Multiple Gen Inheritance Cats

8/12/2019 Multiple Gen Inheritance Cats

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Lesson Aims

You will seeexamples of the mainways by whichfeatures areinherited.

You will record anexample of eachinheritance patternincluding a genetic

diagram. You will see lots ofcats

monohybrid

dominance sex linkage

multiple alleles

dihybrid

The coat colour of cats shows a large amount ofdiscontinuous variation.

This suggests that each cats coat colour is likely to beproduced by the alleles of a large number of genes .

Despite the complexity that this large number of genescauses, each one is inh

erited in the same way.

parentalphenotypes

parentalgenotypes

gametegenotypes

offspringgenotypes

offspring

phenotypes

AA Aa

this that

A A a

A a A AA Aa

A AA Aa

are this (AA) and are that (Aa),

the probability that it will be this is 0.5


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Lesson Aims



diagram.

monohybrid

dominance

sex linkage multiple alleles

dihybrid

Monohybrid inheritance

This is when a small number of phenotypes (usually only 2or 3) are the result of one gene.

The gene has more than one allele (often 2 but it can bemore).

One allele is usually dominant . This means that it isexpressed whenever it is present in an individual.

The other allele is recessive . It is only expressed if it is the

only allele present in an individual.

MM or Mm mm


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Incomplete or Co-dominance

Sometimes the dominance of one allele isnt complete.

This usually results in three phenotypes produced by twoalleles instead of two.

Two phenotypes are produced by homozygous genotypes,the third phenotype is produced when an individual isheterozygous .

The third condition is often intermediate between the other

two phenotypes.

Ss

ss

SS


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Sex linkage

The locus of some genes is on the sex chromosome .

The gene is only present on the X chromosome because the Y chromosome has a different structure.

Females have 2 copies of these genes but males only haveone since females have two X chromosomes.

The ratio of males and females with particular phenotypesin a set of offspring can be unequal.

XoXo or X oYXOXO or X OXo orXOY


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Multiple alleles

Each gene locus can have more than 2 alleles.

An allele may be dominant to some alleles but recessive toothers.

This situation produces more than 2 different phenotypes.

Each individual has 2 alleles present in their cells at anyone time.

BB or Bb or Bb l

b lb l

bb or bb l


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Dihybrid inheritance

A phenotype can be produced by the action of two (ormore) genes, each with several alleles.

The expression of the two pairs of alleles can interactdirectly or indirectly to produce the phenotype.


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Dihybrid inheritance

A phenotype could be produced by the action of two (ormore) genes, each with several alleles.

The expression of the two pairs of alleles can interactdirectly or indirectly to produce the phenotype.


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Guess theparents!


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Lesson Aims



diagram.

monohybrid

dominance


dihybrid

Multiple gene inheritance

Cat coat colour is the result of the inheritance of a largenumber of different genes.

Multiple Gen Inheritance Cats

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