Variant 1 (0-25)

1.

1 point

... and... viewed cells under magnification in the latter half of the seventeenth century

Tomas Hunt Morgan

Antoni Van Leeuwenhoek

Robert Hooke

Matthias Schleiden

2.

1 point

Watson and Cricket showed that the structure of DNA usually is a

Macromolecules

Double helix

Linear polymer

3.

1 point

Three scientists associated with development of the cell theory in the nineteenth century where

Edwarth Tatum

Rudolf Virchow

Theodor Schwann

Matthias Schleiden

Antoni Van Leeuwenhoek

4.

1 point

Cell membranes

Contain lipid molecules that have both a fatty part and water soluble part, are made of RNA

May be associated with proteins or cell wall structure, which add strength and stability to the outer surface of cells

Are formed of a single layer of fatty molecules called lipids, may contain cholesterol

5.

1 point

A procaryotic cell

Has organelles

Has genes

Has a plasma membrane

Contains a nucleus

Contains DNA

6.

1 point

List at least three functions of cell membranes

All choices are correct

7.

1 point

Describe at least three functions of small molecules in cells

They serve as an energy source for the cell when they are degraded

Other small molecules are used to send signals within and between the cells

Small molecules serve as substrates for making macromolecules

Some small molecules are used to store cellular energy

8.

1 point

In most biological membranes, ... molecules make up the two leaflets of the bilayer into ... molecules are embedded

Oligosaccarides

Galactolipids

Phospholipids

Protein

9.

1 point

The transmembrane domains of most integral membrane proteins have ... secondary structure

beta sheet

glycocalyx

ectrinsic

alpha helix

10.

1 point

Abundant in the plasma membrane of mammalian cells, ... is an amphiphathic lipid that contains four hydrocarbon rings

glycophorin

phosphatidylcholine

cholesterol

11.

1 point

Glycolipids and glycoproteins are located preferentially in the ... face of the ... membrane, or cell surface

extrinsic

exoplasmic

apical

plasma

12.

1 point

The major integral membrane proteins in mammalian red blood cells are ..., whose monometric form spans the lipid bilayer a single time and ..., which spans the bilayer at least twelve times

glycophorin

band 3 protein

cardiolipin

catalase

13.

1 point

Membrane proteins that do not interact with the hydrophobic portion of the membrane are called...or...proteins.

integral

peripheral

extrinsic

lysosomal

intrinsic

14.

1 point

Carbohydrates containing several sugar units, which are present in many glycolipids and glycoproteins, are called...

galactolipids

oligosaccharides

phospholipids

glucocerebrosides

15.

1 point

The concept that integral membrane proteins diffuse in a "sea" of lipid is part of the...model of membrane structure

fluid-mosaic

alpha helical

sucrase-isomaltase sucrase-isomaltase sucrase-isomaltase c) sucrase-isomaltase

16.

1 point

Common chemical features of all membrane lipids include

sugar constituents

a hydrophobic domain

a glycerol backbone

a polar portion

a phosphate group

17.

1 point

Phospholipids in a fluid, pure phospholipid bilayer frequently undergo

movement from the membrane to the aqueous phase

flexing of acyl chains by movement about the c-c bonds

rotational movement around their long axis

flip flop from one leaflet to the other

lateral diffusion

18.

1 point

Which of the following characteristics generally are correlated with an increase in the fluidity of a lipid bilayer?

an increase in unsaturation of the phospholipid fatty acyl chains

addition of cholesterol to a bilayer whose phospholipids are in the gel state

an increase in the temperature of the bilayer

an increase in the lenth of the fatty acyl chains

more van der Waals interactions among the lipid species

19.

1 point

Integral membrane proteins

are embedded in the phospholipid bilayer or are covalently attached to a lipid segment that is embedded in the bilayer

can be glycoproteins

usually can be removed from the membrane by solutions of high ionic

are amphiphathic molecules

usually are soluble in the absence of detergents

20.

1 point

Lipid-anchored membrane proteins

are sometimes covalently attached to glycosylated phospholipids

are considered to be peripheral membrane proteins

include transforming proteins such as v-Src, which is anchored by an amide linkage to myristic acid

include farnesylated proteins

are found on both faces of the plasma membrane

21.

1 point

Fluorescence recovery after photobleaching

is typically used to measure the rotational motion of membrane lipids and proteins

is typically used to measure lateral diffusion of membrane lipids and proteins

involves fluorescent labeling of cell-surface molecules

has demonstrated that lipids diffuse freely over short distances, but generally not over longer distance, in fibroblast membranes

can be used to determine the fraction of labeled membrane associated molecules that are mobile as well as the rate of lateral motion

22.

1 point

Polarized cells in animals

are general feature of epithelial tissue, which lines body cavities

include erythrocytes and most other blood cells

have a plasma membrane divided into specialized regions of different function

have the same protein molecules exposed on their apical basolateral surfaces

may be sealed together by plasmodesmata to form a barrier to the passage of most small molecules that (plasmodesmata → plant cells!)

23.

1 point

Tight junctions in epithelial cells

can completeply inhibit lipid diffusion between the basolateral and apical surfaces

permit lipid diffusion between the apical surfaces of adjacent cell-surface

appear as an interlocking network of ridges in the plasma membrane in freeze-fracture electron micrographs

are located at the junction of the apical and basolateral surfaces

are sensitive to Ca2+ levels

24.

1 point

Many transformed cells release growth factors that subsequently stimulate the same cells from which they were released. This type of signal pathway is termed:

autocrine

mesocrine

endocrine

exocrine

paracrine

25.

1 point

The process of communication by extracellular signals does not include:

proteolytic cleavage of a hormone immediately prior to interaction with its receptor

glycosylation of hormone initiated by binding to its receptor

a change in the metabolism of the target cell

detection of a hormone by its receptor

removal of a hormone by its target cell or extracellular degradative enzyme