Define the quaternary structure of proteins.

The assembly of multiple polypeptide chains into a functional protein complex

Define 'mutation' in genetics.

A change in the DNA sequence

Define a carbohydrate's basic molecular formula.

CH2O (carbon, hydrogen, oxygen in a two-to-one hydrogen to oxygen ratio)

Define gluconeogenesis.

The synthesis of glucose from non-carbohydrate sources

Define oxidative stress and its impact on cells.

Imbalance between free radicals and antioxidants, leading to cell damage

Define 'polypeptide'.

A long chain of amino acids

Define 'lipid bilayer'.

A thin polar membrane made of two layers of lipid molecules; these membranes are flat sheets that form a continuous barrier around cells

Define 'allosteric regulation' in enzymes.

Regulation of an enzyme's activity through binding of a molecule at a site other than the enzyme's active site

Define 'monosaccharide' with an example.

Simplest form of carbohydrates, e.g., glucose

Define a phospholipid and its role in cells.

A lipid containing a phosphate group; forms the primary structure of cell membranes

Define 'apoptosis' and its significance in multicellular organisms.

Programmed cell death, crucial for development and maintaining cell populations

Define the primary structure of proteins.

Linear sequence of amino acids in a polypeptide chain

Define 'ecosystem'.

A biological community interacting with its environment

Define anabolism and catabolism.

Anabolism is the synthesis of complex molecules; catabolism is the breakdown of complex molecules.

Define 'genetic code'.

The set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells

Define 'active transport' in cell biology.

Movement of molecules across a membrane requiring energy

Define 'denaturation' of proteins.

A structural change in proteins that results in the loss of their biological properties, typically caused by heat or chemicals

Define the role of chlorophyll in photosynthesis.

Absorbs light energy to convert carbon dioxide and water into glucose and oxygen

Define secondary structure of proteins.

Alpha helices and beta sheets formed by hydrogen bonding

Define the structure and function of microtubules.

Cylindrical tubes of tubulin that provide structural support and play a role in cell division and intracellular transport

Define 'lipids' and list two functions.

A group of naturally occurring molecules that include fats, waxes, sterols; functions include energy storage and forming cell membranes

Define the role of neurotransmitters in the nervous system.

Chemical messengers that transmit signals across a synapse from one neuron to another

Define tertiary structure of a protein.

Three-dimensional folding pattern of a protein due to side chain interactions

Define the structure of an alpha helix.

A right-handed coil or spiral conformation of amino acids in proteins, stabilized by hydrogen bonding

Define 'metabolism'.

All chemical reactions that occur in living organisms to maintain life