Biology Terms

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gene

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The basic unit of inheritance by which inherited characteristics are transferred from parents to offspring, consisting of a length of DNA on a chromosome.

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Allele

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One alternative form of a gene, occupying a specific positions (locus) on a chromosome

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Loci

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The position along the chromosome where genes occur, so alleles of the same gen occupy the same locus

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Genotype

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The genetic constitution of an organism

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Phenotype

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The characteristics displayed by the organism- the way in which the genotype is expressed (appearance of organism)

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Dominant allele

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An allele that affects the phenotype of the organism, whether present in the heterozygous of homozygous condition.

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Recessive allele

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An allele that affects the phenotype of the organism only when the dominant allele is absent

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Homozygous

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A diploid organism that has inherited the same allele from both parents

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Heterozygous

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A diploid organism that has inherited different alleles from each parent.

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Test cross

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Testing a suspected heterozygote by crossing it with a known homozygous recessive

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Codominant alleles

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Pairs of alleles that both affect the phenotype when present in a heterozygote

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Carrier

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An individual with a recessive allele of a gene that does not affect their phenotype- especially one responsible fore a genetic disorder such as colour blindness or haemophilia

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Degenerate code

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The triplet code contains more codons that there are amino acids to be coded, so most amino acids are coded for by more than one codon.

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sex linkage

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the association of a characteristic with gender, because the gene controlling the characteristic is located on a sex chromosome.

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Ecology

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The study of living things

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Ecosystems

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A stable, settled unit of nature consisting of a community of organisms, interacting with each other and with their surrounding physical and chemical environment.

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Habitat

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The locality in which an organism occurs, is normally found.

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Population

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all the living thingfs of the same species in a habitat,

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Community

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All the living things in a habitat or ecosystem

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Species

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A group of individuals of common ancestry that closely resemble each other and that can interbreed to produce fertile offspring.