Why are alleles that are lethal in a homozygouse individual able to be passed on in a heterozygouse individual?

Answer 1

Ok, so a lethal allele is basically a gene that causes an orgnism to die. Now here is the weird part it is not inherited or expressed like every other trait as we know so far. There is one key characteristic pattern for these types of alleles and that it is is a dominant allele in an autosome that is that one of the 22 chromosomes in humans that IS NOT a sex chromosome!! Here is the wierd part -- these diseases that lethal alleles express appear later in life way after the reproductive age, so during mitosis there is no "bad gene" or mutation for the cell to either repair or go through apoptosis (cell death - kind of self abort) doesn't have time to get rid of it ... if it did natural selection would have occurred and the allele would have been eliminated during our time of evolution!!

Some are recessive allele in autosome and it is very different from the dominant autosomes. For an autosomal receissive allele bother parents HAVE to be heterozygous in order for one of their children to run a one in four chance to express the disease. Where as if one parent has the dominant autosome 50 50 chance is that the offspring will express the disease...

Answer 2

The description is of a recessive lethal allele where any individual with two recessive alleles dies. If we assume that a homozygous recessive individual succumbs to the disease before they reproduce the frequency of the lethal allele will diminish over time in the population. At some point the frequency of the allele stabilizes at a very low level and is then maintained.

If the homozygous individual is able to reproduce the frequency of the allele will be

maintained.

If the heterozygous individual gets an advantage (as in sickle-cell anemia) the frequency increases overtime until it reaches maximum effect....even if the homozygous lethal individual does not reproduce.

This is a very simplified explanation...

Answer 3

Sometimes the organism reproduces before the allele is lethal or before it is even noticeable to it.

Also, your question can answer itself. If an organism is heterozygous and the disorder is only possible with 2 recessive genes (such as Cystic Fibrosis), the allele can pass through the family tree undetected for generations. Consult a pedigree chart if my answer is not detailed enough. A visual really helps in this case.

Answer 4

The simplest explanation is that it is masked from being expressed in the heterozygous condition and carried by these individuals. A bit more complex that that, but the simple answer will suffice here.

Answer 5

it must be a recessive charateristic.

so if D is ok and d is death

you can have DD(homozygous dominant)-healthy

Dd-Heterozygous healthy

if two Dd mate, there is a 1/4 chance of dd

An example might be the allele that causes sickle cell anemia when homozygous. Individuals with only one recessive allele have a resistance to malarial parasites.

Answer 6

Considering that animals such as mammals get one gene from their father and another from their mother, if one of those parents provides a non-lethal and therefore functional allele, then it doesn't matter if they have one.

If they have two then there would be no other 'backup' allele.

Answer 7

because a heterozygous parent (with one normal and one abnormal allele) can still pass the potentially lethal allele on to their child, who might in turn also be heterozygous.

Answer 8

Not

Answer 9

yo no se que es!!!