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3.5.1.1. Albinism (problems solved)

Inheritance of albinism. Autosomal recessive inheritance. (Page 2)

As we have already seen, albinism is caused by a recessive allele that only manifests itself in the genotype when it is homozygous. With this simulator you can practice to see what the possible offspring would be like as you assign the parents the phenotype of normal, carrier or albino people.

Curiosity: Son of the Moon

Surely you have heard the song by Mecano entitled Son of the Moon many times but you have not heard it as you are going to do it now.

Fool who does not understand
the history tells
than a gypsy female
conjured the moon until dawn
crying he asked
when the day arrives
marry a calé.
You will have your man brown skin
the full moon spoke from the sky
but in return I want
son first
that you father him
that who his son immolates
not to be alone
little was going to love him.
chorus:
Luna you want to be a mother
and you can't find wanting
make you a woman
tell me silver moon
what do you intend to do
with a skin boy ah-aaah ah-aah
Child of the moon.
From a cinnamon father a child was born
white as the back of an ermine
with gray eyes
instead of olive
albino moon child
damn his stamp
this son is from a payo
and I don't shut up.
chorus
Gypsy believing himself dishonored
he went to his wife knife in hand
Whose son is it?
you have cheated on me fixed
and to death he wounded her
then he went to the mountain
with the child in her arms
and there he left him.
chorus
And on nights when there is a full moon
It will be because the child is in good spirits
and if the child cries
the moon will wane
to make him a crib
and if the child cries
the moon will wane
to make a crib for him.
José María Cano (1988)

This legend tells of the tragedy that happened to a gypsy woman who made a pact with the Moon. The two felt a deep loneliness and reached an agreement that the woman would accept a man who loves her who would send her the Moon, but in return, the woman would give her the first child she had with her husband.

The two gypsies marry and the child is born as a result of that marriage, his parents are surprised because the child was not born with the same racial traits as his parents, but rather an albino. According to the lyrics of the song, the child was born "white as the back of an ermine and with gray eyes, an albino moon child", despite the fact that his parents were dark-skinned and dark-eyed. The gypsy, the boy's father, does not accept that he is his son, denies paternity and confronts his wife, accusing her of having been unfaithful to him with a payo (not a gypsy), after which he stabs her and lets her die; Later, she takes the child in her arms and takes him to the mountain where she leaves him so that he also dies. Later, it will be the Moon that takes care of him, the one that will become his mother.

In addition to this legend, we should also remember the drama suffered by albinos in some areas of Africa.

Genetics problem 11

A couple has an albino son. Neither parent has this characteristic. Explain how this can happen and suggest the possible parental genotype for that gene. What proportion of albino and non-albino offspring can be expected in the offspring?

Genetics problem 12

How can they be the children of an albino who marries a normal woman without a family history of albinism?

Genetics problem 13

How can they be the children of an albino who marries a normal woman whose father was an albino?

Genetics problem 14

Albinism is caused by a recessive allele a.

a) What are the phenotypes and genotypes of the F2 resulting from the crossing of an albino father and a normal non-carrier mother (assuming they were not human)?

b) What if the mother was a carrier?

Genetics problem 15

Albinism is an autosomal recessive character (a) with respect to normal pigmentation (A). Indicate what the descendants would be that an albino man would have in the following cases:

a) with a woman with homozygous normal pigmentation;

b) with a woman of normal pigmentation whose mother was albino;

c) with a woman with normal pigmentation, one of whose grandparents was heterozygous.

Reason the answers representing the diagrams of the possible crosses.

Genetics problem 16

Heterozygous normal color mice are crossed, where the N gene (normal color) is dominant over the n gene (albino).

a. What proportion of the offspring will be of normal coloration? List the genotypes.
b. From an offspring of 12 mice, how many do we expect to be homozygous?