Va rog imi trebuie URGENT O moleculă de ADN bicatenar este alcătuită din 3600 de nucleotide, din care 700 conţin guanină. Stabiliţi următoarele:
a)numărul de nucleotide care conţin adenină ;
b)numărul legăturilor duble și triple din molecula de ADN;
c)succesiunea nucleotidelor din catena complementară a ARN știind că ADN –ul are următoarea secvenţă de nucleotide: CGTATCGTA.

Tatăl are grupa de sânge A(II) în variantă heterozigotă, iar mama are grupa AB(IV) . Stabiliți următoarele:
a)genotipurile celor doi părinți;
b)genotipurile posibile ale copiilor;
c)fenotipul copiilor din prima generație.

Într- o familie tatăl este hemofilic și mama este purtătoare, dar sănătoasă. Stabiliți:
a)genotipurile posibile ale descendenților
b)procentul descendenților sănătoși.

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an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.