Cell Compartmentalization - AP Biology

Membrane-bound organelles have been an

important component in the evolution of complex,

multicellular organisms. Which of the following

best summarizes an advantage of eukaryotic cells

having internal membranes?

• Eukaryotic cells are able to reproduce faster because of the presence of organelles.

• Some organelles, such as mitochondria and chloroplasts, are similar to prokaryotic cells in structure.

• Organelles isolate specific reactions, increasing metabolic efficiency.

• Compartmentalization leads to a higher mutation rate in DNA, which leads to more new species.

Which of the following depicts the most probable pathway of processing and packaging a secretory protein within a eukaryotic cell?

• Secretory vesicles → rough endoplasmic

  reticulum → Golgi body → cell membrane

• Rough endoplasmic reticulum → Golgi body

  → secretory vesicles → cell membrane

• Golgi body → secretory vesicles → rough

  endoplasmic reticulum → cell membrane

• Secretory vesicles → Golgi body → rough

  endoplasmic reticulum → cell membrane

Researchers have proposed a model of chloroplast evolution. According to the model, chloroplasts evolved from a small prokaryotic organism that was engulfed by an ancestral eukaryote. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host.

Which of the following observations best supports the model?

• Chloroplasts are separated from other subcellular compartments by semipermeable membranes.

• Prokaryotic and eukaryotic organisms both acquire nutrients from the surrounding environment.

• Eukaryotes evolved after prokaryotes and have more complex structures.

• Chloroplasts and some prokaryotes share similar photosynthetic reactions.

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Which of the following observations best supports the claim that mitochondria evolved from once-free-living prokaryotic cells by the process of endocytosis?

• Mitochondria produce ATP

• Mitochondria contain proteins

• Mitochondria exchange substances with the cytosol.

• Mitochondria are surrounded by a double membrane.

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Euglenids are single-cell eukaryotes that live in aquatic environments. The chloroplasts found inside euglenids are enveloped by three membranes, as represented in Figure 1. The inner membrane of euglenid chloroplasts resembles the thylakoid membrane.

Which of the following claims about the origin of the euglenid chloroplast is best supported by the three-membrane structure of the envelope?

• It originated from the spontaneous assembly of organic molecules into a lipid bilayer inside a free-living prokaryote.

• It originated from the fusion of the plasma membranes of two different free-living photosynthetic prokaryotes.

• It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by a single endosymbiotic event.

• It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events.

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NGSS.HS-LS4-2

Two competing hypotheses exist regarding the cell membrane structure. One hypothesis states that membrane structure is static and membrane components throughout the bilayer are rigidly bound. Alternatively, the other hypothesis states that cell membranes are a fluid mosaic in which membrane components may drift within the bilayer around the surface of the cell. An experiment is set up in which membrane proteins of two different cells are fluorescently labeled with two different colors and then fused as shown in Figure 1.

Which of the following results, one hour after membrane fusion, best supports the alternative hypothesis that the cell membrane is a fluid mosaic?

• 
• 
• 
• 

What are cells made of?

• Your mom

• Organelles

• Other cells

• Mitochondria

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Why are organelles not in one big compartment?

• Organelles are too small

• They would crash and destroy other organelles

• So organelles can specialize

• To have specialized environments

Why are cells small?

• So they can have a higher surface area to volume ratio.

• So they can have a higher volume to surface area ratio.

• So they can have a lower volume to surface area ratio.

• So organelles do not have that much space in the cell

Since eukaryotic cells are big, how do they get nutrients to the center efficiently?

• compartmentilization

• specialization

• They have your mom in there to help them

• Cell cycle control