Endomembrane System

Concept: Endomembrane System Overview


Concept: Endoplasmic Reticulum


Concept: Golgi Apparatus


Concept: Lysosomes and Vacuoles


Problem: Alcohol prevents the synthesis of molecules that are involved in the breakdown of certain proteins. Which of the following organelles in the liver would be most affected by alcohol:


Problem: Why does the Rough ER have so many ribosomes?


Problem: Where do vesicles enter the Golgi apparatus? Why do vesicles go there?


Problem: What organelle do plants use to maintain cell rigidity?


Endomembrane System Additional Practice Problems

List two organelles that belong to the Endomembrane System and give a function for each.

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Compared with other cell components (organelles, cell membrane or nucleus), themitochondria would be the only one that would:

A. produce ATP via glycolysis

B. use significant amounts of oxygen to produce ATP

C. use a chemiosmotic complex to produce ATP.

D. form an electrochemical gradient across a membrane

E. release protons (H+)

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How is a dialysis membrane selectively permeable - what permeates and what does not?

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How is a cell membrane selectively permeable - what permeates and what does not?

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Choose which protein/(s) in the list below are synthesized by ribosomes attached to the ER.

A. A protein that resides in the chloroplast

B. A protein that will be secreted into the extracellular space

C. A nuclear protein

D. A membrane protein that shuttles between the plasma membrane and an endosome

E. A protein that resides between the inner and outer nuclear membranes

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Provide two similarities and two differences in the molecular mechanisms of how proteins are transported into the ER and into the nucleus.

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Why cells have membrane potential? Which ions are high inside? Which ions are low inside?

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What is the function of ER?

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What is the importance of the resting membrane potential to cells such as neurons and muscles? What about other cells of the body? Do they also have a resting membrane potential?

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What is the major difference between gated and non-gated ion channels? Give an example of two different gating signals.

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What distinguishes channel proteins from transporter proteins in cellular membranes?

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What makes channels proteins selective for transport of a particular ion or small molecule?

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What are biological membranes composed of?

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Why do eukaryotes have so many intracellular membrane-bound compartments?

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Which of the following statements about SNARE-mediated membrane fusion are correct? More than one answer may be selected. 

a. SNAREs from both the cell plasma membrane and the vesicle combine to form a complex that drives membrane fusion.

b. Fusion is triggered by the presence of K .

c. The lipid bilayers of the fusing membranes undergo rearrangement involving changes in membrane curvature.

d. SNAREs are peripheral membrane proteins.

e. Formation of the SNARE complexes results from changes in membrane curvature.

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Describe the cell membrane. What molecules comprise it? What makes it selectively permeable? Why is it so important?

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The membrane of an animal cell nucleus contains phosphatidylcholine in which a significant number of the fatty acid residues are saturated. After reading Section 11.7, would you expect this to increase or decrease the fluidity of the membrane structure?

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Explain how organisms are able to maintain a relatively constant membrane fluidity when faced with extremes in temperatures.

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Discuss how molecules move across the cell membrane by active transport and passive transport.

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For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in? How will this affect its probability of depolarization?

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In order for a milk protein to be secreted, it must be moved between organelles: 

a. In spheres of lipid bilayer called vesicles

b. By release into the cytoplasm

c. By translation in each organelle

d. Attached to transporter proteins

e. By the fusion of organelles with each other

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In order for a milk protein to be secreted, its mRNA must first be translated on ribosomes: 

a. In the cytoplasm

b. In the nucleus

c. Attached to the Golgi

d. Attached to the rough endoplasmic reticulum

e. Attached to the smooth endoplasmic reticulum

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Which are recycling centers for the cell? 

a. Ribosome and Golgi apparatus

b. Endoplasmic reticulum and chloroplast

c. Mitochondria and nucleus

d. Central vacuole and lysosome

e. All are correct

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A central vacuole: 

a. Produces protein

b. Produces turgor pressure

c. Produces mRNA

d. Stores genetic information

e. Produces energy from nutrients

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Which of the following are cellular digestion centers? 

a. Peroxisomes and ribosomes

b. Lysosomes and peroxisomes

c. Ribosomes and chloroplasts

d. Chloroplasts and ribosomes

e. Lysosomes and Golgi apparatus

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The Golgi apparatus is not: 

a. An organelle

b. A processing center

c. Studded with ribosomes

d. A stack of membrane enclosed sacs

e. Involved with secretion of cellular substances

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The rough or smooth endoplasmic reticulum do not: 

a. Produce proteins

b. Produce lipids

c. Detoxify poisons

d. Produce mRNA

e. Form vesicles for transport to the Golgi apparatus

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When a cell is deprived of oxygen, its lysosomes tend to burst and release their contents into the cell. As a result of this that cell will:

a. recycle damaged organelles

b. produce additional ER

c. undergo cell division

d. produce replacement lysosomes

e. undergo autolysis

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Lipid synthesis occurs in which eukaryotic organelle?

a. rough ER

b. smooth ER

c. lysosomes

d. mitochondria

e. nucleolus

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The eukaryotic organelle that is directly involved in the transport of proteins synthesized on the surface of the rough ER is called

a. mitochondria

b. vacuole

c. cytoskeleton

d. Golgi complex

e. nucleus

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Some ribosomes are embedded into

a. chromosomes

b. smooth endoplasmic reticulum

c. rough endoplasmic reticulum

d. histones

e. vacuoles

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Plant cells often have a large membrane-bound sac that is used for storing water and other substances. This organelle is called

a. nucleus

b. chloroplast

c. Golgi body

d. centriole

e. central vacuole

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Membrane-bound organelles that contain powerful enzymes found in cells are known as

a.  lysosomes

b.  plastids

c.  vacuoles

d.  liposomes

e.  ribosomes

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Which of the following is  not the name of a membrane-bound compartment in a eukaryotic cell?

a. Ribosome

b. ER lumen

c. Mitochondrial matrix

d. Stroma

e. Golgi lumen

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