Topic 1.4 Proteins Flashcards
Proteins consist of:
Hydrogen (H), Carbon (C), oxygen (O) and Nitrogen (N)
Protein containing foods - the only source of nitrogen
Amino acid structural formula:
All have the same structure:
central carbon bonded to one:
- hydrogen amino group (NH2)
- Carboxylic acid group (COOH)
What distinguishes amino acids?
The fourth attachment or side group - alters shape, size, charge etc.
May involve a single atom or group of atoms.
Why are proteins more complex out of carbs and lipids?
The side-group as each side group varies from one amino acid to the next.
How many amino acids are required by the body?
20
Essential amino acids
9 essential amino acids
Cannot be synthesised by the body or cannot produce them in amounts sufficient for meeting the body’s requirements.
*must be consumed
Non-essential amino acids
Can be synthesised by the body.
Essential amino acids
Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
Conditionally essential
non-essential amino acids become essential.
- injury, stress, illness
Complete protein
- contains all 9 essential amino acids
- may not contain all non-essentials
- high biological value
Incomplete proteins
- do not contain one or more essential amino acids
- low biological value
Complementary protein
Combination of incomplete proteins to obtain all essentials.
How are excess amino acids stored?
They cannot be stored; thus dietary protein is vital to consume on a daily basis.
Complete proteins sources
Animal sources: meat and eggs
Vegan: chia seeds
Incomplete protein sources
Tofu and soybeans
Is gelatin a complete protein?
No. It does contain the essential amino acid tryptophan.
Complementary protein sources
Beans on toast or peanut butter on wholegrain bread.
Protein structure
Polypeptide bond links each amino acid forming a polypeptide chain.
- through a condensation reaction, similar to when monosaccharides combine to form Di’s.
Condensation
combination of two molecules to form a larger molecule by producing water as a by-product.
Synthesising enzymes
Synthesize enzymes that act as catalysts to speed up biochemical reactions in the body, aiding in metabolism.
Synthesising hormones
that regulate heart rate, blood glucose levels, growth and development.
Synthesising antibodies
Which defends the body against invading antigens or viruses.
Regulating fluid and acid-base levels
Produces albumin which controls and regulates the movement of liquids into and out of cells.
Functions of Proteins
Structurally required for growth, maintance and repair of body tissue.
Bones, muscle, nerves
