Pearson International Advanced Level Biology Unit 1 - Molecules, Transport and Health

Vocabulary flashcards covering core biological concepts from Unit 1, including biological molecules, cardiovascular system, cell transport, enzymes, and genetic principles.

Hydrogen bonding

An electrostatic attraction between a hydrogen atom in one polar molecule and a small electronegative atom.

Polar molecule

A molecule that has positive and negative ends due to differences at each end.

Specific heat capacity of water

The amount of heat energy required to raise the temperature of $1\,\text{kg}$ of water by $1\,^\circ\text{C}$.

Latent heat of vaporisation

A measure of the heat energy needed to vaporise a liquid.

Cohesion

The attraction of one water molecule to another due to hydrogen bonds.

Monosaccharides

Monomers of carbohydrates composed of Carbon, Hydrogen, and Oxygen with the general formula $\text{C}_n(\text{H}_2\text{O})_n$.

Condensation reaction

The process in which two OH groups of two monosaccharides eliminate 2 Hydrogen atoms and 1 Oxygen atom, releasing water and forming a glycosidic bond.

Hydrolysis reaction

The process in which a water molecule is reintroduced into a glycosidic bond which breaks it.

Maltose

A disaccharide formed from $\alpha\text{-glucose} + \alpha\text{-glucose}$, sourced from malt.

Sucrose

A disaccharide formed from $\alpha\text{-glucose} + \text{Fructose}$, sourced from sugar cane.

Lactose

A disaccharide formed from $\alpha\text{-glucose} + \text{Galactose}$, sourced from milk.

Amylose

An unbranched component of starch made of $\alpha\text{-glucose}$ molecules with 1,4 glycosidic bonds, forming a helical shape and making up $30\%$ of starch.

Amylopectin

A branched chain component of starch made of $\alpha\text{-glucose}$ molecules with 1,4 and $\alpha\,1,6$ glycosidic bonds at branching points every 20-30 units, making up $70\%$ of starch.

Glycogen

A polymer of $\alpha\text{-glucose}$ with $\alpha\text{-1,4}$ and $\alpha\text{-1,6}$ glycosidic links used for carbohydrate storage in animals, with branching every 10 units.

Triglyceride

A lipid formed by the condensation of 3 fatty acid chains and 1 glycerol molecule, forming ester bonds.

Phospholipids

A group of polar lipids consisting of a negatively-charged hydrophilic phosphate head, a glycerol unit, and two uncharged nonpolar hydrophobic fatty acid tails.

Primary Structure of Proteins

The sequence of amino acids held together by polypeptide bonds in a polypeptide chain.

Secondary Structure of Proteins

The structure of a protein molecule resulting from regular coiling or folding into an $\alpha\text{-helix}$ or $\beta\text{-pleated sheet}$, maintained by hydrogen bonds.

Tertiary Structure of Proteins

The precise folding and coiling of alpha-helices and beta-pleated sheets held together by hydrogen bonds, ionic bonds, disulphide bridges, and hydrophobic interactions.

Quaternary Structure of Proteins

The three-dimensional arrangement of two or more polypeptides, or a polypeptide and a non-protein component, in a protein molecule.

Globular proteins

Proteins that curl up into a spherical shape with hydrophobic regions inside and hydrophilic regions outside, making them soluble in water.

Fibrous proteins

Proteins that form long strands, are insoluble in water, and perform structural roles in the body.

Tunica intima

The innermost layer of blood vessel walls consisting of a single layer of endothelial cells to reduce friction and ease blood flow.

Tunica media

The middle layer of artery walls containing smooth muscles, elastic fibers, and connective tissues.

Tunica adventitia

The outer layer of blood vessel walls containing smooth muscles, collagen fibers, and connective tissues.

Cardiac output

The volume of blood pumped by the heart in one minute.

Stroke volume

The volume of blood pumped by the heart in one beat.

Bohr effect

The shift in the oxygen dissociation curve caused by carbon dioxide levels, where high partial pressure of $\text{CO}_2$ lowers blood pH and reduces haemoglobin's affinity for oxygen.

Atherosclerosis

The hardening and narrowing of arteries caused by the build-up of fibrous plaque called an atheroma.

Atheroma

A fat deposit that accumulates under damaged arterial endothelium, leading to plaque formation.

Thrombus

A blood clot formed within a blood vessel.

Hypertension

A resting blood pressure reading above $140/90\,\text{mmHg}$.

Hypotension

A resting blood pressure reading below $90/60\,\text{mmHg}$.

Fluid mosaic model

A model proposed by Singer and Nicholson in 1972 describing the cell membrane as a fluid phospholipid bilayer with proteins forming a mosaic pattern.

Simple diffusion

The passive movement of molecules from high to low concentration down a concentration gradient through the phospholipid bilayer.

Facilitated diffusion

The passive movement of molecules from high to low concentration down a concentration gradient through specific channel or carrier proteins.

Osmosis

The diffusion of water molecules down a water potential gradient through a partially permeable membrane.

Active transport

The movement of molecules from low concentration to high concentration across a cell membrane through carrier proteins, requiring energy in the form of ATP.

Lock and key model

An enzyme catalysis model where the shape of an enzyme's active site is complementary to the shape of the substrate molecule.

Induced fit model

An enzyme action model where the active site shape is not complementary initially, but alters its tertiary structure upon substrate entry to fit around it.

Activation Energy ($E_A$)

The amount of energy required for a chemical reaction to begin.

Phosphodiester bond

A covalent bond formed via condensation between the phosphate group of one nucleotide and the pentose sugar of another in a polynucleotide chain.

Transcription

The first stage of protein synthesis in the nucleus where part of a DNA molecule unwinds and RNA polymerase catalyses the creation of an mRNA transcript.

Translation

The second stage of protein synthesis in the cytoplasm where mRNA attaches to a ribosome and tRNA molecules bring specific amino acids to build a polypeptide.

Antisense strand

The template strand of DNA read in the $3'$ to $5'$ direction during transcription to synthesize a complementary mRNA molecule.

Cystic fibrosis

A recessive inherited disorder caused by a mutation in the CFTR gene on chromosome 7, producing non-functional chloride channels and thick, sticky mucus.

Fick's Law of Diffusion

A mathematical relationship stating that the rate of diffusion is proportional to $\frac{\text{Surface area} \times \text{Concentration difference}}{\text{Thickness of membrane}}$.

DCPIP

An oxidising agent used in practical tests that turns from blue to colourless when reduced by an antioxidant such as Vitamin C.