Question

question 22
0.25 pts
how do vesicles move from place to place in an organized way within the cell?
molecular motors pull them along the microtubules and microfilaments of the cytoskeleton
vaults pull them along the microtubules and microfilaments of the cytoskeleton
rafts pull them along the microtubules and microfilaments of the cytoskeleton
microvilli and flagella move them along the microtubules and microfilaments of the cytoskeleton
question 23
0.25 pts
projections from the cell that move materials and mucus are called:
cilia.
flagella.
microvilli.
microtubules.
question 24
0.25 pts
skin cells (epithelial) are held tightly together by:
gap junctions.
desmosomes.
tight junctions.
adhesions.

Explanation:

Question 22

To determine how vesicles move within the cell, we analyze each option:

• Molecular motors (like kinesin and dynein) are known to transport vesicles along the cytoskeleton's microtubules and microfilaments.
• Vaults are involved in nuclear transport and not vesicle movement.
• Rafts are membrane microdomains, not for vesicle transport.
• Microvilli increase surface area, flagella move the cell, not vesicles along cytoskeleton. So the correct option is the first one.

For cell projections moving materials/mucus:

• Cilia are hair - like projections that beat to move mucus and materials (e.g., in respiratory tract).
• Flagella are for cell movement (e.g., sperm).
• Microvilli increase surface area (absorption), not move materials.
• Microtubules are part of cytoskeleton, not cell projections for moving materials. So the correct option is cilia.

For holding skin (epithelial) cells tightly:

• Gap junctions allow communication, not tight holding.
• Desmosomes anchor cells (e.g., in skin for tensile strength).
• Tight junctions prevent leakage (e.g., in gut), but desmosomes are more for tight holding in skin. Wait, actually, tight junctions also hold cells, but desmosomes are key for epithelial (skin) cell adhesion. Wait, correction: Tight junctions form a barrier, desmosomes (anchoring junctions) hold cells tightly. But in skin, desmosomes are prominent. Wait, no, the options: tight junctions are also for holding, but desmosomes are more for strong adhesion. Wait, the correct answer is desmosomes? Wait, no, let's recall: Epithelial cells (skin) are held by desmosomes (anchoring junctions) which provide strong adhesion. Tight junctions are for sealing. So the correct option is desmosomes? Wait, the options: gap junctions (communication), desmosomes (anchoring), tight junctions (sealing), adhesions (general term). Wait, actually, in skin, desmosomes are the main junctions for tight holding. So the correct option is desmosomes.

Answer:

A. Molecular motors pull them along the microtubules and microfilaments of the cytoskeleton

Question 23