Princeton Review AP Biology Prep, 2021 by The Princeton Review

Author:The Princeton Review [The Princeton Review]
Language: eng
Format: epub
Publisher: Random House Children's Books
Published: 2020-08-11T00:00:00+00:00

DNA Polymerase adds nucleotides to an existing strand.

Ligase brings together the Okazaki fragments.

Topoisomerase cuts and rejoins the helix.

RNA primase catalyzes the synthesis of RNA primers.

Key History

The reason that we know that the DNA is the inheritable material is because of several key experiments. The first turning point was achieved by Avery, MacLeod, and McCarty. They isolated various cellular components from a dead virulent strain of bacteria. Then they followed up on a previous experiment by Griffiths and added each of these cellular components to a stain of living non-virulent bacteria. Only the DNA component of the deadly bacteria was able to change the second bacteria into a deadly strain capable of reproducing. This means that DNA must be responsible for passing traits and is inheritable.

The next important experiment was done by Hershey-Chase. They used bacteriophages, which are a special type of virus. They labeled the protein parts of some viruses with radiolabeled sulfur and they labeled the DNA parts of other viruses with radiolabeled phosphorus. When the viruses infected bacteria, only the labeled DNA was inside, but they were still able to replicate and make progeny viruses. Thus they proved that only DNA is required to pass on information. The protein was not required.

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