DNA Sequence And Gene Mutation
This chapter is about DNA sequence and gene mutation, and we also discuss activity of enzymes.
What is the complementary strand for the following DNA sequence?
3′ – CTA TAG GAG ACT CAT – 5′
5′ – GAT ATC CTC TGA GTA – 3′
What is the complementary sequence for the following DNA sequence?
5′ – GCC ATC TCG AAT – 3′
5′ – ATT CGA GAT GGC – 3′
Which mRNA molecule would be made using the following template DNA sequence?
5′ – ACG TTC GAC AAG – 3′
5′ – CUU GUC GAA CGU – 3′
Assuming 100% reaction efficiency, how many DNA copies are created after the completion of four complete PCR cycles?
16
What is the function of DNA polymerase in the process of PCR?
It recognizes the primers and uses the available dNTPs to replicate the template DNA sequence.
114 115 116 117 − Amino Acid Number
His Arg Lys Gly − Amino Acid Sequence
CAC CGC AAG GGG − Normal Gene RNA Sequence
CAC CGC UAG GGG − Mutant Gene X RNA Sequence
Which type of mutation does Mutant Gene X display?
Nonsense mutation
In sickle-cell disease, the glutamic acid (Glu) at position number seven is mutated to valine (Val).
What change in codons corresponds to this mutation?
GAA to GTA
What are possible blood types of the parents of a patient with blood type AB?
A and B
Studies have shown that increased expression of two genes called SIRT1 and SIRT2 is associated with chronic exposure to cocaine and contributes to drug addiction.
What difference in the regions of the SIRT1 and SIRT2 genes in people addicted to cocaine increases their expression?
The nucleosomes become more widely spaced.
Mice with low levels of agouti gene expression tend to have yellow fur and are obese, while mice with higher levels of expression are brown and of normal weight. Studies show that expression of the agouti gene in mice can be controlled by epigenetics.
What scenario describes epigenetic regulation of the agouti gene?
Mother mice fed methyl-rich diets during pregnancy give birth to offspring with decreased agouti gene expression compared to those fed a methyl-poor diet.
Oxidative damage to DNA can often result in the alteration of a single nucleotide.
Which DNA repair mechanism would repair this type of damage?
Base excision repair
Xeroderma pigmentosum (XP) is a recessive genetic disease that occurs when one or more of the genes that perform nucleotide excision repair are nonfunctional.
Why do XP patients have a much higher incidence of skin cancer than the general population?
The mutation rate of all other genes is higher due to failure to repair.
Which reaction is responsible for the formation of polypeptides?
Dehydration
Which term describes the order of amino acids in a peptide chain?
Primary structure
When using heat to denature a protein, which force is the first to be disrupted as temperature increases?
Hydrophobic interactions
A commonly used technique for protein denaturation is adding an acid or a base to dramatically change the pH.
Which force is most impacted by this change in pH?
Ionic bonds
An active elderly patient is becoming frequently disoriented, having trouble recalling her daily routine, and becoming aggravated easily. She forgets words and places and has difficulty recognizing her children.
Which biochemical event is responsible for this patient’s behavior?
Protein aggregation
In which situation could a body function be disrupted by altering protein structure?
a. A mutation in calcium phosphate results in weak bones
b. A mutation in glycogen results in increased blood sugar levels
c. A mutation in a triglyceride results in obesity
d. A mutation in aconitase blocks an essential step in aerobic metabolism – correct
How can an alteration in protein structure lead to a disease state?
A mutation replaces an isoleucine with an aspartic acid in a transcription factor protein, which blocks the normal folding of the protein and its function in the expression of certain genes.
Which structural level shows the greatest difference when comparing denatured proteins with the normal version of the protein?
Tertiary
Frying an egg changes the egg white from a clear liquid to an opaque solid.
Which molecular change in the albumin protein causes this change in appearance?
Hydrophobic interactions form between denatured egg white proteins.
What is the driving mechanism of plaque formation in prion diseases?
Propagation of misfolding from one protein to another
Which feature of a protein made of a single polypeptide chain is most directly responsible for its function?
Three-dimensional structure
How does the Bohr effect describe the relationship between carbon dioxide levels, blood pH and the amount of oxygen bound to hemoglobin?
An increase in carbon dioxide production leads to a decrease in blood pH, causing hemoglobin to release oxygen more readily.
Which statement describes the binding of oxygen gas to a heme group?
a. The binding of oxygen gas to heme changes the structure of the heme group.
b. Oxygen gas binds to heme with greater affinity than other gas molecules.
c. Oxygen gas binds directly to the four porphyrin nitrogen atoms in the heme group.
d. Up to four oxygen gas molecules can bind to each heme group.
Which characteristic of myoglobin makes it an effective oxygen storage molecule?
It has a high affinity for Oxygen
At low O 2 concentrations, how does myoglobin’s affinity for O 2 relate to hemoglobin’s affinity for O 2?
Myoglobin has a much greater affinity for O 2 than hemoglobin does.
How does pH level promote the deoxygenated conformation of hemoglobin?
When pH lowers, excess H + binds to negatively charged side chains on hemoglobin and changes ionic bonds between subunits to favor the T-state
What is occurring in surrounding tissues as the amount of hemoglobin saturated with oxygen increases?
The amount of carbon dioxide decreases.
What is feedback inhibition?
Reversible, noncompetitive inhibition of an enzyme in a pathway by a product of that pathway
Which form of enzyme regulation is likely to be used by an organism to control the catalytic activity of its enzymes as it adapts to changes in available nutrients?
Feedback inhibition
How does heating beyond optimum temperature inactivate enzymes?
By changing the enzyme’s three-dimensional shape
What occurs in enzymes during the phenomenon of induced fit?
Substrate binding causes a conformational change.
Which portion of the enzyme does the substrate bind to?
Active site
Which type of inhibition occurs when a particular drug binds to the allosteric site of an enzyme and subsequently changes the enzyme’s structure?
Noncompetitive
What occurs immediately after the appropriate molecule enters the active site of an enzyme?
The enzyme binds the molecule to form an enzyme-molecule complex.
How is energy provided for ATP production during the final stage of aerobic metabolism?
Protons diffuse through a transmembrane protein.
How does insulin impact carbohydrate metabolism?
It stimulates the uptake of glucose from the blood by cells in the body.
How does insulin reduce blood glucose levels?
It increases the translocation of GluT4 transporters to the cell membrane.
Approximately how many ATP molecules can be produced from a single molecule of glucose during aerobic metabolism?
30
Which cellular condition prompts the cell to perform fermentation rather than the Krebs cycle?
Lack of O2
What causes the symptoms of noninsulin-dependent (Type 2) diabetes?
There are not enough GluT4 transporters on plasma membranes.
Which metabolic pathway involves coenzyme A, NAD, and FAD?
Beta oxidation
Which molecule is pyruvate directly converted to under aerobic conditions?
Acetyl-CoA
How many molecules of lactate are required to produce one molecule of glucose?
2
What is the role of oxygen in aerobic metabolism?
It acts as the final electron acceptor in the electron transport chain
Which pathway is triggered by increased levels of epinephrine and provides a quick increase in available glucose?
Glycogenolysis
Which type of molecule can be used in gluconeogenesis?
Amino acid
Which molecule acts as the primary signal for glycogen breakdown?
Glucagon
What is a possible chemical formula for a monounsaturated fatty acid?
C 8H 14O 2
What is the function of the class of lipids known as eicosanoids?
They act as signaling molecules.
What is a glycolipid?
A polymer of monosaccharides covalently attached to a membrane lipid.
Which component of red blood cells determines blood type in the ABO blood group system?
Glycolipids and glycoproteins
Which vitamin is not absorbed by phospholipid micelles?
Vitamin C
Which event is stimulated by release of glucagon into the blood?
Increase in lipolysis of triglycerides
What occurs in an otherwise healthy person whose diet has very few carbohydrates and high levels of fats?
Acetone is produced in the blood.
Where is mRNA located and what is it’s function?
Location: made in the nucleus, moves to the cytoplasm
Function: brings information from DNA in nucleus to ribosomes in cytoplasm; directs synthesis of polypeptides
Where is rRNA located and what is it’s function?
Location: ribosomes
Function: site of polypeptide synthesis; NOT involved in coding
Where is tRNA located and what is it’s function?
Location: cytoplasm
Functions: transports amino acids to ribosomes; positions each amino acid at correct place on polypeptide chain
What are the proton coding sequences along a stretch of DNA called?
exons
The 3-nucleotide region on one end of a tRNA molecule is called a(n) ______
anticodon
During initiation of transcription, RNA polymerase binds to a region of the DNA called the ______
promoter
The _____ strand of DNA gives the sequence of the RNA to be made, but the _____ strand is the DNA strand used to make the RNA.
coding, template
Recruitment of RNA polymerase and subsequent production of a new RNA transcript of a gene constitute what is known as _____
gene expression
What is the complementary DNA strand for the DNA sequence 5′-ATT CGG GCT CCC -3′?
5′- GGG AGC CCG AAT -3
What is one direct effect of inhibiting translation?
Production of proteins would stop
Recall that the DNA polymerase must bind a double-stranded nucleotide polymer before it can start making its own DNA polymer. What helps the DNA polymerase to overcome this problem in DNA replication?
RNA primers
Blood type is an example of what type of inheritance?
co-dominance
What is the correct order for the steps in the Polymerase Chain Reaction (PCR) process?
Denaturation, annealing, and elongation
Following transcription, what would be the resulting mRNA sequence from this template strand:5′-ACA GCT GTC-3′
5′-GAC AGC UGU-3′
All amino acids share a common backbone structure with a _____ group, a _____ group, and a side chain (R group) attached to a central _____.
carboxyl, amino, carbon
Peptide bonds form between two amino acids via a _____ reaction.
dehydration
_____ _____ is the order of amino acids in a protein. The amino acids are held together by peptide bonds and do not change.
Primary structure
_____ _____is the localized shape that is formed by hydrogen bonding patterns of amino acid backbone atoms. The most common are the alpha helix and beta sheet.
Secondary structure
_____ _____ is the result of different secondary structures interacting with one another via their R groups. These interactions include hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bonds.
Tertiary structure
Proteins with more than one polypeptide have _____ _____.
quaternary structure
The largest force governing protein structure is the _____ effect.
hydrophobic
_____ _____ form when two cysteine R groups are in close proximity and the two sulfur atoms form a covalent bond between them.
Disulfide bonds
_____ is the loss of a protein’s native (functional) three-dimensional structure due primarily to the loss of tertiary structure; it is not the breaking of peptide bonds.
Denaturation
Primary structure consists of the order of ______ in a protein. These are held together with ______ bonds that are formed by a ______ reaction.
amino acids, peptide, dehydration
In order to fulfill their function, proteins must fold in proper, three-dimensional conformations. Which one of the following molecules, available in a cell, is likely to help a protein fold properly?
chaperones
_____ are enzymes that use a phosphate donor, usually ATP, to add a phosphate to another molecule.
Kinases
Myoglobin and hemoglobin each have different numbers of subunits and this affects their respective oxygen storage and delivery capabilities. How many subunits do myoglobin and hemoglobin each have?
One, four
Patients with sickle cell anemia have atypical hemoglobin, which will distort the red blood cells into sickle shape during oxygen delivery. The substitution of a hydrophilic amino acid with a ____________amino acid in hemoglobin subunits results in the polymerization of hemoglobin, leading to the sickling of red blood cells.
hydrophobic
When binding hemoglobin or myoglobin, CO binds in place of _________.
Oxygen
Carbonic anhydrase is an important __________ present in the red blood cells that aids in efficient transportation of carbon dioxide in the form of _________, from tissues to lungs.
enzyme, bicarbonate ions
Hemoglobin binds to the oxygen at (high/low) pH and releases oxygen at (high/low) pH.
high, low
Hemoglobin acts as a buffer and controls the pH of the blood by binding to __________.
H+ ions
In the lungs, the CO2 concentration is _____ and the pH is ____, while in the tissues the CO2 concentration is ____ and the pH is _____.
low, high, high, low
In locations where the pH is low, hemoglobin will be in the ___ state, allowing it to _____ oxygen more effectively.
T, release
Increased levels of 2,3-BPG will _____ the affinity for oxygen by binding to and stabilizing the ___ state of hemoglobin. The action of 2,3-BPG allows hemoglobin to _____ oxygen more effectively, which is similar to the effect of _____ pH on the action of hemoglobin.
decrease, T, release, low
In comparison to adult hemoglobin, fetal hemoglobin has a _____ affinity for oxygen because it _____ _____ 2,3-BPG well.
higher, doesn’t bind
As carbon monoxide binds to hemoglobin, the protein subunits change conformation to allow carbon monoxide to bind faster. This process is called __________.
positive cooperativity
Carbon dioxide (decreases/increases) hemoglobin’s affinity for oxygen, while carbon monoxide (decreases/increases) it.
decreases, increases
Myoglobin _____ oxygen, whereas hemoglobin _____ oxygen.
stores, transports
Hb binds to CO with a (lower/higher) affinity than oxygen and stabilizes the ___ state.
higher, R
When hemoglobin changes from T to R, it has ________ affinity for oxygen.
high
When hemoglobin changes from R to T, it has _______________ affinity for oxygen.
low
When the oxygen concentration is high, the heme shape is _____________. When the oxygen concentration is low, the heme shape is ______________shape.
planar, bent
The Bohr effect is a relationship between hemoglobin’s oxygen binding behavior in conjunction with the pH of the surroundings. When the H+ ion concentration increases, the pH of the solution _________________.
decreases
Hemoglobin and myoglobin proteins bind to molecular oxygen. However, the protein part of the hemoglobin does not bind directly to the oxygen. Instead, a specific atom helps bind the oxygen. Which one of the following will help hemoglobin directly bind to the oxygen?
Select one:
a. Histidine
b. Carbon monoxide
c. Iron–correct
d. Heme
The symptoms of sickle cell anemia are primarily because red blood cells are misshaped. This is due to ____.
a mutation in the beta hemoglobin gene which leads to the insertion of valine into the hydrophobic patches on deoxygenated hemoglobin
Relative to the peripheral tissues, the pH in the lungs is _______ because __________________.
higher, the protons (H+) that were combined with hemoglobin quickly bind to bicarbonate (HCO3-) to form CO2; the CO2 is then exhaled
Metabolic pathways that use energy from ATP to build compounds are referred to as _____ pathways.
anabolic
To form acetyl-CoA from glucose, the glucose must first be split in half by a pathway in the cell cytosol called _____.
glycolysis
To form acetyl-CoA from fatty acids, the carbon chains that make up fatty acids are broken into two-carbon units by a pathway in the mitochondria called _____.
beta-oxidation
_____ _____ generates the majority of all ATP in most cells and is the culminating process of cellular respiration.
Oxidative phosphorylation
_____ are single carbohydrate monomers, often referred to as sugars. They consist of three to six carbons and are classified by the number of carbons they possess.
Monosaccharides
_____ are carbohydrates made of two monosaccharides bonded together. These small polymers also have names that end in -ose.
Disaccharides
_____ are long, often very complex carbohydrates. They can consist of tens, hundreds, or thousands of individual sugar molecules and have several different uses.
Polysaccharides
_____ is the addition of a phosphate group to a molecule, most often from ATP.
Phosphorylation
The final products of glycolysis are two molecules of _____.
pyruvate
In human cells, glycolysis takes place in the cytoplasm. The products of the glycolysis will enter the _________________ to continue with aerobic respiration.
mitochondria
Aerobic respiration requires oxygen. Oxygen has a role in which of the following pathways:
Select one:
a. Glycolysis
b. Electron transport chain–correct
c. Gluconeogenesis
d. Citric acid cycle
During periods of strenuous exercise the muscle cells can become anaerobic. Without oxygen, the electron transport chain cannot continue and the citric acid cycle slows down. In such situations, how do cells make ATP?
Select one:
a. There is no requirement for ATP in the muscles.
b. Pyruvate remains untransformed.
c. Pyruvate is transformed to lactate.-correct
d. Pyruvate produces acetyl Co-A and enters the citric acid cycle.
The citric acid cycle could be inhibited by high concentrations of _____ due to feedback inhibition.
NADH
In an exercising muscle cell under anaerobic conditions, _____ from glycolysis is turned into _____ in order to regenerate _____ for further rounds of glycolysis, which produces ___ ATP per round for the muscle cell to use. The Cori cycle allows _____ to be turned into _____ via gluconeogenesis in the liver at the expense of ___ ATP. This means that, overall, the Cori cycle creates a deficit of ___ ATP.
pyruvate, lactate, NAD+, 2, lactate, glucose, 6, 4
Carbohydrate loading is a common practice among endurance athletes. Often, three days before a big endurance event, they are known to eat large amounts of complex carbohydrates which leads to the storage of glycogen in their muscles. The stored glycogen increases their endurance by providing a steady supply of glucose during the event by the process of _______________.
glycogenolysis
Insulin controls both carbohydrate and fat metabolism. Which of the following statements describes the effects of insulin?
Select one:
a. Stimulates fatty acid production and storage
b. Stimulates the glucose uptake
c. Inhibits the glycogen breakdown
d. All of these – correct
The pancreas can regulate and maintain glucose homeostasis by secreting different hormones in response to varying blood glucose levels. The pancreas secretes insulin in response to high blood glucose levels, whereas ______________ is secreted in response to ________________ glucose levels.
glucagon, low
While treatment with Metformin is beneficial for many individuals with type 2 diabetes, it does increase the risk of lactic acidosis (accumulation of lactate in the blood that results in lower blood pH) in those who take it. What effect of metformin directly contributes to this potential risk?
Decreased gluconeogenesis in the liver
A risk factor associated with the use of metformin in the treatment of diabetes is lactic acidosis. Acidosis is associated with a _____ in blood pH, due to a(n) _____ in the concentration of hydrogen ions (H+). Given this change in blood pH, hemoglobin is more likely to _____ oxygen.
decrease, increase, release
Emma has an A1C level of 7.0% in her blood. A1C is a form of__________________.
hemoglobin
The polysaccharide cellulose is composed of sugar monomers linked through ______ linkages, with their CH2OH groups in _________ direction relative to the neighboring monomer.
beta, opposite
Glycolysis produces two ATP molecules. Through what process are these ATP molecules made?
substrate level phosphorylation
What product of beta oxidation is able to enter the citric acid cycle?
Acetyl CoA
What process is shared between anaerobic and aerobic Metabolism ?
glycolysis
Which of the following processes does NOT take place in the mitochondria of a cell?
Select one:
a. Production of FADH2
b. Creation of a proton gradient
c. Production of CO2 in the citric acid cycle
d. Conversion of pyruvate to lactic acid – correct
Which process is stimulated when glucagon is released into the bloodstream?
Select one:
a. Glycogenolysis – correct
b. Glycogenesis
c. Triglyceride synthesis
d. Glucose uptake
Which of the following chemical formulas represents a monosaccharide?
Select one:
a. NH2CH2COOH
b. C6H6O6
c. CH3(CH2)4COOH
d. C6H12O6 – correct
Which process is stimulated when insulin is released into the bloodstream?
glycogenesis
What is the largest source of energy storage in the normal human body?
triglycerides in adipose
Which of the following directly provides the energy necessary for the conversion of ADP + P to ATP by ATP synthase?
Select one:
a. Protons moving down a concentration gradient from the intermembrane space to the mitochondrial matrix
b. FADH2 transferring a high energy electron to Protein Complex II – correct
c. Oxygen binding to protons to form water
d. Cytochrome c accepting an electron from NADH
If a patient is healthy and has a normal oxygen concentration in her blood, approximately how many ATP are produced for every molecule of glucose that is aerobically metabolized?
30
What process takes place in the inner membrane of the mitochondria?
electron transport train
While barbiturates are potent inhibitors of Complex I in the Electron Transport Chain, they do not completely block electron transport because___________.
Select one:
a. NADH is able to interact directly with Complex II
b. FADH2 donates electrons to Complex II – correct
c. of increased activity of Coenzyme Q10.
d. FADH2 donates electrons to Complex I.
Where is energy stored in an ATP molecule?
In the bonds between the phosphate groups
In a fatty acid, the _____ carbon is found at the end of the fatty tail, furthest away from the _____ group.
omega, carboxyl
Which lipid has a 4-ring structure?
Sterol
A patient who is on a no-fat diet is at particular risk of deficiency in:
Select one:
a. Vitamin A – correct
b. Glucose
c. Insulin
d. Iron
During starvation, triglycerides can help supply some of the body’s glucose needs. Which breakdown product of triglycerides can be used to make glucose?
glycerol
Which is likely to be liquid at the lowest temperature?
Select one:
a. CH3(CH2)6CH=CH(CH2)2COOH
b. CH3(CH2)16COOH
c. CH3(CH2)4CH=CH(CH2)8COOH
d. CH3(CH2)3CH=CH(CH2)2CH=CH(CH2)3COOH correct
Which of the following accurately describes the steps involved in fatty acid synthesis?
Which of the following accurately describes the steps involved in fatty acid synthesis?
Select one:
a. Acetyl-CoA is transported to the mitochondrial —> Biotin transfers a carboxylate group to acetyl-CoA –> The malonyl group is transferred to a carrier protein –> malonyl ACP combines with acetyl-CoA, –> malonyl-CoA is added repeatedly to the growing fatty acid.
b. Triglycerides are broken into glycerol and acetyl-CoA –> acetyl-CoA enters mitochondria –> Acetyl-CoA enters the CAC —> The products of the CAC move on the ETC to generate fatty acids.
c. Acetyl-CoA is transported to the cytoplasm —> Biotin transfers a carboxylate group to acetyl-CoA –> The malonyl group is transferred to a carrier protein –> malonyl ACP combines with acetyl-CoA, –> malonyl-CoA is added repeatedly to the growing fatty acid – correc
d. Lactic acid moves into the liver –> The liver uses ATP to generate pyruvate —> 2 pyruvates combine to form a new fatty acid—
Which set of molecules are produced by the beta oxidation of fatty acids?
Select one:
a. Acetyl CoA, NADPH, malonyl CoA
b. CO2, H2O, and ATP
c. Acetoacetyl CoA and HMG CoA
d. Acetyl CoA, NADH, FADH2 correct
Through mandatory state testing, a 2-day-old newborn is found to have medium chain acyl-CoA dehydrogenase deficiency (MCADD). This enzyme deficiency interferes with the baby’s ability to break down medium chain fatty acids via beta oxidation. Her parents need to be given specific instructions on what the baby can ingest. Which of the following is CORRECT about this baby:
Select one:
a. She should never be given complex carbohydrates in her diet.
b. She will have less ability to store and utilize glycogen than a baby without the disease.
c. She will not be able to utilize adipose tissue for ATP production as effectively as a baby without the disorder. correct
d. All of her calories must come entirely from protein.
Which of the following contributes to the development of ketoacidosis in a diabetic patient?
Select one:
a. An increase in citric acid cycle intermediates, which increases the amount of oxaloacetate that acetyl-CoA can combine with to enter the citric acid cycle.
b. The increased production of citrate from acetyl-CoA.
c. Low rates of fatty acid oxidation.
d. A reduction in citric acid cycle intermediates, which decreases the amount of oxaloacetate that acetyl-CoA can combine with to enter the citric acid cycle. – correct
Which of the formulae below describes a saturated fatty acid?
Select one:
a. C6H6OH
b. C16H32O2
c. C12H22O2
d. C12H22O11
b – This formula contains 2 oxygen atoms and twice as many hydrogen atoms as carbons so it is therefore a saturated fatty acid.
Fatty acids with ___-configuration double bonds do not pack together well which lowers their melting point.
cis
Which best describes fatty acid hydrogenation?
Select one:
a. Saturated fatty acids have hydrogen added to them to increase their melting point.
b. Hydrogenation converts some unsaturated fatty acids into saturated fatty acids. – correct
c. Hydrogenation of fatty acids produces only the trans-configuration at the double bond.
d. Monounsaturated fatty acids are the only fatty acids that can be hydrogenated.
Which compounds make up the greatest reserves of energy in our bodies?
Triglycerides