A 25-year-old female comes to the clinic complaining of fatigue and palpitations. She has been undergoing immense stress from her thesis defense and has been extremely tired. The patient denies any weight loss, diarrhea, cold/heat intolerance. TSH was within normal limits. She reports a family history of "blood disease" and was later confirmed positive for β-thalassemia minor. It is believed that abnormal splicing of the beta globin gene results in β-thalassemia. What is removed during this process that allows RNA to be significantly shorter than DNA?
A3'-poly(A) tail
BExons
CIntrons
DmicroRNAs
EsnRNPs
An investigator is comparing DNA replication in prokaryotes and eukaryotes. He finds that the entire genome of E. coli (4 × 106 base pairs) is replicated in approximately 30 minutes. A mammalian genome (3 × 109 base pairs) is usually replicated within 3 hours. Which of the following characteristics of eukaryotic DNA replication is the most accurate explanation for this finding?
AReplication inhibition at checkpoint
BAbsence of telomerase enzyme activity
CDNA compaction in chromatin
DSimultaneous replication at multiple origins
EMore efficient DNA polymerase activity
An investigator isolates bacteria from a patient who presented with dysuria and urinary frequency. These bacteria grow rapidly in pink colonies on MacConkey agar. During replication of these bacteria, the DNA strands are unwound at the origin of replication, forming two Y-shaped replication forks that open in opposite directions. At each replication fork, daughter strands are synthesized from the template strands in a 5′ to 3′ direction. On one strand, the DNA is synthesized continuously; on the other strand, the DNA is synthesized in short segments. The investigator finds that three enzymes are directly involved in elongating the DNA of the lagging strand in these bacteria. One of these enzymes has an additional function that the others do not possess. Which of the following steps in DNA replication is unique to this enzyme?
AElongation of lagging strand in 5'→3' direction
BExcision of nucleotides with 5'→3' exonuclease activity
CPrevention of reannealing of the leading strand and the lagging strand
DCreation of ribonucleotide primers
EProofreading for mismatched nucleotides
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