DNA Replication and Repair Flashcards

Flashcards related to DNA Replication and Repair

DNA

The hereditary material passed from one generation to the next.

Griffith (1928)

Discovered transformation in bacteria called Streptococcus pneumoniae, indicating DNA is the hereditary material.

Avery, MacLeod, and McCarty (1940s)

Determined that extracts with intact DNA were the only ones that could transform cells to become virulent, supporting the hypothesis that DNA is the hereditary material.

Hershey and Chase (1940s)

Used bacteriophages and radioactively labeled DNA and protein to confirm that DNA, not protein, is the genetic material.

Semiconservative Replication

Each old DNA strand is copied to generate a new DNA strand, so each new chromosome is composed of one strand of old DNA and one strand of newly synthesized DNA.

Conservative Replication

The original chromosome is copied but remains unchanged, so one chromosome is composed of old strands and the other of new strands.

Dispersive Replication

The replication process generates two new chromosomes with new and old sections of DNA mixed together randomly.

Meselson-Stahl Experiment

Supported semiconservative DNA replication as the mechanism by which hereditary material is duplicated.

Origin of Replication

Chromosome sequence where the DNA replication process begins.

Helicase

Catalyzes breaking of hydrogen bonds between two DNA strands to separate them.

Single-Stranded DNA Binding Proteins (SSBPs)

Attach to separated strands to prevent them from reannealing with each other.

Topoisomerase

Relieves torsional strain by cutting and rejoining the DNA ahead of the replication fork.

Deoxyribonucleoside Triphosphates (dNTPs)

Monomeric nucleotide building blocks with three phosphate groups that make up a DNA strand and provide energy for linking monomers.

Primase

Synthesizes a short RNA segment that serves as a primer for DNA synthesis.

DNA Polymerase

Enzyme that performs DNA synthesis by adding dNTPs only to the 3' end of an existing strand, proceeding in the 5' -> 3' direction.

DNA Polymerase I

Removes RNA primers and fills in the gaps with dNTPs.

DNA Ligase

Forms continuous DNA strands by catalyzing the final covalent bonds.

Leading Strand

New DNA strand synthesized continuously in the 5' -> 3' direction towards the replication fork.

Lagging Strand

Synthesizes it discontinuously in the 5' -> 3' direction away from the replication fork, lagging behind the fork.

Okazaki Fragments

Short discontinuous pieces synthesized on the lagging strand.

Replisome

Multi-subunit protein complex including two DNA pol III enzymes that participate in DNA replication.

Telomeres

Sequences at the ends of linear chromosomes

Telomerase

Enzyme that helps preserve the integrity of chromosome's telomeres by adding more repeating bases to the ends of lagging strand templates.

Proofreading

DNA polymerase checks constantly for the proper match between paired bases during DNA synthesis, removing mispaired base.

Mismatch Repair

Mismatched bases are detected outside of DNA synthesis, primarily during the G1 and G2 phases of the cell cycle. Mismatch repair enzymes remove a section of the strand and fill in the correct bases.

Nucleotide Excision Repair

Recognizes and removes DNA damage, such as thymine dimers caused by UV light, with enzymes that remove the single-stranded DNA in the damaged section.

Xeroderma Pigmentosum (XP)

Rare autosomal recessive disease characterized by the development of skin lesions, caused by mutations in nucleotide excision repair proteins resulting in inability to repair UV-damaged DNA.