. In the early days of ribosome research, before the exact role of ribo- somes was clear, a researcher made the following observation. She could find, in sedimentation experiments on bacterial lysates, not only 30S, 50S, and 70S particles but also some particles that sedi- mented at about 100S and 130S. When she treated such a mixture with EDTA, everything dissociated to 30S and 50S particles. Upon adding divalent ions, she could regain 70S particles, but never 100S or 130S particles. (a) Suggest what the 100S and 130S particles might represent, in light of current knowledge of protein synthesis. What important dis- covery did the researcher miss? (b) Why do you think reassociation to 100S and 130S particles did not work?

. In the early days of ribosome research, before the exact role of ribo- somes was clear, a researcher made the following observation. She could find, in sedimentation experiments on bacterial lysates, not only 30S, 50S, and 70S particles but also some particles that sedi- mented at about 100S and 130S. When she treated such a mixture with EDTA, everything dissociated to 30S and 50S particles. Upon adding divalent ions, she could regain 70S particles, but never 100S or 130S particles. (a) Suggest what the 100S and 130S particles might represent, in light of current knowledge of protein synthesis. What important dis- covery did the researcher miss? (b) Why do you think reassociation to 100S and 130S particles did not work?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter4: Cells

Section: Chapter Questions

Problem 7TYK: Which of the following statements about proteins is correct? a. Proteins are transported to the...

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Imagine protein X, destined to span theplasma membrane. Assume that the mRNA carrying the geneticmessage for protein X has already been translated by ribosomesin a cell culture. If you fractionate the cells (see Figure 6.4), inwhich fraction would you find protein X? Explain by describingits transit through the cell.
Watch this video (http://openstaxcollege.org/l/ribosome) to learn about ribosomes. The ribosome binds to the mRNA molecule to start translation of its code into a protein. What happens to the small and large ribosomal subunits at the end of translation?
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Which of the following statements about proteins is correct? a. Proteins are transported to the rough ER for use within the cell. b. Lipids and carbohydrates are added to proteins by the Golgi complex. c. Proteins are transported directly into the cytosol for secretion from the cell. d. Proteins that are to be stored by the cell are moved to the rough ER. e. Proteins are synthesized in vesicles.
Which of the following sequences correctly lists in order the steps involved in the incorporation of a proteinaceous molecule within a cell? protein synthesis of the protein on the ribosome; modification in the Golgi apparatus; packaging in the endoplasmic reticulum; tagging in the vesicle synthesis of the protein on the lysosome; tagging in the Golgi; packaging in the vesicle; distribution in the endoplasmic reticulum synthesis of the protein on the ribosome; modification in the endoplasmic reticulum; tagging in the Golgi; distribution via the vesicle synthesis of the protein on the lysosome; packaging in the vesicle; distribution via the Golgi; tagging in the endoplasmic reticulum
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41. Many secretory proteins are synthesized as inactive precursors called a. proproteins b. secretomes c. chaperons d. glycoproteins e. exosomes
What's the similarities between lysosomes and peroxisomes?
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