7.Study_guide_Cell_Structure__Answers

7.Study_guide_Cell_Structure__Answers - Study guide...

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Study guide (Kopachik) Cell Structure and Cytoskeleton Answers Questions: 1. Classify the following cells: mycoplasma, E. coli, cyanobacterium, yeast, fungi, algae, large soil amoebae, plant cell, hepatocyte. Are they prokaryote or eukaryote, do they have peptidoglycan cell walls, mitochondria, lysosomes, peroxisomes, nucleoli, and would they be sensitive to a prokaryotic antibiotic like penicillin, or like chloramphenicol. cell – prok/euk- pept’glyn- mito- lyso’me –perox.- nucleoli- sensitivity myco prok yes no no no no yes E. coli prok yes no no no no yes cyano. prok yes no no no no yes yeast euk no yes yes yes yes no 1 fungi algae no amoeba. “ pl. cell no hepat. (1) penicillin inhibits prokaryotic peptidoglycan synthesis and therefore does not affect eukaryotic cells whereas chloramphenicol inhibits prokaryotic and the related mitochondrial ribosome function ( not the cytoplasmic ribosomes) 2. What is the main evidence for the endosymbiont theory regarding DNA? What would be further evidence for it? Mitochondria and chloroplasts have their own DNA with genes that are prokaryotic-like in sequence (the ribosomal RNA for instance is more similar in sequence and function to prokaryotes than to the nucleolar-encoded ribosomal RNA). Furthermore their DNA also is circular as in prokaryotes, not linear as in eukaryote nuclear DNA. Further evidence comes from sensitivity to chloramphenicol mentioned above . 3. What limits cell size to about 20-50 um? How can a neuron cell be very long (about a meter ) in a human and longer in bigger animals?
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Biophysical constraints of diffusion limit cell size. The surface area for transport in and out of the cell only increases by the square of length whereas volume and therefore metabolism increases by the cube of the length. Some cells can be very long as are neurons but very thin; they still have problems in that the nucleus is very far from the end of the neuron.
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7.Study_guide_Cell_Structure__Answers - Study guide...

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