Question

The image below shows the process of DNA replication. Identify the components of the process

Answer 1

See below.

Step-by-step explanation:

The biological process of creating two identical copies of DNA from a single original DNA molecule is known as DNA replication.

A double helix of two complementary strands makes up DNA. These strands are split apart in the replication process. The method of semi-conservative replication uses each strand of the original DNA molecule as a template to create its counterpart.

This process is carried out by several enzymes which are listed below along with their activity

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1. DNA Dependent DNA POLYMERASE is a class of enzymes that is responsible for all organisms' DNA replication processes. It accelerates DNA replication in the 5′ to 3′ range.
2. The enzyme known as TOPOISOMERASE is involved in the over- or under-winding of DNA.
3. HELICASE—Using the energy from ATP hydrolysis, which is characterized by the breakdown of hydrogen bonds between annealed nucleotide bases, helicases are frequently employed to separate the strands of a DNA double helix or a self-annealed RNA molecule.
4. DNA GYRASE, a particular kind of topoisomerase, relieves strain caused by DNA helicase's unwinding action.
5. DNA LIGASE- Joins the OKAZAKI FRAGMENT of the lagging strand and re-anneals the semi-conservative strands.
6. PRIMASE - Primase catalyzes the production of a short primer, which is a ssDNA template-specific piece of RNA (or DNA in other species).

REPLICATION FORK -

1. INITIATION: The beginning of DNA replication takes place at certain locations in DNA known as ori-sites or regions. Enzymes often recognize these locations and initiate the process. As opposed to C-G base pairs, which produce three hydrogen bonds, A-T base pairs only form two hydrogen bonds, making them easier to strand split. As a result, these sites are typically "AT-rich" (rich in adenine and thymine bases). Following the discovery of the origin, enzymes create a pre-replication complex that unzips the double-stranded DNA. The enzyme topoisomerase is involved in this process.
2. ELONGATION: The 5'-3' activity of the DNA polymerase enzyme. Now, a new strand was created by DNA polymerase enzymes in the direction of 5′ to 3′ (note: the DNA template is read in 3' to 5' direction). RNA primers were simultaneously created by the primase enzyme and utilised by the polymerase to create new strands of RNA.

Due to the 5′ - 3′ orientation of the DNA polymerase enzyme, two types of strands are formed.

1. LEADING STRAND - A DNA polymerase with high processivity that has the direction 5′ - 3′ (template strand 3′-5′) extends the continuous strand from the primer in the same direction as the replication fork that is expanding. One RNA primer is applied to the leading strand.
2. LAGGING STRAND - It is the discontinuous strand whose synthesis is going in the opposite direction of the replication fork that is developing. Each primer extends the lagging strand intermittently to create Okazaki fragments. A low processivity DNA polymerase that is different from the replicative polymerase enters to fill the gaps after RNase eliminates the priming RNA pieces. Multiple primers are applied to the lagging strand, and then the Okazaki fragments are joined by the ligase enzyme, filling in the gaps.
3. TERMINATION - Replication forks meet and end at several locations throughout the chromosome because eukaryotes start DNA replication at various locations; it is unknown how these are controlled. Termination necessitates the halting or blocking of the DNA replication fork's forward motion. When termination occurs at a particular locus, it includes the interaction of two elements: (1) a DNA sequence known as a termination site sequence, and (2) a protein that binds to this region to actually cease DNA replication.

- Thank you.