DNA replication can stall as a consequence of the replication machinery encountering hairpin DNA structures that can form due to inverted repeats and palindromic sequences
When DNA replication stalls, double-strand breaks in the DNA can occur, causing severe genetic and cellular consequences. Both Werner syndrome (premature onset of age-related phenotypes and cancer) and Bloom syndrome (cancer) are the result of mutations in helicase, an enzyme that unwinds hairpin structures. Helicase most likely breaks which type of bonds in a hairpin?
A. glycosidic
B. phosphodiester
C. hydrogen
D. peptide
E. covalent
C
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One of the most pathogenic hemorrhagic fever viruses belongs to the _________ family
a. Filoviridae b. Flaviviridae c. Papovaviridae d. Picornaviridae
This phylum of nonvascular plants has about 6000 known living species. It includes the genus
Marchantia, whose members can reproduce asexually via cups called gemmae.
a. Hepatophyta b. Pterophyta c. Bryophyta d. Lycophyta e. Anthocerophyta
In sponges, spicules are secreted by amoeboid cells
____________________ Indicate whether the statement is true or false.
What is the animal in the accompanying figure?
a. mosasaur b. plesiosaur c. pterosaur d. thecodont e. ichthyosaur