Genetic Definitions

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GENE
A section of DNA that codes for a specific protein e.g. gene for eye colour.
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ALLELE
A different/alternative form of the same gene e.g. blue eyes, brown eyes or green eyes.
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GENOTYPE
The alleles carried for a particular gene e.g. BB Bb or bb.
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PHENOTYPE
The outward expression of a gene - an organism's characteristics e.g. tongue rolled, non-roller.f
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DOMINANT ALLELE
The allele that is always expressed if present and is expressed when even only one copy is present.
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RECESSIVE ALLELE
The allele that is only expressed when the dominant allele is absent. The allele is only expressed when two copies are present.
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CODOMINANCE
When two or more alleles have the same level of dominance in heterozygotes, both alleles will be expressed. Three phenotypes are often seen instead of two.
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LOCUS
The fixed position of a gene on a chromosome.
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HOMOZYGOTE
An organism that carries two copies of the same allele e.g. BB or bb.
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HETEROZYGOTE
An organism that carries two different alleles e.g Bb.
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HOMOZYGOUS
Having two identical alleles of a gene e.g. BB or bb.
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HETEROZYGOUS
Having two different alleles of a gene e.g. Bb.
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AUTOSOME
A non-sex chromosome.
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SEX-LINKED
When a gene is located on a sex chromosome.
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X-LINKED
When a gene is located on the X chromosome.
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EPISTASIS
When the allele of one gene prevents the expression of an allele of another gene.
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F1 GENERATION
The offspring from the first mating/breeding e.g. sons and daughters.
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F2 GENERATION
The offspring from the second mating/breeding e.g. grandsons and granddaughters.
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PURE BREEDING
When the individual is homozygous for a gene e.g. BB or bb.
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CARRIER
A person carrying an allele which is not expressed in the phenotype but that can be passed on to offspring.
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MULTIPLE ALLELES
More than two alleles of the same gene.
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GENETIC PEDIGREE DIAGRAMS
These show an inherited trait/characteristic in a group of related individuals.
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MONOHYBRID INHERITANCE
The inheritance of a single gene controlled by different alleles.
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MONOHYBRID CROSSES
These show the likelihood of alleles being inherited by offspring of particular parents.
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GAMETES
Sex cells which contain only one allele for each gene.
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PUNNETT SQUARE
A genetic diagram used to predict genotypes and phenotypes of offrsping.
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Other cards in this set

Card 2

Front

A different/alternative form of the same gene e.g. blue eyes, brown eyes or green eyes.

Back

ALLELE

Card 3

Front

The alleles carried for a particular gene e.g. BB Bb or bb.

Back

Preview of the back of card 3

Card 4

Front

The outward expression of a gene - an organism's characteristics e.g. tongue rolled, non-roller.f

Back

Preview of the back of card 4

Card 5

Front

The allele that is always expressed if present and is expressed when even only one copy is present.

Back

Preview of the back of card 5
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