BIO QUIZ 4 (1)

Which one of the following molecules would MOST likely require a transport protein to cross the plasma membrane of a red blood cell

C6H12O6

An amphipathic molecule is one that

contains both polar and nonpolar regions

Which of the following have cell walls? (Select all that apply.)

plant cells fungal cells bacterial cells

Long, saturated fatty acid tails _____ lipid mobility and _____ membrane fluidity

reduce; decrease

Passive transport of a molecule across a lipid bilayer only occurs if there is a significant difference in the concentration of that molecule from one side of the bilayer to the other

False

Purified phospholipids gather together and form membranes only if the appropriate enzyme is present.

False

What type of molecule is NOT associated with a cell's plasma membrane

RNA

A beaker contains two solutions of salt dissolved in water. The two solutions have different concentrations (measured by molarity, M) and are separated by a membrane that is permeable to both salt and water

Side A is hypotonic relative to side B.

The sodium-potassium pump is an example of

an antiporter

Which of the following would be expected to decrease the fluidity of a membrane?

an increase in phospholipid fatty acid chain length and an increase in chain saturation

A protein that is temporarily associated with a biological membrane is a(n)

peripheral membrane protein

The lipid components of cellular membranes often include

phospholipids and cholesterol.

How is a micelle different from a liposome

All of these choices are correct. Micelle phospholipids have bulky head groups. A micelle is composed of a single layer of phospholipids. Micelle phospholipids have a single fatty acid tail.

What factors are required for net movement of a substance to occur by facilitated diffusion

All of these choices are correct: a transport protein a concentration gradient a plasma membrane

Why does active transport require ATP

An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration

If FRAP is performed on two membranes, one at 25ºC and the other at 40ºC, which one of the following results would most likely be observed

Both membranes would recover fluorescence in the bleached area, but the membrane at the warmer temperature would recover more rapidly

The beaker in the illustration below contains two solutions of salt with different concentrations (measured by molarity, M). The two solutions are separated by a membrane that is permeable to both salt and water.

Net diffusion of water from A to B and of salt from B to A.

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

O2, water (H2O), glucose, sodium ions (Na+)

A researcher is using a modified version of FRAP. She has devised a technique that allows her to label all the peripheral membrane proteins with a fluorescent tag, and has bleached a specific area of the cell membrane. After 24 hours, she notices that fluorescence has returned to the bleached area. What can she deduce from this experiment

Peripheral membrane proteins can move freely within the cell membrane

Paramecium is a unicellular organism that lives in fresh water. Suppose you are studying two populations of this organism: one population lives in a pond in northern Ontario, Canada, and the other lives in a pond in southern Florida. If you examined the plasma membranes of both of these populations at the same time of year, what difference would you expect to find between the two populations' cell membranes?

The fatty acid side chains in the membrane phospholipids of the Florida Paramecia would generally be longer and would be more saturated compared to those in the membranes of the Canada Paramecia

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

The phospholipid tails would orient toward the solution

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

The polypeptide chain is likely to span the membrane seven times

In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain the proper degree of fluidity. As summer turns to fall and eventually into winter, which of the following would you predict you would observe in the plasma membranes of organisms that are unable to regulate their body temperature

a decrease in phospholipid fatty acid side chain length and a decrease in side chain saturation

The electrical component of an electrochemical gradient is due to

a greater concentration of positive charges on the side of the membrane with the highest concentration of protons

Which one of the following is considered an integral membrane protein

a protein with its N-terminus in the cytoplasm and its C-terminus in the extracellular space

Which of the following is a common function of membrane proteins

attachment signal reception catalysis transport

The plasma membranes of some plant cells use transport proteins to move protons out of the cell against their concentration gradient. This is an example of

active transport

You are studying the transport of a particular substance into epithelial cells grown in culture. You notice that you can only find the substance inside the cell when ATP is present. How is the protein moving through the membrane

active transport

The movement of water into, or out of, a cell is an example of

both osmosis and diffusion

A phospholipid molecule in a membrane can

both spin (rotate around its vertical axis) and move side to side (lateral movement)

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

both the chloride concentration gradient and the electrical gradient of the cell

The random movement of molecules is referred to as

diffusion

Suppose you are studying the transport of a certain polar molecule across the plasma membrane of cells in culture. Over a period of time, you measure the concentration of a polar molecule inside and outside of the cells. You find that the concentration of the molecule is lower in the cell but is gradually increasing. You also measure the ATP concentration inside the cell and find that it is not changing. Which of the following is probably responsible for the transport of this polar substance into the cell?

facilitated diffusion

Which component of a phospholipid is found in the interior of a lipid bilayer?

fatty acids

Which property of phospholipids allows membrane proteins involved in the same biochemical pathway to associate with each other?

formation of lipid rafts

The active maintenance of a constant internal environment is referred to as

homeostasis

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)

hydrophobic molecules, small polar molecules, large polar molecules, ions

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

lipid rafts

Some plant cells take advantage of the high concentration of protons outside the cell to move solutes, such as sucrose, across the plasma membrane into the cell where the sucrose concentration is already relatively high. This type of transport is an example of

secondary active transport

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 cotransport of calcium and sodium?

secondary active transport by an antiporter

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

the addition of acid to change the pH

The term homeostasis refers to the ability of

the cell to control and maintain its internal environment.

Figure 5.2 shows a common biological phospholipid called phosphatidyl choline. Which of the following is NOT a component of phosphatidyl choline?

three fatty acids

Amino acids with hydrophobic side chains are often found in the region of an integral membrane protein that spans the membrane

true