DNA Structure & Replication Lecture Summary

These flashcards cover the key concepts from the lecture notes on DNA structure and replication, aiding in preparation for the exam.

What is the structure of DNA?

DNA consists of a phosphate sugar backbone, nitrogenous bases (adenine, guanine, cytosine, and thymine), and forms a double helix structure.

What is the significance of complementary base pairing in DNA?

Complementary base pairing involves specific pairing of a purine to a pyrimidine, where adenine pairs with thymine (A-T) and guanine pairs with cytosine (G-C) for proper DNA structure.

What is semi-conservative replication?

Semi-conservative replication is the method by which DNA is replicated, where each old strand is used as a template to synthesize a new complementary strand.

What is the role of DNA helicase in DNA replication?

DNA helicase unwinds the DNA double helix during replication.

What is the function of DNA Polymerase III?

DNA Polymerase III synthesizes the new DNA strand by adding nucleotides to the 3' end of an RNA primer in the 5' to 3' direction.

What are Okazaki fragments?

Okazaki fragments are short sequences of DNA synthesized on the lagging strand during DNA replication, as it is synthesized discontinuously.

What role does DNA ligase play in DNA replication?

DNA ligase seals the gaps between Okazaki fragments on the lagging strand after the RNA primers are replaced with DNA.

How does telomerase function?

Telomerase synthesizes telomeres, which are repetitive nucleotide sequences at the ends of chromosomes that protect genetic information during DNA replication.

What is the purpose of proofreading during DNA replication?

Proofreading is the process where DNA Polymerase III checks for and corrects errors in the newly synthesized DNA strand.

What happens if DNA Polymerase III is inhibited?

If DNA Polymerase III is inhibited, DNA replication cannot finish properly, affecting both leading and lagging strands.

What is mismatch repair?

Mismatch repair is the process that occurs after replication to correct errors that were not fixed during replication, with DNA Polymerase I removing mismatched bases.

What is the polarity of DNA?

Polarity in DNA refers to the 5' to 3' directionality of the strands, which is important for replication and transcription.

Why do telomeres shorten with age?

Telomeres shorten as cells divide, losing genetic information and contributing to the aging process.

What is the function of topoisomerase during replication?

Topoisomerase alleviates the twisting force ahead of the replication fork to prevent tangling of the DNA strands.

What are single-stranded binding proteins (SSBPs) responsible for?

SSBPs stabilize single DNA strands during replication to prevent them from re-annealing or forming secondary structures.

What enzymes are involved in removing RNA primers during DNA replication?

DNA Polymerase I removes RNA primers and replaces them with DNA nucleotides.