Euk Cell Bio Chpt 11 | Quizlet

Organisms that live in cold climates adapt to low temperatures by doing which of the following?

increasing the amounts of unsaturated fatty acids in their membranes to help keep their membranes fluid

Which is the most abundant phospholipid in animal cell membranes?

phosphatidylcholine

phosphatidylcholine

This abundant phospholipid has a hydrophilic head that consists of choline linked to a phosphate group. The "phosphatidyl" part of the name of a phospholipid refers to the phosphate-glycerol-fatty acid portion of the molecule. Although it is found in all plant and animal cells, it is absent from the membranes of bacteria.

When the transport vesicle shown below fuses with the plasma membrane, which monolayer will face the cell cytosol?

The orange monolayer will face the cytosol.

The layer that is facing the cytosol will always face the cytosol

All of the carbohydrates in the plasma membrane face the cell exterior. Which direction do the carbohydrates on internal cell membranes face?

the lumen of the vesicle or organelle

Shown is a schematic diagram of a membrane phospholipid. Which segment could carry a positive charge?

A

In phosphatidylcholine, the most common phospholipid in cell membranes, this chemical group (choline) contains a positively charged nitrogen atom.

Shown is a schematic diagram of a membrane phospholipid. Which segment will always carry a negative charge?

B

represents the phosphate group, which is always negatively charged.

Which is true of the molecule shown below?

It makes the bilayer less fluid.

It is amphipathic.

It is a lipid.

Which membrane would show a more rapid recovery of fluorescence in a FRAP study?

a membrane containing a larger proportion of unsaturated fatty acids

Why must all living cells carefully regulate the fluidity of their membranes?

to permit membrane lipids and proteins to diffuse from their site of synthesis to other regions of the cell

to allow membranes, under appropriate conditions, to fuse with one another and mix their molecules

to ensure that membrane molecules are distributed evenly between daughter cells when a cell divides

In 1925, scientists exploring how lipids are arranged within cell membranes performed a key experiment using red blood cells. Using benzene, they extracted the lipids from a purified sample of red blood cells. Because these cells have no nucleus and no internal membranes, any lipids they obtained were guaranteed to come from the plasma membrane alone.

The extracted lipids were floated on the surface of a trough filled with water, where they formed a thin film. Using a movable barrier, the researchers then pushed the lipids together until the lipids formed a continuous sheet only one molecule thick.

The researchers then made an observation that led them to conclude that the plasma membrane is a lipid bilayer.

Which of the following would have allowed the scientists to come to this conclusion?

The extracted lipids covered twice the surface area of the intact red blood cells.

In an electron transport chain, electrons are passed from one transmembrane electron carrier to another, driving proton movement across a membrane (see image below). The protons then flow through ATP synthase (not shown) to generate ATP.

In a 2018 article (Budin, et al., Science vol. 362) researchers probed how membrane fluidity affects electron transport chain activity and ATP production in E. coli by manipulating membrane fluidity and measuring respiration. How could researchers have increased membrane fluidity?

increase the proportion of phospholipids with unsaturated fatty acids