DNA replication

Define DNA replication

Process of synthesising exact copies of DNA with identical base sequences

What are the key reasons for DNA replication

Growth, Reproduction, Tissue replacement

Where does DNA replication take place

In the nucleus of eukaryotic cells

What is semi-conservative replication

Occurs during DNA replication when each new DNA molecule consists of one original strand and one newly synthesised DNA. The original strand serves as the template strand for the newly synthesised DNA

Define PCR

Polymerase Chain Reaction is a process where specific segments of DNA are amplified (specific segments of DNA are copied)

Explain the process of PCR

Denaturation,Annealing, Extension

Explain Denaturation with regards to PCR

DNA strand is heated to 94-98C to break hydrogen bonds between nitrogenous bases

Explain Annealing with regards to PCR

Temperature is lowered to 50-65C, primers anneal to complementary sequences on single strands of DNA, primers provide an initiation point for DNA synthesis

Explain Extension with regards to PCR

Temperature is raised to approx. 72C, where DNA polymerase synthesises new DNA strands by adding nucleotides to primers

What is gel electrophoresis

A process used to separate DNA fragments based on size and charge

Explain the process of gel electrophoresis

DNA samples are loaded into agarose gel wells, and an electric current is applied, causing the negatively charged DNA fragments to migrate towards the positive electrodes. Smaller fragments travel faster, allowing for effective separation based on size

Which tools are used for amplifying and separating DNA

PCR and gel electrophoresis

Suggest and describe three applications of PCR and Gel electrophoresis.

PCR: medical diagnosis for detecting infections from pathogens, genetic testing for amplifying genes linked to inherited diseases, forensic testing for DNA profiling at crime scenes.Gel electrophoresis: genetic fingerprinting for comparing DNA profiles for forensic and paternity testing, detection of genetic disorders for visualising DNA mutations, RNA protein analysis for studying gene expression

Explain the directionality of DNA polymerase

5’ phosphate group attached to the 5th carbon of sugar molecule

3’ hydroxyl group (-OH) attached to 3rd carbon of sugar molecule

During DNA replication, DNA polymerase replicates in the 5’ to 3’ direction, meaning it only adds nucleotides to 3’ end of growing strand

When a nucleotide us added to the growing strand (3’ end) it is referred to as deoxyribonucleoside triphosphate (dNTP)