Molecular Genetics — Flashcards

Flashcard 71: How many DNA strands are cut by Type I and Type II topoisomerases?

Answer: Type I - one Type II - two

Flashcard 72: What is the function of primase in DNA replication?

Answer: makes an RNA primer on which DNA pol III can initiate replication

Flashcard 73: What is the function of DNA polymerase III in DNA replication?

Answer: Prokaryotic elongates, 5' to 3' exonuclease proofreading activity, 3' to 5'

Flashcard 74: What is the function of DNA polymerase I in DNA replication?

Answer: Prokaryotic degrades RNA primer, replaces with DNA

Flashcard 75: Identify the nitrogenous base (5-methyluracil):

Answer: Thymine

Extra: Thymine is a pyrimidine found in DNA. It is replaced by Uracil in RNA. Deamination of cytosine forms uracil, while methylation of uracil forms thymine.

Flashcard 76: Definition of alternative splicing

Answer: Process by which different segments of a pre-mRNA transcript are selectively treated as introns or exons, allowing for multiple different protein products to be produced from a single gene.

Flashcard 77: exon

Answer: segments of DNA that contain the actual coding sequence for the gene product

Flashcard 78: intron

Answer: intervening, noncoding segments of DNA

Flashcard 79: Which carbon of a nucleotide bears the phosphates?

Answer: 5'

Flashcard 80: What is the function of ligase in DNA replication?

Answer: ligates adjacent Okazaki fragments