BIOL 110 Basic Concepts and Biodiversity Learning Guide Tutorial Subcellular Architecture of the Eukaryotic Cell In this tutorial we will investigate eukaryotic cells and the roles of their various structures and organelles Read through the questions below before you begin reading the eukaryotic cell tutorial Then as you read the tutorial fill in your answers to help you prepare for our class session In addition to the questions below as you read through the tutorial ask yourself what did I learn on this page Before our class session answer the following questions from the online tutorial Morphology of intracellular membranes revealed by in situ cryo electron tomography What cellular structures can you make out in the above image IMAGE Y S BYKOV et al 2017 eLIFE 6 e32493 1 Membranes play four general roles in the cell Briefly explain those roles in your own words 2 What property allows O2 and CO2 to cross a lipid bilayer without aid or membrane proteins Why do water glucose and other sugars need transport proteins 3 You are looking under a microscope and observe a cell with a well defined nucleus rough endoplasmic reticulum with bound ribosomes smooth endoplasmic reticulum and free ribosomes suspended in the cytoplasm a Given these features is this most likely a prokaryotic or eukaryotic cell b How do you know c Which of these features will also be found in both prokaryotic and eukaryotic cells Where is the nucleus located in a eukaryotic cell Describe the structure of the nucleus What is its 4 primary function 5 What is the difference between free and bound ribosomes Can free ribosome become a bound ribosome Explain your reasoning 6 Describe the relationships among organelles of the endomembrane system showing the flow of proteins through the various organelles 7 After reading about lysosomes and a real life example Protein transport and a human genetic disease answer the following questions Tay Sachs disease is a genetic condition that causes an accumulation of gangliosides in the brain s neurons i e nerve cells This accumulation is caused by a mutation that affects the function of organelles called lysosomes a What is the function of a lysosome in a eukaryotic cell What is the function of hydrolase enzymes in a lysosome What type of molecule is a hydrolase b What type of molecules are gangliosides How can the accumulation of gangliosides cause Tay Sachs disease 8 Use the following table to compare and contrast the different components of the cytoskeleton Make note of the protein subunits monomer of cytoskeletal components in the key features area The Cytoskeleton Compare and Contrast Microtubules Intermediate Filaments Microfilaments Key Features Subunit Major Protein s Key Features Subunit Major Protein s Lamins Key Features Subunit Major Protein s Cellular Structure Processes Cellular Structure Processes Cellular Structure Processes Example in action Example in action Example in action Size circle one Smallest Middle Largest Size circle one Smallest Middle Largest Size circle one Smallest Middle Largest 10 What is the evidence that supports the origins of mitochondria and chloroplasts as endosymbionts of eukaryotic cells 11 List what concepts or ideas from this tutorial are new to you During our class session work with your peers LAs and instructor to answer the following questions 1 The amphipathic nature of phospholipids causes them to spontaneously form a lipid bilayer in an aqueous solution In the space below draw a representation of phospholipid bilayer labeling the following structures hydrophilic phosphate heads hydrophobic hydrocarbon tails and hydrophobic core of the bilayer Why is the hydrophobic core important 2A The structure of the membrane results in selective permeability This means that some substances can readily pass through the lipid portion of the membrane while other substances need to cross the membrane via transport proteins Using your knowledge of the structure of a membrane see your drawing above fill in the chart below that describes the permeability I e ability of molecules to travel across a membrane of some example molecules Assume NO PROTEINS are present in the membrane Charged polar or non polar Can it cross without a protein Molecule Oxygen O2 Protons H Glucose Water 2B Proteins that help transport molecules across the phospholipid bilayer most likely have R groups that are A only hydrophobic B only hydrophilic C both hydrophobic and hydrophilic 3 Draw and describe the two general paths of a protein produced by the eukaryotic cell One path should show the pathway of a protein that will be exported outside of the cell via organelles of the endomembrane system The other path should show a protein that will be used by the cell in the cytoplasm Start both paths in the nucleus Your diagram should include the terms listed below that are in no particular order Some terms will be used for both paths some will only be used for one of the two paths Reference your online tutorial if needed Terms rough endoplasmic reticulum free ribosome bound ribosome Golgi apparatus DNA mRNA nucleus cytoplasm nuclear pore secretory vesicle plasma membrane transport vesicle polypeptide transcription translation 4 A cell that secretes proteins acquires a mutation that results in polypeptides bypassing the Golgi apparatus What will be wrong with the proteins secreted from this cell A They will contain too many amino acids B They will have too few amino acids C They will be missing post translational sugars D They will be stuck in the ER E Nothing will be wrong with them 5 Science in Action Chemotherapy There are several chemicals that target components of the cytoskeleton and can be used as chemotherapeutic drugs to stop the division of cancerous cells Cancer is caused by uncontrolled cell division Normal genes that control cell division can mutate leading to a cell that divides out of control Because cancer cells are rapidly dividing these drugs are more likely to influence the cancer cells although they can also damage normal cells leading to some of the side effects of chemotherapy One of these drugs is Taxol the brand name for paclitaxel This chemical was first isolated from the bark of the rare Pacific Yew tree but is now made semi synthetically as docetaxel Taxol binds to microtubules and makes them rigid so that they can no longer perform their normal function thus inhibiting cell division Based upon what you have learned about the cytoskeleton in the tutorial how
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