LS 3 2006 Sample test

LS 3 2006 Sample test - 1. Living organisms on earth can be...

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1. Living organisms on earth can be generally classified into three groups, Eukaryota, Eubacteria, and Archaea. What of the following best describes these groups? A). Eubacteria are prokaryotic whereas Archaea are eukaryotic organisms B). Archaea genomes contain multiple linear chromosomes C). Bacterial genomes are usually as complex as chloroplast genomes D). Eubacteria genomes usually contain circular DNA 2. From what you have learned about model organisms, what of the following statements is not true? A). Treatments for human diseases may come from studies of Arabidopsis B). Availability of genome sequences greatly facilitates biological researches C). Studies of fly and worm cannot help improving human health D). Basic research that not directly related to study of human disease has contributed significantly to our understanding and treatment of human disease 3. Radioisotopes are often used in molecular biology studies. Select the statement in the following that is incorrect about radioisotopes A). Isotopes are atoms that have different number of neutron but the same number of protons B). Isotopes are atoms that have the same number of electrons but different number of neutron C). Radioisotopes are potentially harmful to people D). Only the radioisotopes that have very short half life are used in molecular biology study 4. Noncovalent bonds are among the most important atomic interactions that help stabilizing the 3- D structure of proteins. What in the following best describes a noncovalent bond? A). Ionic interaction never exist in an integral membrane protein because membrane is a hydrophobic environment B). The orientation of hydrogen bonds between different amino acids explains why an alpha helix does not bend easily C) Noncovalent bonds are often stronger than covalent bonds D) Hydrogen bonds usually form among atoms that don’t get along with water 5. Amino acids are characterized by their chemical properties. What in the following statements about amino acids is incorrect? A). Aspartate and glutamate contribute to the overall positive charge of a protein. B). Methionine and cysteine are the only two amino acids found in proteins that contain sulfate C). Glycine is the smallest amino acid found in proteins D). Alanine, leucine, isoleucine, and tyrosine are often found in hydrophobic motifs of a protein
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6. Motif is a particular combination of secondary structure, whereas domain is a compactly folded region of a protein. Select the statement in the following that is most likely incorrect A). The four subunits of a hemoglobin molecule are often referred to as four domains B). The same domain can be found in hemoglobin and myoglobin C). A myoglobin may have three motifs and five domains D). A hemoglobin may have five domains and three motifs 7. Protein modification refers to chemical changes of a protein after translation, which of the following is incorrect about protein modification? A). Disulfide bonds form between cysteine residues
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LS 3 2006 Sample test - 1. Living organisms on earth can be...

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