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Please
be careful in your reading of all of the instructions and the questions. Please ask if you have any problems in
understanding what is required for each question. Write yourname on the examand the scantron sheet.
Numbers
1 through 10 are either true (A) or false (B). Please place your answer on the
scantron sheet. Mark clearly and erase
completely. (1 point each/10 total//10
overall)
1.___ Dialysis is defined as a cell
membrane experiencing diffusion of solute molecules moving primarily from a
region of higher solute concentration to a region of lower solute concentration.
2.___Molecules that move
directly through the phospholipid bilayer of the membrane most rapidly by means
of simple diffusion are charged, highly polar and small in size.
3.___ During receptor mediated
endocytosis the cell produces long pseudopods that can enclose whole bacterial
cells and this produces small endocytotic vesicles that peroxisomes attach to
once they are inside the cell.
4.___ A protein molecule that is
responsible for moving sodium atoms out of the cell and potassium atoms into
the cell, each against their concentration gradients, is an example of an active
transport, antiport-carrier protein.
5.___
If electrogenic pumps are embedded in the cell membrane of a bacterial
cell and are moving hydrogen ions from the cytoplasm to the extracellular
region then you should conclude that the extracellular region has a higher pH
and a more negative charge than the cytoplasm.
6.___The active
transport of sodium ions from the cytoplasm of a eukaryotic cell to the
extracellular space would be an example of an electrogenic pump creating a
situation of unequal sodium distribution, an ion concentration gradient, a
gradient of charge and stored potential energy.
7.___ Lysosomes may be involved in
the digestion of cells and debris, taken in from the outside environment in
contractile vacuoles, through the process of autophagy.
8.___ Proteins that are
referred to as multi-pass proteins are integral transmembrane proteins with
repeated alpha helical motifs passing through the cell membrane and they are
produced by bound ribosomes associated with the rough ER.
9.___ Glycolipid anchored proteins
are made exclusively by free ribosomes and are found exclusively attached to
the intracellular surface of the plasma membrane.
10.___The pseudopod (filipod/lamellapod)
extensions of cell membranes are formed internally by components of the
cytoskeleton called microtubules and require keratin proteins to form.
Numbers
11 through 20 matching. Please make only
one choice for each, no choice is used twice and some choices are not used at
all. Please also note that some answers require you to fill in two letters
on the answer sheet. For example choiceJ requires letter spacesB
& C filled in.
(1 pt ea/ 10 tot//20 overall)
11.___
Carrier A.
Organelle that is responsible collecting water from the cytoplasm of a protistan
cell (Paramecium) and actively
pumping water to the extracellular environment utilizing myosin motor proteins.
12.___ Coenzyme B.
This term is utilized to identify the organic, non-protein cofactor molecules
that form a permanent portion of an enzyme’s structure by binding to the
apoenzyme.
13.___
Cilia C. The movements of ER/Golgi vesicles
in the anterograde direction through the endomembranous system are dependent on
the movement of these motor proteins in the microtubule + direction.
14.___ Clathrin D.
This term is used to identify the membrane channel protein responsible for
rapid diffusion of the cellular solvent molecule.
15.___Contractile
Vacuole E. This is an example of an
organic cofactor of an enzyme that binds temporarily to the protein portion of
the enzyme, many are commonly called vitamins.
16.___
Pseudopods F(AB) Flexible cellular
extension with internal microtubule protein 9+2 structure and has associated dynein
motor proteins that can move (bend) the structure at a rate of 40-60 times
/sec.
17.___Keratin G(AC) Formed by actin
microfilaments during endocytosis when a macrophage of your immune system
consumes a bacterial cell or large clusters of cellular debris.
18.___Kinesin H(AD)The
protein triskelion material that is directly associated with coated vesicle
formation and binding to receptor proteins.
19.___Myosin I(AE). These are the key
type of motor proteins associated with cytokinesis in dividing cells,
cytoplasmic streaming in plants and muscle contraction in animal cells.
20.___Prosthetic
group JBC). Integral
transmembrane protein that is required for the active transport of molecules
across the membrane.
K(BD).
These are the key motor proteins associated with the bending of the
microtubules found making up the structure of flagella and cilia.
L
(BE).These
proteins are key components of the cytoskeleton of the epithelial cells of your
body, and represent a prime example of intermediate filaments in those cells.
Numbers 21 through 29 are multiple
choice. For each please mark theone best answer.
(
2pts ea/ 18 tot// 38 overall).
21.__
How would you describe the location involving the binding of a substrate to an enzyme?
A. It would also bind to a noncompetitive
inhibitor by means of irreversible binding.
B. It would be able to bind to an allosteric
activator by means of irreversible binding.
C. It would bind to any molecule that has the
chemistry of a noncompetitive inhibitor.
D. It would be the portion of the enzyme to be
involved in catalyzing a chemical reaction
E. It would be the site where a coenzyme would
bind after the completion of catalysis.
22.__ Which of the following would be
categorized as: Amolecule whosestructure
would allow binding to the same location as the normal substrate, is classified
as a type of venom molecule with a conformation similar to the normal substrate,
and result in permanent dysfunction (inhibition) of the enzyme.
A.
noncompetitive reversible inhibitor
B.
allosteric regulatory inhibititor
C.
competitive irreversible inhibitor
D.
irreversible allosteric inhibitor
E.
competitive reversible activator
23.___ If an allosteric enzyme is
located in a cellular metabolic pathway that is regulated by feedback
inhibition then which of the following would you expect to be true of that
feedback system.
A. The molecule that is the
allosteric inhibitor should be the final product of the metabolic pathway.
B. The molecular product of the
first enzyme would be the inhibitor of the metabolic pathway.
C.
The catalytic subunit of the allosteric enzyme would bind to a competitive
inhibitor.
D. The regulatory subunit of the
allosteric enzyme would be bound to a noncompetitive inhibitory molecule.
E.
The regulatory enzyme would be at the final position, the last reaction, of the
metabolic pathway.
24.___ Which of the
followingis not a true characterization of enzymes or enzyme function.
A.
Enzymes are composed primarily of proteins
but may also have inorganic and organic cofactors attached.
B.
Enzymes lower the activation energy required
by a chemical reaction.
C.
Enzymes can be altered in function and/or
form by high temperature or extremes of pH.
D.
Enzymes can be used over and over because
they are not altered as a result of the involvement in a chemical reaction.
E.
Enzymes are never changed in shape during
their activities as they catalyze chemical reactions.
25.___
Which of the following is an incorrect representation of membrane structure.
A.
Membranes are described as being a fluid mosaic with both a highly flexible
nature and a composition including lipids, proteins, and carbohydrates.
B. The phospholipid bilayer of the
membrane has both a hydrophobic interior and both external surfaces are
hydrophilic.
C. The
two leaflets of the bilayer are typically very similar in terms of the variety
of phospholipids present, with very little difference in composition.
D.
Glycolipid anchored proteins are located on the exterior surface of the
membrane and lipid anchored proteins are on the interior surface.
E. Integral
and integral transmembrane proteins of the membrane all have an amphipathic
nature.
26.____
Which of the following is acorrect statement concerning the process of osmosis
associated with a selectively permeable membrane. Consider our model system
discussed in class.
A. Water
cannot diffuse from a hypertonic solution to a hypotonic solution.
B. Cells
placed in isotonic solutions have no solute diffusing through their cell
membrane therefore the cell looks the same as before, no change in appearance.
C. Animal
cells that are placed in a hypertonic solution typically swell to the point of
lysis (cytolysis), due to gain of water.
D. Water
will primarily flow (diffuse) through a membrane from a hypotonic solution into
a hypertonic solution.
E. The
greater the solute concentration differences between two solutions the slower
the rate of osmosis that will occur between those two solutions.
27.__
Which of the followingis an incorrect
conclusion (prediction) concerning cells and the adaptations associated with S/V. Cells are :
A. small
and/or spherical to reduce S/V ratio.
B. large
and/or spherical to maximize S/V ratio.
C. large
and/or irregular to reduce S/V ratio.
D. small
and/or irregular to maximize S/V ratio.
E. small
with increased internal membranes to minimize S/V.
28.__
Which of the followingis not correctconcerning elements of the cytoskeleton and motor proteins.
A. Dynein motor proteins are associated with
microtubules and have the capacity to move vesicles toward the negative end of
the microtubule.
B. Vesicles that are moved between the ER and
Golgi are “carried or pulled” along microtubules by motor proteins.
C. The processes of cyclosis (cytoplasmic
streaming) and contractile vacuole function are both associated with the
interactions of myosin motor proteins with microfilaments.
D. The key events associated with skeletal
muscle contraction are interactions between keratin intermediate filaments and
kinesin proteins.
E. Microfilaments are associated with the
internal support and structure of the cell processes called microvilli and
pseudopods.
29.__
Which of the followingis not correct concerningthe formation of protein coated vesicles.
A. The coating proteins attach to membrane peripheral
protein receptors but only after the membrane has formed itself into a vesicle.
B. Protein coated vesicles are associated with
both the anterograde and retrograde movement of vesicles between components of
the endomembranous system.
C. Clathrin proteins may be associated either
with receptor mediated endocytosis or the formation of lysosomal vesicles.
D. Coating proteins must be able to attach to
receptor proteins external Golgi domains (cytoplasmic domain) but only after a
mannose 6 phosphate protein is attach to the luminal Golgi domain of the
receptor protein.
E. Protein coated vesicles may attach to motor
proteins like kinesins or dyneins, and are moved by these motor proteins to their
target membranes for fusion.
Please use the
following space to correctly complete the following illustration.
This will be used for 30-34. (2 pts ea/10 tot // 48 overall)
You have a cell of 20% solute
concentration. Assume a simple solution of only 1 solute and 1 solvent
molecule.In each of the three cases
(A,B,C) in the lower part of the illustration the arrows are for thedialysis occurring between the
cellular (intracellular) solution and the extracellular solution. The solvent molecule is also able to freely
diffuse.
CELL
solvent = solute =20%
The
cell from above is placed into the following solutions A, B and C and the
resultingdialysis represented by
the arrows. Tonicity comparison arefrom
theextracellularsolutionto theintracellular solution. Assume
osmosis also freely occurs.
Tonicity ________ _________ _________
A. Extracellular
Solution B. Extra. Solution C. Extra. Solution
solvent = solvent = solvent =
solute = solute = solute =
Using
the illustration above and the letter choices A, B, C please answer the
following questions.
NOTE:
You may need to use more than one letter to correctly answer the questions.
30.___ In which situation(s) is
the cell’s cytoplasmhypotonic
compared with the surrounding (extracellular)
solution.
31.___In
which extracellular solution(s) might thesolvent
concentration be75%.
32.___In which of the solutions would the cell
experienceosmosis occurring in both
the extracellular and intracellular directions.
33.___
Which of the cells would experience anet
intracellular movement of thesolvent
molecules.
34.___
In which of the solutions would the cell (if abacterial cell) experience the potential forplasmolysis.
Numbers
35 and 36 are expanded multiple choice questions. Please read the descriptions carefully and
draw some conclusion about the appropriate explanations. Please choose the2 best answers for each. (4
pts each/ 8 total/52 overall)
35.___ You are analyzing a cell and
noteprotein molecules that are
organized with the following regions (domains).
The protein has a portion of its structure composed of a number (approx.
15-20) of hydrophobic amino acids that areembedded
in the phospholipid bilayer of the plasma membrane, there are 12 of these
regions in the proteins structure . The
protein has anextracellular domain
that includes a structure that can bend or flex so that it can extend straight
out from the rest of the protein orfold
over the extracellular surface of the protein. You note that as the concentration of Na+
(sodium ions) in the extracellular environment increases the protein changes
shape so that itsextracellular domain
flexes and points directly out from the protein surface. This change in shape exposes anopen passage that extends through the
protein. When this occurs you note that
the Na+ readily pass through thisstable passage whilesimultaneously
molecules of NAD+ also move through another region of the open protein
passage. The materials moving through
the membrane are both seen tomove
towards their lower concentration in the intracellular space. The description of this protein suggests that
it is ….. (mark all appropriate choices//2).
A. Clearly this is a description of a
protein that is triggered to change shape by a change in the ion concentrations
in the extracellular environment and allow the facilitated diffusion of Na+.
B. The change in shape of this protein
clearly points to an active transport carrier protein associated with the
regulation of ion concentration in the cell.
C. This protein is definitely a kind of
antiport carrier protein that is performing cotransport and therefore should be
designated a cotransporter protein.
D. This seems to best fit a
transmembrane protein classified as a gated channel and in addition it should
be called a symport protein.
E. This is the type of receptor protein
that is commonly associated with receptor mediated endocytosis and is
responsible for the uptake of NAD+ from the environment.
36.___
While you are investigating the movement of materials through bacterial cell
membranes you note the following. The cells
areactively utilizing ATPs to push
a large number ofprotons (H+)
into the extracellular space. The charge of the exterior of the cell
becomes much more positive relative to the intracellular space and theexternal pH drops rapidly. The cells you are culturing are being
provided with glucose molecules as a nutrient source but havedepleted much of theglucose in their environment. The bacterial cellsmust actively move glucose molecules from the extracellular
environment to the cytosol to maintain their metabolic activity and growth. As
you observe the cells you note asimultaneous
increase in theintracellular glucose concentrationand an increase in thepH of
the extracellular environment. Thisprocess
continues as the bacterial cell works topump protons from the cell and at thesame time glucose continues toconcentrate
in the interior of the cell. These events most clearly point to the cell ……
(mark all appropriate choices // 2)
A.
This cell is definitely producing a strong concentration of glucose molecules
inside the cell by the facilitated diffusion of the glucose across the
membrane.
B.
This cell is able to concentrate the glucose in this way due to the facilitated
diffusion of protons through an H+/glucose cotransporter protein.
C.
The protein involved in the movement of the Hydrogen ions to the cell exterior
is functioning as an antiport active transport channel protein.
D.
The protein that performs the concentration of glucose in the cell must be a
symport carrier protein that uses proton movement to power active transport.
E.
This is clearly a situation that the organisms cannot maintain and with time
the organisms will establish an equilibrium situation with equal concentrations
of protons on both sides of the membrane.
37
through 40 are fill in the blanks. Read
carefully and be as precise as possible, one, two or more words may be needed
for an answer. Place these answers in
space(s).(2pts/8 tot //61 overall)
37.__________________________
This is an organelle with the
following qualities: double membrane, organelle interior called amatrix, specialized protein embedded in
a highly folded internal membrane calledcristae,
only in eukaryotes and this is the region of the cell responsible forATP production in the cell. (1 word)
38.______________________ _______________________
This is an amino acid regionapproximately
15 amino acids longfound near the
N-terminus of some proteins. This region of amino acids determine that the
protein isattached to by SRP in the
cytoplasm and their production is then completed by abound ribosome. This region of these proteins is responsible for
regulating the movement of these proteins through thetranslocons of the ER. (2 words)
39.________________________ _____________________ __proteins____ This type of membrane proteins are associated with theintracellular surface of the cell
membrane and they do not have hydrophobic amino acid regions. They are produced in the cytoplasm byfreeribosomesand then are attached tofatty acid lipids that are inserted in the cell membrane. (2 words)
40.______________________________________________________This type of endocytosis is associated
with the production ofactin
microfilament bundles, these bundles are responsible for the extension of
the cell membrane into projections calledpseudopods.
The pseudopods connect around cellular debris or foreign cellsforming a vacuole inside the cell. Once
in the celllysosomes attach to the
vacuole and inject digestive enzymes.
Numbers
41 discuss the concept of S/V in terms of cells. What is S/V? Why do cells
“want” tomaximize S/V? What key
adaptations do cells have to maximize S/V?Explain anexception to these ideas provided by thehuman or frog ovum. Use
complete sentences for the following.
Please make sure you are clear and concise.No illustrations please. (4 pts/
65 overall)
Number
42 is your longer answer / illustration question. You will need tochoose one of the following to answer. With this question you need to be complete
and fully cover the topic. You need to
make sure you have sufficient illustration(s) material to present the
topic. Make sure all illustrations are
labeled clearly and that your answer directly references your illustration.
(10
pts // 75 total)
A. Classification of transport proteins. Various membrane associated proteins are
involved in the movement of materials across cell membranes. Theclassification
of these proteins involves an organization that includes(1) the nature of substances moved (number
and direction),(2) the action of
the protein during transport (shape change or not) and(3) the energetics of the transport process (active or
passive). Make sure all of these
components are addressed and after that include the concept ofcotransporter systems and secondary active
transport as a component of your presentation. Make sure to relate the idea
ofelectrogenic pumps and the
potential uses of the gradient created.
B. Components of the cytoskeleton. You should be able to explain the basic
protein components of the cytoskeleton.
How do they compare /contrast in term of size, form? Types of components –microfilaments, intermediate filaments, microtubules. Composition, examples, size and function of
each group. Make sure to make a clear
presentation of how these elements interact with motor proteins. Motor proteins associated with each.Kinesins, dyneins, myosins. Relate the key features of the cellular
structure calledflagella/cilia. Association the role of cytoskeletal elements
withintracellular transport,
osmoregulation, cell division and cytoplasmic streaming.
C.
Structure and function of endomembranous system.You should be able to outline thestructural and functional features of
the endomembranous system of the eukaryotic cell. You should describe each of the components
separately and their interactions.Include:
ER, vesicles, Golgi, Lysosomes and their association with the cell membrane and
the role of ribosomes in the production of proteins. Make sure you clearly represent in yourillustration the orientation (topology)
of lipids and proteins in relation to their production and final location. Please note where key functions oflipid synthesis, protein production,
protein and lipid glycosylation, and sphingolipid production take place.
Place your answer with clear
illustrations in the following sections.
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