Lecture 4 - Macronutrients Part 3: Protein

Flashcards covering the vocabulary and core concepts of protein science, including structure, digestion, synthesis, and nutrition.

Proteos

The Greek word from which protein is derived, meaning 'primary' or 'taking first place'.

Enzymes

Biochemical proteins that act as catalysts in reactions, such as breaking larger molecules apart or linking glucose molecules to make glycogen.

Hormones

Chemical messengers secreted by endocrine glands, such as insulin, glucagon, and thyroid hormone, that are transported via the blood to target tissues.

Immunoproteins

Protein structures such as antibodies that are essential components of the immune system.

Haemoglobin

An iron-containing transport protein responsible for carrying oxygen to the cells.

Albumin

A transport protein that carries calcium, zinc, and $B_6$ through the bloodstream.

Buffer

A compound that drastically reduces the change in pH that would occur after the addition of a strong acid or base to a solution.

Amino acid

The building blocks of protein, consisting of an amino group ($NH_3$) on one end and a carboxylic acid on the other.

Peptide

A chain of amino acids, usually referring to a small protein molecule.

Oligopeptide

A term used to describe shorter chains of amino acids.

Pepsin

A stomach enzyme that functions at a low pH to break large protein molecules down into smaller peptides.

Cholecystokinin (CCK)

A hormone that signals the body to slow down gastric emptying, stimulates the pancreas to secrete alkaline juice, and signals the brain to feel full.

Enterocytes

Intestinal cells where the absorption of free amino acids and small peptides occurs.

Essentiality

Refers to the body's requirement for specific amino acids that cannot be synthesized internally and must be consumed in food.

Deamination

The process of removing the amine group (ammonia or $NH_3$) from an amino acid during catabolism.

Urea cycle

A process in the liver where toxic ammonia is converted into urea to be transported to the kidneys for excretion.

Gluconeogenesis

The creation of glucose from non-carbohydrate sources, such as using the carbon skeleton of deaminated amino acids.

Zero nitrogen balance

A state in a healthy person where the amount of nitrogen consumed equals the amount of nitrogen excreted.

Negative nitrogen balance

A condition occurring during infection or trauma where a person excretes more nitrogen than they consume.

Protein synthesis

The process by which the body reassembles amino acids from food into specific protein molecules as coded by DNA.

Transcription

The process occurring in the cell nucleus where double-stranded DNA is copied into matching messenger RNA (mRNA) components.

Translation

The process where mRNA travels to a ribosome in the cytosol and is used as a template to link amino acids into a protein molecule.

Codon

A 3-letter 'word' made from nucleic acids (G, C, A, and U) that translates into a specific amino acid.

Protein needs calculation

A standard nutritionist method estimating total protein needs as $0.8\,g$ protein per $kg$ of body weight.

Complete protein

Foods, primarily from animal sources like eggs and meat, containing all essential amino acids in physiologically significant proportions.

Incomplete protein

Plant-based protein sources, such as grains and legumes, that lack one or more essential amino acids.

Complementary proteins

The combination of different vegetable protein sources to provide a full complement of essential amino acids (e.g., rice and beans).

Serotonin

A neurotransmitter that helps people feel happy, calm, and alert; it is synthesized from the amino acid tryptophan using $B_6$.