TLS Online TPP Program

#Question id: 346


The partial negative charge in a molecule of water occurs because ________.

#XL - S Microbiology
  1. the oxygen atom donates an electron to each of the hydrogen atoms

  2. the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus

  3. the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms

  4. one of the hydrogen atoms donates an electron to the oxygen atom

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TLS Online TPP Program

#Question id: 5752

#XL - R Botany

base change that changes a codon for an amino acid to a stop codon

TLS Online TPP Program

#Question id: 5753

#XL - S Microbiology

A bacterial histidine mutant was plated on minimal medium and a single colony grew. You decide to sequence the histidine biosynthetic gene of the revertant and discover that the original mutation is still present.  This colony must have been able grow due to a

TLS Online TPP Program

#Question id: 5754

#XL - S Microbiology

A cell is exposed to EMS (a mutagen that causes guanine to mispair with thymine) and allowed to undergo a few rounds of DNA replication.  The mutational event caused by this mutagen will be

TLS Online TPP Program

#Question id: 5755

#XL - S Microbiology

A researcher studying bacterial toxin predicts that a lysine within the toxin is important for binding it’s target cell.  She used site-directed mutagenesis to change a codon for lysine (AAA) to one for asparagine (AAU).  However, the mutant toxin still binds to its target cell just as well as the wild-type toxin bound and appears to have no other changes. This type of mutation is probably

TLS Online TPP Program

#Question id: 5756

#XL - S Microbiology

Type of mutation caused by an addition or deletion of a base in a polypeptide-encoding part of a gene

TLS Online TPP Program

#Question id: 5757

#XL - S Microbiology

A new E. coli mutant was tested for auxotrophy. The mutant grows on:

minimal medium (M) + arginine (A) + proline (P)

M + P + histidine (H)

M + A + H + P

but not on M or on M + A + H. The mutant requires