Exam 4: Fundamentals of Molecular Biology

Imagine you are a student trying to decode the genetic code. An artificial mRNA molecule consisting of poly-CA (5ʹ... CACACACACACACAC..3ʹ) yields a polypeptide consisting solely of histidines and threonine, and another artificial mRNA consisting of poly-CAA (5ʹ...CAACAACAACAACAA...3ʹ) yields three different polypeptides: polythreonine, polyglutamine, and polyasparagine. On the basis of this information, which codons can you assign to which amino acids?

RNA is copied from DNA through a process called _______.

What technique would you use to determine if the level of a specific mRNA had been increased in response to an inducer?

cDNA made from genomic DNA is used to create cDNA libraries.

Why are dideoxynucleotides used in DNA sequencing?

The polymerase chain reaction is used to amplify specific fragments of DNA in vitro.

Nucleic acid hybridization is the

The enzyme that synthesizes DNA using RNA templates is called

A restriction enzyme with a four-base recognition site would cleave DNA with a statistical frequency of once every

Addition or deletion of one or two nucleotides in the coding part of a gene produces a nonfunctional protein, whereas addition or deletion of three nucleotides often results in a protein with nearly normal function. Explain.

When thymidine and adenosine interact within a DNA molecule, they form

Eggs and sperm are

In Meselson and Stahl's experiment, cells were grown in media containing ¹⁵N in place of ¹⁴N, and then the cells' DNA was separated by equilibrium centrifugation. This experiment demonstrated that DNA

If a plasmid does not contain an origin of replication, what would happen if you were to transfect it into bacteria?

In experiments using polymerase chain reactions (PCR), it is often more difficult to amplify through regions of DNA that are high in GC content versus those regions that are either lower in GC content or are AT-rich. Based on your knowledge of DNA structure, explain why.

According to the "central dogma" of molecular biology, information flows from DNA to RNA to protein. In its original version, the dogma stated that information does not flow in the reverse direction. To what extent is this true?

RNA molecules that serve as templates for protein synthesis are called _______ RNAs.