Question

explain DNA formation in details

Answer 1

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DNA replicates during S phase of interphase in a cell cycle. DNA is replicated so that each chromosome consists of double stranded DNA and equal amount of DNA is distributed in the nuclei of both the daughter cells. A replication is the process by which genetic information stored for future generation is duplicated. DNA replication results in the production of exact copies of DNA to be shared between two cells. DNA replication DNA replication occurs during each cell division. *During replication, the enzyme helicases unwind and uncoil the DNA double helix into single strands of DNA by the breakdown of hydrogen bonds. *DNA polymerase is the the main enzyme that catalyses the replication process. *It is a DNA-dependent as it uses the DNA template to catalyse the polymerisation of deoxyribonucleotides. *The deoxyribonucleoside triphosphates that act as substrates also serve as the energy source for the reaction. The terminal phosphates in the deoxyribonucleoside triphosphates break down to provide energy as ATP. *Topoisomerase helps in the separation of a DNA helix. *As a result, replication bubbles are formed that extend as a Y-shaped replication fork. *This replication fork is actually a small opening in the DNA helix where replication occurs. *Replication occurs continuosly on the strand that has 3'-5' polarity. It is known as the leading strand. *Replication on the other template strand with 5'-3' is discontinuous. It is known as the lagging strand. *These discontinuously replicated fragments are also known as Okazaki fragments. *These are then joined by the enzyme DNA ligase. *Thus at the end of replication process there are two molecules of double stranded DNA.

Answer 2

Step 1: Initiation

The point at which the replication begins is known as the Origin of Replication (oriC). Helicase brings about the procedure of strand separation, which leads to the formation of the replication fork.

Step 2: Elongation

The enzyme DNA Polymerase III makes the new strand by reading the nucleotides on the template strand and specifically adding one nucleotide after the other. If it reads an Adenine (A) on the template, it will only add a Thymine (T).

Step 3: Termination

When Polymerase III is adding nucleotides to the lagging strand and creating Okazaki fragments, it at times leaves a gap or two between the fragments. These gaps are filled by ligase. It also closes nicks in double-stranded DNA.

each human being begins their life as a single cell, which divides to form two cells, and these two go on to form four Now while all this is happening, our DNA is also being divided into these cells. The cell does make a second copy, so when two daughter cells are formed; each one of them gets a complete set of DNA.