Cell Structures & Secretory Pathway
A cell produces many proteins for export. Which organelle has the ribosomes that make them?
Rough ER
Intestinal microvilli are supported mainly by which cytoskeletal filament?
Actin microfilaments
At low temperatures, would more saturated or unsaturated fatty acid tails help keep a membrane fluid?
Unsaturated tails
Cl⁻ moves down its gradient through a channel. Does this directly require ATP?
No; it is facilitated diffusion.
A cell finishes S phase. Has its chromosome number doubled?
No; DNA was copied, producing sister chromatids.
A secreted protein has been processed by the Golgi. What carries it to the plasma membrane?
A secretory vesicle
Vesicles have microtubule tracks and ATP but cannot travel. What type of protein may be missing?
Motor proteins
Why do unsaturated tails help prevent a membrane from becoming too rigid?
Their bends keep phospholipids from packing tightly.
An ATP-powered H⁺ pump creates a gradient that drives sucrose into a cell. What type of transport brings in sucrose?
Secondary active transport
Which structure organizes spindle microtubules and moves toward a cell pole?
Centrosome
Which two organelles have evidence of bacterial ancestry through endosymbiosis?
Mitochondria and chloroplasts
Fluid leaks between neighboring epithelial cells. Which junction is most likely failing?
Tight junctions
A carbohydrate chain is attached to a protein on the cell surface. Name the structure and one function.
Glycoprotein; cell recognition
A plant cell loses water and its membrane pulls away from its cell wall. What happened to the surrounding solution?
It became hypertonic.
What could happen if a cell enters anaphase while one chromosome is not attached to the spindle?
Daughter cells may receive unequal chromosome numbers
A histone is made on a free ribosome. Does it travel through the ER and Golgi to reach the nucleus?
No. It enters through a nuclear pore.
Which plant cell connection serves a similar communication role to an animal cell’s gap junction?
Plasmodesmata
Why can two organelles have different membrane functions even though both have phospholipid bilayers?
Their membranes contain different proteins.
An ATP-powered proton pump stops working. What happens to sucrose uptake through an H⁺ cotransporter?
It decreases as the H⁺ gradient weakens.
A cell has 24 centromeres at anaphase. How many chromosomes will each daughter cell have?
12
Trace a secreted protein from its gene to the outside of the cell.
Nucleus → mRNA → ribosome on rough ER → transport vesicle → Golgi → secretory vesicle → exocytosis.
A cell has cilia with intact microtubules, but the cilia cannot beat. Which motor protein may be missing?
Dynein
A glycoprotein is delivered to the plasma membrane in a vesicle. Where will its carbohydrate chain face?
Outside the cell; it faced the vesicle’s interior before fusion.
A cell’s LDL receptors stop working. What happens to LDL uptake by that cell?
It decreases because LDL cannot bind for receptor-mediated endocytosis.
A cell enters mitosis with damaged DNA because its G₂ checkpoint fails. What could happen to its daughter cells?
Its daughter cells can inherit genetic abnormalities, mutations and genomic abnormalities, mutations, or genomic instability