Edexcel IAL Biology Unit 1

Flashcards of key vocabulary from the provided lecture notes.

Hydrogen bond

A relatively weak link between two atoms in which a weakly negative atom attracts another weakly positive atom.

Colloid

A mixture in which very small particles of one substance are distributed evenly throughout another substance. The solute particles of colloid are larger than the particles of the solvent.

Emulsion

Tiny droplets of one liquid suspended in another liquid.

Suspension

A solid mixed with a liquid in which the particles will separate out if the mixture is not constantly moved or stirred.

Glycosidic bond

A covalent bond between two monosaccharides.

Condensation reaction

A reaction in which two molecules are linked together with the elimination of a molecule of water.

Hydrolysis reaction

A reaction in which a molecule of water is used in breaking a chemical bond (the reverse of a condensation reaction).

Saturated fatty acid

One in which all the bonds between carbon atoms in the hydrocarbon chain are single covalent bonds. (C-C)

Unsaturated fatty acid

One in which all the bonds between A fatty acid in which one of more pairs of adjacent carbon atoms in the hydrocarbon chain are linked by double covalent bond

Ester bonds

The bonds formed during condensation reactions between glycerol and three fatty acids

Amino acid

The monomer from which dipeptides, polypeptides and proteins are made.

Zwitterion

An ion with both positive and negative charges.

Peptide bond

A covalent bond between the amino group of one amino acid and the carboxyl group of other amino acid. Each peptide bond is formed by a condensation reaction.

Active site

The small part of the enzyme molecule that binds to its specific substrate and causes the catalysis.

Activation energy

The energy needed by a reaction to occur; energy barrier that must be overcome before reactants reach their temporary transition state.

Hydrophilic

Refers to substances that will mix with water (water-loving)

Hydrophobic

Refers to substances that will not mix with water (water-hating).

Bilayer

A single structure made of two layers of molecules, used mainly to describe the arrangement of phospholipids in a cell membrane.

Glycoprotein

Protein with a carbohydrate prosthetic group; functions include cell-cell recognition or receptor sites.

Integral proteins

Proteins present in the cell surface membrane that are partially or totally buried within the lipid bilayer.

Peripheral proteins

Proteins present in the cell surface membrane that are superficially attached to the lipid bilayer.

Passive transport

Transport that does not require energy; diffusion and osmosis are forms of passive transport.

Diffusion

Net movement of molecules of a fluid from region of their high concentration to a region of low concentration.

Facilitated diffusion

Specialised form of diffusion in which there is net movement of molecules from a region of their high concentration to a region of low concentration through channel proteins.

Osmosis

Movement of solvent molecules (water) from a region of their high concentration to a region of low concentration through a partially permeable membrane.

Active transport

Movement of substances across a cell surface membrane against a concentration gradient using energy in the form of ATP.

Endocytosis

Movement of materials into cells.

Exocytosis

Moving substances out of cell.

Aorta

Artery that carries oxygenated blood away from the heart to the body.

Arterioles

The very smallest branches of the arterial system, furthest from the heart.

Prothrombin

A large protein that is converted into thrombin.

Thrombin

An enzyme that acts on fibrinogen, converting it to fibrin.

Fibrin

Substance that forms a mesh of fibers to create a blood clot.

Systole

Contraction of the heart.

Diastole

Relaxation of the heart.

Endothelial

The lining of blood vessels.

Atheroma

Fatty deposit in the arteries.

Aneurysm

Bulge in the artery severely weakened.

Antihypertensives

Drugs that reduce blood pressure.

Statins

Drugs that lower the level of cholesterol in your blood.

Anticoagulants

Prevents the blood clotting too easily.

Mononucleotides

The single units; nucleotides.

Purine

Two nitrogen-containing rings.

Pyrimidine

One nitrogen-containing ring.

semi-conservative replication

The process in which two copies of a DNA molecule are made and in which both parent stands remain intact and act as templates for the formation of new, complementary strands.

Codon

A sequence of three base pairs on the DNA or RNA is known as a codon.

Gene

A sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain.

Transcription

Process by which the DNA nucleotide base sequence of a gene is copied into the RNA nucleotide base sequence.

Translation

Process by which the genetic code is converted into protein molecules directed by RNA.

Mutation

Rare, random change in DNA.

Allele

Different versions of a gene that produce variation of the characteristic.

Genotype

The genetic information of an individual organism.

Phenotype

The set of observable characteristics of an individual, resulting from the interaction of its genotype with its environment.

Recessive

Alleles that are only expressed in the phenotype when no dominant allele is present.

Dominant

Alleles that are expressed in the phenotype even if a recessive allele is present.

Homozygote

If both alleles coding for a particular characteristic are identical.

Heterozygote

If the two alleles coding for a characteristic are different.

Monohybrid cross

When one gene is considered at a time in a genetic cross.