Each strand of s DNA molecule contains nitrogenous bases that pair with other nitrogenous bases in very specific ways. A diagram of a section of DNA is shown. DNDA Strand 3' _|___|___|___|___|___|___|___|___|_ __|___|___|___|_ 5' T G T A G C T G C G C G T Which DNA strand is complementary to the one shown above?

The complementary DNA strand, according to the nucleotide sequence of the other strand is 3' - A C A T C G A C G C G C A - 5'

Explanation:

Each strand of DNA is made up of specific sequences of the four nucleotides present in this molecule, adenine, thymine, cytosine and guanine.

In double-stranded DNA, one strand complements the other —according to the complementarity of nitrogenous bases— where a purine, adenine and guanine, are joined with a pyrimidine, thymine and cytosine, respectively:

According to this, the complementarity of the strands is:

    5' - T G T A G C T G C G C G T - 3'

    3' - A C A T C G A C G C G C A - 5'

The DNA strands remain linked by hydrogen bonds between their nitrogenous bases, until such time as they must be separated for transcription.

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.