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BIO SCI E109 Chapter Notes - Chapter 5.1-5.4: Lipid Bilayer, Cell Membrane, Membrane Transport Protein

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School
UC-Irvine
Department
Biological Sciences
Course
BIO SCI E109
Professor
Catherine Loudon

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Document Summary

Chapter 5: transport across the plasma membrane 5. 1-5. 4. The lipid bilayer is made up of 3 types of lipid molecules- phospholipids, cholesterol, and glycolipids. Integral proteins are proteins that are firmly embedded in the plasma membrane. Membrane proteins serve as channels, carriers, receptors, enzymes, linkers, and cell identity markers. Selective permeability- the property of the cell membrane to allow some substances to pass through more readily than others. The lipid bilayer is permeable to non-polar molecules, steroids, and small uncharged polar molecules like water and urea. The bilayer is non-permeable to ions and large polar molecules like glucose. Cholesterol content can also be a factor. The higher the amount of cholesterol there is in the bilayer, permeability of water decreases. Concentration gradient- the difference in the concentration of a chemical from one place to another, such as from one place to another, such as from the inside to the outside of the plasma membrane. (ex.

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Related Questions

Please check P1&P2 & help with P3

P1.

A. DNA

B. Glycogen

C. Ribosome

D. miRNA

E1. Triacylglycerol

E2. Cyclic AMP

F. Acetyl CoA

G. Testosterone

H. ATP

I. Tau

1. Which molecules contain nucleotides? A, H, F, E2, D, C?

2. Which molecules contain at least one fatty acid? E1

3. Which molecules contain amino acids? I

4. Which molecules contain a sugar? A, B, H, E2, D, F

P2.

A. Phospholipid

B. Glycolipid

C. Cholesterol

D. None

1. Which molecules are amphipathic? A, B, C

2. Which molecules would decrease fluidity of plasma membrane? A?, B?, C

3. Which molecules are important for cell-cell recognition? B?

4. Which molecules are located solely on the intracellular surface of the plasma membrane, facing the cytosol? D

P3. 1. Describe where the following amino acids would be found in the glucose transporter (GLUT2) - part of the protein exposed to the lipid bilayer or within the interior of the transporter - and provide reasoning.

1A. Valine

1B. Serine

Acidic, basic, nonpolar, uncharged polar

2. Which amino acids form hydrogen bonds that shape tertiary structure?

3. Which amino acids allow transmembrane proteins to span the lipid bilayer?

True or False? True False
1. Proteins rapidly pass artificial membrane (liposome).--------------------------------------------------------------------------------------( ) ( )
2. Amphiphatic detergent such as SDS spontaneously forms bilayer inwater. ------------------------------------------------------------( ) ( )
3. Cholesterol does have a hydrophilic head and hydrophobic tail.-------------------------------------------------------------------------( ) ( )
4. Fat molecules are one of the major components of the plasmamembrane.------------------------------------------------------------- ( ) ()
5. Phospholipid molecules such as phosphatidylcholine spontaneouslyform bilayer. ----------------------------------------------------( ) ( )
6. Flippase facilitates lateral movement of phospholipids withinthe plane of the membrane.----------------------------------------- ( ) ( )
7. Glycolipids make bilayer less permeable to small water solublemolecules.----------------------------------------------------------- ( ) ()
8. Membrane inner leaflet is enriched with phosphatidylcholine,Sphingomyelin, and Glycolipid. -----------------------------------( ) ( )
9. Plasma membrane proteins can have an enzyme activity.--------------------------------------------------------------------------------( ) ( )
10. A single pass membrane protein must have an amphiphatic alphahelix.-------------------------------------------------------------- ( )( )
11. Plasma membrane proteins can be linked to a lipid molecule atthe outer leaflet of the plasma membrane. --------------------- ( )( )
12. The lateral motility of membrane proteins can be restricted bytight junctions.------------------------------------------------------ ( ) ()
13. Channel proteins have specific binding sites for ions and thusslower than carrier proteins.--------------------------------------- ( ) ( )
14. An antiport would function as a symport if its orientation inthe membrane were reversed. ---------------------------------------( ) ( )
15. A transmembrane pore can be formed by multiple amphipathicalpha helices. ----------------------------------------- ( ) ()
16. Porin proteins form water-filled channels in the outer membraneof a bacterium and are mostly composed of beta sheets. ---- ( ) ()
17. Glucose uniporters localize at the apical side of theintestinal epithelium.------------------------------------------------------------ ( ) ()
18. GAP junction is a selective pore for anions.-----------------------------------------------------------------------------------------------( ) ( )
19. A voltage-gated Na+ channel adopts only two conformationstates: open and closed.----------------------------------------------- ( ) ( )
20. Voltage gated K+ channel opens faster than the Voltage gatedNa+ channels.-------------------------------------------------------- ( ) ()
21. Opening of chloride channel at the synapse will help to fire anaction potential.------------------------------------------------------ ( ) ()
22. The nuclear pore complex forms a gate through which moleculespass the nucleus uni-directionally. -------------------- ( ) ()
23. A completely folded protein is imported into a mitochondrionthrough a large non-selective pore.--------------------------------- ( ) ( )
24. ER signal sequence contains multiple lysine and arginineresidues.----------------------------------------------------------------------( ) ( )
25. The plasma membrane is a sorting station of inward endocyticpathway.---------------------------------------------------------------- () ( )
26. The trans Golgi functions as a sorting station of outwardsecretory pathway.----------------------------------------------------------- ( ) ()
27. Vesicles budding from ER are coated with Clathrin.----------------------------------------------------------------------------------------( ) ( )
28. RabGTPases and tethering proteins are the major specificitydeterminant of vesicle transport system. --------------------------( ) ( )
29. v-SNARE proteins are one of the tethering proteins.------------------------------------------------------------------------------------( ) ( )
30. In secretory cells, the constitutive and regulatory pathways ofexocytosis diverge at the cis Golgi network. ------------------ ( )( )
31. Many proteins are posttranslationally glycosylated at tyrosineresidues in the ER.------------------------------------------------- ( ) ( )
32. Cells import LDL molecules exclusively through pinocytosis.-------------------------------------------------------------------------( ) ( )
33. Cells recycle LDL receptors from lysosome to the plasmamembrane.----------------------------------------------------------------- () ( )
34. Phagosomes fuse with late endosome.------------------------------------------------------------------------------------------------------( ) ( )
35. Small vesicles from ER near the plasma membrane can fuse withthe plasma membrane upon bypassing Golgi apparatus. -- ( ) ()
36. If a Sec mutant showed an accumulation of newly synthesizedproteins at ER,
then the Sec gene is likely a component of vesicle-buddingmachinery of trans-Golgi network.------------------------------------ ( ) ( )
37. A signal recognition particle is a single pass trans-membraneprotein of the ER membrane.---------------------------------------- ( ) ( )
38. Typical animals cells display higher levels of intracellularsodium than extracellular compartments.------------------------------ ( ) ( )
39. Typical animals cells display higher levels of intracellularchloride than extracellular compartments.----------------------------- ( ) ( )
40. The Na-K Pump is a GTPase that can adopt active and inactiveconformational states.----------------------------------------------- ( ) ( )
1. Phospholipase
C-­-ß
produces
phosphatidylinositol
3,4,5-­-trisphosphate
and
diacylglycerol.
(
)
(
)
2. PDGF
activates
GPCR.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
3. Rho
is
an
example
of
heterotrimeric
G
proteins.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­-
(
)
(
)
4. All
members
of
the
G
protein
coupled
receptors
interact
with
small
GTPase
Ras.
-­--­--­--­--­--­--­--­--­--­-
(
)
(
)
5. Adrenaline
is
an
example
of
the
ligands
for
the
RPTK
family.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
6. Ras
GEF
activates
RPTK.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
7. PH
domain
containing
proteins
bind
to
activated
EGFR.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
8. Ligands
for
GPCR
proteins
induce
dimerization
of
the
receptor.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
9. Grb2
is
an
adaptor
protein
that
binds
to
a
phospho-­-tyrosine
residue
of
activated
RPTK
through
a
PH
domain.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
10. When
a
cell
is
expressing
a
large
number
of
dominant
negative
EGFR
proteins,
an
introduction
of
a
constitutively
active
Ras
mutant
will
allow
EGF
signaling.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
11. PI3K
generates
phosphatidylinositol
3,4,5-­-trisphosphate
from
IP3.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
12. Calcium
inhibits
PKC.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
13. cAMP
activates
PKA.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
14. The
MAP
kinase
ERK
inhibits
MAP
kinase
kinases.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­-
(
)
(
)
15. cAMP
is
an
example
of
a
first
messenger.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­----­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
16. All
7-­-Transmembrane
receptors
are
G
Protein
Coupled
Receptors.
-­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
17. Both
Ga
and
Gß
subunits
of
the
heterotrimeric
G
protein
can
mediate
GPCR
signaling.
-­--­--­-
(
)
(
)
18. Both
Ga
and
Gß
subunits
of
the
heterotrimeric
G
protein
have
GTPase
activity.
-­--­--­--­--­--­--­--­--­--­--­--­-
(
)
(
)
19. The
Gas
subunit
of
the
heterotrimeric
G
protein
suppresses
the
function
of
Adenylyl
cylase.
(
)
(

A set of erythrocytes is placed in a beaker of 0.9% NaCl.Nothing appears to happen to the cells. Why?

0.9% NaCl is hypertonic to the cells.

Sodium blocks the movement of water.

0.9% NaCl is hypotonic to the cells.

0.9% NaCl is iostonic to the cells.

water has not moved at all.

Question 2

Select one answer.

Which substance would be mostlikely to pass through a lipid bilayer/plasma membrane withoutembedded proteins?

water

a steroid hormone

a large fatty acid

a large peptide hormone

a sodium ion

Question 3

Select all that apply.

Which of the following can cross the cell’s plasmamembrane without the assistance of protein transporters?Select all that apply.

large polar molecules

positively charged ions

small hydrophobic molecules

gasses

Question 4

Select one answer.

Biological Membranesare:

symmetrical.

impermeable.

static.

dynamic.

Question 5

Select one answer.

How does the selectivepermeability of the membrane help the cell.

This allows the cell to maintain the proper shape.

This allows the cell to regulate what enters and exits

This allows the cell to maintain a constant temperature.

All of these

Question 6

Select one answer.

What is the role of carbohydratesin the plasma membrane?

cellular identification

adhesion

transport materials across the membrane

help maintain fluidity

Question 7

Select one answer.

Which component of the plasmamembrane has the widest variety of functions?

sterols

carbohydrates

phospholipids

proteins

Question 8

Select one answer.

All of the following have aneffect on the fluidity of a membrane except:

interactions among fatty acids in the core of the bilayer

the cholesterol content

the ratio of saturated to unsaturated fatty acids

the presence of integral proteins in the membrane