Question

In your own words, describe how DNA reproduces to make new DNA molecules

Answer 1

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The process of DNA duplication is called DNA replication. Replication follows several steps that involve multiple proteins called replication enzymes and RNA.

DNA STRUCTURE

DNA or deoxyribonucleic acid is a type of molecule known as a nucleic acid. It consists of a 5-carbon deoxyribose sugar, a phosphate, and a nitrogenous base.

Step 1: Replication Fork Formation

Before DNA can be replicated, the double stranded molecule must be “unzipped” into two single strands. In order to unwind DNA, these interactions between base pairs must be broken. DNA helicase disrupts the hydrogen bonding between base pairs to separate the strands into a Y shape known as the replication fork. This area will be the template for replication to begin.

Replication progresses in the 5' to 3' direction. the replication fork is bi-directional; one strand is oriented in the 3' to 5' direction (leading strand) while the other is oriented 5' to 3' (lagging strand).

Step 2: Primer Binding

Once the DNA strands have been separated, a short piece of RNAcalled a primer binds to the 3' end of the leading strand. Primers are generated by the enzyme DNA primase

Step 3: Elongation

Enzymes known as DNA polymerases are responsible creating the new strand by a process called elongation. Because replication proceeds in the 5' to 3' direction on the leading strand, the newly formed strand is continuous.

The lagging strand begins replication by binding with multiple primers. Each primer is only several bases apart. DNA polymerase then adds pieces of DNA, called Okazaki fragments, to the strand between primers. This process of replication is discontinuous as the newly created fragments are disjointed.

Step 4: Termination

Once both the strands the formed exonuclease removes all RNA primers from the original strands and replaces them with appropriate bases. Another exonuclease “proofreads” the newly formed DNA to check, remove and replace any errors. DNA ligase joins Okazaki fragments together forming a single strand.The ends of the parent strands consist of repeated DNA sequences called telomeres. enzyme telomerase catalyzes the synthesis of telomere sequences at the ends of the DNA. the parent strand and its complementary DNA strand coils into the double helix shape. In the end, replication produces two DNA molecules, each with one strand from the parent molecule and one new strand