Biology (Patterns of Inheritance) Question!! :)

[thehopefuldentist]

Hi all,
Currently studying for my DAT using all of Orgoman's materials (amazing stuff) and am slightly confused.

How are codominance and linked genes differentiated? Codominance refers to two inherited alleles being completely expressed whereas linked genes refer to two traits being expressed by the same chromosome.
Are they differentiated by codominance showing up 100% of the time and linked genes having varied inheritance pattern percentages?

Any help would be appreciated.

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[Juggernaut604]

Good question!

When looking at a gene, we have to remember that we have two alleles (versions of a gene), one from each parent. These two different alleles can be expressed in different ways. Sometimes, they are both expressed (like AB blood group, where a person produces "A" and "B" glycoproteins on their cell membranes), and we call this co-dominance. Other times the two alleles create a mixed phenotype (think pink flowers vs red or white flowers), and we call this incomplete dominance.

Now, on a chromosome we have many different genes. Each gene will have two alleles (one from each parent located on two homologous chromosomes), but you nonetheless have millions of genes on each chromosome. If, on a chromosome, two genes are fairy close to each other, they are likely to stay together during meiosis. When two genes (not two alleles for the same gene) on a chromosome stay together (like the genes for red hair and freckles), we call them linked genes.

Hope that was helpful!

 

[thehopefuldentist]

Good question!

When looking at a gene, we have to remember that we have two alleles (versions of a gene), one from each parent. These two different alleles can be expressed in different ways. Sometimes, they are both expressed (like AB blood group, where a person produces "A" and "B" glycoproteins on their cell membranes), and we call this co-dominance. Other times the two alleles create a mixed phenotype (think pink flowers vs red or white flowers), and we call this incomplete dominance.

Now, on a chromosome we have many different genes. Each gene will have two alleles (one from each parent located on two homologous chromosomes), but you nonetheless have millions of genes on each chromosome. If, on a chromosome, two genes are fairy close to each other, they are likely to stay together during meiosis. When two genes (not two alleles for the same gene) on a chromosome stay together (like the genes for red hair and freckles), we call them linked genes.

Hope that was helpful!

VERY HELPFUL! My confusion actually came about when I was doing a question on red-hair and freckles from cliffs. Thank you very much!

 

[Bersabeh]

Hi all,
Currently studying for my DAT using all of Orgoman's materials (amazing stuff) and am slightly confused.

How are codominance and linked genes differentiated? Codominance refers to two inherited alleles being completely expressed whereas linked genes refer to two traits being expressed by the same chromosome.
Are they differentiated by codominance showing up 100% of the time and linked genes having varied inheritance pattern percentages?

Any help would be appreciated.

gene linked together are inherited together, resulting in no variation of the coming generation since they do not give opportunity of crossing over. Codominance is 2 different alleles expressing themselves equally.