Exam 1 Questions Flashcards
About chirality of organic molecules, in human biochemistry, generally
Sugars and amino acids will randomly obtain D or L to reach 50% L and 50% D to maximize the entropy
Most sugars and amino acids are D
Most sugars are D, most amino acids are L
Most sugars are L, most amino acids are D
Most sugars and amino acids are L
Most sugars are D, most amino acids are L
The cofactor FAD and FMN share the same vitamin precursor, which is?
Vitamin B1
Vitamin B5
Vitamin B2
Vitamin B4
Vitamin B3
Vitamin B2
Nutrients absorbed by intestine mucosa use circulatory system to reach cells for metabolism. Regarding nutrient transportation, which of the following statement is incorrect?
Amino acids. sugars and water soluble vitamins reach right atrium via portal vein, hepatic vein & inferior vena cava
Lipids and lipid soluble vitamins reach right atrium via lymphatic ducts and superior vena cava
Pulmonary vein carries oxygen rich blood to left atrium
Blood rich in nutrients and oxygen is pumped out by left ventricle to Aorta and circulated to body cells
In the lungs, oxygen is taken up by blood (red blood cells) and reaches the right atrium via pulmonary vein and superior vena cava
In the lungs, oxygen is taken up by blood (red blood cells) and reaches the right atrium via pulmonary vein and superior vena cava
How many electrons do carbon and oxygen have at their valence shells, respectively?
3, 4
1, 2
4, 5
4, 8
4, 6
4, 6
In biochemistry, resonance structure may stabilize a metabolite
True
False
True
Which of the following vessels transports amino acids and glucose rich blood from gastric-intestinal tissues to the liver?
Hepatic artery
Lymph duct
Hepatic vein
Inferior vena cava
Portal vein
Portal vein
During ATP synthesis, the mitochondrial inner membrane has a transporter called phosphate translocase that simultaneously transports a phosphate and a proton from the P-side into the mitochondrial matrix. This transporter belongs to the family of:
Uniporter
Symporter
Antiporter
Symporter
In TCA cycle. the step that generates a GTP is:
Succinyl CoA to succinate
a-KG to succinyl CoA
Succinate to fumarate
Malate to fumarate
Fumarate to malate
Succinyl CoA to succinate
Enzumes can be modified by covalent modifications (aka. posttranslational modifications), and phosphorylation is the most common form of such modifications. The following amino acids are subject to phosphorylation except for:
Glycine
Serine
Hydroxylated proline
Threonine
Tyrosine
Glycine
In enzyme-catalyzed reactions, the activation energy is usually significantly lowered by the interactions between enzyme and substrate. These interactions include the following, except for:
Hydrophilic force
Charge (ion) -mediated interaction
Hydrogen bond
Van der waals force
Hydrophobic force
Hydrophilic Force
B family vitamins absorbed by small intestine will travel to liver via:
Bile duct
Hepatic lymph duct
Hepatic artery
Hepatic vein
Portal vein
Portal vein
Organic metabolites are usually complicated large molecules, but a given biochemical reaction usually involves a specific functional group. The functional group shown in figure attached (in blue) is?
Carbonyl
Acyl
Acetyl
Aldehyde
Carboxyl
Carboxyl
The reaction: ATP to ADP + Pi releases energy. Which of the following statements is NOT correct?
Actual concentration of ATP may influence the actual ΔG
Concentration of Mg++ in the reaction may influence the actual ΔG
Actual concentration of Pi may influence the actual ΔG
Actual type of enzyme used to catalyze this reaction may influence the actual ΔG
Actual concentration of ADP may influence the actual ΔG
Actual type of enzyme used to catalyze this reaction may influence the actual ΔG
In TCA cycle. the enzyme that catalyzes the conversion of fumarate to malate is called?
Fumarate dehydrase
Fumarate dehydrogenase
Fumarate hydratase (fumarase)
Fumarate:malate oxidoreductase
Malate dehydrogenase
Fumarate hydratase (fumarase)
About the regulation of TCA cycle, which of the following statement is NOT correct?
In response to an increase of ADP level, the TCA cycle is accelerated.
In response to an increase of NADH, the TCA cycle is inhibited
In response to an increase of Ca++ concentration, the TCA cycle slows down
In response to an increase of ATP level. the TCA cycle slows down
The rate is regulated through three regulatory enzymes: citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase complex
In response to an increase of Ca++ concentration, the TCA cycle slows down
This course will focus on specific aspects of biochemistry, which does not include:
Breaking down carbohydrate to produce ATP
Disposal of metabolic wastes
Biosynthesis of important biomolecules
Genetics and expression of genetic information
Catabolism of fatty acids in human cells
Genetics and expression of genetic information
Biochemical reactions in human body are usually catalyzed and regulated by protein-based enzymes, and the overall activity can be, in turn, regulated by various signals the cells receive. The possible mechanisms by which an enzyme function can be regulated include
The stability of the mRNA that is encoding the protein
Stability of the protein itself
Transcription speed of the gene encoding the protein
Presence of inhibitory or stimulatory subunits that interact with the catalytic subunit
All of them
All of them
The role of the molecular oxygen in cellular respiration is to be used:
As the final electron acceptor to oxidize acetyl-CoA at stage 2 to form CO2
As the final electron acceptor at stage 3 to form H2O
As the final electron donor at stage 3 to form water
As the final electron donor to oxidize carbon at stage 2 to form CO2
To oxidize glucose at stage 1 of cellular respiration, forming acetyl-CoA
As the final electron acceptor at stage 3 to form H2O
In the body of heterotrophic animals, normal metabolism depends on photosynthesis taking place in autotrophic organisms because photosynthesis:
Provides reduced carbon sources
Fixes nitrogen, providing a nitrogen source
Generates molecular oxygen
Provides both reduced carbon sources and reduced nitrogen sources
Provides both reduced carbon sources and molecular
oxygen
Provides both reduced carbon sources and molecular
oxygen
All the following TCA cycle enzymes are in mitochondrial matrix, except for:
Malate dehydrogenase
Isocitrate dehydrogenase
Alpha-ketoglutarate dehydrogenase
Aconitase
Succinate dehydrogenase
Succinate dehydrogenase
During active biosynthesis, when a metabolite is removed from the TCA cycle for biosynthesis:
Replenishing mechanism termed anaplerosis, which uses anaplerotic reactions to replenish the metabolites of Krebs cycle
The cycle will temporarily stop, until the biosynthesis completed
The TCA metabolites usually are not involved in biosynthesis
As long as you can feed acetyl CoA into the mitochondria, the TCA cycle will run automatically
The removed metabolite usually is not important, hence not affecting the cycle
Replenishing mechanism termed anaplerosis, which uses anaplerotic reactions to replenish the metabolites of Krebs cycle
When a reversible reaction has a positive value of ΔG’o
The reaction can move towards the formation of product if the concentration of product is low enough, such as being continuously drained to form subsequent metabolite, or subsequent metabolic
pathway
The existence of enzyme will help to push the reaction forward to form products
The reaction can move towards the formation of product if the substrate is very stable
The only way to push the reaction forward is to use ATP
The reaction reverses, converting product to substrate
The reaction can move towards the formation of product if the concentration of product is low enough, such as being continuously drained to form subsequent metabolite, or subsequent metabolic
pathway
About a protein-based enzyme, which statement is correct?
If another protein associates with the enzyme and facilitates its function, it is called a coenzyme
Only very few proteins can function as enzymes in living systems
Some cofactors or coenzymes covalently bind to enzymes, they are called prosthetic groups.
When a cofactor binds to the enzyme, it may either enhance or inhibit the enzyme activity
Simple metal irons cannot serve as cofactor of enzymes: they have to be first incorporated into any organic molecule, such as iron into heme, in order to be a cofactor
Some cofactors or coenzymes covalently bind to enzymes, they are called prosthetic groups.
Mass spectroscopy is frequently used in metabolic research. If a scientist wants to test whether the carbon atoms in acetyl-CoA is incorporated into OAA by mass spectroscopy, the ideal carbon
isotope to use is:
12C acetyl-CoA
None
Mix of: 13C acetyl-CoA and 14C acetyl-CoA
14C acetyl-CoA
13C acetyl-CoA
13C acetyl-CoA
In Michaelis Menten Kinetics, Km indicates the substrate concentration that results in a Vo equivalent to 50% Vmax
True
False
True
See structure given in attached file: Oxaloacetate is
I
II
III
IV
V
III
According to the textbook, which statement about the cellular respiration is NOT correct:
The second stage is oxidation of acetyl-CoA in Krebs cycle to reduce NAD+ and FAD
The first stage is glycolysis
Has three stages
The first stage is the generation of acetyl-CoA
The third stage is the generation of ATP by electron transfer and oxidative phosphorylation
The first stage is glycolysis
An enzyme is known to follow the Michaelis Menten kinetics. When increasing concentrations of an inhibitor was used to characterize the kinetics, the plot is given in figure 1. This plot indicates that the inhibition is?
Mixed
Uncompetitive
Competitive
Noncompetitive
Uncompetitive
Regarding energetics of reaction types, which of the following statement is correct?
Formation of new bonds are achieved by group transferring and is usually independent of energy input
None is correct
Isomerization reactions involve intramolecular rearrangement of functional groups, hence depending on energy input
Oxidation of reduced carbons is usually exergonic
Hydrolysis reactions are usually endergonic
Oxidation of reduced carbons is usually exergonic
In the presence of carbon monoxide in the mitochondria:
Both ATP production and oxygen consumption will be inhibited
Only complex IV will be inhibited, complex I and complex III will keep working, with decreased ATP production
CoQ oxidized, Cyt c reduced
CoQ will be reduced, Cyt c will be mainly oxidized
Both CoQ and Cyt c will be at the oxidized status
Both ATP production and oxygen consumption will be inhibited
About allosteric regulation of enzyme activity:
The modulator molecule serves as a cofactor to stimulate the enzyme activity
The enzyme must have two subunits: catalytic and regulatory subunits
If an inhibitory modulator binds the regulatory site, it may cause conformational change to impede the enzyme and substrate interaction.
The modulator molecule binds the catalytic sites, promotes the enzyme and substrate interaction
A positive modulator usually binds to the regulatory site, and inhibitory modulator usually binds to the catalytic site
If an inhibitory modulator binds the regulatory site, it may cause conformational change to impede the enzyme and substrate interaction.
In biochemistry, most reactions are catalyzed by protein based enzymes. About protein-based enzymes, which statement is correct?
Disulfide bond play roles in enzyme interaction with substrate
Apoenzyme is the term to indicate a completely functional enzyme complex
Tertiary structure refers to the formation of alpha-helix and beta sheet
Holoenzyme is the whole functional enzyme complex including cofactor or cofactors
Primary structure of enzyme means the native structure of a protein prior to form complex with other subunits
Holoenzyme is the whole functional enzyme complex including cofactor or cofactors
When an enzyme-catalyzed reversible reaction reaches equilibrium,
If more enzymes are added. the reaction will proceed forward
The standard transformed free energy change under this condition (DeltaG’0) is 0
The free energy change (DeltaG) under this condition is 0
If more products are added, the reaction moves forward to form even more products, called inducibility
Products can be purified by completely removing the substrates from the reaction
The free energy change (DeltaG) under this condition is 0
The most reliable way to confirm that a protein can be phosphorylated is to carry out an in vitro (in test tube) kinase assay. In such an assay, the protein to be tested is mixed with a kinase and
ATP containing radioactive phosphate, normally 32P. If the protein can be phosphorylated, the radioactive isotope Phosphorus will be incorporated into the protein and turn the protein radioactive. If you are asked to perform such an assay, which type of ATP will you use?
ATP, with the radioactive 32P at beta position
ATP, with the radioactive 32P at gamma position
dATP, with the radioactive 32P at alpha position
ATP, with the radioactive 32P at alpha position
dATP, with the radioactive 32P at gamma position
ATP, with the radioactive 32P at gamma position
An uncoupler inhibitor of cellular respiration-
Shuts down the TCA cycle, but electron transfer and ATP production continue..
Shuts down the proton pumps, no proton pumped out to P-side, but electron transfer continues
Facilitates the protons move back from P-side to N-side freely, thus no ATP generated, but electron transfer continues…
Shuts down the electron transfer to O2, ATP production and TCA cycle continue…
Shuts down the ETC transfer process, but TCA cycle continues…
Facilitates the protons move back from P-side to N-side freely, thus no ATP generated, but electron transfer continues…
The overall enzyme function may be regulated by:
Transcriptional control of mRNA levels and enzyme levels
Association with regulatory subunits
Allosteric modulators
Covalent modification-triggered subcellular sequestration or protein stability
All of them
All of them
About essential fatty acids, which statement is most accurate?
They not healthy, so should be completely removed from our diet if possible
They are poly-unsaturated fatty acid that can easily dissolve in water
They are characterized by multiple hydroxyl (-OH) groups
Contains both hydrophobic and hydrophilic groups, made by specialized human hepatocytes
They are fatty acids with double bounds at either Omega3 or Omega6, or both positions
They are fatty acids with double bounds at either Omega3 or Omega6, or both positions
About biosynthetic function of TCA cycle, which statement is NOT correct?
Malate can be removed from the cycle to synthesize fatty acids
Oxaloacetate can be removed from the cycle to synthesize phosphoenolpyruvate (PEP)
a-ketoglutarate can be used to synthesize amino acids
oxaloacetate (OAA) can be removed from the cycle to synthesize amino acids
succinyl-CoA can be removed to synthesize heme
Malate can be removed from the cycle to synthesize fatty acids
About heme, which of the following statements is NOT correct?
Is needed for red blood cells
Is needed for cytochrome family of enzymes
Is needed in oxygen transportation in red blood
Is needed for ETC
Is needed for aconitase activity in Krebs cycle
Is needed for aconitase activity in Krebs cycle
See structures given in attached file: alpha-ketoglutarate is?
I
II
III
IV
V
II
What is the vitamin precursor required for biosynthesis of cofactor NAD+ and NADP+?
Vitamin B3
Vitamin B7 (biotin)
Vitamin B5
Vitamin B2
Vitamin BI
Vitamin B3
Thermogenin or UCP1 is a protein encoded by UCP1 gene. This proteins is mainly expressed in brown adipocytes. Its biological function is:
Generating heat
Regulating the proton motive force
Facilitating ATP production
Regulating electron transport chain efficiency
No specific function. byproduct of evolution
Generating heat
in human cells. the most common form of energy molecule that thermodynamically links catabolic reactions to anabolic reactions is:
ATP
NADH
Acetyl-CoA
FADH2
Fatty acids
ATP
Which complex of the ETC is NADH-quinone oxidoreductase?
Complex IV
Complex III
Complex I
Complex V
Complex II
Complex I
