Chapter 2 - Key definitions

Diffusion

The net movement of substances from a region of its higher concentration to a region of its lower concentration. It is a passive process and continues until equilibrium is reached.

Hydrophobic

Non-polar, uncharged molecules or regions of molecules that repel water.

Hydrophilic

Polar, charged molecules or regions of molecules that do not repel water.

Passive

A process that does not require energy.

Facilitated Diffusion

The movement of substances from a region of its higher concentration to a region of its lower concentration using a protein.

Osmosis

The net movement of free water molecules from a solution with a lower concentration of solute to a higher concentration of solute across a partially permeable membrane.

Chromosome

A long DNA molecule which contains genes that code for several different proteins.

Gene

A sequence of bases that codes for a protein.

Allele

A different version of a gene.

Locus

The position of a gene on a chromosome.

Degenerate

More than one triplet codes for an amino acid.

Mutation

A change in the base sequence of DNA.

Genotype

The combination of alleles in an organism.

Phenotype

Observable characteristics of an organism which is coded for by its alleles.

Homozygous

Having two identical alleles on both chromosomes at a specific locus.

Heterozygous

Having two different alleles on both chromosomes at a specific locus.

Dominant

Only needs one copy of the allele to be expressed in phenotype.

Recessive

Needs two copies of the allele to be expressed in the phenotype.