Allosteric stimulation involves a second site. Whereas the ATCase substrate stimulation targets the active site. This is an example of unexpected kinetics as the result of a complex multi-protein complex.
CTP is able to influence the activity of ATCase. This is an example of:
Inhibition by an eventual product of the enzymatic pathway.
How many carbons in a gluycopyranose ring?
Hemoglobin modified by reducing glucose.
Mannose 6-phosphate is the label to direct a glycoprotein to the:
Built upon a single polysaccharide involving two simple sugar repeats.
What is unique about N-linked sugars as opposed to 0-linked sugars?
N-linked sugars tend to be linked to larger proteins
They have a structured core at the attachment site.
What can be said about N-linked polysaccharides?
They are linked to proteins
They are linked to asparagine
They have a common core of simple sugars
The sugar in the core is often modified
Glycogen is composed of repeating units of:
Glycose linked by alpha linkages
It normally contains a nitrogen attached to the sugar backbone.
Often contains a sulfate group
Contains pyranose sugars
Sorting of proteins according to attachment of saccharides takes place in:
A lectin is:
A protein able to recognize a specific saccharide structure
If the hyaluronic acid were removed from cartilage, what changes do you think would result in the physical structure of the tissue?
It would become less structured
Mucins are glycoproteins. What may be said of them?
They contain many attached polysaccharides
The proteins are arranged end-to-end
Glycosaminoglycans commonly contain:
Parts of the pentasaccharide core:
A glucose pyranose ring would be formed by interactions of the reactive groups on which sugar carbon atoms?
1 and 5
Glucose and galactose are what type of isomer?
A catabolic reaction often involves:
The destruction of biological molecules
The generation of energy
If you were to fully oxidize a methyl group to CO2 and H2O, approximately how much energy would be produced?
FAD is involved in which type of reaction in the body?
Is ATP the highest energy compound in the cell?
How many Kcal of energy are produced when an alcohol is converted to an aldehyde?
When carbon is converted to CO2, what happens to oxygen?
It is reduced
How far do you imagine a person could run without the replenishment of ATP in the muscle?
What is the first to be depleted in the muscle upon the initiation of vigorous exercise?
What is the difference between a catabolic reaction and an anabolic reaction?
An anabolic reaction involves the use of energy to build up biomolecules.
An anabolic reaction tends to utilize ATP
The regulation of glycolysis and gluconeogenesis can be compared as follows:
ATP inhibits glycolysis and ADP inhibits gluconeogensis
Pyruvate kinase is NOT inhibited by:
During gluconeogensis, pyruvate is converted to phosphoenol pyruvate. What is required?
ATP & GTP
Phospenolpyruvate is converted to pyruvate during glycolysis, and the reverse happens in gluconeogensis. What is the difference?
In glycolysis, one high-energy phosphate is produced, while in gluconeogensis, two high energy phosphates are utilized.
3 enzymes that are regulated during glycolysis:
What role does CO2 play in gluconeogenesis
It is important for the formation of phosphoenolpyruvate from pyruvate
The cory cycle involves:
Transfer of glucose to the muscle
What would happen if lactate were not removed from the muscle during active glycolysis?
Glycolysis would be inhibited
How many ATP and/or GTP are converted to the diphosphate to generate glucose during gluconeogenesis?
How many irreversible steps are involved in gluconeogenesis?
Glyceraldehyde 3-phosphate dehydrogenase utilizes:
A thiol intermediate
Which step is reversible?
d. glyceraldehyde 3-phosphate dehydrogenase
Aldolase and Glyceraldehyde 3-phospate dehydrogenase
Which enzyme commits the sugar molecule to the glycolytic pathway?
What is the first irreversible step in glycolysis?
Gluconeogensis takes place primarily in the:
True or False.
If pyruvate is produced during glycolysis, it must be metabolized to lactate.
The energy required for the formation of the first ATP in glycolysis comes from:
The oxidation of a carbon atom
Why does dihydroxyacetone phosphate not predominate in the cell?
a. it is unstable
b. it is metabolized to form more glucose
c. it is metabolized directly to form acetyl-CoA
d. its formation is kinetically very slow
e. none of the above
e. none of the above
Which of these has the highest energy phosphate?
e. glyceraldehyde 3-phosphate
The formation of phosphoenolpyruvate during glycolysis requires:
A dehydration reaction
The formation of 1,3-biphosphoglycerate:
Requires the production of NADH
Which product of triose phosphate isomerase is favored thermodynamically?
During glycolysis in microorganisms, followed by fermentation, one glucose produces:
True or false.
During glycolysis, six-carbon sugar molecules remain cyclic at all times.
The substrate utilized in the formation of phosphoenolpyruvate during glycolysis is:
Triose phosphate isomerase:
Upon substrate binding undergoes a steric change to eliminate water from the active site.
Is extremely rapid
Does not require molecular oxygen
Takes place in many pathogenic organisms
Requires an ATP
Promotes the retention of glucose in the cell
Undergoes a dramatic conformational change upon substrate binding
Product of phosphoglycerokinase has:
Phosphates on carbon 1 and 6
What happens to NADH in the absence of oxidation?
It must be recombined with the products of glycolysis to yield ethanol or lactate
In glycolysis, what are the irreversible steps?
Steps 1,3, and 10
Pyruvate kinase makes:
Phosphoglycerate mutase makes:
Phosphoglycerate kinase makes:
Glyceraldehyde 3-phosphate dehydrogenase makes: `
In the 3-carbon phase of glycolysis, ATP is___.
In the 6-carbon phase of glycolysis, ATP is____.
In glycolysis, is glyceraldehyde the major or minor product?
What is the first committed step of glycolysis?
Phosphorylation of fructose 6-phosphate to fructose 1,6-biphosphate
What type of environment promotes a reaction with phosphate?
Triose phosphate isomerase makes _______ from ________.
Dihydroxyacetone phosphate and glyceraldehyde 3-phosphate from fructose 1,6-biphosphate
Aldolasemakes _____from ______.
Glyceraldehyde 3-phosphate from Fructose 1,6-biphosphate
Phosphofructokinase + ATP makes _____ from _______.
Fructose 1,6-biphospate + ADP from Fructose 6-phosphate
Phosphoglucose isomerase makes _____ from_____.
Fructose 6-phosphate from glucose 6-phosphate
Hexokinase + ATP makes _____ from ______.
Glucose 6-phosphate + ADP from glucose
Aldolase makes _____ from _______.
Glyceraldehyde 3-phosphate and dihydroxyacetone phosphate from Fructose 1,6-biphosphate
Phosphofructokinase makes _____ from _____.
Fructose 1,6-biphosphate from Fructose 6-phosphate
Phosphoglucose isomerase makes ____ from _______.
Fructose 6-phosphate from Glucose 6-phosphate
In glycolysis, how many ATP are produced per glucose molecule?
The three possible products of glycolysis:
Where does energy come from in the absence of oxygen?
The oxidation of carbon
Regulation of the Citric Acid Cycle primarily takes place at steps that:
Produce new products that can be used by the cell
How is oxaloacetate regenerated in the citric acid cycle?
By dehydration of malate
How many high-energy electron-containing molecules are generated by the Citric acid cycle?
3NADH and 1FADH
Describe the carbon released as CO2 upon dehydration of isocitrate:
It does not come from pyruvate
Which step in the citric acid cycle involves the attachment of CoA?
Dehydration of alpha-ketoglutarate
Fro succinate to oxaloacetate. two high -energy molecules are formed. What can be said about this reaction?
A FADH2 is formed upon the conversion of a C-C bond to a C=C bond.
From what molecule is the energy derived to form CoA linkage in pyruvate dehydrogenase i.e., which does CoA displace?
The energy to drive citrate formation from acetyl CoA and oxaloacetate comes from:
The energy in the CoA linkage
The energy derived from oxidation of a carbon atom
The release of CO2
In pyruvate dehydrogenase, the acetate is transferred from one member of the enzyme complex to another. What coenzyme is responsible for this transfer?
True or False.
CoA is utilized during the Citric Acid Cycle only during the formation of Acetyl CoA, which is eventually metabolized by the cycle.
True or False.
it is not possible in a complex pathway like the citric acid cycle to contain a step that requires large amounts of energy.
During the complete cycle of pyruvate dehydrogenase activity:
Acetate is bound to TTP
Acetate is bound to lipoid acid
Acetate is bound to CoA
The dehydration of malate:
Is inhibited by phosphorylation
Is inhibited by NADH
Is inhibited by ATP
The first CO2 released from citrate comes from:
The carboxylate carbon atom located nearest the ketone group of oxaloaceate
When fumarate is converted to malate in the citric acid cycle:
One water is used only
During the citric acid cycle, one acetate enters the cycle and eventually is able to produce:
Two CO2 molecules, 8 high energy electrons and GTP
The FO formation of ATP synthase produces how many ATP molecules when 10 ions pass through it?
What type of electron transporters are in Complex 1?
In ATP synthase:
The F1 subunit does not move, but a rotating protein changes activity of the subunits.
Which member of the citric acid cycle is also considered a member of the electron transport chain?
Mitochondria contain two membranes. What can be said about the inner membrane?
it is larger in surface area than the outer membrane
It is associated with members of the electron transport chain
Why is it that electrons derived from succinate dehydrogenase Complex 2 do not generate as much energy as from NADH?
These electrons pass through only Complex 3&4
For each turn of ATP synthesis, how many ATP molecules are produced?
The energy involved in driving ATP synthesis in the mitochondria is derived from:
Ionic charge differences
The motive force involved in driving ATP synthesis in the mitochondria comes from:
High hydrogen ion concentration in the inner-membrane space of the mitochondria
Complex III of the electron transport chain
Receives electrons directly from ubiquinone
Gives one electron to cytochrome C
Cytochrome C is:
Freely soluble in the inner-membrane space
In the ATP synthase, one turn:
Requires approximately 11 hydrogen ions to pass into the matrix
Electrons within Complex 1 the ubiquinone NADH-Q oxidoreductase, are passed from:
From NADH to sulfur-iron containing complexes
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