DNA, DNA Replication and Repair

These flashcards cover essential concepts related to DNA structure, replication, and repair mechanisms that are important for understanding genetic stability and integrity.

What is the primary function of DNA in living organisms?

To store, retrieve and translate genetic instructions necessary for making and maintaining a living organism.

Who was the first to systematically study DNA and what did he call the substance he isolated?

Friedrich Miescher, who called the substance "nuclein."

What is the double helical structure of DNA primarily based on?

The pairing of purines (Adenine and Guanine) with pyrimidines (Thymine and Cytosine).

What are nucleotides and what are their three components?

Nucleotides are the building blocks of nucleic acids, consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base.

What are base pairs in DNA?

A pairs with T and G pairs with C, held together by hydrogen bonds.

What is the process by which DNA is duplicated called?

DNA replication.

What is semiconservative replication?

A process where each new DNA molecule consists of one old strand and one new strand.

What is the role of RNA primers in DNA replication?

To provide a starting point for DNA polymerase to begin synthesizing new DNA strands.

What enzyme synthesizes the RNA primer?

Primase.

Explain mismatch repair in DNA.

A system that corrects errors that escape proofreading by removing a portion of the DNA strand containing the error and resynthesizing the correct sequence.

What are the two basic strategies for repairing double-strand breaks in DNA?

Nonhomologous end joining and homologous recombination.

What is unique about homologous recombination in DNA repair?

It uses an undamaged double helix as a template to repair the broken strand, resulting in no loss of genetic information.

Who won the Nobel Prize in Chemistry in 2015 for work related to DNA repair mechanisms?

The researcher who investigated the Nucleotide Excision Repair (NER) mechanism.

What is the primary function of DNA in living organisms?

To store, retrieve and translate genetic instructions necessary for making and maintaining a living organism.

Who was the first to systematically study DNA and what did he call the substance he isolated?

Friedrich Miescher, who called the substance "nuclein."

What is the double helical structure of DNA primarily based on?

The pairing of purines (Adenine and Guanine) with pyrimidines (Thymine and Cytosine).

What are nucleotides and what are their three components?

Nucleotides are the building blocks of nucleic acids, consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base.

What are base pairs in DNA?

A pairs with T and G pairs with C, held together by hydrogen bonds.

What is the process by which DNA is duplicated called?

DNA replication.

What is semiconservative replication?

A process where each new DNA molecule consists of one old strand and one new strand.

What is the role of RNA primers in DNA replication?

To provide a starting point for DNA polymerase to begin synthesizing new DNA strands.

What enzyme synthesizes the RNA primer?

Primase.

Explain mismatch repair in DNA.

A system that corrects errors that escape proofreading by removing a portion of the DNA strand containing the error and resynthesizing the correct sequence.

What are the two basic strategies for repairing double-strand breaks in DNA?

Nonhomologous end joining and homologous recombination.

What is unique about homologous recombination in DNA repair?

It uses an undamaged double helix as a template to repair the broken strand, resulting in no loss of genetic information.

Who won the Nobel Prize in Chemistry in 2015 for work related to DNA repair mechanisms?

The researcher who investigated the Nucleotide Excision Repair (NER) mechanism.

Which enzyme is responsible for adding new nucleotides to a growing DNA strand?

DNA polymerase, which adds nucleotides specifically to the 3' end of the growing strand.

What is the function of DNA helicase during replication?

It unwinds and separates the two strands of the DNA double helix by breaking the hydrogen bonds between base pairs.

What are Okazaki fragments?

Short, discontinuous segments of DNA synthesized on the lagging strand during DNA replication.

What is the role of DNA ligase?

It joins DNA fragments together by catalyzing the formation of phosphodiester bonds, effectively sealing the sugar-phosphate backbone.

What is the difference between the leading and lagging strands?

The leading strand is synthesized continuously in the 5' to 3' direction toward the replication fork, while the lagging strand is synthesized discontinuously in segments away from the fork.

What is the function of topoisomerase?

It relieves torsional strain and prevents the DNA double helix from becoming too tightly wound (supercoiled) ahead of the replication fork.

What are telomeres and why are they significant?

Repetitive DNA sequences at the ends of chromosomes that protect genetic material from degradation during successive rounds of replication.

What is DNA proofreading?

A mechanism by which DNA polymerase identifies and corrects mispaired bases immediately as they are added during synthesis.