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Slide 1

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By Tilly :)…read more

Slide 2

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What is an allele?
· An allele is something which is coded for the
same gene or characteristic, but is a different
version of that gene.
· Most genes have more than one type.
· For example, eye colour. People have
different eye colours, such as green, brown,
grey and blue. These different eye colours
are different alleles of the same gene.…read more

Slide 3

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Examples of alleles
Tongue rolling
Ear lobe shape
Skin colour…read more

Slide 4

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Examples of alleles
Hair colour…read more

Slide 5

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What is dominant and
· Dominant alleles are always expressed if present. This
includes brown hair and brown eyes, and also faulty genes
like the gene for Huntington's disease. If a parent passes on
one of these alleles to their child, then this will be the allele
which is expressed regardless of the other parent's allele.
· Recessive alleles can only be expressed if both parents
pass on the same allele. So only a recessive allele can be
present for it to show. This includes ginger hair, blue eyes
and the faulty gene for cystic fibrosis. These will only be
expressed when they are the only form of the gene present
in an offspring's genetics.…read more

Slide 6

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Examples of dominant
and recessive alleles
Brown hair is
dominant, ginger hair
Brown is dominant is recessive.
Blue is recessive…read more


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