Proteins

Proteins

Long chains containing more than 50 amino acids. Performs many functions in body including structural, transport, and enzyme functions.

Amino Acids

The building blocks of proteins, linked by peptide bonds.

Polypeptides

Long chains of more than 2 amino acids that form proteins

Peptide Bond

A covalent bond formed between two amino acids through a dehydration reaction; it involves the carboxyl group of one amino acid and the amine group of another.

Alpha Helix Secondary Structure (of proteins)

Corkscrew shape, peptide backbone held in place by hydrogen bonds, R groups of amino acids point outwards

Triple Helix Secondary Structure (of proteins)

Rope-like, has 3 alpha-helix polypeptide chains woven together giving it strength

Beta-pleated Sheet Secondary Structure (of proteins)

Polypeptide chain arranged side by side, peptide backbone held together by hydrogen bonds, R groups above and below the sheet

Tertiary Structure (of proteins)

Folding of protein into a 3D structure containing alpha-helical and beta-pleated structures, held together by interactions between R groups.

Quaternary Structure (of proteins)

Combination of two or more polypeptides, stabilised by interactions between R groups

Denaturation

When proteins lose their conformation (shape) due to factors such as heat, chemicals, pH changes, metal ions or agitation, resulting in loss of function.

Transcription

The first step of protein synthesis, where a segment of DNA is copied into messenger RNA (mRNA).

Translation

Second step of protein synthesis. mRNA is decoded to synthesise proteins with aid of tRNA and ribosomes.

Collagen

A structural protein that provides strength and support in connective tissues, typically found in skin and cartilage.

Myoglobin

A protein that binds oxygen in muscle tissues → forms a pocket allowing oxygen to be stored and transported

Hemoglobin

The protein in red blood cells responsible for transporting oxygen; it consists of four subunits (polypeptide chains) arranged in a quaternary structure.

R Groups (side chains)

The variable groups attached to the central carbon of amino acids that determine the characteristics and functions of the proteins.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid during protein synthesis.

tRNA (transfer RNA)

A type of RNA that brings specific amino acids to ribosome during translation based on mRNA codon.

basic structure of amino acids

Alpha carbon, hydrogen, amino and carboxyl group (consistent) and R-Group / side chain (varies)

Primary structure (of proteins)

Sequence of amino acids in a polypeptide chain

Enzymes

Proteins that act as catalysts to accelerate chemical reactions in the body.

Antibodies

Proteins produced by the immune system to identify and neutralise foreign objects such as bacteria and viruses.

Insulin

A hormone and protein that regulates blood sugar levels by facilitating uptake of glucose into cells

primary structure of 2 polypeptide chains linked by disulfide bonds. ‘A chain’ has 21 amino acids, ‘B chain’ has 30 amino acids.