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What makes you, you and me, me? Genes or environment? How we look and act is the result of the interaction of our genes with our environment. Even identical twins, with an identical genetic make-up, have unique phenotypes.

This resource provides explanations of the key concepts encountered in when exploring what makes each of us unique – the ‘basics’ that every student should understand.

DNA

Deoxyribonucleic acid (DNA) is a molecule that contains the instructions needed for an organism to develop and function. These instructions are stored as a code made up of 4 chemical bases: adenine (A), guanine (G), cytosine (C) and thymine (T).

Gene

A segment of a DNA molecule (a sequence of bases) that codes for a particular protein and determines the traits (phenotype) of the individual. A gene is the basic unit of heredity in a living organism.

Protein

Proteins are molecules made of amino acids. They are coded for by genes and play a central role in biological processes and form the basis of living tissues. Enzymes, antibodies and haemoglobin are examples of proteins. Some proteins play more than one role in the body, for example, cohesin proteins.

Genome

The entire set of genetic material found in the chromosomes of a species. For example, in humans, this consists of approximately 3.1 billion base pairs of DNA, which contain 20–25 thousand genes.

Chromosome

A structure made up of DNA and proteins that contains genes. Humans have 23 pairs of chromosomes that are found in the cell nucleus.

Genotype

The genetic make-up of an individual organism. Your phenotype is a result of the interaction between your genotype and your environment.

Phenotype

The observable physical or biochemical characteristics of an individual organism, determined by both genetic make-up and environmental influences.

Gene expression

The use of a gene to make a protein. Involves transcription of the DNA sequence into RNA and translation of the RNA into an amino acid sequence (or protein).

Trait

A characteristic of a living organism, such as the height of a plant or the hair colour of a mammal.

Allele

Alleles are alternative forms of the same gene that occupy the same location on a chromosome. Different alleles of a gene generally serve the same function (for example, they code for a protein that affects eye colour) but may produce different phenotypes (for example, blue eyes or brown eyes) depending on whether the allele is dominant or recessive.

Environmental factors

In this case, factors in the environment that may influence your phenotype, for example, sunlight, nutrition or chemicals.

Model organism

A model organism is a non-human species used by scientists to better understand particular biological research questions, for example, zebrafish and fruit flies.

Genetics

The study of genes, heredity and variation in living organisms.

Meiosis

A type of cell division that creates egg and sperm cells for sexual reproduction. Meiosis results in variation amongst a population by creating genetically distinct gametes.

Gamete

Male (sperm) or female (egg) reproductive cells that contain a single set of chromosomes and are specialised for fertilisation.

    Published 18 October 2016