Which of the following is a possible future benefit of stem cell research?

a. developing a vaccine for cancer

b. reversing damage from a heart attack

c. generating embryos from nonliving tissue

d. increasing a person's intelligence quotient

I say the answer is B. (Reffering to a recent science article talking about "The hope of treating myocardial infarction with stem cells".)

A stem cell (CS), in particular embryonic, is a mother cell, called "pluripotent", capable of both self-renewal in the long run and to differentiate in any cell type (heart, bone, etc.). Their therapeutic interest is to regenerate damaged tissues or organs, a less burdensome alternative to organ transplantation.

We use CD34 + (adult CS) found in bone marrow because they persist throughout life and can act on various possible body tissues. these can create new blood vessels and regenerate myocardial tissue. Finally, they are the only ones able, at each of their division, to give at the same time a myocardial cell by differentiation and a new stem cell which ensures the durability of the graft.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

read more on -