Part A: Conceptual Questions How many molecules of amino acids do you take with a piece of 500 grams of meat? (on average an amino acid is ~100 Daltons)
Meat isn’t 100% protein; it’s typically composed of ~20% protein, ~20% fat, and ~60% water. So 500g of meat will approximately contain 100g of protein. Since Daltons is the unit used to measure the weight of small molecules and 1 Dalton is approximately $1.66 \times 10^{-24}$ grams. Since we need to calculate the number of molecules of AAs in our meat, let’s first convert the mass of one AA into grams: $$100\text{ Da} \times (1.66 \times 10^{-24}\text{ g/Da}) = 1.66 \times 10^{-22}\text{ g}$$ Then we divide the total protein mass by the mass per AA: $$\frac{100\text{ g}}{1.66 \times 10^{-22}\text{ g/molecule}} \approx 6.02 \times 10^{23}\text{ molecules}$$ So the total number of AA molecules in 500 g of meat is approximately $6.02 \times 10^{23}$, which is coincidentally (and elegantly) about 1 Mole of amino acids.
