Three major types of RNAs are mRNA, rRNA, and tRNA. For each of the conditions below, predict the consequences in terms of the population of proteins being synthesized in a particular cell
What qualitative and quantitative changes, if any, are expected in the individual protein involved (if one is involved) and in the population of proteins in this cell?
(a) a frameshift mutation in the heterozygous state
(b) a deletion of a significant proportion of ribosomal genes (rDNA)
(a) Population of proteins: Half of the protein products of that gene will be defective, and the other half will be normal. Individual protein: The protein should show multiple amino acid substitutions "downstream" from the point of the mutation. If a nonsense triplet is introduced, the protein will be shortened in the substituted region.
(b) Population of proteins: There would be an overall reduction in protein synthesis. Individual proteins: All of the proteins would be made in their normal form but at reduced levels.
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The reason that starvation during prenatal development raises the risk for cardiovascular and metabolic problems in adulthood is that
A) starvation before birth and cardiovascular and metabolic disorders are all caused by a single mutation. B) metabolism in the fetus shifts to preserve vital organs, accelerating weight gain in childhood. C) lack of nutrients damages the heart in the uterus. D) the child remembers the lack of nutrition in the uterus and eats too much.
What step occurred first in the evolution of life?
a. formation of protein-RNA systems b. formation of lipid spheres c. formation of membrane-bound protocells d. formation of ATP e. spontaneous formation of lipids, proteins, carbohydrates, and nucleotides
At what level of organization does life begin?
A. Reproductive organs B. Cell C. Molecule (water) D. Molecule (DNA) E. Population
Ome botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures cannot be used to support this view?
a. cell wall b. cell membrane c. cytosol d. tonoplast e. symplast