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This year, like many past years, you begin to feel very sleepy after eating a large helping of Thanksgiving turkey. Some people attribute this sleepiness to presence of the amino acid tryptophan in turkey. Tryptophan can be used by the body to produce serotonin, which can calm the brain's activity and help to bring on sleep. a. What mass in grams of tryptophan is in a \(0.25-\mathrm{lb}\) serving of turkey (assume tryptophan accounts for \(1.0 \%\) of the turkey mass)? b. What mass in grams of tryptophan is in \(0.25\) quart of milk (assume tryptophan accounts for \(2.0 \%\) of milk by mass and that the density of milk is \(1.04 \mathrm{~kg} / \mathrm{L}\) )?

Short Answer

Expert verified
There are approximately 1.134 grams of tryptophan in a 0.25-lb serving of turkey and approximately 4.932 grams of tryptophan in 0.25 qt of milk.

Step by step solution

01

Convert weight from pounds to grams.

First, we need to convert the weight of the turkey serving from pounds to grams because our answer needs to be in grams. To do this, we use the conversion factor 1 lb = 453.592 grams. So, we have: \(0.25~\text{lb} × \dfrac{453.592~\text{g}}{1~\text{lb}}\)
02

Multiply the turkey mass by the percentage of tryptophan.

Now, we know that tryptophan accounts for 1% of the turkey mass. To find the mass of tryptophan in the 0.25-lb serving, multiply the turkey mass in grams by 1%: \((0.25~\text{lb} × \dfrac{453.592~\text{g}}{1~\text{lb}}) × 0.01\)
03

Calculate the mass of tryptophan.

Perform the calculations to find the mass of tryptophan in the turkey serving: \((0.25 × 453.592) × 0.01 = 113.398~\text{g} × 0.01 = 1.13398~\text{g}\) Thus, there are approximately 1.134 grams of tryptophan in a 0.25-lb serving of turkey. #b. Tryptophan mass in the milk#
04

Convert the volume of milk from quarts to liters.

First, we need to convert the volume of milk from quarts to liters, as we have the density of milk in kg/L. To do this, we use the conversion factor 1 quart = 0.946353 L. So, we have: \(0.25~\text{qt} × \dfrac{0.946353~\text{L}}{1~\text{qt}}\)
05

Calculate the mass of milk.

To find the mass of the milk, we need to multiply the volume of milk in liters by its density: \((0.25~\text{qt} × \dfrac{0.946353~\text{L}}{1~\text{qt}}) × \dfrac{1.04~\text{kg}}{1~\text{L}}\) Now we need to convert the mass from kilograms to grams using the conversion factor 1 kg = 1000 g: \(((0.25 × 0.946353) × 1.04)~\text{kg} × \dfrac{1000~\text{g}}{1~\text{kg}}\)
06

Multiply the milk mass by the percentage of tryptophan.

We know that tryptophan accounts for 2% of the milk mass. To find the mass of tryptophan in the 0.25-qt milk, multiply the milk mass in grams by 2%: \((((0.25 × 0.946353) × 1.04)~\text{kg} × \dfrac{1000~\text{g}}{1~\text{kg}}) × 0.02\)
07

Calculate the mass of tryptophan.

Perform the calculations to find the mass of tryptophan in the milk: \((((0.25 × 0.946353) × 1.04) × 1000) × 0.02 = 246.597~\text{g} × 0.02 = 4.93194~\text{g}\) Thus, there are approximately 4.932 grams of tryptophan in 0.25 qt of milk.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Amino Acids in Nutrition
Understanding the role of amino acids in nutrition is vital for grasping why certain foods may affect your well-being. Amino acids are organic compounds that combine to form proteins, which are essential for the structure, function, and regulation of the body's tissues and organs. There are twenty different amino acids that can form a protein, and nine of these are considered essential, meaning that they must be obtained from our diet.

The amino acid tryptophan, found in protein-rich foods such as turkey and milk, is among these essential amino acids. It is a precursor to serotonin, a neurotransmitter that influences sleep and mood. The percentage of tryptophan in foods can vary. For instance, it is typically around 1% of the mass of turkey, while it can be 2% of the mass in milk. Adequately calculating how much tryptophan you’re getting from your meals involves understanding the mass of the food consumed and its tryptophan concentration.

Nutritional Impact of Amino Acids

Ensuring adequate intake of essential amino acids is critical due to their impact on various body functions. They are not only the building blocks of proteins but are also involved in metabolic pathways, energy production, and the synthesis of hormones and neurotransmitters.
Serotonin Production
Serotonin production in the human body is an excellent example of a biochemical process that has direct implications on our health and mood. Tryptophan is hydroxylated and then decarboxylated to produce serotonin, a neurotransmitter also known as 5-hydroxytryptamine (5-HT). This process is complex and requires several nutrients and enzymes to work correctly.

Serotonin is synthesized in the brain and intestines, but it’s the brain serotonin that has a significant influence on mood, emotion, and sleep. Consuming foods high in tryptophan can increase serotonin levels since the availability of tryptophan in the brain affects the rate of serotonin synthesis. This is why consuming a meal with tryptophan-rich foods like turkey can contribute to feelings of drowsiness or a calming effect. The relationship between tryptophan intake, serotonin production, and mood highlights the intimate connection between diet and brain function.
Chemical Calculations
In chemistry, accurate calculations are fundamental for understanding and predicting the outcomes of reactions and compositions of substances, as seen when we determine the content of tryptophan in foods. In the given exercises, the mass of tryptophan in a serving of turkey and milk was calculated using conversion factors to adjust units and percent composition to find the specific quantity of interest.

Conversion Factors in Chemical Calculations

Unit conversion is an essential skill when performing chemical calculations, as different measurements may be used depending on the context. In these exercises, pounds were converted to grams, quarts to liters, and kilograms to grams to work within a consistent unit system. Furthermore, the percentage of an element within a compound or a nutrient within food must be accounted for to extract meaningful information about the substance's actual content.

These calculations not only enable scientists to understand material compositions but also provide practical information for everyday life, such as nutritional content, necessary for informed dietary decisions.

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