Chemistry · Rung 18 of 24

Carbohydrates, proteins and fats

A living thing is made mostly of three families of carbon molecules, and all three are chains. Carbohydrates are sugars chained together and give quick energy: bread, pasta, rice. Proteins are amino acids chained together, twenty different kinds, and they build and repair: meat, pulses, eggs. Fats are a head with three long tails and they store energy and insulate from cold: oil, nuts. Fat stores more than twice as much per gram as a carbohydrate, about nine kilocalories against four, which is why the body's long reserve is fat and not sugar: as starch we would weigh twice as much for the same energy. The astonishing part is in the proteins: the order of the amino acids decides how the chain folds, and how it folds decides what it does, so the same list of twenty pieces gives an enzyme, a hair or an antibody depending on the order.

Where this sits

Comes after
Carbon chemistry

Exercises from this rung

Generated by the app, from easiest to hardest

  1. Which foods are mainly proteins?

    • meat and pulses
    • water and salt
    • bread and pasta
    • oil and nuts

    Why Proteins are for building and repairing the body, and they are mainly in meat and pulses. All three are carbon molecules, and all three are chains: a carbohydrate is sugars chained together, a protein is amino acids chained together, and a fat is a head with three long tails.

    easier

  2. Which foods are mainly carbohydrates?

    • meat and pulses
    • water and salt
    • oil and nuts
    • bread and pasta

    Why Carbohydrates are for quick energy, and they are mainly in bread and pasta. All three are carbon molecules, and all three are chains: a carbohydrate is sugars chained together, a protein is amino acids chained together, and a fat is a head with three long tails.

    in between

  3. What are proteins made of?

    • Amino acids
    • Nucleotides
    • Sugars
    • Fatty acids

    Why Of amino acids chained together, twenty different ones, like a necklace made from twenty kinds of bead. The astonishing part is that the order of the beads decides how the chain folds, and how it folds decides what it does: the same list of twenty pieces gives an enzyme, a hair or an antibody depending on the order.

    harder