Human blood types are characterized by the presence absence of surface markers known as a tigers on the surface of red blood cells, According to model 1 how many blood types are found in the human population

characterized by presence or absence of antigens

the blood types are A, B, O, AB

Explanation:

There are two antigens and two antibodies that are mostly responsible for the ABO types.  The specific combination of these four components determines an individual's type in most cases. Erythrocytes and serum were related to the presence of antigens on these erythrocytes and antibodies in the serum. these antigens  are A and B, and depending upon which antigen the erythrocytes express, blood either belonged to blood group A or blood group B. A third blood group contained erythrocytes that reacted as if they lacked the properties of A and B, and this group was later called "O" blood group. The fourth blood group AB, was added to the ABO blood group system. These erythrocytes expressed both A and B antigens.

Blood group   Antigen present on RBC    Antibodies in serum    Genotype(s)

      A                        antigen A                             anti-B                     AA or AO

      B                        antigen B                             anti-A                     BB or BO

      AB              both A and B antigen                 none                         AB

      O                           none                           anti-A and anti-B           OO

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

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