BIO 2112 Final

As a biochemist in a pharmaceutical company, you are working to develop a drug that will stop the cell cycle in tumor cells. Which of the following factors should the drug target in order to halt the cell cycle?
A. Cyclin dependent kinase
B. Cyclin
C. Mitotic spindle
D. Kinetochore
E. All of the above

All of the above

Mutation of the Ras G-protein can contribute to the development of a variety of cancers including lung, urinary bladder, and colon. Which of the following activities in the cancer inducing Ras G-protein is lost due to mutation?
A. GDP release
B. GTP binding
C. ATPase
D. GTPase
E. ATP binding

GTPase

A DNA sequence that can activate expression of a tissue-specific gene located 10,000 base pairs away is a(n):
A. Promoter
B. Enhancer
C. TATA box
D. Intervening sequence

Enhancer

The region of a gene that binds to general transcription factors and RNA polymerase II is a(n):
A. Enhancer
B. Intervening sequence
C. Intron
D. Promoter

Promoter

A protein in muscle cells has an amino acid sequence that is 90% identical to a protein expressed only in neurons. Interestingly, both proteins are encoded by the same gene. How did this single gene give rise to slightly different proteins in two different cell types?

A. Tissue-specific splicing factors
B. Alternative mRNA splicing
C. Micro RNA binding
D.A and B

A and B

All of the following chromatin modifications lead to the transcriptional activity of a gene except:
A. Methylation of cytosine residues (5-methyl-cytosine) in the promoter of the gene
B. Acetylation of lysine residues in the amino terminus of histone H3
C. Methylation of lysine residue 4 in the amino terminus tail of histone H3
D. Acetylation of lysine residues in the amino terminus of histone H4

Methylation of cytosine residues (5-methyl-cytosine) in the promoter of the gene

Angelman syndrome patients are profoundly impaired due to the absence of ubiquitin ligase
in certain cells of the brain. Ubiquitin ligase attaches a ubiquitin molecule to old, damaged, or unnecessary cellular proteins, thus marking them for degradation. (Brain cell function is compromised in Angelman patients due to the failure to eliminate damaged cellular proteins.) Ubiquittinated proteins are eliminated by the:
A. Proteosome
B. Nucleosome
C. Apoptosome
D. Degradasome

Proteosome

What type of mutation occurs when an error in DNA replication inserts two nucleotides into the coding region of a gene?
A. Missense
B. Nonsense
C. Frameshift
D. Silent

Frameshift

The Deadly Amanita mushroom (with a distressing resemblance to the delightful Morel) produces a toxin, α-amanitin, that inhibits the activity of mammalian RNA polymerase II. What category of RNA is not transcribed when the Deadly Amanita is eaten? (Death occurs after 24-48 hours following great discomfort)
A. micro RNA
B. Transfer RNA
C. Ribosomal RNA
D. Messenger RNA
E.A and D

A and D

Features that stabilize a messenger RNA in the cytoplasm include all of the following except:

A. 3' untranslated region (3' UTR)
B. 5' cap (7-methyl guanine)
C. Poly (A) tail
D. Introns

Introns

The translation complex includes all of the following except:

A. Transfer RNA
B. Small ribosomal subunit
C. Large ribosomal subunit
D. Messenger RNA
E. Aminoacyl-tRNA synthetase

Aminoacyl-tRNA synthetase

During the elongation stage of translation, which site on the ribosome does an activated t-RNA first bind?

A. A site
B. E site
C. P site

A site

All of the following statements about peptide bond formation are true
except:

A. The peptide bond is catalyzed by a ribosomal RNA
B. The peptide bond is formed in the A site
C. Peptide bond formation is energetically favorable
D. The peptide bond is catalyzed by a peptide synthetase

The peptide bond is catalyzed by a peptide synthetase

A cell divides to produce two daughter cells that are genetically identical.

Mitosis

Homologous chromosomes synapse and crossing over occurs.

Meiosis I

Centromeres uncouple and chromatids are separated from each other.

Mitosis and Meiosis II

Chiasmata hold homologous chromosomes together.

Meiosis I

Homologous chromosomes, in the form of tetrads, are arranged on the metaphase plate.

Meiosis I

Four genetically varied haploid cells are produced.

Meiosis II

The process is preceded by replication of the DNA.

mitosis and meiosis I

A reductional division halves the number of chromosome sets per cell from diploid to haploid.

Meiosis I

Arranges the descriptions below in an order that most logically illustrates a sequence of meiosis.
1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus
2. Alignment of tetrads at the metaphase plate
3. Separation of sister chromatids
4. Separation of the homologues; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs

A. 1, 2, 3, 4, 5
B. 5, 4, 2, 1, 3
C. 5, 3, 2, 4, 1
D. 5, 2, 4, 3, 1

5, 2, 4, 3, 1

Origins of genetic variation among offspring include all of the following except:

A. Independent segregation
B. Independent assortment
C. Crossing over
D. Random fertilization

Independent segregation

What would occur if the repressor of an inducible operon were muted so that it could not bind to the operator?

A. Irreversible binding of the repressor to the promoter
B. Reduced transcription of the operon's genes
C. Continuous transcription of the operon's genes
D. Overproduction of the Catabolite Activator Protein (CAP)

Continuous transcription of the operon's genes

What would occur if the operator sequence is removed from the lac operon?

A. The operon would be transcribed continuously
B. The operon would no longer be transcribed
C. The operon would be transcribed at a very slow rate
D. The lac repressor would bind to the first gene in the operon

The operon would no longer be transcribed

In the tryptophan operon, the trp repressor blocks transcription when it binds to

A. The operator
B. The promoter
C. The inducer
D. Tryptophan

The operator

The light reactions of photosynthesis yield three products. They are:

A. O2, NADPH, and ATP
B. CO2, NADP, and ATP
C. O2, NADP, and ATP
D. H2O, NADPH, and ATP

O2, NADPH, and ATP

Factors that are critical for the light reaction in plants are:

A. Photons (light energy)
B. Water (H2O)
C. A complex of Ca 2+, Mn ions, and Mg2+
D. All of the above
E. A and B only

All of the above

In a yeast cell undergoing mitosis, several chromosomes are not yet attached to kinetochore microtubules. For this reason, the yeast cell halts its progress until all its chromosomes are associated with kinetochore microtubules. The yeast cell then resumes cell division. In which phase of mitosis did the yeast cell stall?

A. Prophase
B. Metaphase
C. Anaphase
D. Telophase/cytokinesis

Metaphase

A biology student is sunbathing on "Beury Beach". UV radiation from the sun causes the development of several thymine dimers in the genome of a keratinocyte (skin cell). Which of the following groups of enzymes will remove the damaged nucleotide bases and restore the normal DNA structure?

A. Helicase, Primase, DNA polymerase
B. Ribonuclease III, DNA polymerase, Cohesin
C. DNA methyltransferase, Histone acetylase, Histone methyltransferase
D. Exonuclease, DNA polymerase, DNA ligase

DNA methyltransferase, Histone acetylase, Histone methyltransferase

Which of the following is false, regarding the law of segregation?

A. It states that each of two alleles for a given trait segregate into different gametes.
B. It can be explained by the segregation of homologous chromosomes during meiosis.
C. It can account for the 3:1 ratio seen in the F2 generation of Mendel's crosses.
D. It can be used to predict the likelihood of transmission of certain genetic diseases within families.
E. It reveals the distance between two genes on a chromosome.

It reveals the distance between two genes on a chromosome.

Which of the following is true for alleles?

A. They can be identical or different for any given gene in a somatic cell.
B. They can be dominant or recessive.
C. They represent alternative forms of a gene.
D. All of the above

All of the above

Mendel's law of independent assortment is demonstrated by:

A. The 9:3:3:1 ratio of phenotypes in an F2 generation.
B. The assortment of different traits into separate gametes.
C. The phenotypic ratio of a dihybrid cross
D. All of the above

All of the above

In a cross AaBbCc x AaBbCc, what is the probability of producing the genotype AABBCC? (Hint: Use a Punnett Square for each gene separately)

A. 1/4
B. 1/8
C. 1/16 D. 1/32
E. 1/64

1/64

The phenotype associated with any gene is a reflection of the molecular interactions of the protein product encoded by each allele. Based on that fact, which of the following statements is false?

A. A mutant phenotype is recessive when the mutant polypeptide does not interfere with the function of the polypeptide encoded by the normal allele.
B. The son of a man with dwarfism, an autosomal dominant disease, has 100% chance of also having dwarfism.
C. Alleles that encode lethal autosomal dominant diseases are less common in the population than alleles that encode lethal autosomal recessive diseases.
D. A mutant phenotype is dominant when the mutant polypeptide interferes with the function of the polypeptide encoded by the normal allele.

The son of a man with dwarfism, an autosomal dominant disease, has 100% chance of also having dwarfism.

Trisomy 21 (Down's syndrome) can occur when two chromosomes 21 remain together during meiosis I in sperm or egg maturation. Which of the following statements is false regarding Down's syndrome?

A. The term for the meiotic malfunction that leads to Down's syndrome is nondisjunction. B. Down's syndrome results from a meiotic malfunction when a microtubule fails to bind to the kinetochore of one of the chromosomes 21.
C. Down's syndrome is an aneuploid condition.
D. Down's syndrome has the most sever phenotype of all known trisomy conditions.

Down's syndrome has the most sever phenotype of all known trisomy conditions.

Females with trisomy X are indistinguishable from women with the normal number of X chromosomes. The reason these women have a normal phenotype is:

A. X-inactivation
B. Xist RNA expression
C. Cytosine methylation
D. All of the above

All of the above

Different breeds of horses exhibit significant differences in size. The genetic basis for size difference among horses is likely to result form:
A. Genomic imprinting of the ubiquitin gene.
B. Allelic variation in growth factor receptor genes.
C. Alternative splicing in tubulin genes. D. All of the above

Allelic variation in growth factor receptor genes.

Viruses are not considered living organisms because they cannot replicate their genomes or translate their mRNA independently. Components of the host cell that are required for the production of a mature DNA virus include al of the following except:

A. Ribosomes
B. Major histocompatibility complex
C. Aminoacyl tRNA
D. DNA polymerase
E. RNA polymerase

Major histocompatibility complex

The rhinovirus infects the epithelial cells that line your respiratory tract. As mature virus is synthesized in the infected cells, the cells fill with virus particles until the cells burst (lysis). The newly replicated virus particles then infect surrounding cells and the cycle continues, producing the symptoms of the common cold that we all have enjoyed from time to time. The best defense(s) against rhinovirus infection is (are):

A. Warm, moist air
B. Leukocytes and lymphocytes
C. Antibiotics
D. Milligram doses of vitamin C

Leukocytes and lymphocytes

Examples of complex patterns of inheritance described in questions 50-53. Match each description with the appropriate inheritance pattern (A-E).
A. Incomplete dominance
B. Polygenic inheritance
C. Pleiotropy
D. Epistasis
E. Codominance


50. Traits that exhibit quantitative variation (skin color or height) and are under the control of several genes.

Polygenic inheritance

Examples of complex patterns of inheritance described in questions 50-53. Match each description with the appropriate inheritance pattern (A-E).
A. Incomplete dominance
B. Polygenic inheritance
C. Pleiotropy
D. Epistasis
E. Codominance


51. The ABO blood group system.

Codominance

Examples of complex patterns of inheritance described in questions 50-53. Match each description with the appropriate inheritance pattern (A-E).
A. Incomplete dominance
B. Polygenic inheritance
C. Pleiotropy
D. Epistasis
E. Codominance


The phenotype of the heterozygote differs from the phenotypes of both homozygotes.

Epistasis

Examples of complex patterns of inheritance described in questions 50-53. Match each description with the appropriate inheritance pattern (A-E).
A. Incomplete dominance
B. Polygenic inheritance
C. Pleiotropy
D. Epistasis
E. Codominance


Cystic fibrosis affects the lungs, the pancreases, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections.

Pleiotropy

A recent epidemic of influenza A killed hundreds of individuals in several countries. What molecular markers were used to identify this strain of influenza A?

A. Hemagglutinin and Neuraminidase
B. Viral DNA and RNA
C. Viral reverse transcriptase
D. Capsid proteins

Hemagglutinin and Neuraminidase

A mutation that inactivates the Ras GTPase activity is a dominant mutation.

A. True
B. False

True

The following statements describe the function of the p53 tumor suppressor except:

A. p53 activates genes that encode DNA repair enzymes
B. p53 activates expression of genes encoding proteins that stop the cell cycle
C. p53 activates apoptosis
D. p53 prevents cells from passing on mutations due to DNA damage.
E. p53 slows down the rate of DNA replication by binding DNA polymerase.

p53 slows down the rate of DNA replication by binding DNA polymerase.

When proto-oncogenes mutate, they can become oncogenes. All of the following statements describe oncogenes and/or their oncoprotein products except:

A. The retinoblastoma protein (pRb) is an example of a tumor promoter.
B. Oncogenes encode proteins that promote cellular growth and division.
C. Examples of proteins that have the potential to become oncoproteins include cyclins, tyrosine kinase receptors, and G-proteins.
D. Oncogenes frequently overexpress their protein product.

The retinoblastoma protein (pRb) is an example of a tumor promoter

Which of the following statements does not describe a mechanism that converts a proto
oncogene to an oncogene?

A. A proto-oncogene is translocated to another chromosome and is now regulated by a very active promoter.
B. A segment of a chromosome that contains a proto-oncogene is deleted (removed) during S phase of the cell cycle.
C. A segment of a proto-oncogene that encodes the ligand binding domain of a receptor protein is deleted during S-phase of the cell cycle.
D. A segment of a chromosome that contains a proto-oncogene is copied three times during S phase of the cell cycle, resulting in amplification of that region of the chromosome.
E. A promoter regulating transcription of a proto-oncogene becomes constitutively (constantly)
active.

A proto-oncogene is translocated to another chromosome and is now regulated by a very active promoter.

All of the following are examples of tumor-suppressor proteins except:

A. DNA repair enzyme MSH3
B. The G2 checkpoint protein CHFR
C. Protein phosphatase 2A
D. Cyclin dependent kinase 2 (cdk2)
E. The cell cycle inhibitor p21

Cyclin dependent kinase 2 (cdk2)

Which of the following statements does not describe benign tumors?

A. Benign tumors are never life threatening.
B. Benign tumors contain cells that have lost control of the cell cycle.
C. Cells from benign tumors do not migrate into the surrounding connective tissue.
D. Benign tumors contain cells that have sustained mutations in both tumor suppressor genes and tumor promoter genes.

Benign tumors are never life threatening

Which of the following statements correctly describes malignant
tumors?

A. Malignant tumors are metastatic.
B. Malignant tumor cells break away from the primary tumor, migrate through the vasculature,
and establish secondary tumors.
C. Malignant tumors cells reactivate segments of the genome that encode proteins that initiate cell migration.
D. All of the above

All of the above

SU5416 is a cancer drug that interferes with the function of the vascular endothelial growth factor receptor (VEGF-R). Which of the following pathways does this drug directly inhibit?

A. Mitotic spindle formation
B. Metastasis
C. Cell motility
D. Cleavage furrow formation
E. Angiogenesis

Mitotic spindle formation

Which of the following is not a factor in the aging process?

A. Mitochondrial genome damage
B. The insulin pathway
C. Macrophage migration
D. Accumulation of mutations throughout the nuclear genome

Macrophage migration

A primary cause of aging are reactive oxygen species (ROS). The following statements describe ROS except:

A. Reactive oxygen species are insufficiently reduced oxygen molecules produced during
electron transport.
B. Reactive oxygen species damage nucleic acids, proteins, and membranes of the cell and its
organelles.
C. ROS damage nuclear DNA at a rate 10-20 times higher than mitochondrial DNA
D. ROS are converted first to hydrogen peroxide (H2O2) and then to water by superoxide dismutase and glutathione peroxidase, respectively.

ROS damage nuclear DNA at a rate 10-20 times higher than mitochondrial DNA

The number of division a cell can undergo is limited by:

A. Cell age
B. Cell size
C. Telomere length
D. All of the above

All of the above

The incidence of age-related diseases has decreased significantly in the 21st century.

A. True
B. False

False

All of the following statements describe DNA synthesis except

A. Helicase unwinds the DNA helix and topoisomerase II cleaves both strands of DNA in order to relieve strain from unwinding
B. Okazaki fragments are joined together by DNA ligase
C. An RNA primer is used for both leading and lagging strands
D. Okazaki fragments are generated by leading strand synthesis

Okazaki fragments are generated by leading strand synthesis

A cell in a banana leaf has very high levels of NADPH in the stroma of the chloroplasts, and inadequate amounts of ATP to power the Calvin Cycle. The mechanism the cell will use to balance ATP and NADHP+ levels is

A. Cyclic electron flow
B. Noncompetitive inhibition of NADP+ reductase
C. Noncompetitive inhibition of Ferredoxin
D. Competitive inhibition of ATP synthase

Cyclic electron flow

Which of the following statements describes energy coupling?

A. Energy released from exergonic reactions used for endergonic reactions.
B. The intermediate molecule in energy coupling is adenosine triphosphate.
C. Energy coupling can occur through the phosphorylation of an enzyme endergonic reaction.
D. All of the above.

All of the above.

Which of the following statements does not describe the flow of enzymes?

A. Glycogen synthesis is achieved through a series of exergonic
B. Lipids are broken down by the cell in order to generate ATP.
C. Glycolysis is a catabolic process that yields energy for the cell.
D. Nucleic acid synthesis is a process that is both anabolic and endergonic.

Glycogen synthesis is achieved through a series of exergonic

Determine the standard free energy (ΔG°) for the following coupling reactions. Is this coupled reaction exergonic or endergonic?

W-X + ATP → Y-Z + ADP + Pi W-X → Y-Z ΔG° = -49.5 kJoules/mole

ADP + Pi → ATP ΔG° = 30.5 kJoules/mole

A. -19 kJoules/mole, exergonic
B. 80 kJoules/mole, endergonic
C. 19 kJoules/mole, endergonic
D. -80 kJoules/mole, exergonic

-19 kJoules/mole, exergonic

An enzyme increases the rate of a reaction by

A. Lowering the energy of activation (EA)
B. Lowering the standard free energy (ΔG°) of the reaction
C. Lowering the free energy (ΔG) of the products
D. Increasing the tendency of the reaction to go to equilibrium

Lowering the energy of activation (EA)

Acetylcholine is a neurotransmitter that binds to receptors that signals muscle contraction. After the signal for muscle contraction the enzyme acetylcholinesterase clears away excess acetylcholine breakdown into acetic acid and choline, thus terminating acetylcholine. Sarin is a chemical warfare "nerve agent" that functions as an inhibitor of acetylcholinesterase and preventing neuromuscular signals from transmitting between neurons from the central nervous system to muscle fibers. The action of Sarin is an example of:

A. Feedback inhibition
B. Noncompetitive inhibition
C. Competitive inhibition
D. Allosteric inactivation

Noncompetitive inhibition

The enzyme Methylenetetrahydrofolate Dehydrogenase-Cyclohydrolase forms with Magnesium (Mg2+) and Folate (Folic acid). This complex functions in the acid and nucleic acid biosynthetic pathways.

80. What is the role of Folate in its association with the enzyme?

A. Apoenzyme
B. Cofactor
C. Coenzyme
D. Holoenzyme

Coenzyme

The enzyme Methylenetetrahydrofolate Dehydrogenase-Cyclohydrolase forms with Magnesium (Mg2+) and Folate (Folic acid). This complex functions in the acid and nucleic acid biosynthetic pathways.


81. What is the role of Magnesium (Mg2+) in its association with the enzyme? A. Apoenzyme
B. Cofactor
C. Coenzyme
D. Holoenzyme

Cofactor

The energy of activation (ΔGuncat) needed to convert reactants to products is 9.9 kJoules/mol. When the reaction is catalyzed by an enzyme that's activation energy (ΔGcat) is 3.6 kJoules/mol. The binding energy (ΔGB) of the reaction is

A. 6.3 kJoules/mol
B. 10.5 kJoules/mol
C. 3.6 kJoules/mol
D. 9.9 kJoules/mol

6.3 kJoules/mol

A list of weak acids with their pKa's is given below. Which will best ionize into its conjugate base?

Acid pKa
Boric acid 9.24
Citric acid 3.13
Formic acid 3.75
Oxalic acid 1.27
Succinic acid 4.21

A. Boric acid
B. Citric acid
C. Formic acid
D. Oxalic acid
E. Succinic acid

Oxalic Acid

What is the buffering range of cacodylic acid (pKa = 6.27)?

A. pH 8.56 - 9.56
B. pH 2.78 - 10.78
C. pH 5.27 - 7.27
D. pH 3.42 - 6.42

pH 5.27 - 7.27

Use the Henderson-Hasselbalch equation to calculate the pH of a one-liter solution containing 0.09 moles of cacodylic acid and 0.9 moles of its conjugate base, cacodylate. The pKa of cacodylic acid is 6.27.

pH = pKa + log [Proton acceptor] [Proton donor]

A. 7.27
B. 6.27
C. 5.27
D. 8.27

7.27

The pH of human blood plasma is controlled by the partial pressure of CO2 in the gas phase and the concentration of HCO3- in the aqueous phase. Based on this information, is the following statement true or false?

The pH of blood plasma is regulated by the rate of inhaling and exhaling. (T or F)

True

Important differences between the electron transport chain (ETC) in the chloroplasts of plant cells and the ETC in the mitochondria of animal cells include all of the following expect:

A. The source of electronegativity used to "pull" electrons down the ETC
B. The structure and function of ATP synthase
C. The splitting of a water molecule
D. The use of Ferredoxin as an electron carrier

The structure and function of ATP synthase

NADH AND FADH2 deliver electron transport chains to the matrix of the mitochondria. Which of the following statements describes ____ H+ ions?

A. The H+ ions form a proton motive force that powers the synthesis of _______
B. The H+ ions are pumped out of the mitochondria, and then out of the ______ electrochemical gradient across the cell membrane
C. The H+ ions function in chemiosmosis
D. A and C

A and C

What are the functions of nicotinamide adenine dinucleotide (NAD+) and (FAD) that function with the enzyme described in question above?

A. Coenzymes
B. Electron shuttles
C. Cofactors
D. All of the above
E. A and B

A and B

There are hundreds of species of bacteria that occupy the human large ... regions of the intestine are anaerobic, meaning there is very little O2 available ... species of bacteria generate ATP by:

A. Chemiosmosis
B. Oxidative phosphorylation
C. Substrate level phosphorylation
D. All of the above

Substrate level phosphorylation

A yeast cell that has been exposed to ultraviolet light has sustained a ... gene that encodes the enzyme phosphofructokinase. The gene now encoded ... nonfunctional enzyme. Which one of the following statements best describes ... of this mutation on the yeast cell?

A. The citric acid cycle and oxidative phosphorylation will be unaffected by...mutation
B. Glycolysis will continue to generate ATP, NADH, and pyruvate
C. The yeast cell will respond to changes in levels of ATP, citrate, and AMP
D. The yeast cell will die, due to lack of ATP
E. The yeast cell will generate ATP by substrate level phosphorylation

The yeast cell will die, due to lack of ATP

Much of the CO2 we exhale is a waste product of catabolism. Which one ... pathways generates this molecule?

A. Glycolysis
B. Citric acid cycle
C. Amino acid biosynthesis
D. Oxidative phosphorylation

Citric acid cycle

A certain strain of yeast is known for producing delicious bread. To make ...yeast in mixed into flour and water and the resulting dough is incubated and heated to ... degrees Fahrenheit. For the bread dough to rise to its maximum level, CO2 ... generated. Which of the following partial pressures of O2 will yield the most ... function?

0%

The term bioavailability refers to how easily molecules, including drugs, can cross the plasma membrane and enter the interior of the cell. Pictured below are four molecules. Based on your knowledge of biological membranes, which of these molecules is most likely to enter the cell by freely crossing the plasma membrane?

A. CH3 - CH2 - CH2 - CH2 - CH3
B. CH3 - CH2 - CH2 - CH2 - NH3+
C. CH3 - CH2 - CH2 - CH2 -C- O
D. Molecule with hexagons

CH3 - CH2 - CH2 - CH2 - CH3

What category of enzyme removes electron (and H+ ions) from organic ... during the breakdown of macromolecules?

A. Ligase
B. Isomerase
C. Lyase
D. Oxidoreductase

Oxidoreductase

Na+ ions are actively transported from the cell to the extracellular space. Na+ ions then flow from a concentration of 145 mM to the interior of the cell where the Na+ ion concentration is
12 mM. The same membrane transporter simultaneously carries glucose from a low extracellular concentration to a relatively higher concentration inside the cell.

A. Facilitated diffusion
B. Active transport
C. Secondary active transport
D. Osmosis
E. Passive diffusion

Secondary active transport

Na+ ions are transported from the interior of a cell with a concentration of 12mM to the extracellular space where the Na+ concentration is 145 mM.

A. Facilitated diffusion
B. Active transport
C. Secondary active transport D. Osmosis
E. Passive diffusion

Active transport

Free water molecules move from a region in the cell containing 50 nM Ca2+ to another region within the same cell with a concentration of 90 nM Ca2+.

A. Facilitated diffusion
B. Active transport
C. Secondary active transport
D. Osmosis
E. Passive diffusion

Osmosis

Estradiol, a small, uncharged molecule, enters a neuron by directly penetrating the plasma membrane.

A. Facilitated diffusion
B. Active transport
C. Secondary active transport
D. Osmosis
E. Passive diffusion

Passive diffusion

H+ ions flow down their concentration gradient, through a transmembrane channel protein in inner membrane of the mitochondria.

A. Facilitated diffusion
B. Active transport
C. Secondary active transport
D. Osmosis
E. Passive diffusion

Facilitated diffusion

The organic molecule generated by the Calvin Cycle that is the precursor (starting point) of all macromolecules in our biosphere is:

A. Glucose
B. Ribulose biphosphate
C. CO2
D. Glyderaldehyde-3-phosphate

Glucose

When a receptor tyrosine kinase binds to a signaling molecule, the conformational changes that occurs in the receptor are:

A. Acetylation and methylation
B. Dimerization and cleavage by a peptidase
C. Dimerization and phosphorylation
D. Signal peptide cleavage and phosphorylation

Dimerization and phosphorylation

Enzymes that inactivate signal transduction cascades include all of the following except:

A. Adenylyl cyclase
B. GTPase
C. Phosphodiesterase
D. Phosphatase

Adenylyl cyclase

Cell surface receptors that transmit signals into the cytoplasm and induce a cellular response include all of the following except

A. Tyrosine kinase receptor
B. Estrogen receptor
C. G-protein-linked receptor
D. Ligand-gated ion channel

Estrogen receptor

A sample of cancer cells is removed from a patient during a biopsy. The cells are places in a culture medium containing amino acids, glucose, ions, and a variety of growth factors. After three days in culture the cells are alive but none of the cells divided. The most reasonable explanation for why the tumor cells did not divide is:

A. The cells have undergone apoptosis
B. The cells do not express specific receptors for the growth factors in the medium
C. The checkpoints in the cells are no longer functioning
D. The calcium concentration in the cytoplasm of the cells is above 300 nanomolar

The cells do not express specific receptors for the growth factors in the medium

Which of the B vitamins listed below play a critical role in ATP synthesis?

A. Niacin
B. Riboflavin
C. Thiamine Phosphotase
D. Pantothetic acid
E. All of the above

All of the above

All of the following statements correctly describe individual steps in the estrogen-signaling pathway except

A. Estrogen binds to its receptor displayed on the surface of a target cell
B. The estrogen-receptor complex migrates into the nucleus
C. The estrogen-receptor complex acts as a transcription factor by binding to DNA and
activating expression of the estrogen-responsive genes
D. Proteins that are synthesized in response to the estrogen-signaling pathway can change
cell behavior

Estrogen binds to its receptor displayed on the surface of a target cell

A surveillance mechanism that prevents a cell from moving into the next phase of the cell
cycle until critical biochemical processes are complete is a:

A. Kinase Inhibitor
B. Transcription factor
C. Checkpoint
D. Termination factor

Checkpoint

At which phase of the cell cycle are mature, non-dividing cells, such as nerve cells, muscle cells, and liver cells maintained?

A. G0
B. G1
C. S
D. G2
E. M

G0

A graduate student is studying a pathological bacterial strain. As a part of a project to develop an antibiotic against the bacterial strain, the student needs to determine the number of proteins present in the ribosome. The best technique for investigating this question is:

A. Cell homogenization and centrifugation
B. Phase contrast microscopy
C. Brightfield microscopy
D. Scanning electron microscopy
E. Transmission electron microscopy

Transmission electron microscopy

Patients with artificial heart valves take a drug called Warfarin to thin the blood and prevent the formation of blood clots around the heart valve. In the liver cells of these patients, the smooth endoplasmic reticulum responds to Warfarin by doing all of the following except:

A. Contributing to the patient's resistance to Warfarin
B. Detoxifying Warfarin by adding methyl groups (-CH3) to its ring structures
C. Increasing in size
D. Increasing the solubility of Warfarin

...

Integrin is a cell surface protein that transmits signals from the extracellular space to the actin microfilaments of the cytoskeleton. Which of the following best describes the pathway used by the cell to synthesize and transport the integrin protein to its final position in the cell?

A. Free ribosome Nuclear pore Nucleolus
B. Free ribosome, lysosome, Golgi, Plasma membrane
C. Nuclear pore, Smooth ER, Transport vesicle
D. Nuclear pore, Rough ER, Golgi, Plasma membrane

Nuclear pore, Rough ER, Golgi, Plasma membrane

Lysosomal storage diseases, such as Tay-Sachs, result in debilitating illness and death. Such diseases are caused by mutations that inactivate important metabolic enzymes that break down macromolecules. The category (type) of enzyme that is mutated in Tay-Sachs is:

A. Hydrolase
B. Lyase
C. Isomerase
D. Oxidoreductase
E. Ligase

Hydrolase

Which of the following is not true regarding the cytoskeleton:
A. The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments
B. The cytoskeleton is synthesized from tubulin, actin, and keratin
C. Motor proteins associated with the cytoskeleton are Dynein and Myosin
D. Intermediate filaments, composed of keratin, are assembled and dissembled rapidly, depending on the needs of the cell

Intermediate filaments, composed of keratin, are assembled and dissembled rapidly, depending on the needs of the cell

Kartagener's syndrome is a rare genetic disorder affecting 1 out of 40,000 individuals. Manifestations of this disease include chronic bronchitis and pneumonia, ear infections, and male infertility (due to immobile sperm). Certain patients with this disorder have a mutant motor protein that cannot activate the "waving" motion of cilia or flagella. The motor protein affected in this disease is:

A. Kinesin
B. Myosin 1
C. Dynein
D. Myosin II

Dynein