Carbohydrates and Lipids Semi-final Examination 2019

Kussmaul respiration is a compensatory mechanism observed in persons with diabetes to balance blood pH. It involves deep, rapid breathing that helps to expel hydrogen ions, which can lower blood pH. Therefore, the correct answer is A and B.

In protein electrophoresis, HDL (High-Density Lipoprotein) migrates in the alpha band. The alpha band refers to a specific region or band on the electrophoresis gel where certain proteins, including HDL, migrate to based on their size and charge. This migration pattern allows for the separation and identification of different proteins in a sample. Therefore, in protein electrophoresis, HDL can be detected and analyzed by its migration in the alpha band.

The correct answer is the product of the Salkowski method, which is CHOLESTADIENYL DISULFONIC ACID and CHOLESTADIENYLDISULFONIC ACID.

The end color in the Salkowski method is red.

Dopamine is the correct answer because it does not require cholesterol as a precursor. Cortisol, estrogen, and aldosterone are all steroid hormones that are synthesized from cholesterol. However, dopamine is a neurotransmitter that is produced from the amino acid tyrosine, not cholesterol.

Ultracentrifugation is the reference method for lipoprotein quantitation because it involves the separation of lipoproteins based on their density using high-speed centrifugation. This method allows for the precise measurement and characterization of lipoproteins, making it the gold standard for lipoprotein quantitation. Agarose gel electrophoresis, chemical precipitation, and immunochemical methods may also be used for lipoprotein quantitation, but they are not as accurate or reliable as ultracentrifugation.

Hydrophobic lipid degradation products, such as short fatty acids, need to be combined with a molecule that can transport them through the aqueous environment of the duodenum cells. Albumin is a protein that can bind to these hydrophobic molecules, forming a complex that can be easily absorbed by the duodenum cells. Chylomicrons are large lipoprotein particles that transport dietary lipids, but they are not involved in the absorption of hydrophobic lipid degradation products. Lipase is an enzyme that breaks down lipids, but it is not involved in the absorption process. Cholic acid is a bile acid that aids in the digestion and absorption of fats, but it is not directly involved in the absorption of hydrophobic lipid degradation products.

The Friedewald formula is used to estimate LDL cholesterol levels in the blood. It calculates LDL cholesterol by subtracting the sum of triglycerides divided by 5 and HDL cholesterol from the total cholesterol level. This formula is commonly used in clinical practice to estimate LDL cholesterol when direct measurement is not available.

NADPH is a coenzyme that plays a crucial role in cellular redox reactions. It acts as a reducing agent, donating electrons to other molecules and thereby neutralizing free radicals and reactive oxygen species. This helps protect the cell from oxidative damage, which can lead to various diseases and aging. Therefore, the statement that the reducing power of NADPH is required for cell protection from oxidative and free radical damage is true.

Lactic acid is produced from pyruvate under conditions with depressed oxygen content because in the absence of sufficient oxygen, the process of aerobic respiration cannot take place. As a result, pyruvate is converted into lactic acid through a process called fermentation. This allows the cells to continue producing ATP, albeit at a lower efficiency compared to aerobic respiration. Therefore, the statement is true.

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Coronary artery disease is the correct answer because it is a condition where the blood vessels that supply the heart with oxygen and nutrients become narrow or blocked due to the accumulation of plaque. This leads to reduced blood flow to the heart, which can result in various lipid abnormalities. These abnormalities, such as high cholesterol levels, can contribute to the development of stiffening of the blood vessels, ultimately leading to coronary artery disease. The other mentioned diseases, Tangier's disease, Fish eye disease, and Gaucher's disease, are not directly related to the given statement.

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The screening and diagnosis of gestational DM (Gestational Diabetes Mellitus) is done through the performance of FBS (Fasting Blood Sugar) and OGTT (Oral Glucose Tolerance Test). FBS measures the blood sugar level after fasting for a certain period of time, while OGTT measures the body's ability to process glucose by monitoring blood sugar levels before and after consuming a glucose drink. These tests help identify if a pregnant woman has gestational DM, which is important for timely management and prevention of complications.

Hexokinase is the first enzyme used in the reference enzymatic method. This enzyme is responsible for catalyzing the phosphorylation of glucose to glucose-6-phosphate. It is an essential step in glucose metabolism and is commonly used in various biochemical assays to measure glucose levels. Hexokinase has a high affinity for glucose and is widely distributed in various tissues and organisms. Its role in the reference enzymatic method makes it a crucial enzyme for accurate measurement of glucose concentration.

The Hantzch method is described as the fluorometric method because it involves the use of fluorescence to measure the concentration of a substance. Fluorometry is a technique that detects and measures the emission of light at a specific wavelength when a sample is excited by a specific wavelength of light. In the Hantzch method, a fluorescent compound is formed as a result of a reaction, and its fluorescence is then measured to determine the concentration of the target substance. This method is commonly used in analytical chemistry and biochemistry for its sensitivity and specificity in detecting and quantifying various substances.

Peroxidase is the coupling enzyme utilized in the most common enzymatic method. Coupling enzymes are used in enzymatic reactions to link the reaction of interest with another reaction that produces a detectable signal. In this case, peroxidase is used to couple the reaction of interest with the production of a colored or fluorescent compound. This allows for the measurement or detection of the reaction. Peroxidase is commonly used in various biochemical assays and diagnostic tests due to its high specificity and sensitivity.

The reagent used in the Folin-Wu method is phosphomolybdate. This reagent is commonly used in the Folin-Wu method to detect and quantify reducing substances, such as sugars and amino acids, in a sample. Phosphomolybdate reacts with the reducing substances in the sample to form a blue color complex, which can be measured spectrophotometrically. Therefore, phosphomolybdate is the correct answer for the reagent used in the Folin-Wu method.

Chylomicrons migrate at the origin in protein electrophoresis because they are the largest lipoprotein particles and have the highest density. This causes them to remain at the starting point of the electrophoresis gel, which is the origin.

The Liebermann Burchardt reaction is a chemical method used to detect the presence of cholesterol. The end product of this reaction is cholestadienyl monosulfonic acid, which is indicated by a green color. Therefore, the correct answer is "Cholestadienyl monosulfonic acid; green color."

Bloor's method for cholesterol determination involves the use of colorimetry and extraction. Colorimetry is a technique used to measure the intensity of color produced by a chemical reaction, which can be correlated to the concentration of a substance. In this case, colorimetry is used to measure the color change that occurs when cholesterol reacts with a specific reagent. Extraction is the process of separating a specific component from a mixture, in this case, cholesterol is extracted from the sample. By combining these two techniques, Bloor's method allows for the accurate determination of cholesterol levels in a sample.

Exogenous refers to substances that originate from outside the body. In the context of cholesterol metabolism, exogenous cholesterol comes from dietary sources. The given statement suggests that this metabolism pathway directs excess cholesterol from cells to the liver. This means that the pathway is responsible for transporting cholesterol that is not needed by the cells, likely derived from the diet, back to the liver for processing and elimination. Therefore, the correct answer is Exogenous.

In the Friedewald method, the divisor is used to calculate the low-density lipoprotein (LDL) cholesterol level. This method is commonly used to estimate LDL cholesterol when triglyceride levels are below 400 mg/dL. The formula used in the Friedewald method is LDL cholesterol = total cholesterol - (HDL cholesterol + (triglycerides/5)). In this case, the correct divisor is 5, as indicated in the answer.

Insulinoma is a rare tumor of the pancreas that produces excessive amounts of insulin, leading to low blood sugar levels (hypoglycemia). When blood sugar levels drop too low, it can cause symptoms such as dizziness and fainting. Therefore, it is true that a patient with insulinoma may exhibit these symptoms due to hypoglycemia.

The correct answer is β-VLDL because it is the only option that is not a known abnormal lipoprotein. Lipoprotein X, IDL, and Lipoprotein (a) are all abnormal lipoproteins, while β-VLDL is a normal lipoprotein.

The property described in the question is amphipathic. This means that the molecule has both hydrophilic (water-loving) and hydrophobic (water-fearing) regions. In this case, the polar hydrophilic group is attracted to water, while the nonpolar hydrophobic fatty acid chains repel water. This combination of properties allows the molecule to interact with both polar and nonpolar substances, making it amphipathic.

In diabetes mellitus type 2, C-peptide levels are detectable. C-peptide is a byproduct of insulin production, and in type 2 diabetes, the body still produces insulin, although it may be insufficient or not used effectively. Therefore, C-peptide can still be detected in the blood. This is in contrast to type 1 diabetes, where C-peptide levels are usually undetectable or very low, as there is little to no insulin production.

Beta hydroxybutyrate is the correct answer because it is the ketone body that has the highest concentration among the other ketone bodies. Acetoacetate and acetone are also ketone bodies, but beta hydroxybutyrate is the predominant ketone body produced during ketosis and is present in the highest concentration in the blood.

DM type I is also known as the ketosis prone diabetes mellitus because it is characterized by a lack of insulin production in the body. This leads to a buildup of ketones, which are acidic byproducts of fat metabolism, in the blood. Ketosis is a state in which the body switches to burning fat for fuel instead of glucose. This can result in the development of diabetic ketoacidosis, a serious condition that can be life-threatening if not treated promptly.

The complete end product of the Folin-Wu method is phosphomolybdenum blue. This is a compound that is formed when the Folin-Wu reagent reacts with certain substances, such as reducing agents like glucose or other compounds containing phenolic groups. The phosphomolybdenum blue complex has a characteristic blue color, which can be used to measure the concentration of the substance being tested. This method is commonly used in biochemical assays to determine the presence or concentration of various compounds in a sample.

HDL, or high-density lipoprotein, is separated from the rest of the lipoproteins by using heparin sulfate as the reagent for pretreatment of the sample. The addition of heparin sulfate, a polyanion, along with a divalent cation helps in the separation of HDL from other lipoproteins. This method is commonly used in laboratory settings to analyze and measure different lipoprotein fractions in blood samples.

Microalbuminuria is a condition where there is a slightly increased amount of albumin in the urine, indicating early kidney damage. The correct answer of 30 to 300 mg/24hrs indicates the range of albumin values that indicate microalbuminuria. This range suggests that albumin levels as low as 30 mg/24hrs and as high as 300 mg/24hrs can be indicative of microalbuminuria. Values below 30 mg/24hrs or above 300 mg/24hrs would fall outside of this range and may suggest different conditions or normal kidney function.

Glucose is the primary source of energy for the body. It is a monosaccharide, which means it is the simplest form of sugar and can be easily broken down and absorbed by the body. Other monosaccharides, such as fructose and galactose, need to be converted into glucose before they can be used for energy. Therefore, glucose is the only monosaccharide directly used by the body for energy.

Chylomicrons do not belong in the lipid profile evaluated in the clinical laboratory because they are large particles that transport dietary fats from the intestines to the liver. They are not measured directly in a lipid profile as their levels can vary greatly depending on recent dietary intake. The lipid profile typically includes measurements of triglycerides, HDL (high-density lipoprotein), and VLDL (very low-density lipoprotein), which provide information about the levels of different types of lipids in the blood and can help assess the risk of cardiovascular disease.

Glycosylated albumin is a form of albumin that has glucose molecules attached to it. It reflects short-term glucose control because the level of glycosylated albumin in the blood increases when blood glucose levels are high over a short period of time. Therefore, statement (I) is true. On the other hand, statement (II) suggests that the test for glycosylated albumin may be used in cases of acute hemolytic anemia. However, there is no known association between glycosylated albumin and acute hemolytic anemia. Therefore, statement (II) is false.

The renal threshold for glucose refers to the blood glucose level at which the kidneys start to excrete glucose into the urine. In a healthy individual, this threshold is typically around 160 to 180 mg/dL. Above this range, glucose spills into the urine as the kidneys are unable to reabsorb all of it. This is an important indicator for diabetes, as elevated levels of glucose in the urine can be a sign of uncontrolled blood sugar levels.

Glucose-6-PO4 cannot directly enter the tricarboxylic acid cycle. Before entering the cycle, glucose-6-PO4 must undergo several enzymatic reactions to be converted into pyruvate, which can then enter the cycle as acetyl-CoA. Therefore, the statement is false.

The glucose dehydrogenase method for glucose is not specific for β-glucose. It is a general method that can be used to measure the concentration of glucose, regardless of its specific form or configuration. Therefore, the statement is false.

The correct pattern of lipoproteins in the ultracentrifugation technique is from lightest to heaviest. Chylomicrons are the lightest, followed by VLDL, then LDL, and finally HDL, which is the heaviest.

The lifespan of red blood cells (RBCs) can affect HbA1C levels. HbA1C is a measure of the average blood glucose levels over the past 2-3 months. RBCs have a lifespan of approximately 120 days, and during their lifespan, they become glycated as glucose attaches to hemoglobin. Therefore, if the lifespan of RBCs is shorter or longer than normal, it can affect the HbA1C levels, leading to inaccurate results. This factor needs to be considered when interpreting HbA1C levels.

Phospholipids are a type of lipid that make up the majority of the cell membrane structure. They have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails, which allow them to form a bilayer in the cell membrane. This arrangement provides a barrier between the inside and outside of the cell, regulating the passage of molecules and ions. Other lipids like fatty acids, cholesterol, and triglycerides have different functions and are not primarily involved in the structure of the cell membrane.

Lipoprotein X is a specific and sensitive indicator of atherosclerosis. Atherosclerosis is a condition characterized by the buildup of plaques in the arteries, leading to narrowing and hardening of the arteries. Lipoprotein X is a type of lipoprotein that is found in high levels in individuals with atherosclerosis. Therefore, measuring the levels of lipoprotein X can be used as an indicator of the presence and severity of atherosclerosis.

Cholesterol is a major lipid that contains an unsaturated steroid alcohol formed from four fused rings and a single side chain tail similar to a fatty acid. It is an essential component of cell membranes and is involved in various biological processes such as hormone synthesis and digestion. Cholesterol is primarily synthesized in the liver and is also obtained from dietary sources. It is transported in the bloodstream by lipoproteins, with high-density lipoprotein (HDL) being considered "good cholesterol" due to its role in removing excess cholesterol from the arteries.

The units used in the ultracentrifugation technique for lipoproteins are Svedberg units. The Svedberg unit (symbol: S) is a unit of time used in sedimentation analysis. It measures the rate at which particles sediment in a centrifugal field. The ultracentrifugation technique involves subjecting a sample to high centrifugal forces to separate particles based on their size and density. By measuring the sedimentation rate of lipoproteins in Svedberg units, scientists can determine their molecular weight and analyze their composition.

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The reagent used in the ultracentrifugation technique for lipoproteins has a specific gravity of approximately 1.063. This specific gravity is important because it allows for the separation of lipoproteins based on their density. By using a reagent with a specific gravity of 1.063, the lipoproteins can be separated into different fractions based on their density, which is crucial for studying their composition and function.

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Cholesterol oxidase is the enzyme involved in the given reaction. It catalyzes the oxidation of cholesterol in the presence of oxygen, resulting in the formation of cholestenone and hydrogen peroxide. This enzyme plays a crucial role in the metabolism of cholesterol and is commonly found in bacteria and fungi.

Glucose oxidase is the first enzyme involved in the most commonly used enzymatic method because it catalyzes the oxidation of glucose to produce gluconic acid and hydrogen peroxide. This enzyme is widely used in various industries, including food and beverage, clinical diagnostics, and biosensor applications. Its ability to specifically act on glucose makes it a valuable tool for measuring glucose levels in blood, detecting glucose in food products, and generating hydrogen peroxide for other enzymatic reactions.

Hexokinase catalyzes the formation of glucose-6-PO4 from glucose and ATP. Hexokinase is an enzyme involved in the first step of glycolysis, which is the breakdown of glucose to produce energy in the form of ATP. It adds a phosphate group to glucose, converting it into glucose-6-PO4. This phosphorylation of glucose is an important step in regulating glucose metabolism and trapping glucose within cells. Therefore, the correct answer is glucose-6-PO4.