BMS 528 Exam 3

Module 9:

Which of the following is not a major component of biological membranes?

A. Nucleic Acids

B. Proteins

C. Lipids

D. Sugars

A

An integral membrane is:

A. A protein whose amino acids are inserted into the membrane

B. A protein whose amino acids are not inserted into the membrane

C. A protein with a lipid modification

D. A protein that is cytoplasmic and associates with the membrane

A

Select all that apply.

The fluid mosaic model of membrane dynamics states that:

A. Membranes are static with lipids and proteins fixed in place

B. Membranes can easily dissociate and are highly permeable

C. Membranes are fluid meaning lipids, proteins and other molecules can migrate or float around within the structure

D. Lipids form a bilayer embedded with other molecules like proteins

CD

Lipids form large covalent polymers like proteins, nucleic acids

A. True

B. False

B

Lipids do not form from large covalent polymers instead associate with other lipids through hydrophobic interactions to form membranes

A. True

B. False

A

Select all that apply.

Fatty acids consist of:

A. A phosphate group

B. Hydrocarbon tail

C. Carboxylic acid

D. Glycerol backbone

BC

Which of the following statements is true:

The fluidity of fatty acids decrease (they become less fluid/ more solid) as...

A. Cis double bonds increase

B. Cis double bonds decrease

C. A carbon tail length decreases

D. None of the above

B, more saturated and more solid

Which of the following is not a component of glycerophospholipids?

A. Glycerol

B. Phosphate

C. Fatty Acid

D. Glucose

D

Cardiolipin has which of the following "shapes" that function to help form crustaceans in the inner mitochondrial membrane?

A. Conical

B. Cylindrical

C. None of the above

A

Lipids with what charge tend to be more concentrated in the inner leaflet plasma membrane?

A. Negative

B. No charge

C. Positive

A

Lipids like cardiolipin have a conical shape. What is the effect of this on membrane structure?

A. Introduce curvature

B. Remove curvature

C. Make membranes more charged

D. None of the above

A

Transmembrane proteins tend to enrich their intracellular sides with positively charged amino acids. Why?

A. Because inner leaflet of lipid bilayer is positively charged

B. Because outer leaflet of lipid bilayer is negatively charged.

C. Because inner leaflet of lipid bilayer is negatively charged

D. None of the above

C

Select the answer that best fits the blank below:

The distribution of different types of lipids is ___________ between the outer and inner leaflets of the plasma membrane?

A. Unequal

B. Even

C. Equal

D. None of the above

A

You have discovered a new lipid that forms an amide bond between its backbone and a fatty acid. This lipid also contains a sugar head group. Which of the following types of lipid does your new lipid resemble?

A. Steroids

B. Glycerophospholipids

C. Gangliosides

D. Cardolipins

C

You observe that the transport of an ion across a membrane has a ∆G = -10. What type of transport is this?

A. Passive

B. Cannot tell with this information

C. Active

A

Glucose transport via GLUT proteins is an example of what?

A. Active transport

B. Secondary active transport

C. Transport via a symport

D. Facilitated Diffusion

D

The Na+ Glucose transport system is an example of which of the following? (Select all that apply)

A. Active transport

B. Symport

C. Passive transport

D. Uniport

AB

Which of the following glycerophospholipids has no net charge/is neutral at pH 7.4?

A. Phosphatidylethanolamine

B. Phosphatidic acid

C. Phosphatidylinositol

D. Phosphatidylserine

A

The picture depicts the structure of cholesterol. Identify any polar portion of the molecule:

A. Section A

B. Cholesterol contains no polar groups

C. Section B

D. Section C

Section A

Two newly discovered fatty acids each have 20 carbon molecules in their tails. Lipid 1 has a higher melting temperature than Lipid 2. Which of the following options would best describe why this might be the case?

A. Lipid 2 is unsaturated with trans-double bonds

B. Lipid 2 is unsaturated with cis-double bonds

C. Lipid 2 is longer than lipid 1

D. Lipid 1 is unsaturated with cis-double bonds

B

Module 10:

A receptor tyrosine kinase is mutated. The mutation stops the RTK from dimerizing. What affect will this have on RTK function

A. None of the above

B. Increase the expression of the RTK

C promote activation of the RTK

D stop activation of the RTK

D

What does GTPase do? Select all that apply

a. Phosphorylated other proteins

B. Bind to guanine nucleotides

C. Hydrolyzed nucleotide triphosphates

d. Function as part of signaling pathways

BCD

RAS proteins are GTPase protein that are frequently mutated in cancer. Mutations in RAS proteins lock protein in its active state, meaning it continually signals to promote cell growth. For over 40 years, scientists have worked to develop inhibitors of RAS but with limited success. Which of the following approaches?

A. Increasing farnesylation of RAS

B. Removing all GTP from cells containing mutate RAS

C. Inhibition of RAS farnesylation

D. Inhibition of Rase kinase activity

C

G proteins are GTPases that bind guanine nucleotides. When they are switched on, they are bound to GTP. What type of reaction do G proteins perform to convert GTP to GDP?

A. Phosphate transfer reactions

B. Hydrolysis reactions

C. Decarboxylation reactions

D. Methyltransferase reactions

B

G proteins are heterotrimers of a, b, y subunits. Which subunit binds to nucleotides?

A. A subunit

B. Y subunit

C. B subunit

D. None of the above

A

Kd is the constant that describes what?

A. The rate of ligand binding to a receptor

B. The concentration of ligand when the receptor is fully bound by ligand

C. The concentration of ligand when the receptor is 50% bound by ligand

D. The concentration of receptor when the receptor is 50% bound by ligand

C

What type of lipid is a precursor for the second messengers IP3 and DAG?

A. Phosphatidic acid

B. Phosphatidulinositiol

C. Phosphatidylserine

D. Cardiolipin

B

Upon activation, some T cells secrete the chemo kind interleukine-2 to enhance the survival and proliferation of the very same T cell producing the cytokine. What type of signaling is this?

A. Paracrine

B. Endocrine

C. Autocrine

D. All of the above

C

Long range signaling tends to be carried out by what general class of ligand?

A. Endocrine

B. Autocrine.

C. Paracrine

D. All of the above

A

Signaling between two cells close in space is carried out by what general class of ligands

A. Autocrine

B. Paracrine

C. Endocrine

D. All of the above

B

Receptor tyrosine kinase must dimerize in order to function

A. True

B. False

A

Receptor tyrosine kinases have how many transmembrane domains?

A. 1

B. 7

c. 2

D. 4

A

Which of the following are mechanisms for "switching receptor signaling off"

A. Reverse activating modifications

B. Second messenger generation

C. Isoprenylation

D. Endocytosis

AD

G protein coupled receptor have how many transmembrane domains ?

A. 1

B. 10

C. 7

D. 5

C

Receptor X and Receptor Y both bind ligand Z. Receptor X binds to ligan Z with a Kd= 40 mM

A. Cannot tell with this information

B. Receptor Y

C. Receptor X

D. Both the same

B

An inverse agonist will have what effect on receptor activity?

A. Block the effect of other agonists but leave the receptor unaffected

B. Partially increase receptor activity

C. Fully activate receptor activity

D. Inhibit receptor activity completely

D.

Which of the following pathways involves a cytokine receptor?

A. EGF signaling

B. Insulin signaling

C. IL-2 signaling

D. Acetylcholine signaling

C

Kon and Koff are both:

A. rates

B. constants

C. ligands

D. receptors

A

Insulin binds to its receptors to facilitate a signaling cascade that causes the translocation of GLUT4 transporters to the surface of the cell. What is the consequence of this?

A. Activation of adenylation cyclase enzymes

B. Inhibition of adenylate cyclase

C. Greater glucose transport across the membrane

D. Reduced glucose transport

C.

Insulin binds to its receptors to facilitate a signaling cascade that causes the translocation of GLUT4. Transporters to the surface of the cell. What class of receptor does insulin bind to?

A. Ion channel

B. Receptor tyrosine kinase

C. Cytokine receptor

D. GPCR

B

CaMP is a second messenger molecule that function to do what?

A. Inhibit protein kinase A

B. Inhibit phospholipase C

C. Activate phospholipase C

D. Activate protein kinase A

D

G protein coupled receptors must dimerize in order to function

A. True

B. False

B

The graph below shows a variety of GPCR ligands with different activities

Would ligand (graph/line) shows the effects of an antagonist?

A. A (dark green line)

B. B (light green line)

C. C Yellow line

D. D orange line

E. E red line

C

Isoprenylation is a post-translational modification of protein. What is added to proteins that are "isoprenylated"?

A. A fatty acid chain

B. A phosphate group

C. An isopropanol molecule

D. A methyl group

A

Module 11:

Which of the following is a crucial component of PCR reaction? Select all that apply?

A. DnTPS

B. Primers

C. Divalent cations

D. DNA polymerase

ABCD

You work in a lab and want to insert a gene into a plasmid. The picture below shows the sequence where the plasmid can by cut by restriction enzymes. Which enzyme will produce sticky ends?

A. Enzyme 1

B. Enzyme 2

C. Both Enzymes

D. Neither enzyme

A.

Which of the following methods separates protein based on only size?

A. Size exclusion chromatography

B. Ion exchange chromatography

c. Native page

D. Affinity chromotagraphy

A

What is recombinant DNA?

a. DNA from bacteria

B. DNA formed using lab methods

C. DNA made by reverse transcription

D. None of the above

B. DNA formed using lab methods

Which of the following DNA elements would be desireable in a vector if your intended purpose was to express a protein? (Select all that apply)

A. Promoter site

B. Restriction enzyme cleavage site

C. Ori site

D. Antibiotic resistance gene

ABCD

Which of the following are not components of a CRISPR Cas9 system?

A. Guide RNA

B. RNA polymerase

C. Optional template for repair

D. Cas9 enzyme

B

Agarose gel electrophoresis is a technique primarily used to separate what type of bio molecule?

A. Nucleic acid

B. Proteins

A

A cDNA library is created from mRNA using what type of primer?

A. Oligo dt

B. Oligo dG

C. Specific primers for every gene

D. None of the above

A

Alkaline lysis denature dsDNA by what mechanism?

A. Making the solution more acidic

B. Heats up DNA

C. Disrupting DNA hydrogen bonding between DNA strands

D. None of the above

C

Why might a viral vector be advantageous for gene therapy?

A. Could insert the gene of interest into the host genome

B. Could spread the gene virally through all cells

C. Could be maintained as a plasmid in eukaryotic cells

D. None of the above

A.

An antibiotic resistance gene in a plasmid would serve what purpose?

A. Selection of bacteria with the plasmid

B. Digestion site for restriction enzymes

C. Promote gene expression

D. Promote plasmid replication

A

What size nucleic acid would migrate furthest down an agarose gel during electrophoresis?

A. Small

B. Both the same

C. Large

A

Practice Exam:

Which option best describes the below fatty acid?

15 carbon molecule with a double on C8

A. 14:1Δ7

B. 14:1Δ8

C. 15:1Δ7

D. 15:1Δ8

D

The picture depicts the structure of cholesterol. Identify any polar portion of themolecule

A. Section A

B. Section B

C. Section C

D. Cholesterol contains no polar groups

A

A lipid modification is added to a protein, in a manner similar to the addition of afarnesyl group to the oncoprotein K-Ras. What is the effect of this modification?

A. Causes protein degradation

B. Targets protein to localize at the cell membrane

C. Causes protein to form higher order structures

D. Makes proteins available for transport around the body

B

A G protein-coupled receptor named CXCR4 binds to its ligand named CXCL12 with a Kd of approximately 2 nM. When the N terminus of the receptor is removed (reffered to here as CXCR4ΔN-term), the Kd of CXCR4ΔN-term is approximately 500 nM. Which of the following options is a likely function of the CXCR4 N-terminus?

A. To bind to heterotrimeric G proteins

B. To activate the receptor

C. The bind the ligand CXCL12

D. To facilitate CXCR4 degradation

C

You have a mixture of two DNA fragments, A and B. Fragment A is 600 basepairs in length, Fragment B is 500 basepairs in length. To separate the two, you perform agarose gel electrophoresis. Which fragment will migrate furthest down the gel?

A. Fragment A

B. Fragment B

C. Both will migrate the same distance

D. Cannot tell with the current information

B

True or false:

Alkaline lysis disrupts DNA base pair hydrogen bonds.

A. True

B. False

A

Transmembrane proteins like ion channels and aquaporin allow for facilitated diffusion across the plasma membrane of molecules like e.g. ions and water.Generally, what effect do these channels have on the rate of diffusion across a membrane?

A. No effect

B. Increase the rate of diffusion

C. Decrease the rate of diffusion

B

When inserting a gene of interest into a plasmid, the use of restriction enzymes isadvantageous for which of the following reasons?

A. Cutting the plasmid and gene to the same length

B. Production of complementary sticky ends on the gene and plasmid

C. Degrading any DNA that is not required for cloning

D. None of the above

B

Which of the following is not a constituent of most membrane lipids?

A. Phopsphates

B. Fatty acids

C. Glycerol/Sphingosine backbone

D. Nitrogen rich base

D

The glycerol backbone of glycerophospholipids contains how many carbons?

A. 1

B. 2

C. 3

D. 4

C

Identify the following lipid: Note: R =a fatty acid

4 fatty acids

3 glycerols

2 phosphate groups

A. Phosphatidylglycerol

B. Phosphatidylserine

C. Phosphatidic acid

D. Cardiolipin

D, properties of cardiolipin

the other three are glycerophospholipids with 2 fatty acids

The "inside positive" rule of membrane protein folding states that:

A. Cytoplasmic portions of membrane proteins are enriched in positively charged amino acids thatassociate with negatively charged phospholipid head groups on the inner leaflet of the plasmamembrane

B. Extracellular portions of membrane proteins are enriched in positively charged amino acids thatassociate with negatively charged phospholipid head groups on the outer leaflet of the plasmamembrane

C. Cytoplasmic portions of membrane proteins are enriched in positively charged amino acids thatassociate with positively charged phospholipid head groups on the inner leaflet of the plasmamembrane

D. Cytoplasmic portions of membrane proteins are enriched in negatively charged amino acids thatassociate with positively charged phospholipid head groups on the inner leaflet of the plasmamembrane

A

What effect will the binding of an agonist likely have on a receptor protein?

A. Induce a conformational change in the receptor

B. Cause receptor degradation

C. Increase the expression of the receptor

D. Inhibit the receptor

A

An experiment was performed in 1970 that involved the following:

• labelling a mouse cell with red-fluorescent antibodies specific to mouseproteins

• labelling a human cell with green-fluorescent antibodies specfic to human proteins

• Fusing the two labelled cells togetherWhat did the result of this experiment show?

A. After cell fusion, mixing of the human and mouse proteins was observed proving membranes arefluid

B. After cell fusion, mouse and human proteins did not mix

C. After cell fusion, cells died proving proteins from other species are toxic to cells

D. None of the above

A

True or False: All cells e.g. erythrocytes and hepatocytes, contain the same ratio of lipids, proteins and sugars.

A. True

B. False

B

The sodium/potassium ATPase is an example of what type of membrane transporter?

A. Uniport B. Symport C. Antiport D. None of the above

C

ATP hydrolysis by the sodium potassium ATPase induces which of the following tooccur?

A. A conformational change in the protein and release of sodium into the extracellular environment

B. Release of energy utilized by another pathway

C. Breakdown of ATP to AMP

D. All of the above

A

A secondary effect of the sodium potassium ATPase in cells of the intestinal lumenis:

A. To inhibit sodium uptake from the intestine

B. To facilitate glucose transport from the intestine

C. To increase potassium absorbtion from the intestine

D. None of the above

B

Which of the following is not an essential component of a PCR reaction?

A. Magnesium

B. Heat stable DNA polymerase

C. Primers

D. DNA ligase

D

The translocon is a complex of proteins that assists with protein folding. Which ofthe following is true about the role of the translocon in membrane protein folding?

A. The translocon is not involved in membrane protein folding

B. The translocon is slighly open on one side to allow hydrophobic amino acids to partition into themembrane

C. The translocon is slighly open on one side to allow hydrophillic amino acids to partition into themembrane

D. The translocon ensures correct disulfide bond formation in membrane proteins

B

A transmembrane protein you are studying has one transmembrane domain and must dimerize to become active. Which of the following amino acids would likely be crucial for the function of your protein?

A. Alanine

B. Tryptophan

C. Tyrosine

D. Lycine

C

What type of molecules can cross the plasma membrane by simple diffusion?

A. Carbohydrates

B. Proteins

C. Water

D. Gases

D

You have two proteins, Protein A and Protein B. Protein A is 20 kDa in size, whileProtein B is 70 kDa in size. You perform size exclusion chromatography toseparate the two. Which protein will elute from your size exclusion column first?

A. Protein A

B. Protein B

C. Both at the same time

D. Cannot tell from this information

B

Which of the following lipid head groups is uncharged at physiological pH?

A. Phosphatidylinositols

B. Phosphatidic acid

C. Phosphatidylserine

D. Phosphatidylcholine

D

Receptor tyrosine kinases MUST dimerize in order to function.

A. True

B. False

A

"An increase in the intensity of a signal through networks of intracellular reactions"is the definition of what process?

A. Signal amplification

B. Signal integration

C. Signal transduction

D. DNA cloning

A

McCune-Albright syndrome is a genetic condition that affects the bones, skin andendocrine system. It is caused by a sporadic activating mutation in a gene thatenocodes for a G protein. The consequence of this mutation is increased ProteinKinase A (PKA) activity and signaling in the PKA pathway.Given this information, which G protein do you think is most likely mutated in McCune-Albright syndrome?

A. Gαi

B. Gαs

C. Gαq

D. Gβ

B