Protein

What Protein covers

Protein is examined in Unit AS 1, Principles of Nutrition — examined, compulsory. It covers functions of protein, amino acids, biological value and complementation, animal and plant sources of protein, novel protein sources and nitrogen balance and protein requirements.

The 5 subtopics

Each one has its own page. CCEA AS Nutrition and Food Science students sit this topic in the first year.

• Functions of proteinProtein's roles in growth, repair, enzymes, hormones, transport, immunity and fluid balance, its energy value, and what happens to surplus amino acids and to children short of protein.Open →
• Amino acids, biological value and complementationIndispensable, dispensable and conditionally indispensable amino acids, biological value, limiting amino acids, reference proteins and protein complementation in everyday meals.Open →
• Animal and plant sources of proteinAnimal and plant protein foods compared for biological value, fat, nutrients, digestibility, versatility and cost, and how a vegan diet can supply enough protein.Open →
• Novel protein sourcesWhat counts as a novel food, mycoprotein, textured vegetable protein, tofu, tempeh, edible insects and cultivated meat, compared with meat for nutrition, cost and versatility.Open →
• Nitrogen balance and protein requirementsNitrogen equilibrium and positive and negative balance, how requirements are set, the adult Reference Nutrient Intake, and worked protein calculations.Open →

What you need to know

Answer each one before you reveal it.

Take Protein further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• HBV protein vs LBV protein

  HBV protein: a food source supplying every indispensable amino acid in the proportions humans need. LBV protein: a food source short of at least one indispensable amino acid.

• Indispensable amino acid vs Dispensable amino acid

  Indispensable amino acid: a protein building block the body cannot make and must obtain from food. Dispensable amino acid: a protein building block the body can make from other building blocks.

• Positive nitrogen balance vs Negative nitrogen balance

  Positive nitrogen balance: a state in which more protein is retained than lost, as during growth. Negative nitrogen balance: a state in which body protein is broken down faster than it is replaced.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What are proteins made from?

   Model answer

   Proteins are long chains of amino acids joined by peptide bonds. Every amino acid contains carbon, hydrogen, oxygen and nitrogen, and some also contain sulfur.

2. 2

   What is the main function of protein in the body?

   Model answer

   The main function of protein is the growth, repair and maintenance of body tissues. Amino acids from the diet are used to build new cells and replace worn-out ones.

3. 3

   Why does a patient recovering from surgery need a good supply of protein?

   Model answer

   New tissue must be built to close the wound, and new tissue is made from amino acids. Protein is also needed for the collagen that forms scar tissue.

4. 4

   How does protein help the body fight infection?

   Model answer

   Antibodies are proteins made by white blood cells. Antibodies bind to specific antigens on pathogens and help destroy them.

5. 5

   Explain why enzymes depend on an adequate protein intake.

   Model answer

   Enzymes are proteins that act as biological catalysts. Digestive enzymes such as pepsin break down food, and other enzymes control reactions inside every cell.

6. 6

   Give an example of a hormone that is a protein.

   Model answer

   Insulin is a protein hormone made by the pancreas. Insulin carries a chemical message that lowers blood glucose.

What is inside Levo

Six ways to work the same material.

Protein revision questions

Is Protein examined at AS in CCEA Nutrition and Food Science?

Yes. It sits in AS 1, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.

What does Protein cover in CCEA AS-Level Nutrition and Food Science?

5 subtopics: functions of protein, amino acids, biological value and complementation, animal and plant sources of protein, novel protein sources and nitrogen balance and protein requirements. Each one has its own page with questions and model answers.

How is Protein organised?

By the CCEA 3310 specification, subtopic by subtopic, so it matches the order you are taught it in.