Biological Science - Chapter 15: DNA and the Gene: Synthesis & Repair

These flashcards cover key concepts and terms related to DNA synthesis and repair as discussed in the lecture.

What are genes made of?

Genes are composed of DNA.

Hershey-Chase Experiment

An experiment that showed that DNA, not protein, is the genetic material by using radioactive isotopes.

Phosphodiester bond

A bond that links deoxyribonucleotides in the DNA backbone, formed between a phosphate group and a hydroxyl group.

Antiparallel strands

DNA strands that run in opposite directions; one runs 5' to 3' and the other 3' to 5'.

Semiconservative replication

A mode of DNA replication where each daughter molecule contains one old strand and one newly synthesized strand.

Leading strand

The DNA strand synthesized continuously toward the replication fork in the 5' to 3' direction.

Lagging strand

The DNA strand synthesized discontinuously away from the replication fork, consisting of Okazaki fragments.

Okazaki fragments

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

Telomerase

An enzyme that extends the telomeres of chromosomes, preventing their shortening during DNA replication.

Nucleotide excision repair

A DNA repair mechanism that removes and replaces damaged segments of DNA.

Mismatch repair

A process that corrects mismatched bases left by DNA polymerase during replication.

DNA polymerase

The enzyme responsible for synthesizing new DNA strands by adding nucleotides in the 5' to 3' direction.

Centrifugation

A technique used to separate DNA based on density during experiments like those by Meselson and Stahl.

Telomeres

Repetitive nucleotide sequences at the ends of linear chromosomes that protect them from degradation.

DNA helicase

An enzyme that unwinds the DNA double helix by breaking hydrogen bonds between the two strands.

Topoisomerase

An enzyme that relieves the tension generated ahead of the replication fork by cutting and rejoining DNA strands.