Chapter 2: Microbiology Pearson

How would you describe Henry's blood pH in comparison with normal ranges? In relation to his observed blood pH, what would he be described as manifesting? (#20)

Henry's blood pH is lower than normal, producing acidosis.

This kind of bacterial pneumonia can be difficult to diagnose. Often, patients (especially elderly adults) may not produce enough sputum for specimen sampling. Gram stains and culture of organisms are the mainstays of diagnostic tests, but they are often inconclusive within the time frame necessary to manage the patient's disease. As such, more rapid testing is needed to make efficient decisions on the etiology of the infection. For this reason, many hospital labs are turning to serology, the use of specific antibody binding, to hasten diagnosis. The immune system produces molecules known as antibodies during an infection. The antibodies float through the body and are attracted to the foreign molecule, known as an antigen. Each antibody interacts with a single specific antigen, so the bonding of an antibody to an antigen is based in molecular interactions. Serology testing involves mixing a patient sample with antibodies and observing a binding event based on chemical bonding principles. Based on the information given, which of the following would you interpret to be the best description of this interaction? (#12)

Ionic bonding.

_____________ are atoms with the same number of protons but a different number of neutrons.

Isotopes.

Select the mismatched statement about functional groups.

Methyl group: R-CO2.

Based on the diagram below, explain why GSD type I patients are discouraged from consuming carbohydrates such as fructose, galactose and lactose. (#20)

Modification and oxidation of such carbohydrates in GSD I patients results in a dangerous accumulation of metabolites such as glycogen, lactate, pyruvate, fatty acids, cholesterol and triglycerides.

Is glycogen an organic or inorganic compound? (#20)

Organic compound.

Why do patients with GSD exhibit hepatomegaly? (#20)

Patients with GSD I cannot release free glucose from glycogen stored in the liver, leading to an accumulation of glycogen within the liver.

Henry's blood work reveals increases in a number of compounds. Using the diagram below, explain the increases in cholesterol, triglycerides, free fatty acids, lactate and pyruvate. (#20)

Patients with GSD I store excess glycogen in the liver which may be converted to glucose-6-phosphate, a precursor for cholesterol, triglycerides, free fatty acids, lactate and pyruvate.

Which type of bond links amino acids together to form a protein's primary structure?

Peptide bonds.

One of the most common causes of pneumonia is Streptococcus pneumoniae, a gram-positive bacterium. Surrounding the bacterium is a thick structural component layer known as a capsule. This capsule is made up of repeating molecular units and serves as a sticky, protective macromolecule. There are over 84 known different molecular configurations of capsule, and it is the primary component of vaccines against this organism. The capsule is the antigen that we commonly detect in the serology testing referred to in the previous question. Based on the information given about capsules, which of the following types of molecules would you suspect comprises an S. pneumoniae capsule? (#12)

Polysaccharide carbohydrate.

The final tests ordered for the patient are a BUN (blood-urea-nitrogen) test, a procalcitonin test, and a CRP test. The BUN test measures kidney function and catabolism (an increased BUN signifies impairment, which is common in pneumonia). Calcitonin is a molecule derived from the splitting of a larger precursor molecule called procalcitonin. In healthy adults, the procalcitonin is converted to calcitonin, which then participates in calcium and phosphorus metabolism. The conversion of procalcitonin to calcitonin is inhibited by bacterial infection and immune responses; so, levels of procalcitonin are often elevated in patients with pneumonia. The other is test for CRP, which is synthesized by the liver and binds to phosphocholine on dead or damaged cells in order to mark those cells for immune responses. Measuring CRP level (normal levels are < 10 mg/ml) is a screen for infection and inflammation, because CRP levels can increase rapidly and markedly when processes go awry (in bacterial infection, CRP levels can range from 40 to 200 mg/ml). Various structural views of urea (for the BUN), procalcitonin, and CRP are shown below. Based on the functional groups and levels of structure you see, all these molecules are related to which macromolecule family? (#12)

Proteins.

Which particle is described incorrectly?

Proton: Found in shells orbiting the nucleus.

In cornstarch therapy, what is the solvent and what is the solute? Match the items in the left column to the appropriate classification categories blanks on the right. Make certain each blank is complete before submitting your answer. Note that some items may not be used. (#20)

Solute: Cornstarch. Solvent: Water.

While the lab is working on the diagnosis for the patient, the critical care team is assessing his basic functions. Since any living organism carries out chemical reactions, an infection skews the body's "normal" laboratory test values as the microbes compromise the body's functions. Another test ordered for the patient is an arterial blood gas (ABG) test. ABGs are performed to measure the pH, and amount of oxygen and carbon dioxide in the blood. The body carefully regulates and maintains blood pH within a very narrow range of 7.35 to 7.45. Abnormal pH values might signify that a patient is not regulating the level of carbon dioxide (CO2). Our patient with pneumonia has a blood pH of 7.52, and the partial pressure of CO2 in his blood is decreasing, likely because he is hyperventilating. Which of the following would be the best description of this situation? (#12)

The patient is in respiratory alkalosis (overly alkaline).

Which statement is true about carbohydrates?

They are a component of the cell wall of different types of organisms.

Which of the following lipids tends to be liquid at room temperature?

Unsaturated lipids.

___________ are usually found in an atom's outermost shell and tend to participate in chemical reactions.

Valence electrons.

Which of the following elements make up the reactants in the chemical equation catalyzed by glucose-6-phosphatase? (#20)

Carbon, Hydrogen, Oxygen.

Referring to the following reaction, identify the product of the reaction. 3H2 (g) + N2 (g) → 2NH3 (g).

2NH3 (g).

Select the true statement(s) about ionic bonds. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

-An ionic bond is an electrostatic force that exists between cations and anions. -An ionic bond requires the transfer of electrons from one atom to another.

Choose the true statement(s) regarding molecular formulas. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

-Carbon is listed first by its chemical symbol "C" in a molecular formula. -The positive ion is listed first followed by the negative ion when writing a molecular formula.

Choose the true statement(s) about micelles. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

-Detergents can form micelles. -Micelles contain both water-loving and water-fearing regions. -Micelles are made by amphipathic molecules.

Choose the true statement(s) about equilibrium. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

-Equilibrium is not a static situation where the reaction just stops. -Reactions at equilibrium have the forward and reverse reactions occurring at the same rate. -By definition, equilibrium is a term that mainly applies to reversible reactions.

Choose the true statement(s) about atoms. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

-The nucleus of an atom contains neutrons. -An atom is the smallest unit of an element.

How would you describe the polarity of the enzyme glucose-6-phosphatase, knowing it is a transmembrane protein? (#20)

Amphipathic.

An electrolyte panel is also ordered for the patient. This test predicts the health of other systems involved in regulating critical metabolic pathways, such as kidney and liver functions. The measurements of these electrolytes results in a calculation known as the anion gap, a sum total of metabolic buffering agents in the blood. Under normal, healthy conditions, the number of cations present is larger than the number of anions present (known as a positive anion gap). The formula to calculate the gap is as follows:Total cations - Total anionsThe normal range for the anion gap is < 11 mEq/L. From the previous question, we predict the gap to be skewed from the pH readout, since the patient's blood pH is high. Sort the following common electrolytes from the panel into the bins (cation) or (anion). (#12)

Cations: Sodium, Calcium, Magnesium, Potassium, Iron. Anions: Phosphate, Chloride, Carbon Dioxide (measured as bicarbonate HCO3).

Hundreds of mutations in the enzyme glucose-6-phospahatase have been discovered; most result in small errors in amino acid sequence. Based on your introductory exposure to protein structure, explain why this would impact the enzyme's function. (#20)

Changes in amino acid sequence affect the structure of the protein, and may promote protein misfolding, potentially decreasing enzyme function.

Choose the mismatched pairing(s). To be marked correct, you'll need to select all mismatched statements, as there may be more than one correct answer.

Dehydration synthesis: A + BC → AC + B.

During vigorous exercise, both carbon dioxide and lactic acid enter the blood in increased amounts. Both compounds have the effect of lowering the blood pH. In order to maintain blood pH within the normal range of 7.35-7.45, we would expect the carbonic acid (H2CO3) portion of the blood buffer system to pick up the extra H+ ions.

False.

Endergonic reactions make products with a lower final energy than the reactants and use more energy than is released.

False.

What kind of bond is broken in order to digest cornstarch? (#20)

Glycosidic, covalent bond.

What do the notations mg/dL and mmol/L mean in the blood work results? (#20)

mg/dl: Milligrams of solute per deciliter of blood. mmol/L: Millimoles of solute per liter of blood.

Compared to a solution with a pH value of 4, a solution with a pH value of 2 has ________ H+ ions.

one hundred times as many.

Isotopes are atoms of the same element that differ in:

the number of neutrons found in the nucleus.