Exam 5: Organizing Principles: Lipids, Membranes, and Cell Compartments

During the translation of mRNA molecules, the new polypeptides are often directed to specific parts of the cell by the presence or absence of short sequences of amino acids called signal peptides. Which of the following would you expect to find in the polypeptide that will eventually fold to become a receptor protein?

The MOST abundant organic molecule in nature is:

Which one of the following cellular compartments does NOT have a double membrane structure separating it from the rest of the cell?

G protein-coupled receptors are transmembrane receptors involved in cell signaling. The amino acid sequence of these proteins reveals that the polypeptide chain of the protein has seven hydrophobic regions. Based on this information, what can you conclude about how the protein is associated with the cell membrane?

A nuclear pore is MOST similar to a:

In which of the following regions of the cell can protein synthesis occur in eukaryotes?

Some diseases result from defective transport across the membrane. For example, cystic fibrosis results when a chloride ion transporter does not function. Which of the following is affected when this transporter does NOT function?

Bacteria are rarely larger than 1-2 m in size, and are typically shaped like rods, spheres, or spirals. What likely accounts for the shape and size of these prokaryotes?

Some lipid rafts are characterized by an accumulation of cholesterol. What does this mean for the fluidity of the raft domain?

Predict how phospholipids arrange themselves when they are placed in a nonpolar solution.

Many environmental factors influence the structure of biological membranes. Which one of the following could permanently disrupt phospholipid bilayers in an aqueous solution?

The signal recognition particle and its receptor on the surface of the endoplasmic reticulum ensure that proteins destined for incorporation into cellular membranes or for export from the cell are translated into the endoplasmic reticulum so that they may be processed through the endomembrane system. If a mutation rendered the signal recognition particle receptor nonfunctional such that the receptor was no longer able to dissociate from the SRP, what would be the most obvious effect on the cell?

A beaker contains two solutions of glucose dissolved in water. The two solutions have different concentrations (measured by molarity, M) and are separated by a membrane that is permeable to water, but not to glucose. Which of the following statements is TRUE?

Specific types of lipids assemble into defined areas of a biological membrane referred to as:

How is a micelle different from a liposome?

Which of the following would be synthesized in and processed by the rough endoplasmic reticulum and Golgi apparatus?

Molecular oxygen (O₂), which is required for the production of ATP by mitochondria, must pass through at least three membranes to get to the enzymes where it is used. O₂ is also produced in chloroplasts and must pass through at least four membranes to be released from the plant. Describe how O₂ moves across biological membranes.

Cells from which domain(s) of life are separated from their environment by a plasma membrane?

Which of the following represents how easily the molecules cross a synthetic membrane composed of phospholipids but not proteins, from most easily (freely permeable) to least easily (not permeable)?

In certain cells, a transport protein moves one calcium ion out of the cell against its concentration gradient while allowing the movement of three sodium ions into the cell down sodium's electrochemical gradient. Which of the following CORRECTLY describes this cotrannsport of calcium and sodium?