chapter 7 membranes

Question 1

What are the top 5 functions of the membrane?

Answer 1

1) Boundary and permeability barrier
2) Organization and localization of function
3) Transport processes
4) Signal detection
5) Cell to cell interactions

Question 2

The ______ surrounds
the whole cell,
whereas _____
compartmentalize
functions within the
cell.

Answer 2

plasma membrane; intracellular
membranes

Question 3

Membrane proteins

Answer 3

carry out and regulate the
transport of substances
across the membrane.

Question 4

Signal transduction

Answer 4

describes the
mechanisms by which signals are
transmitted from the outer surface to
the interior of a cell

Question 5

Adhesive junctions

Answer 5

hold cells
together and are mediated by
cadherins.

Question 6

Tight junctions

Answer 6

form seals that
block the passage of fluids
between cells.

Question 7

Gap junctions

Answer 7

allow for
communication between
adjacent animal cells and
plasmodesmata perform a
similar function in plant cells

Question 8

Chemical signal molecules

Answer 8

usually
bind to membrane proteins, known as
receptors, on the outer surface of the
plasma membrane.

Question 9

Phospholipids

Answer 9

consists
of a backbone with two
fatty acids, a negatively
charged phosphate
group, and a charged
head group attached to
the phosphate.

Question 10

Glycolipids

Answer 10

are formed by
the addition of carbohydrates
to lipids

Question 11

Cerebrosides

Answer 11

are
neutral glycolipids;
each molecule has an
uncharged sugar as its
head group

Question 12

ganglioside

Answer 12

has an
oligosaccharide head
group with one or more
negatively charged
sialic acid

Question 13

Sterols

Answer 13

The membranes of
most eukaryotes
contain significant
amounts of sterols.

Question 14

cholesterol,

Answer 14

The main sterol in
animal cell membranes

Question 15

Plant cell membranes
contain small amounts
of ____,
whereas fungal cell
membranes contain
____, similar to
cholesterol.

Answer 15

phytosterols; ergosterol

Question 16

Phospholipids can also move within the monolayer,
via

Answer 16

lateral diffusion

Question 17

Membranes
Function
Properly
Only in the

Answer 17

fluid state

Question 18

Membrane fluidity is
influenced by

Answer 18

sterols

Question 19

Most organisms can regulate membrane fluidity by

Answer 19

varying the lipid composition of the membranes.

Question 20

Integral Membrane Proteins

Answer 20

with hydrophobic regions
embedded in the interior membrane
bilayer

Question 21

integral
monotopic proteins

Answer 21

are
embedded in just one
side of the bilayer

Question 22

transmembrane
proteins

Answer 22

span the
membrane and protrude
on both sides

Question 23

Peripheral Membrane Proteins

Answer 23

bound to membrane
surfaces through weak
electrostatic forces and
hydrogen bonds

Question 24

Lipid-Anchored Membrane Proteins

Answer 24

are located on the surfaces of
membranes. They are covalently
bound to lipid molecules embedded in the bilayer.

Question 25

Proteins bound to the inner surface of the plasma membrane are linked to fatty acids, or ____.

Answer 25

isoprenyl groups

Question 26

Electrophoresis

Answer 26

is a group of techniques that use an electric field to separate charged molecules according to size

Question 27

Western blotting

Answer 27

After electrophoresis, polypeptides can be identified This technique is important for identifying which proteins are in a sample and their relative abundance.

Question 28

Electrophoresis uses various support media, most commonly _____ or ______.

Answer 28

polyacrylamide; agarose

Question 29

membrane reconstitution

Answer 29

proteins are extracted from membranes and separated individually

Question 30

The purified proteins are mixed with phospholipids to form vesicles call

Answer 30

liposomes

Question 31

why are liposomes important?

Answer 31

Liposomes can be loaded with specific molecules and tested for their ability to carry out certain functions

Question 32

X-ray crystallography

Answer 32

can be used to determine the structure of proteins that can be isolated in crystalline form is widely used to determine the three- dimensional structure of proteins.

Question 33

An alternative approach called ___ analysis can be used.

Answer 33

hydropathy

Question 34

Site-specific mutagenesis

Answer 34

allows determination of how certain amino acids affect protein function.

Question 35

Membrane proteins involved with intercellular communication include  Proteins that form ____ at ____ in animal cells  Proteins that make up ____ in plant cells

Answer 35

connexons; gap junctions; plasmodesmata

Question 36

Uptake and secretion of molecules

Answer 36

the mechanisms by which cells move molecules across their membranes, either entering the cell (uptake) or leaving the cell (secretion)

Question 37

____ take part in targeting, sorting, and modifying proteins in the endoplasmic reticulum and Golgi complex

Answer 37

membrane proteins

Question 38

Membrane proteins participate in ____, the digestion of a cell’s own organelles or structures.

Answer 38

autophagy

Question 39

Do membrane proteins play a role in light detection?

Answer 39

Yes

Question 40

In animal cells, a cytoskeletal meshwork of ____ membrane proteins underlies the plasma membrane of many kinds of cells.

Answer 40

peripheral

Question 41

Glycosylation

Answer 41

the post-translational modification of proteins where sugar molecules, called glycans, are attached to them

Question 42

The most common sugars are

Answer 42

galactose, mannose, N- acetylglucosamine, and sialic acid.

Question 43

The ___blood group system depends on genetically determined structural differences in the branched carbohydrate attached to a specific glycolipid in red blood cells.

Answer 43

ABO

Question 44

glycocalyx

Answer 44

In animal cells, the carbohydrate groups of plasma membrane glycoproteins and glycolipids form a surface coat

Question 45

Functions of the glycocalyx include

Answer 45

cell-cell recognition and adhesion, protection of the cell surface, and the creation of permeability barriers.