Biology - D1.1: DNA Replication

What are the key processes DNA replication is required for? Why?

reproduction, growth & tissue replacement, because DNA is the code of life

What does DNA replication result in?

2 molecules with identical base sequences, which are exact clones of the parent cell

How are DNA molecules organized in cells?

into a chromasome. In prokaryotes, they are circular with a naked DNA. in eukaryotes, they are linear with a DNA wrapped around histone proteins to form nucleotides

What is the nature of DNA replication? Explain.

semi-conservative, because a double helix is formed with 1 strand from the template parent molecule that is copied, and 1 newly-synthesized strand.

What is complementary base pairing?

the binding of adenine with thymine and cytosine with guanine

What is the role of complementary base pairing in DNA replication?

It stabilizes the newly formed DNA double strands, and allows a high degree of accuracy in copying the gene sequence.

What are the two different enzymes in DNA replication? Explain the roles.

Helicase and DNA polymerase.

Helicase unwinds the double helix and breaks the hydrogen bond between bases to separate the parent strands.

A DNA polymerase then adds free nucleotides containing different bases to synthesize new strands.

What are the two methods of amplifying and separating DNA to conduct replication?

Polymerase chain reaction and gel electrophoresis.

What is polymerase chain reaction? What are the components needed for PCR?

It is the replication of DNA under lab conditions, by using heat to double the amount of DNA. Primers, which are single-stranded polymers used to signal the starting point of synthesis; and taq polymerase, which are heat-tolerant enzymes used to grab free nucleotides.

Outline the process of PCR.

First, denaturation occurs via heating the DNA sample to break its hydrogen bonds. Then, temperature is decreased so primers can anneal to the end of strands. Lastly, elongation occurs as the sample is heated to its optimal temperature for taq polymerase extend the primers for building the new strands.

What is gel electrophoresis? Explain its process.

It is process by which DNA molecules are separated with an electric current by length. DNA fragments are added to one end of porous gel, then electricity is applied with the negative electrode at the DNA end. As DNA is also negative, the repelling force moves DNA through the gel.

What are the factors determining the movement of DNA molecules in gel electrophoresis?

The size of molecules and the type of gels. The smaller the molecule, the quicker it moves, as they are less impeded by the gel matrix. Different sized pores also affect the speed of movement.

How are PCR and gel electrophoresis commonly used?

in DNA profiling fpr paternity or forensic investigations. PCR is carried out to amplify the DNA available, while gel electrophoresis is used to create banding patterns for DNA comparison.