AAMC FL 3

"HRP catalyzes the oxidation of aromatic amines and phenols. The oxidation occurs at the ring substituent. The proposed catalytic mechanism involves the formation of a porphyrin-based cation radical through reaction with hydrogen peroxide as shown in Reaction 1. The aniline free radicals generated in the oxidation reactions undergo coupling to produce the dimer, and subsequent oxidation and coupling reactions produce the polymer." Based on the passage, what is the structure of the product of the reaction between 8-hydroxyquinoline-5 sulfonate and HRP? On back.

A. A couple of things from the passage allows you to glean that it is A. The passage states: "HRP catalyzes the oxidation of aromatic AMINES and PHENOLS. The oxidation occurs at the ring SUBSTITUENT." Because the oxidation occurs at a phenol or amine, we automatically know that it can't be (C) or (D). What helps us decide between (A) and (B) is that the passage states that the oxidation has to occur at a RING SUBSITUENT and the nitrogen in the second ring is NOT a substituent, it is actually a part of the ring. So it has be the OH substituent on the phenol that is getting the radical.

The best-performing PANI had a maximum conductivity of 5.0 × 10-3 (Ω∙cm)-1. What is the resistivity of the best-performing PANI described in the passage? A. 0.002 Ω•cm B. 50 Ω•cm C. 200 Ω•cm D. 500 Ω•cm

C. 200 Ω•cm REMEMBER: resistivity = 1/conductivity resistivity = 1/(5 x 10^-3). resistivity = 0.2 x10^3 = 200 Ω•cm If you didn't know the equation, you could see that they literally gave you ONE number in the passage and that all of the units are inverse of the units they give you, so you would do inverse of that number :)

What is pK?

pK is kind of like Km. pK is the -log of K and K is the equilibrium constant which is the [unfolded]/[folded], because that was the reaction being tested. So larger K values are more unstable because for a given pH or temperature they are more unfolded. Since a larger K means a smaller pK then smaller pK values mean that something is more unstable (exhibit more cooperativity in unfolding).

The Cgr1 and Cgr2 proteins are produced from: A. separate mRNAs transcribed from different promoter sequences upstream of each gene. B. a single mRNA transcribed from a single promoter sequence upstream of the operon. C. a single RNA transcribed from a single promoter sequence and alternately spliced to produce separate mRNAs. D. separate mRNAs translated from a single promoter upstream of the operon.

(B) B. a single mRNA transcribed from a single promoter sequence upstream of the operon. Bacteria have operons, also known as polycistronic mRNA. This means that multiple genes are coded from one promoter and one terminator region and one mRNA. (A) would be applicable to eukaryotes, but not prokaryotes because they only have one promoter. (C) Prokaryotes do NOT have post-transcriptional processing (i.e alternative splicing, 5' cap, poly-A tail, RNA interference). (D) Prokaryotes will transcribe one polycistronic mRNA (from operon region), not multiple, transcribed from one promoter that encodes for various genes (also, this option says translation, and sis, we already KNOW that that's wrong).

What is the elaboration likelihood model (ELM)?

(D) The Elaboration Likelihood Model for Persuasion (ELM) is a more cognitive approach that focuses on the why/how of persuasion. Two ways in which information is processed: -Central Route of Persuasion: The degree of attitude change depends on quality of the arguments by the persuader. How much we are persuaded depends on quality of persuasion. ARGUMENT/WORDS are central! -Peripheral Route of Persuasion: looks at superficial/expertise/non-verbal persuasion cues, such as attractiveness/status of persuader. The doctor himself is peripheral (he is the one delivering the words!)

For the pedigree, what are some things that are true for the following: A. Autosomal dominant B. Autosomal recessive C. X-linked recessive D. Y linked

1. If the disease or condition skips generations, it must be recessive. In other words, if two healthy parents have a child with the condition, it cannot possibly be a dominant trait. For a child to have the disease, he or she must have inherited at least one disease allele from a parent, and if the disease were dominant, that parent would show the disease phenotype. Since the parent does not, it must be recessive. 2. If more males than females have the disease or condition, it is more likely to be X-linked recessive. This isn't a guarantee; due to simple chance, more males than females could have a condition even if it were autosomal (located on a non-sex chromosome). However, remember that females have two X chromosomes, so they will not display the disease phenotype if they have only one recessive disease allele. In contrast, males have only one X chromosome, so one "disease" allele is enough for them to have the condition. 3. Furthermore, if a disease is X-linked recessive, fathers will never pass it down to their sons. Fathers give sons their Y chromosomes, not X! For this reason, affected males must always receive their disease allele from their mothers, who could be either carriers or fully affected themselves. 4. If only males have the condition, it's probably Y-linked, though these conditions are very rare. Only males carry Y chromosomes! 5. If all children of affected mothers have the condition, but no children of affected fathers and healthy mothers do, it's probably mitochondrial. Mitochondria have their own genetic material, which is passed down through the maternal line. A number of diseases are inherited in this fashion.

Enzymes work best within specific temperature and pH ranges, and sub-optimal conditions can cause an enzyme to lose its ability to bind to a substrate. What factors affect Enzyme kinetics and how?

1. Temperature: Raising temperature generally speeds up a reaction, and lowering temperature slows down a reaction. However, extreme high temperatures can cause an enzyme to lose its shape (denature) and stop working. 2. pH: Each enzyme has an optimum pH range (i.e pepsin the stomach is LOW pH). Changing the pH outside of this range will slow enzyme activity. Extreme pH values can cause enzymes to denature. 3. Enzyme concentration: Increasing enzyme concentration will speed up the reaction, as long as there is substrate available to bind to. Once all of the substrate is bound, the reaction will no longer speed up, since there will be nothing for additional enzymes to bind to. Substrate concentration: Increasing substrate concentration also increases the rate of reaction to a certain point. Once all of the enzymes have bound, any substrate increase will have no effect on the rate of reaction, as the available enzymes will be saturated and working at their maximum rate.

What is body temperature?

37 degrees Celsius

Which of the following compounds is most likely to be a major product in Step 2 if the aldol condensation is NOT followed by a dehydration reaction? (Back)

A because the dehydration step is what causes the Aldol condensation (the double bond instead of the carbonyl), otherwise it is just an aldol addition, as is shown in A. You will NEVER have a double bond and an OH in aldol addition at the second carbonyl!

The average osmotic pressure of ocean water is 28 atm corresponding to a concentration of 0.50 M solutes (approximated as NaCl). What is the approximate concentration of solutes (also approximated as NaCl) present in blood with an osmotic pressure of 7 atm? A. 0.12 M B. 0.25 M C. 2.0 M D. 3.5 M

A. 0.12 M Be careful not make a math error. 7 atm x (0.5 M/28 atm) = 3.5 M/28 = a little less than 1/7. 1/5 = 0.2 and 1/10 = 0.1, so the answer has to be between 0.1 and 0.2 so A is the only answer that works here.

Once the radioactivity began to decline (at about 1250 s), how many seconds elapsed until ½ of the radioactive Protein X was lost from the cell? A. 100 s B. 200 s C. 300 s D. 500 s

A. 100 s Be careful when reading the graphs! DON'T EYEBALL, do the math using real numbers on the axes. First, on the y-axis, see where the protein concentration was at initial decline (4,000) at 1250 s and see how much time has passed when it is at 2,000 (1/2 is lost), around 1350 s. it has definitely NOT reached 1400 even, so it can't be anything above 150 seconds (eliminating B-C).

Based on the information presented in the passage, which correlation coefficient provides the best estimate of the association between SES and level of exposure to stress? A. -0.20 B. -0.05 C. +0.15 D. +0.50

A. -0.20 The passage states: "Regardless of the relative effect of race, research has established that people in lower socioeconomic positions face disproportionate exposure to certain stressors. Such disproportionate exposure, especially when combined with weak stress mediators, can explain persistent mental and physical health disparities." So basically, low SES = more exposure to stress. A negative correlation. The relationship between the two exists and is relatively strong, so it has to be closer to -1. I chose (B), but that would mean that there isn't a very strong correlation between the two at all.

Digoxin is a cardiac glycoside, which has a positive inotropic effect (increases the force of contraction) on heart muscle by inhibiting the Na+K+ ATPase on the myocardial cell membrane. Digoxin is not effective in all patients with congestive heart failure because it can be inactivated and excreted as the metabolite dihydrodigoxin. Researchers hypothesized that gut microbiota may inactivate digoxin. Eggerthella lenta, a gram-positive bacillus, can reduce digoxin, although high levels of arginine inhibit this reaction. An operon containing two genes, cardiac glycoside reductase 1 and 2 (cgr1 and cgr2), was upregulated in E. lenta (strain DSM2243) cultured in the presence of digoxin. Dihydrodigoxin levels in the culture medium of E. lenta cells would most likely be highest in which data set? A. 2 B. 4 C. 6 D. 8

A. 2 It is important to realize here that digoxin REDUCED will produce the metabolite dihydrodigoxin (2 H's, reduced = gain of electrons). The passage mentions that digoxin can be INACTIVATED via gut microbiota that can REDUCE IT, so you make the connection that it is being REDUCED to dihydrodigoxin. Arginine blocks this reduction, leading to more digoxin and less reduced version, dihydrodigoxin. So if we want to have high levels of dihydrodigoxin, we want to have LOW levels of arginine. That eliminates (B) and (D). To decide between (A) and (C), we have to see the other variable, cgr2 which is a gene that codes for the cardiac glycoside reductase, meaning INCREASED reduction of digoxin so increased dihydrodigoxin. (A) data set 2 is the only one that shows high levels of cgr2 and low levels of arginine, both of which lead to high levels of reduced digoxin.

Based on the information in the passage, what is the most likely mechanism of inheritance for HPRCC? A. Autosomal dominant B. Autosomal recessive C. X-linked recessive D. Y linked

A. Autosomal dominant Looking at the pedigree, we can rule out a couple of things. The disease is NOT (D) Y-linked, because if so, only sons would have it, but we see that daughters AND sons are affected. The disease is NOT autosomal recessive (B), because the disease does NOT skip a generation. If the disease or condition skips generations, it must be recessive. In other words, if two healthy parents have a child with the condition, it cannot possibly be a dominant trait. For a child to have the disease, he or she must have inherited at least one disease allele from a parent, and if the disease were dominant, that parent would show the disease phenotype. Since the parent does not, it must be recessive. The disease is NOT x-linked recessive (C) because we see that affected fathers have passed it down to their sons and not daughters (child 4 and 5). If a disease is X-linked recessive, fathers will never pass it down to their sons, and more males will have it than females. Fathers give sons their Y chromosomes, not X! For this reason, affected males must always receive their disease allele from their mothers, who could be either carriers or fully affected themselves. This must mean that it is (A), autosomal dominant.

Which of the following is a second period element that is a covalent network solid in its standard state? A. Carbon B. Phosphorous C. Oxygen D. Iodine

A. Carbon GRAPHITE!

Reaction 2 on back. The blood glucose meter uses test strips loaded with an enzyme and additives, and is calibrated to take a fixed volume of solution (usually blood). It measures the amount of Reaction 2, a two-electron oxidation, that takes place. Based on the total amount of Reaction 2 and the volume of the sample, the concentration of glucose can be measured and displayed. What additional substance is necessary for Reaction 2 to take place? A. FAD B. NADH C. H2O D. Acetyl-CoA

A. FAD The passage states that glucose here is undergoing a "2 e- OXIDATION", meaning that the glucose molecule is being oxidized, so it is LOSING e- (reducing agent). This means that a cofactor is needed that will be reduced, in that it will GAIN e- (oxidizing agent or oxidant). In this case, NADH, H20, and Acetyl CoA are all reduced cofactors (reducing agents, reductant) that would be oxidized in the reaction. The only cofactor in this list that could undergo reduction is FAD.

Which of the following properties of a 2.3 MHz ultrasound wave remains unchanged as it passes into human tissues? A. Frequency B. Wave speed C. Amplitude D. Wavelength

A. Frequency Frequency of a wave is not affected by the medium through which it propagates. A changing medium will change: Wave speed Amplitude Wavelength

According to the passage, relative to slow-twitch fibers, fast-twitch fibers are likely to exhibit which property? A. Greater Ca2+-pumping capacity B. Increased capillary density C. More mitochondria D. Higher levels of oxygen-binding proteins

A. Greater Ca2+-pumping capacity Fast-twitch (Type II Muscle Fibers) -quick contraction for activities that require maximum effort and short duration -less capillary density (low blood supply) -less mitochondria (aerobic + anaerobic respiration) -instant but less efficient oxygen consumption -lower myoglobin/hemoglobin (oxygen binding proteins) -pale-colored -better in fat burning -larger diameter -generate more force -fatigue quickly/easily -high intensity but short duration activities -greater hypertrophy Slow-twich (Type I Muscle Fibers) -slow contraction for endurance -greater capillary density (greater blood supply) -MORE mitochondria (aerobic respiration ONLY) -slow and efficient oxygen consumption -higher myoglobin/hemoglobin (oxygen binding proteins) -deep red-colored -better in glucose burning -smaller diameter -generate less/weak force -fatigue slowly (resistant to fatigue) -best suited for low force for a longer period of time -lower hypertrophy

What is the balanced equation for the nonproductive reaction when lysine is the substrate? A. H+ + NADPH + O2 → NADP+ + H2O2 B. 2H+ + O2 → H2O2 C. FAD + NADPH + H+ → FADH2 + NADP+ D. 2H2O + O2 → 2H2O2

A. H+ + NADPH + O2 → NADP+ + H2O2 1st step: NADPH + FAD -> NADP+ + FADH- 2nd step: FADH- + O2- + H+ -> FADH-OOH + FAD **The passage mentions that FAD is a regenerated factor in step 2, so it won't be in the balanced equation. Unproductive step: FADH-OOH -> H2O2 Balanced non-productive reaction: NADPH + O2 + H+ -> NADP+ + H2O2.

Radioactive tritium (3H) labeled guanine has been used to measure the rate of biochemical processes that involve its binding or incorporation. (Look on the back for molecular structure.) Guanine Given that water is the solvent for this type of experiment, what is the best site for tritium labeling? A. I B. II C. III D. IV

A. I The goal of this experiment is to see where guanine is found or binding to, so you want the tritium to be in a location where it is unlikely to be lost in the course of binding. All of the nitrogens can readily gain or lose hydrogens, so it isn't worth using any of them. The question says that radioactivie tritium 3(H) is attached to the Hydrogen on guanine. The question says they use this labeled guanine to see where guanine binds and incorporates itself into. If you place guanine in water, it's going to hydrogen bond with the water at the donor and acceptor sites and remember the radioactive tritium is on HYDROGENS so this would be lost in the water so how are you gonna see where guanine binds if all your radioactive shit is in the water and not on guanine. Need to pick a place where the Hydrogen would not be lost to H-bonding with water aka the one w/ no LP to give away, so spot I.

In humans, brain imaging studies have shown that differences in neural activity among adults are associated with reported childhood adversities. Which imaging technique is best suited for localizing brain areas, as described in the studies of neural activity (paragraph 3)? A. PET B. EEG C. MRI D. CT

A. PET In this question, they are asking about a brain imaging technique that will both look at structure (brain area activation) AND function (neural activity). The two best imaging techniques for structure and function are PET (radioactive tracer attached to glucose molecule) and fMRI (magnetic resonance for changes in blood flow and oxygenation to different regions of the brain). EEG is strictly function (brain waves), while MRI (magnetic resonance) and CT (x-ray) are more geared towards brain structure.

The researchers also assessed aspects of the household environment, analyzing parental personality traits, such as conscientiousness and neuroticism, as well as examining parental sensitivity to children's needs. The personality traits used in Study 2 are consistent with which perspective on personality? A. The Five Factor Model B. The psychodynamic approach C. The Myers-Briggs inventory D. The biopsychosocial model

A. The Five Factor Model Neuroticism and conscientiousness are both characteristics of the 5 factor model.

Within the intestines, unabsorbed fats are broken down into fatty acids by intestinal bacteria. Given this, excess unabsorbed fats most likely have which of the following effects within the intestines? A. They increase the osmotic pressure within the intestines, leading to diarrhea. B. They decrease the osmotic pressure within the intestines, leading to diarrhea. C. They increase the osmotic pressure within the intestines, leading to constipation. D. They decrease the osmotic pressure within the intestines, leading to constipation.

A. They increase the osmotic pressure within the intestines, leading to diarrhea. The answer to this question is A because an excess of unabsorbed fats in the intestines inhibits normal water and electrolyte absorption, resulting in increased osmotic pressure and diarrhea. Water follows solutes- since the fat is forced to stay in the intestine, the intestine is "hypertonic" to the outside environment and water flows in to dilute the solutes, causing water stool (diarrhea). Remember, osmotic pressure is the "sucking in" pressure!

Which statement is supported by the data in Table 2? A. Young adults report attending religious services less often than older adults. B. Age is the most significant factor in determining if one will attend religious services. C. Half of all Americans attend religious services weekly. D. There is a significant positive correlation between age and religious attendance.

A. Young adults report attending religious services less often than older adults. The table is showing Pew's survey data on various age groups and their religious survey attendance. We have NO information about statistical significance (D), or about how many Americans of the total population attend religious services/sample size (C) or whether age is the MOST significant factor because we were not given multiple variables and nothing about significance either!

Figure 1 in on the back. Based on Figure 1, the best conclusion is that: A. all therapies are equally effective 6 months after treatment. B. CT has the most promising immediate effects. C. both BT and CT are as effective individually as CBT. D. CT is effective only at the 6-month follow-up.

A. all therapies are equally effective 6 months after treatment. KEEP TRACK OF ERROR BARS AND ASTERIX FOR SIGNIFICANCE! We can see that after 6 months of treatment, there is no statistically significant difference between the three types of treatment, indicating that they are equally as effective. (B) and (C) are false because we see that there is a statistically significant difference between CBT and CT (though not between CT and BT), with CBT being more effective than CT. (D) is wrong because we see that CBT maintains its effects at the follow-up and 6 month follow up.

Which statement best accounts for the hereditary transmission of SDH-linked paraganglioma in a parent-specific manner? SDH is: A. an imprinted gene. B. a Y-linked gene. C. an X-linked gene. D. a tumor suppressor gene.

A. an imprinted gene. Imprinted genes are genes whose expression is determined by the parent that contributed them. Imprinted genes violate the usual rule of inheritance that both alleles in a heterozygote are equally expressed. (B) It's not Y-linked because the passage is saying that both paternal and maternal transmission are possible. if it was Y-linked, maternal transmission would not be possible. (C) it's not X-linked because both sexes can inherit the mutated gene from either the father or the mother and will have the same genotype (there is no specification to whether only female or male offspring carry the mutated version of this gene). Individuals have 2 copies of the gene as usual, one from mom and one from dad (such as on a somatic cell). Imprinted genes are re-marked according to the individual's own sex in their gametes, so the phenotype of offspring will be affected (marked for silencing) only if the mutated gene is inherited from the father (only after paternal, not maternal, transmission). The mother mutated gene has been silenced epigenetically.

Certain viruses contain RNA as their genetic material. One of the ways these RNA viruses replicate themselves is to: A. code for or carry a transcriptase that copies viral RNA. B. infect microorganisms possessing RNA as their genetic material. C. alter the host cell's polymerase in order to synthesize progeny viral RNA from the viral RNA template. D. stimulate the transcription of specific sequences of the host's DNA, which, in turn, direct the assembly of viral particles.

A. code for or carry a transcriptase that copies viral RNA. Only retroviruses require reverse transcriptase. Positive-sense viral RNA is similar to mRNA and thus can be immediately translated by the host cell using host cell machinery. Negative-sense viral RNA is complementary to mRNA and thus must be converted to positive-sense RNA by an RNA polymerase that the virus carries before translation. Retrovirus- they use reverse transcriptase to convert the viral RNA into cDNA which is then copied to produce a double stranded molecule of viral DNA. After this, the viral DNA is integrated into the host genome using the viral enzyme integrase. Then, expression of the encoded genes leads to forming new virions.

In its lowest-energy electron configuration, zinc has a: A. filled 3d energy level and a filled 4s energy level. B. half-filled 3d energy level and a filled 4s energy level. C. filled 3d energy level and a half-filled 4s energy level. D. half-filled 3d energy level and a half-filled 4s energy level.

A. filled 3d energy level and a filled 4s energy level. Remember, 4s fills before 3d, but you would have fully filled d orbital since zinc is the last element in that transition metal period and has enough electrons to fill both. SIS, the only exception to the electron configuration pattern is CHROMIUM and COPPER. HERE IS WHY: Copper has one less electron than zinc, so one electron from the 4s will move to the 3d, so that the 3d is filled. So for copper a half-filled 4s and filled 3d is most stable (so C). Cr (chromium), it's most stable/low energy state is when the 4s is half filled and the 3d is half filled (so D). So one electron from the 4s moves to the 3d to make the 3d also half filled. So the general rule is, if you can move one electron from the s-orbital to either half-fill or completely fill the d-orbital, then you should do it.

Butyrate is structurally related to β-hydroxybutyrate (βOHB), the major source of energy for mammals during prolonged exercise or starvation. If HDAC inhibition by βOHB is a physiological response in living animals, the information in the passage indicates it is likely to occur when: A. there is sustained fatty acid oxidation. B. the pentose phosphate shunt is activated. C. there is increased gluconeogenesis. D. the Cori cycle is occurring.

A. there is sustained fatty acid oxidation. The key thing to understand here was from information provided from the passage. The passage says that βOHB is a major source of energy for animals during prolonged exercise or starvation. Rememeber: βOHB is a ketone body formed from beta-oxidation of fatty acids (fatty acids cannot cross BBB, so ketone bodies are formed that can cross BBB) when there is starvation. (D) Cori cycle occurs during periods of prolonged exercise and is the process by which anaerobic metabolism the muscles create lactate and that lactate is brought from muscle to the liver where it is converted from pyruvate back to glucose and then sent back to muscles or stored as glycogen. However, βOHB is NOT a component of the Cori cycle, so it wouldn't explain why there are high levels of it. Same with (C) gluconeogenesis which is an initial starvation response but NOT a prolonged starvation response (lasts 2-3 days before going into fatty acid oxidation /ketogenesis) because the precursors of gluconeogenesis are lactate, glycerol from TAG, and glucogenic AA (all except L and K) and the body doesn't want to use up valuable protein/muscles (AA). (B) PPP is active during the fed state, as it is in charge of producing NADPH, and shunting carbons back to glycolysis or gluconeogenesis, and provides precursors for amino acid and nucleotide biosynthesis.

Suppose that a blood vessel of cross-sectional area A carries microbubbles at a speed v into a capillary bed. If the capillary bed is made up of n capillaries, each with cross-sectional area a, with what speed will the blood flow in the capillary bed? Options on other side.

A1V1 = A2V2 Blood vessel --> Capillaries (made up of n capillaries with a cross-sectional area) A1V1 = naV2 Soving for V2 we get: A1V1/na So b.

If no braking occurs, a total of how much power would be required to keep the railcar moving at 40 m/s? A 60 kg person stands inside a 20,000 kg railcar that is attached to a locomotive. For experimental purposes, the person has a ball, a string, a 600 nm wavelength laser, a concave lens, a 100 mF capacitor, and some 12 V, 100 W lightbulbs. The ball and string can be joined to make a pendulum of mass M and length L. After the locomotive releases the railcar, two systems are available to slow the moving railcar. The first system connects an electric generator to the railcar's wheels to charge a 12 V battery mounted on the railcar. Engaging the generator to the wheels puts a decelerating force of 5000 N at 40 m/s, and the force declines linearly with speed. This generator transfers about 80% of the kinetic energy dissipated by this braking force to the battery. The second system allows the person to slow the railcar by the friction of its wheels against a stationary surface in a manner similar to that of the brakes on an automobile. This system can generate a maximum braking force of 14,000 N. The rolling friction of the wheels and the internal friction between the wheels and axles contribute a continuous 1000 N decelerating force any time that the railcar is in motion. (Note: Use g = 10 m/s2 and c = 3.0 × 108 m/s, if needed.) A. 16 kW B. 40 kW C. 600 kW D. 800 kW

B. 40 kW The question is asking about the "no breaking" situation, meaning we are strictly working with the information in the passage that says, "the rolling friction of the wheels and the internal friction between the wheels and axles contribute a continuous 1000 N decelerating force any time that the railcar is in motion." On an FBD, we would see that the only force acting on the object when it is in motion is the friction force that is slowing it down. Because we want the railcar to be going at a CONSTANT velocity, we need all of the forces acting on it to equal 0 or cancel out. That means that the force opposing the frictional deceleration is 1000 N. Next, we are interested in the power to maintain the constant velocity, which is P = w/t or P = Fd/t which is the same as P = F x v. The velocity here is 40 m/s. So P = (1000 N x 40 m/s) = 40,000 Nm/s = 40 kW. 1 W = Nm/s or J/s

When two amino acids are joined via a peptide bond, what is the mass of the byproduct of this reaction? (Note: Assume that the amino acids were not modified by protecting groups.) A. 17 amu B. 18 amu C. 32 amu D. 44 amu

B. 18 amu The key here is recognizing that the question is asking about the mass of the "BYPRODUCT" of the joining of 2 AA to form peptide bond--WATER is the byproduct :) So basically asking you to calculate mass of water. Tricky tricky :)

The blood glucose meter uses test strips loaded with an enzyme and additives, and is calibrated to take a fixed volume of solution (usually blood). It measures the amount of Reaction 2, a two-electron oxidation, that takes place. Based on the total amount of Reaction 2 and the volume of the sample, the concentration of glucose can be measured and displayed. The glucose meter measures the current produced during Reaction 2. If 0.67 μmol of electrons were measured, what mass of glucose was present in the sample? (Note: The molar mass of glucose is 180 g/mol = 180 μg/μmol.) A. 20 μg B. 60 μg C. 90 μg D. 270 μg

B. 60 μg Not sure why I got this wrong :/ Math error. Glucose is undergoing a 2 e- oxidation (so 2 mols of e-). 0.67 x 10^-5 mol e- (1 mol glucose/2 mol e-) (180 g glucose/1 mol glucose). >90 g glucose/2 = >45 g glucose! So (B) is the best answer!

The isoelectric focusing points pI for four proteins are shown in the following table. Look at table on back! At which buffer pH would two out of four of the proteins adhere to a cation-exchange column? A. 3.0 B. 7.0 C. 9.5 D. 11

B. 7.0 REMEMBER: In Cation-exchange, you are interested in POSITIVE molecules. In Anion-exchange, you are interested in NEGATIVE molecules. So + charged molecules will adhere to the cation-exchange, meaning those AA that are + charged at pH 7. From the table, we know that A and B are going to be + charged at pH 7, and C and D are going to be - charged at pH 7. + charged molecules will only happen when pH is less than pI.

Compounds 3 and 4a are shown below. (Back) Which of the carbons in Compound 3 corresponds to the carbon marked with an asterisk in Compound 4a?

B. C2

Which component of the electron transport chain is defective in cells from an SDH-linked paraganglioma tumor? A. Complex I B. Complex II C. Complex III D. Complex IV

B. Complex II Note about Complex III: -The process by which the electrons are transferred from the ubiquinol to cytochrome c is known as the Q cycle. This cycle actually consists of two mini-cycles called half-cycles. In the first half-cycle, a ubiquinol molecule attaches onto complex III and transfers the two electrons to the complex. One of these electrons moves onto the Rieske center, then onto cytochrome c1 and finally onto cytochrome c. Note that cytochrome c, unlike ubiquinone, can only carry a single electron at any given time. 4 Cyt C's used to transfer 4 electrons to Complex IV to give to water.

Sociodemographic differences in alcohol use disorders Biological and behavioral mechanisms provide a foundation for understanding the epidemiology of alcohol use disorders (AUDs). One area of research involves assessing the contribution of psychosocial stressors to AUDs. Some theoretical models predict that exposure to prejudice and discrimination will contribute to elevated levels of alcohol consumption among some racial and ethnic minority groups. However, patterns of use generally fail to support this prediction. For example, African Americans and Hispanic Americans have lower rates of alcohol consumption and AUDs than white Americans." The predictive models described in the final paragraph of the passage are most likely based on which assumption? A. Some psychosocial stressors will be perceived as out-group socialization. B. Exposure to some psychosocial stressors will be attributed to social identity. C. The health consequences of some behaviors will affect identity formation. D. The socioeconomic gradient in health will affect some minority groups.

B. Exposure to some psychosocial stressors will be attributed to social identity. I chose (D) but it is not correct because the SES gradient is not relevant to prejudice and discrimination and how they impact specific racial/ethnic identities. The final passage is talking about how some minorities will experience more discrimination and prejudice due to their identification as members of certain racial/minority groups and this will lead them to elevated OH consumption. The passage is making the case that stress may contribute to AUDs, minorities should have higher levels of them. Thus there is the assumption that that minorities are more predisposed to prejudice and discrimination, stress-causing events.

If the NDU gene is amplified inside cells leading to overexpression of the protein, what event is likely to occur under hypoxic conditions? A. Oxygen consumption within the mitochondria will increase further. B. Oxygen consumption within the mitochondria will decrease further. C. Complex IV will further increase its activity. D. Complex IV will further decrease its activity.

B. Oxygen consumption within the mitochondria will decrease further. Got this right but wanted to include it to emphasize that reading variables presented in the graphs AND the asterix in the graph to show statistical significance is CRITICAL! That's how you would choose between (B) and (D). We are looking specifically in the hypoxic condition between WT and NDU-KO (two bars on the right side). There is a statistically significant difference between WT and NDU-KO for oxygen consumption in the hypoxia condition, but NOT for Complex IV activity for hypoxia condition.

Which statement about the unfolding cooperativity and pK of the oligonucleotides is consistent with the data in Figure 1? A. The oligonucleotide with the highest pK displays the highest unfolding cooperativity. B. The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. C. The oligonucleotide with the second highest pK displays the highest unfolding cooperativity. D. The oligonucleotide with the second highest pK displays the lowest unfolding cooperativity.

B. The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. pK is the -log of K and K is the equilibrium constant which is the [unfolded]/[folded], because that was the reaction being tested. So larger K values are more unstable because for a given pH or temperature they are more unfolded (kind of like Km!). Since a larger K means a smaller pK then smaller pK values mean that something is more unstable, and given the Tm at the end, 5hmc-WT is the least stable. The trace of CD vs pH show use that 5hmc-WT is also the most cooperative. So the species with the lowest pK (lowest stability, 5hmc-WT) is also the species that is most cooperative. Here, the pK in the graph would be the pH at which you have 50% of the signal (the graph is giving you pH depending unfolding). And we know a cooperative graph would have the sigmoidal shape you see with the 5hmc-WT curve, so this has the highest cooperativity for unfolding. In this case, that curve also has the lowest pK (50% unfolded at the lowest pH), making B correct. The highest pK would be for 5mC- WT.

The adrenal medulla is part of which branch(es) of the peripheral nervous system? A. The somatic nervous system only B. The sympathetic branch of the autonomic nervous system only C. The parasympathetic branch of the autonomic nervous system only D. Both the sympathetic and the parasympathetic branches of the autonomic nervous system

B. The sympathetic branch of the autonomic nervous system only The sympathetic nervous system stimulates the adrenal medulla to release adrenergic hormones, Epinephrine and Norepinephrine, and the post-ganglions release E/NE (to target organs), while pre-ganglions release to acetylcholine only. Parasympathetic pre and post-ganglions release acetylcholine or acetylcholine and nitric oxide only (to target organs).

Every time a volunteer in a sleep study begins to exhibit rapid eye movements (REM), the experimenter wakes the person up. On the following night, when his or her sleep is uninterrupted, the person will most likely: A. have difficulty falling asleep. B. have more REM sleep than usual. C. have less REM sleep than usual. D. have the same sleep pattern as before the study.

B. have more REM sleep than usual. REM rebound is the lengthening and increasing frequency and depth of rapid eye movement sleep which occurs after periods of sleep deprivation. When people have been prevented from experiencing REM, they take less time than usual to attain the REM state.

The researchers' decision to use individual (NOT group) therapy in each of the treatment sessions reduced the potential influence of: A. classical conditioning. B. observational learning. C. operant conditioning. D. elaboration likelihood.

B. observational learning. The design decision to conduct individual therapy sessions helped control for the extraneous influences of other patients during the therapy sessions, and observational learning is the only form of learning among the options that requires the presence of others. (D) The Elaboration Likelihood Model for Persuasion (ELM) is a more cognitive approach that focuses on the why/how of persuasion. Two ways in which information is processed: -Central Route of Persuasion: The degree of attitude change depends on quality of the arguments by the persuader. How much we are persuaded depends on quality of persuasion. ARGUMENT/Words are central! -Peripheral Route of Persuasion: looks at superficial/expertise/non-verbal persuasion cues, such as attractiveness/status of persuader. The doctor himself is peripheral (he is the one delivering the words!)

Pairs of research participants interacted for 10 min. They rated themselves and their partners on personality traits and then rated the accuracy of their partners' ratings of them. The partners' ratings were rated as more accurate if they were close to participants' own self-ratings. This finding illustrates: A. the self-fulfilling prophecy. B. self-verification. C. the self-serving bias. D. self-efficacy.

B. self-verification. Self-Verification refers to the tendency to seek out and agree with information that is consistent with one's self concept. I chose (C) but self-serving bias refers to the tendency to attribute internal factors for success and external factors for failure, particularly when someone is explaining their own behavior (it is similar to the other biases: fundamental attribution error -others' behaviors -and actor-observer bias--> you and others' behaviors). It wouldn't apply in this case when a person is rating the accuracy of anothers' rating of them (there is no behavior being explained here or evaulation of circumstances around behavior). Self-efficacy is one's belief that they have the ability and skills required to achieve something. Self-fulfilling prophecy is when expectations and/or labeling then works to affect the outcome, even if the original assessment was not necessarily true

"The unreacted zinc granules are also dried and weighed. A 2:1 ratio of moles of iodine atoms to zinc atoms in the product is consistently obtained. The mass of iodine and reacted zinc equals the mass of product." The limiting reagent in the experiments described in the passage is: A. iodine. B. zinc. C. methanol. D. iodide.

B. zinc. The passage mentioned there was unreacted zinc that was collected and weighed. I interpreted then that Iodine, the other reactant, was then used up and so was the limiting reagent. Limiting reagents are based on the reactants (NEVER PRODUCTS, so D is FALSE). You can cross out any answers that consist of products, and iodide is one of our products so this wouldn't be an option. Zinc was left over once the reaction goes to completion, but no statement was made that there was unreacted I. This in combination with the fact that you needed two of I to make a product, then it's more likely that will be used up faster than the zinc.

See graph on other side. Which statement is best supported by the data using the anti-AcTubK40 antibody? A. HDACs acetylate many types of target protein besides histones. B. βOHB is not a general deacetylase inhibitor. C. βOHB is present in the nucleus but not the cytoplasm. D. βOHB inhibits different deacetylases compared to butyrate.

B. βOHB is not a general deacetylase inhibitor. When βOHB is inhibiting:↑ [ βOHB ] → ↓ deacetylation activity → ↑ Acetylation level According to Figure 1, βOHB does not change AcTubk40 acetylation level, but changes the other two, showing that βOHB is specific to the other two, thus it is not a general deacetylase inhibitor. I chose (A) initially, but be careful with language like "many types"- we were only given βOHB's HDAC inhibition activity for ONE other protein besides histones, tubulin, so this wouldn't make sense (C) nothing to really support that it is exclusively in the nucleus- BOHB was administered outside the cells (cells were exposed to it, it wasn't "injected into the nucleus" or something, which means it must diffuse through both the plasma membrane and the cytoplasm to get into the nucleus and affect HDACs ---> therefore its unlikely that BOHB is only in the nucleus. (D) There's no data presented indicating which HDACs butyrate acts on.

What is the period of the voltage source that operates the plasma pencil? A. 2000 ns B. 1500 ns C. 1000 ns D. 500 ns

C. 1000 ns Period is where one full "wave" or "line" is completed, so from where the wave starts and ends back at its original point is one period. So here, the period is 1000 ns! Also, Period (T) = 1/f

What is the concentration of hydroxide ion for the solutions with the highest pH that was studied? A. 10^-10 B. 10^-6 C. 10^- 4 D. 10^-2

C. 10^- 4 Based on the graph, the highest pH that was studied was 10. This means that pH + pOH = 14 14 - 10 = 4 (pOH) pOH = log [OH-] 10^pOH = [OH-] 10^-4 = [OH-]

A tall tube is evacuated, and its stopcock closed. The open end of the tube is immersed into a container of water (density 10^3 kg/m3) that is open to the atmosphere (pressure 10^5 N/m2). When the stopcock is opened, how far up the tube will the water rise? A. 1 m B. 5 m C. 10 m D. 20 m

C. 10 m P=pgh P = F/A = pgv/area = pgh 10^5 = (10)(10^3)h 10^5/(10^4) = 10

A researcher criticizes the methods used in the study, stating that teachers' ratings may not be a valid way of assessing the students' emotional problems. Which hypothetical finding is most likely to reduce this concern? A. A positive correlation between the number of emotional problems observed in students and the number of classmates reading below grade level B. A negative correlation between the number of emotional problems observed in students and the number of disruptions experienced by the teacher per day C. A positive correlation between the teachers' ratings of the number of emotional problems observed in students and the parents' rating of the same variable D. A negative correlation between the teachers' ratings of the number of emotional problems observed in students at two different times

C. A positive correlation between the teachers' ratings of the number of emotional problems observed in students and the parents' rating of the same variable Validity is basically assessing: are you measuring what you are intending to measure (is your manipulation of the IV a good manipulation). Reliability is consistency in your measurements (i.e interrater reliability). A consistent measure between teachers and parents' rating on the number of emotional problems would indicate that the teachers' ratings are valid! I chose (A) which isn't wrong, but it isn't telling us about the validity of the IV that we are interested in, emotional problems and the rating for that. It would support the hypothesis, but it wouldn't address the concerns regarding the validity of the teachers' ratings of the emotional problems.

The pH of a 1 L phosphate buffer solution was measured as 7.6, but the experimental procedure calls for a pH 7.2 buffer. Which method will adjust the solution to the proper pH? (Note: The pKa values for phosphoric acid are 2.2, 7.2, and 12.3.) A. Add enough 1 M Na2HPO3 to increase the phosphate anion concentration ten-fold. B. Add 1 M NaOH to neutralize a portion of the hydronium ions found in the solution. C. Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species. D. Add 100 mL distilled, deionized water to dilute the basicity of the buffer.

C. Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species. By POE, we can arrive at the correct answer. In this problem, we want to lower the pH of the buffer solution (make it more acidic). That automatically cancels out B, because adding 1 M NaOH, which is a STRONG base would raise the pH of the buffer (by 1 pH). (A) would also not work because adding 1 M of Na2HPO3 would also most likely decrease the pH by 1, giving us 6.6 (D) For MCAT purposes, diluting a solution does NOTHING to the pH because you are diluting A- and the HA the same amount. Adding small volumes of water will not have a significant effect on pH although there is some change, the concentration of H+ and OH- change by the same factor so no net effect. This makes us arrive at (C). What C is basically saying is the following (look at image): The general disassociation reaction is NaH2PO3<-> Na2HPO3 + H+ The more the reaction favors the dissociation of the monosodium phosphate, the more acidic the solution. Altering the ratio to favor the monosodium/disodium phosphate to favor the monosodium species is a fancy way of saying increasing the monosodium concentration. This increases the concentration of reactants, which will push the reaction right (forming more H+). This, in turn, decreases the pH of the solution.

Individual M has longer limbs and muscles than Individual N. Both individuals lift the same amount of weight from the ground to their shoulders an equal number of times. If all repetitions were completed in synchrony, which statement about the amount of work completed by the individuals is true? At the end of the workout: A. both individuals will have done the same amount of work because the force was applied for the same duration of time. B. Individual M will have done less work because the object was moved a greater distance. C. Individual N will have done less work because the object was moved a shorter distance. D. Individual M will have done more work because the muscle contracted faster to achieve synchrony with Individual N.

C. Individual N will have done less work because the object was moved a shorter distance. Passage states that "The length of a muscle fiber does not contribute to the force it generates. Length, however, is important in determining how much work the muscle can do. Assuming two muscles have the same CSA, the longer muscle would perform more work because work is the product of force times the distance shortened." Longer muscle = more work = longer displacement Shorter muscle = less work = shorter displacement individual N.

"In addition to omission errors, such as failing to report something that was said, many of the errors were intrusions, such as a detail that was consistent with the situation but missing from the initial report. " Which statement is the most reasonable explanation for the observation of intrusion errors in Study 2? A. False information was encoded. B. Memory is prospective. C. Memory is reconstructive. D. Repressed information was retrieved.

C. Memory is reconstructive. Intrusion errors occur when information that is related to the theme of a certain memory, but was not actually a part of the original episode, become associated with the event. This makes it difficult to distinguish which elements are in fact part of the original memory. Basically, the people could be recalling more information about the event because of generic information that they heard, and incorporating into their own memory of the event resulting in a false memory of the event (related to errors in source monitoring). (A) False information gets encoded at the time of the event, and should be consistent even a year later, so wouldn't explain the intrusions that are being mentioned here. (D) Repressed memories are usually recovered through some kind of therapy or active bringing it out (nothing in the passage indicates that these memories were repressed). (B) Prospective memory is the memory related to a future action (recalling a planned intention in some future time).

Based on the information in the passage and in Figure 1, what effect does epigenetic modification have on iM pH-dependent denaturation? A. Both methylation and hydroxymethylation result in significantly decreased stability because cytosine is more readily deprotonated. B. Both methylation and hydroxymethylation result in significantly decreased stability because cytosine is more readily protonated. C. Only hydroxymethylation results in significantly decreased stability because cytosine is more readily deprotonated. D. Only hydroxymethylation results in significantly decreased stability because cytosine is more readily protonated.

C. Only hydroxymethylation results in significantly decreased stability because cytosine is more readily deprotonated. The cytosine wouldn't be protonated at higher pH (so D is WRONG). As pH increases, groups will get deprotonated because there are less protons in solution to protonate (remember, increasing pH means less acidity). Thus because the cooperative curve for 5hmC happens much earlier than the other two, you can infer that the "equivalence point" would be at a much lower pH than the other groups. That means that as pH goes up, that group is more likely to be deprotonated leading to decreased stability. The wild type and methylated DNA samples seem to respond similarly to pH changes, meaning that methylation doesn't really impact stability. On the other hand hydroxymethylation seems to produce a curve that looses a particular signal much more quickly as you increase pH (more deprotonated = less stable at lower pH = more denaturing via cooperativity).

"Digoxin is a cardiac glycoside, which has a positive inotropic effect (increases the force of contraction) on heart muscle by inhibiting the Na+K+ ATPase on the myocardial cell membrane." Which type of membrane transport is directly affected by cardiac glycosides? A. Simple diffusion B. Facilitated diffusion C. Primary active transport D. Secondary active transport

C. Primary active transport

When designing a study to test the hypothesis that controlling for SES should reduce racial differences in stress, which data would a researcher be LEAST likely to include in an aggregate measure of SES? A. Occupational status B. Income sources C. Social capital D. Educational attainment

C. Social capital The three main components of SES are: 1. INCOME 2. EDUCATION 3. STATUS (occupation) Social capital is not one, because oftentimes lower SES groups have greater social capital (i.e immigrant groups have tighter knit communities and stronger social networks (bridging) and norms of reciprocity and trust (bonding) within those networks).

Which statement CANNOT be concluded from Table 1? A. Americans' confidence in religious institutions has declined from 1973 to 2013. B. More than 60% of Americans had a great deal or quite a lot of confidence in organized religion in 1973. C. The change in percentage of Americans who have very little confidence in organized religion between 1973 and 2013 is statistically significant. D. The change in percentage of Americans who have very little confidence in organized religion between 1973 and 2013 represents an overall increase.

C. The change in percentage of Americans who have very little confidence in organized religion between 1973 and 2013 is statistically significant. The table is NOT showing us anything about statistical significance- we only have numbers and confidence levels. NOTHING indicating statistical significance. Other than that, the rest of the options are true.

The enzyme used in the blood glucose meter described in the passage is classified as: Look at reaction on the back! A. a transferase. B. an isomerase. C. an oxidoreductase. D. a hydrolase.

C. an oxidoreductase. The glucose is being oxidized (think of phenol to quinone), losing the H bond! The only enzyme that catalyzes oxidation-reduction reactions are oxidoreductase.

What is the general structure of a hydroxamic acid?

C. is hydroxamic acid. The passage mentions that subsequent acetylation of the hydroxylamine nitrogen in Compound 2 produces a hydroxamic acid, which is used by the organism to complex iron. Acetyl group is RC=O, and the hydroxylamine is the nitrogen at the far left end of compound. I chose (D) but we can see that the acetylation in that compound is not to the nitrogen, but another carbon, also that is not an acetyl group (secondary nitrogen instead of the primary nitrogen).

See graph on back. Monkeys were raised on a diet of either high- or low-quality protein, and then were given free access to high- and low-quality protein diets. The diet preference for both groups of monkeys is shown. (Note: Both groups of monkeys consumed the same amount of food.) The data indicate that: A. the feeding behavior of monkeys was not affected by either prior diet type. B. prior protein insufficiency was a stronger predictor of future feeding behavior than prior protein sufficiency. C. prior feeding history influenced future feeding behavior in monkeys raised on a high-quality protein diet only. D. the feeding behavior was solely determined by both prior diet types.

C. prior feeding history influenced future feeding behavior in monkeys raised on a high-quality protein diet only. LOOK AT ERROR BAR OVERLAP. NO OVERLAP MEANS SIGNIFICANT DIFFERENCE. So (A) is clearly false because we can see that monkeys raised on a high protein diet had a preference for a high protein diet when given a choice, whereas monkeys on the low protein diet didn't have a preference (no error bar overlap). For (A) to be true, both diet types should not have shown a preference. (B) is false because protein insufficiency (low protein diet) did not show a significant diet preference. (D) is not true because there was a difference in preference between monkeys in the high and low protein diet (preference in high, but NOT in low)--so both diet types did not contribute to a preference later on.

What are the names of the 4 complexes in ETC?

Complex I: NADH Reductase Complex II: Succinate Dehydrogenase Complex III: CoHQ2-Cyt C Reductase Complex IV: Cyt C Oxidase

If Compound 2 is replaced with Compound X, what will be the structure of the final product of steps 1 and 2? (Note: Assume that the yields of steps 1 and 2 are not affected by the substitution.) Look at the reaction mechanism on the back.

Count your carbons!

Which of the following graphs shows the radioactivity of the antibody-Protein X precipitate in the extracellular growth medium if Hypothesis 2 is correct? Two hypotheses were proposed to explain the sudden decline in radioactivity that occurred after about 1200 s. Hypothesis 1 The decline is the result of random, nonspecific degradation of the protein by proteolytic enzymes. Hypothesis 2 The decline occurs when a precursor to Protein X is modified to produce a mature form of Protein X that is subsequently secreted by the cell.

D. Read the question carefully to see what the graph is giving you! The radioactivity is measured as incorporation of AA into protein creation. The graph in the passage is giving us protein X concentration INSIDE the cell (radioactively labeled), the question stem is asking about protein X concentration once it has LEFT the cell in the EXTRACELLULAR environment (we are looking for the "perspective" of the extracellular environment). The second hypothesis is saying that the decline in radioactivity at 1200 s as measured in the cell is because a mature form of protein X is created and secreted (transported) into the extracellular environment, so we should see the radioactivity increase at a period of 1200 s. To choose between (C) or (D) where radioactivity is increasing after 1200 s, we should realize that the (C) would indicate that the protein is being secreted as SOON as it is translated, but this is not the case, because there is a time when radioactivity in the cell is increasing as the protein is being built in the cell with the radioactively labelled AA and then secreted into extracellular environment.

The relative thermodynamic stability of isomeric organic compounds can be inferred from which of the following types of experimental data? A. Boiling points B. UV-visible absorption spectra C. Mass spectroscopic fragmentation patterns D. Heats of combustion

D. Heats of combustion Thermodynamic stability is referring to the bonds within a molecule, as in how stable a certain molecule is. The question stem is asking about thermodynamic stability, or chemical energy. This has to do with how stable the bonds are IN the molecule. Boiling point only tells you how tightly the molecule "holds onto" other molecules of its kind. Boiling point is INTERmolecular (a physical property), thermodynamic stability is INTRAmolecular (a chemical property). The question is asking about the quality of the compounds themselves, so you shouldn't be thinking about a property that requires more than one molecule (like boiling point).

A common column material used in size-exclusion chromatography is dextran, a polysaccharide of glucose. Which type of interaction most likely occurs between proteins and the dextran column material? A. Aromatic B. Hydrophobic C. Salt bridge D. Hydrogen bonding

D. Hydrogen bonding In this question, we are considering how the molecules are going to interact with the stationary phase (the column) which is made of polysaccharides (H-bonding). Glucose has no carbon-carbon double bonds and its ring structure is made up not of six carbons but of five carbons and an oxygen. Thus, it is neither aromatic nor unsaturated. It is an aldose, meaning it has an aldehyde group at one end of the molecule (when drawn as straight chain) and forms a six-membered ring (unlike a six-carbon ketose, like fructose, which forms a five-membered ring, a furanose). It contains no nitrogen so it cannot be an amine. Glucose as OH which means that it CANNOT be hydrophobic (B). It doesn't have any ionic interactions so (C) is false (no metal!). It is definitely NOT aromatic (A).

Which action(s) could contribute to the positive inotropic effect of digoxin on cardiac myocytes? Positive inotropic effect is defined as: (increases the force of contraction) I. Decrease transport of Ca2+ to the extracellular environment. II. Increase availability of intracellular Ca2+ to bind to troponin. III. Increase overall Ca2+ stores in the sarcoplasmic reticulum. A. II only B. III only C. I and II only D. I, II, and III

D. I, II, and III Anything that leads to an increase of intracellular [Ca++] will always increased contractility. Ca2+ is released into the muscle cell when an action potential is triggered. If there is more Ca2+ in SR, then more will be released upon an AP (III) This is what allows troponin to move out of the way and allow the actin and myosin to bind to one another to generate force (II). When the AP ends, Ca2+ is pumped out, typically back into the sarcoplasmic reticulum but some of it can be pumped into the extracellular environment (look at picture). Basically, if you stop the movement of Ca2+ out of the cell, there is more left in the cell which leads to more myosin-actin cross bridges which generates more force (I). More Ca2+ in SR = higher gradient.

The rate of a typical enzymatic reaction is increased by which of the following changes? A. Decrease in a substrate concentration B. Increase in pH from 6.8 to 7.4 C. Increase in the energy of activation D. Increase in temperature from 20°C to 37°C

D. Increase in temperature from 20°C to 37°C (D) is the only one that will increase the rate of reaction (to a temperature that is analogous to physiological temperature and that won't denature the enzyme). (A) and (C) will slow reaction rate down. (B) enzymes all function at different optimal pHs, so changing pH to a specific pH will not equally impact ALL enzymes to increase the rate of reaction (and extreme pH will cause enzyme to denature). Enzyme reaction rate will be increased by: 1. Increased temperature (37 is normal physiological temperature)--but temperatures that are too high will denature the enzyme 2. Increasing enzyme concentration (at least until all substrate is bound to active sites, more than that won't affect the rate) 3. Increased substrate concentration (MM curve), until all active sites are filled and then enzyme will hit Vmax (upon which no further addition of substrates will increase rate of reaction). 4. Decreased energy of activation

What is the identity of the substance that has undergone net reduction after the Reaction 1 is complete? Look at reaction 1 on back. A. NADP+ B. FAD C. H2O2 D. O2

D. O2 From reaction 1, we can see that O2 is reduced to H2O. I chose (B) but since FAD is being oxidized and then regenerated, so reduced, which isn't a "NET REDUCTION" like the question is asking :/

"The heme iron is coordinated by a single histidine residue, and the calcium ions are coordinated by various Asp, Ser, Thr, Val, Gly, and Ile residues through both side chain and backbone interactions." Which atom is most likely involved in the coordination of calcium ions found in HRP? A. Hydrogen B. Carbon C. Nitrogen D. Oxygen

D. Oxygen The key here was finding the part of the passage that talks about which AA coordinate ca2+ ions via the backbone/side chain interactions. "The heme iron is coordinated by a single histidine residue, and the calcium ions are coordinated by various Asp, Ser, Thr, Val, Gly, and Ile residues through both side chain and backbone interactions." This means that the AA are participating in coordinate covalent bond with Ca2+, and that the element that is participating in the bond has to be a LEWIS BASE (e- DONOR). Asp, Ser, and Threonine ALL have O- in their side-chains and Val, Gly, and Ile all have O- in the backbone. It wouldn't be (C) nitrogen (which also has capacity to act as a lewish base), because nitrogen has a partial positive charge in the AA backbone (see picture), so wouldn't act as a Lewis base in this case and wouldn't participate in a coordinate-covalent bond with the Ca2+ ions. Oxygen has a partial - charge in the backbone, and so it WILL act as a lewis base.

The researchers recommended that public health agencies pay particular attention to these parents, who may be struggling to satisfy their children's needs while experiencing distress from their own needs. At the end of Study 2, the researchers' recommendation suggests that parents in food-insecure households are subject to which role dynamic? A. Role engulfment B. Role confusion C. Role conflict D. Role strain

D. Role strain Role conflict (C) is when an individual struggles to manage MULTIPLE roles. However, there is just ONE role being looked at in this study, the parental role, and how parents are struggling address their children's needs while addressing their own. Role strain refers to difficulty managing just one role. Since there is only one role to manage (i.e. the parental role) this is the correct answer the relevant statement in the passage refers to how researchers recommended interventions focusing on parents who experience stress from trying to satisfy both their children's needs and their own needs. By identifying tension stemming from the parental role, the recommendation suggests role strain (which refers to stress from different expectations associated with a single role). For parents with depression, the parental role can cause competing obligations of satisfying their children's needs when they are coping with psychological distress (and thus are unable to meet their own needs).

Which experimental condition is NOT necessary to achieve reliable data for Michaelis-Menten enzyme kinetics? A. Initial velocity is measured under steady state conditions. B. Solution pH remains constant at all substrate concentrations. C. The concentration of enzyme is lower than that of substrate. D. The reaction is allowed to reach equilibrium before measurements are taken.

D. The reaction is allowed to reach equilibrium before measurements are taken. All of the other 3 are required to achieve reliable data for Michaelis-Menten :) (A) One of the requirements for Michaelis-Menten is the steady state assumption - that the rate of formation of ES complex is equal to the rate of dissocation. Without this, the rate laws are different and M-M kinetics are no longer applicable. I think when you first start the rxn it starts at a higher rate than what is its 'steady state' so you have to ignore that first bump in activity and measure from the more consistent Vo. (B) pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity. Extreme pH values can cause enzymes to denature. (C) If you have [E] > [S], there will always be a free active site open, and you'll never reach vmax. Enzyme concentration remains constant, and the addition of more substrate would drive the equilibrium towards [E][S] complexes. You want to saturate the enzyme to get that classic hyperbolic curve where velocity isn't increasing anymore. Increasing the substrate concentration will NOT increase Vmax. (D) If the reaction reaches equilibrium, the measurements would all be the same and the rate would be Keq. Equilibrium would then be the fine spot in-between were the substrate is dissociating back into its individual enzyme + substrate, while forming an ES complex at a similar rate. If we have reached this position, we are already "saturated" and adding more substrate will not increase Vmax. So if you only start measuring from here, you will be unable to gather any preliminary data, such as Vo.

Which of the following best describes the functional relationship between distance d and time t in the figure? A. t ∝d ^-1 B. t ∝d ^-2 C. d ∝ t D. d ∝ t^2 **BONUS: draw graphs for each of these relationships.

D. d ∝ t^2 This is a positive, linear, exponential relationship. Options (A) and (B) are looking at negative linear/exponential relationships. (C) is positive, but a linear relationship.

What are the types of evolution?

Divergent Evolution is when species develop dissimilar characteristics (dolphin vs. puma) but came from common ancestor. Parallel evolution is when related species evolve similarly over a long period of time, and is usually related to facing similar environmental pressures, different ancestors. Convergent evolution is when multiple species develop similar characteristics, even if they did not have a common ancestor with these characteristics (shark vs. dolphin--similar environmental pressures)-different ancestors.

What are the 6 enzyme classifications and examples of each?

Ligase example is DNA ligase.

What is the equation for energy stored by a capacitor? What is the equation for charge stored by a capacitor?

Energy stored by a capacitor: Ucap = 1/2 (CV)^2 Charge stored by a capacitor: Q = CV

"A study was done on the tissues of rats treated with microbubbles burst by 2.3 MHz ultrasound. It was observed that the burst microbubbles made openings of ~2.5 × 104 μm^2 through the capillary walls." Assume that in the study with the rat tissues, fluid flows at a speed of 0.30 mm/s through a typical capillary opening caused by a burst microbubble. Given this, which of the following is closest to the volume flow rate of fluid passing through the opening? A. 4.5 × 10^6 μm3/s B. 7.5 × 10^6 μm3/s C. 1.2 × 10^7 μm3/s D. 4.5 × 10^7 μm3/s

Find the relevant information in the passage, and then find the number corresponding to that. In this case, they were talking about the "study", so we know that we are working with ~2.5 × 104 μm^2. FLOW RATE = Area x Velocity Next, UNIT/DIMENSIONAL ANALYSIS WILL CHANGE YOUR LIFE! Even if you don't know what the equation is, you can see that μm3/s, so we must be MULTIPLYING the two numbers! The rest is math, albeit VERY confusing math :)

What is the flow rate equation?

Flow rate = area x velocity

If the generator-brake system alone were engaged when the railcar was moving, which of the following graphs would most accurately represent the subsequent speed of the railcar? On back. After the locomotive releases the railcar, two systems are available to slow the moving railcar. The first system connects an electric generator to the railcar's wheels to charge a 12 V battery mounted on the railcar. Engaging the generator to the wheels puts a decelerating force of 5000 N at 40 m/s, and the force declines linearly with speed. This generator transfers about 80% of the kinetic energy dissipated by this braking force to the battery. The second system allows the person to slow the railcar by the friction of its wheels against a stationary surface in a manner similar to that of the brakes on an automobile. This system can generate a maximum braking force of 14,000 N.

Graph D. The passage states that "engaging the generator to the wheels puts a decelerating force of 5000 N at 40 m/s, and the force declines linearly with speed"... FORCE decreases LINEARLY with speed, basically meaning that ACCELERATION is decreasing linearly with speed, so VELOCITY must be decreasing EXPONENTIALLY with respect to time! REMEMBER! Acceleration is the DERIVATIVE of velocity vs. time!

What is an imprinted gene?

Imprinted genes are genes whose expression is determined by the parent that contributed them. Imprinted genes violate the usual rule of inheritance that both alleles in a heterozygote are equally expressed. An imprinted gene is one in which only one copy is expressed based on parent of origin. Individuals have 2 copies of the gene as usual, one from mom and one from dad. However, the gene will only be expressed from the maternal or paternal chromosome. i.e. in Angelman's syndrome, only the maternally-inherited copy of the gene is active. The silencing of the other (paternal) copy is achieved via epigenetic marking. Imprinted genes are re-marked according to the individual's own sex in their gametes. i.e. For a male, the active Angelman's gene (inherited from his mom) will be marked as silent in his sperm (since that gene copy will be paternally inherited by the resulting zygote) Examples: 1. IGF2 — the gene encoding the insulin-like growth factor-2 In humans (and other mammals like mice and pigs) the IGF2 allele inherited from the father (paternal) is expressed; the allele inherited from the mother is not. If both alleles should begin to be expressed in a cell, that cell may develop into a cancer. 2. IGF2r — the gene encoding the cell receptor for Igf-2 In mice the IGF2r allele inherited from the mother is expressed; that from the father is not. Differential imprinting accounts for this. 3. XIST — the gene encoding the RNA that converts one of the X chromosomes in a female cell into an inactive Barr body. This process is random in the cells of the female fetus and thus is NOT an example of imprinting. However, all the cells of her extraembryonic membranes (which form the amnion, placenta, and umbilical cord) have the father's X chromosome inactivated. Imprinting of theXIST locus accounts for this.

Does increasing the substrate concentration increase Vmax in Michaelis-Menten kinetics?

NO! Keep in mind that at Vmax, adding more substrate will do nothing because all the enzymes are saturated. Typically the only way to increase Vmax is to increase the amount of enzyme.

Do eukaryotes have operons?

No, each gene is regulated by its own promoter. An operon is a group of genes controlled by the same promoter (often leading to polycistronic expression). Eukaryotes do not have operons, but they most certainly do not have polycistronic expression. They definitely have repressors, activators, and promoters.

What are the equations and units for power?

P = Work/Time = Force x velocity P = Change in E / Time 1 W = 1 Nm/s = 1 J/s

Describe how the Trp operon system is repressible and the Lac-operon system is inducible.

PROKARYOTIC TRANSCRIPTION!!!! OPERONS ONLY HAPPEN IN PROKARYOTES! If you have lots of Tryptophan, you don't need to actively produce more. So Trp binds to repressor and the complex binds to the operon so no RNAP cannot access to make transcript that makes Trp for bacteria. Lac operon is inducible. Ideally you want 2 conditions: 1) low glucose (cuz otherwise bacteria would happily use glucose), 2) high lactose concentration. High lactose --> high allactose --> bind to repressor and release it from the operon so RNAP can access it to make enzyme that digest lactose. Low glucose --> lots of cAMP --> CAP binding protein binds to upstream of repressor --> efficient transcription.

What is polycistronic mRNA?

Policystronic mRNA is seen primarily among prokaryotes where one mRNA carries coding information and internal punctuation for the translation of more than one protein. The term polycistronic is used to describe an mRNA corresponding to multiple genes whose expression is also controlled by a single promoter and a single terminator. Polycistronic mRNAs are also called operons. All eukaryotic mRNAs are monocistronic.

What is the difference between primary and secondary active transporters? Give examples of each.

Primary transporters use ATP to move molecules against their concentration gradient. *unique transmembrane proteins for that ion* 1 molecule is moved at a time Use ATP Example: Sodium/Potassium pump (Na+/K+ ATPase pump), Calcium pump (Ca2+ pump) in muscles H+ pump in stomach. Secondary transporters use energy from the concentration gradient difference of one molecule to drive another molecule against its concentration gradient *symporters and antiporters* 2 molecules/more moved at a time. Does NOT use ATP. Example: glucose-sodium pump Na+/Ca2+ exchanger Na+/PO4- transporter

What are the various stages of sleep and what type of waves characterizes each stage?

Sleep stages: Your brain goes through distinct brain patterns during sleep. 4 main stages that occur in 90 min cycles. First three stages are categorized in non-rapid eye movement sleep (non-REM) - N1, N2, N3. N1 (Stage 1): Dominated by theta waves. Strange sensations (seeing or hearing things that are not there) - hypnagonic hallucinations hypnic jerks- muscle twitches you sometimes experience as you fall asleep. N2 (Stage 2): deeper stage of sleep. People in N2 are harder to awaken. We see more theta waves, as well as sleep spindles and K-complexes. -Sleep spindles are a burst of rapid brain activity. Some researchers think that sleep spindles help inhibit certain perceptions so we maintain a tranquil state during sleep (sleep through loud noises) -K-complexes suppress cortical arousal and keep you asleep. Also help sleep-based memory consolidation (some memories are transferred to long term memory during sleep, particularly declarative/explicit memories). N3 (Stage 3) - slow wave sleep. Very difficult to awaken. Characterized by delta waves. Where sleep walking/talking in sleep happens. Declarative Memory consolidation. "regular breathing and regular slow brain waves." Right as you go to bed. REM (rapid-eye movement) stage. Eyes move rapidly beneath your eyelids but most of your other muscles are paralyzed. Most dreaming occurs during REM sleep, so paralysation inhibits actions. Most important for memory consolidation. Formation of episodic memories. Combination of alpha, beta, and dyssynchronous waves, similar to beta waves seen when awake. More REM as you wake up. Beta waves are alert waves. Acronym: BATS-Drink Blood (beta alpha theta sleep- spindle/K-complex delta beta) Cycle through these 4-5 times per sleep, each one 90 minutes. Order within cycle goes from N1 -> N2 -> N3 -> N2 -> REM -> N1. How long each stage lasts depends on how long you've been asleep and your age (babies spend more time in REM sleep)

What is the difference between social capital and cultural capital?

Social Capital: the networks of relationships among people who live and work in a particular society, enabling that society to function effectively. Social Networks provide a valuable resource. Social capital is believed to result in various health benefits for the individual, including reductions in the health risk of chronic inflammation. Partly related to social support, social capital emphasize the tangible resources provided by network members (whereas social support tends to focus on emotional resources). Both social support and social capital suggest that social contracts will be beneficial to individual health and well-being. Social Network: -Peer network -Family network -Community network Cultural capital refers to non-financial social assets that promote social mobility beyond economic means. Examples can include education, intellect, style of speech, dress, physical appearance. Refers to knowledge, skills, education, and similar characteristics that are used to make social distinctions and that are associated with differences in social status. Can also expose you to cultural capital, ex. If parents exposing, you to trips abroad and learning foreign languages. Or cultural items in house you know a lot about. With this knowledge you may gain some reward.

True or false. In the peptide bond, the N has a partial + charge and the O has a partial negative charge.

TRUE. Thus, their interactions with substrates etc. will be based on this charge character.

What is the purpose of the PPP?

The PPP (Phopshate Pentose Pathway) is important to maintain carbon homoeostasis, to provide precursors for nucleotide and amino acid biosynthesis, to provide reducing molecules for anabolism, and to defeat oxidative stress. The pentose phosphate pathway (PPP) branches from glucose 6-phosphate (G6P), produces NADPH and ribose 5-phosphate (R5P), and shunts carbons back to the glycolytic or gluconeogenic pathway. It is a major regulator for cellular reduction-oxidation (redox) homeostasis and biosynthesis (reduction of glutathione which is important for glutathione perioxidase's conversion of H2O2 to H2O).

How do you obtain absolute temperature from the Kelvin scale?

The absolute temperature in the Kelvin scale is obtained by adding 273 to the Celsius temperature.

True or false. Half-filled d orbital and full filled d-orbitals are more stable even if it means not fully filling the s orbital.

True! This is where the exceptions for chromium and copper come in. 4s will fill up before the d orbitals, however, if the d-orbital can be half-filled or fully filled, then an electron will move from the 4s orbital to the d-orbital.

True or false. A phosphotase is a type of hydrolase.

True. A phosphatase is an enzyme that uses water to cleave a phosphoric acid monoester into a phosphate ion and an alcohol.

True or false. Proteases are a type or hydrolase.

True. Proteases are from the hydrolase family of enzymes. Protease, synonymous with "peptidase" or "peptide hydrolase," is any enzyme that hydrolyzes peptide bonds using water (water is the molecule that is actually doing the hydrolysis.