Exam 1 Mole. Cell Bio

Which pair of values best fills in the blanks in the following statement?

On average, eukaryotic cells are __________ times longer and have __________ times more volume than prokaryotic cells.

A) 10; 1000

B) 5; 100

C) 10; 200

D)10; 100

A) 10; 1000

True or False: Protozoans are single-celled eukaryotes with cell morphologies and behaviors that can be as complex as those of some multicellular organisms.

True

The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances?

A) carbon dioxide

B) sulfur

C) nitrogen

D) oxygen

D) oxygen

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but NOT true of RNA?

A) It has 5´-to-3´ directionality.

B) It is single-stranded.

C) It contains uracil.

D) It contains thymine.

D) It contains thymine.

Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks. Which of the monosaccharides below fills this important role?

A) ribulose

B) ribose

C) glucose

D) fructose

B) ribose

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets?

A)palmitic acid

B) triacylglycerol

C) cholesterol

D) isoprene

B) triacylglycerol

Maintaining pH and salt concentrations is critical to keeping proteins functional. What is the molecular mechanism by which pH affects protein function?

A) Only the primary structure is altered, which changes the folding and function of the protein.

B) The hydrogen bonds within the polypeptide backbone that form the secondary structures are completely disrupted.

C) The N- and C-terminus amino acids with their amino and carboxyl ends can change the shape of the entire protein.

D) A few of the polar R-groups can change charge, and the new attraction or repulsion can alter the shape of the protein.

D) A few of the polar R-groups can change charge, and the new attraction or repulsion can alter the shape of the protein.

The correct folding of proteins is necessary to maintain healthy cells and tissues. The presence of unfolded proteins is associated with some neurodegenerative disorders such as Alzheimer’s disease, Huntington’s disease, and Creutzfeldt–Jakob disease (the specific faulty protein is different for each disease). What happens to these disease-causing, unfolded proteins?

A) They bind a different target protein.

B) They are degraded.

C) They form structured filaments.

D) They form protein aggregates.

D) They form protein aggregates.

Motor proteins use the energy in ATP to transport organelles, rearrange elements of the cytoskeleton during cell migration, and move chromosomes during cell division. Which of the following mechanisms is sufficient to ensure the unidirectional movement of a motor protein along its substrate?

A) A conformational change is coupled to ATP hydrolysis.

B) The substrate on which the motor moves has a conformational polarity.

C) A conformational change is coupled to the release of a phosphate (P_i).

D) A conformational change is coupled to the binding of ADP.

A) A conformational change is coupled to ATP hydrolysis.

The Ras protein is a GTPase that functions in many growth factor–signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells?

A) a change that decreases the affinity of Ras for GTP

B) a change that prevents Ras from being made

C) a change that increases the affinity of Ras for GDP

D) a change that decreases the rate of hydrolysis of GTP by Ras

D) a change that decreases the rate of hydrolysis of GTP by Ras

Photosynthesis enables plants to capture the energy from sunlight. In this essential process, plants incorporate the carbon from CO₂ into high-energy __________ molecules that plant cell mitochondria use to produce ATP.

A) protein

B) fiber

C) sugar

D) fat

C) sugar

True or False: If you sequenced the genome of one type of differentiated cell in a plant or animal, it would include unique sequences that are not found in the genome of a second type of differentiated cell from the same plant or animal.

False

Which of the following are examples of isomers?

A) glycogen and cellulose

B) adenine and guanine

C) glucose and galactose

D) alanine and glycine

C) glucose and galactose

Select the answer that best completes the following statement: Chemical reactions in living systems occur in an __________ environment, within a narrow range of temperatures.

A) aqueous

B) extracellular

C) organic

D) optimal

A) aqueous

Triacyclglycerols are examples of:
A) nucleic acids.

B) lipids.

C) proteins.

D) monosaccharides.

B) lipids.

Which of the following is NOT a feature commonly observed in β sheets?

A) extended polypeptide backbone

B) parallel regions

C) coiled-coil patterns

D) antiparallel regions

C) coiled-coil patterns

Two or three α helices can sometimes wrap around each other to form coiled-coils. The stable wrapping of one helix around another is typically driven by __________ interactions.

A) hydrophilic

B) hydrophobic

C) ionic

D) van der Waals

B) hydrophobic

Energy required by the cell is generated in the form of ATP. ATP is hydrolyzed to power many of the cellular processes, increasing the pool of ADP. As the relative amount of ADP molecules increases, ADP can bind to glycolytic enzymes, which will lead to the production of more ATP. The best way to describe this mechanism of regulation is

A) feedback inhibition.

B) oxidative phosphorylation.

C) substrate-level phosphorylation.

D) allosteric activation.

D) allosteric activation.

Cyclic AMP (cAMP) is a small molecule that associates with its binding site with a high degree of specificity. Which types of noncovalent interactions are the most important for providing the “hand in a glove” binding of cAMP?

A) van der Waals interactions

B) hydrophobic interactions

C) hydrogen bonds

D) electrostatic interactions

C) hydrogen bonds

The octameric histone core is composed of four different histone proteins, assembled in a stepwise manner. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following histone proteins does NOT form part of the octameric core?

A) H4

B) H2A

C) H3

D) H1

D) H1

Which of the following chemical groups is NOT used to construct a DNA molecule?

A) nitrogen-containing base

B) phosphate

C) six-carbon sugar

D) five-carbon sugar

C) six-carbon sugar

The inactivation of one X chromosome is established by the directed spreading of heterochromatin. The silent state of this chromosome is __________ in the subsequent cell divisions.

A) maintained

B) erased

C) switched

D) completed

A) maintained

In addition to the repair of DNA double-strand breaks, homologous recombination is a mechanism for generating genetic diversity by swapping segments of parent chromosomes. During which process does swapping occur?

A) transposition

B) DNA repair

C) meiosis

D) DNA replication

C) meiosis

How many replication forks are formed when an origin of replication is opened?

A) four

B) two

C) one

D) three

B) two

Genetic Changes acted on by selectuon are best described as the fundamentals of what process?

A) Evolution

B) Regeneration

C) DNA Replication

D) Reproduction

A) Evolution

True or False: All cells require oxygen in order to survive.

It is false because some cells perform anaerobic respiration.

True or False: Organisms that have inherited their genetic instructions from a common ancestor share the same DNA sequences.

False

What is a drawback to using electron microscopy?

A)It can be used only to view samples that are sliced very thinly.

B) It cannot be used to view a whole cell or organism.

C) It can be used only to view the atomic details in structures larger than a riboseme.

D) It cannot be used to view living cells.

D) It cannot be used to view living cells.

What is a drawback to using light microscopy?

A)It can be used only to view samples that are sliced very thinly.

B) It cannot be used to view a whole cell or organism.

C) It cannot be used to view living cells.

D) It cannot be used to view structures smaller than a bacterium.

D) It cannot be used to view structures smaller than a bacterium.

Some antibiotics target features that are unique to bacterial cells and absent from our own cells. Which of the following would present a safe target for a new antibiotic?

A) Nuclear Envelope

B) Plasma Membrane

C) EEndoplasmic Reticulum

D) Cell Wall

D) Cell Wall

Which of these three classifications is included within one of the others: prokaryotes, eukaryotes, or archaea?

A) Eukaryote

B) Prokaryote

C) Archaea

C) Archaea

True or False: Genome sequencing has revealed that archaea and bacteria—which are both prokaryotes—differ as much from each other as either does from the eukaryotes.

False

Which cellular component separates the DNA of eukaryotic cells from the cytosol?

A) Cell Wall

B) Plasma Membrane

C) Smooth Endoplasmic Reticulum

D) Nuclear Membrane

D) Nuclear Membrane

Which structure or process mediates the exchange of materials between the endoplasmic reticulum, Golgi apparatus, the lysosomes, and the outside of the cell?

A) Cytosol

B) Peroxisomes

C) Simple diffusion across the membrane

D) Transport Vesicles

D) Transport Vesicles

Which term best describes a pair of genes (or gene products) that derived from a common ancestral gene?

A) Analogous

B) Superfluous

C) Homogeneous

D) Homologous

D) Homologous

Which of the following is frequently studied as a model vertebrate?

A) Drosophila Melanogaster

B) Arabidopsis Thaliana

C) Jellyfish

D) Zebrafish

D) Zebrafish

Which statement is NOT true of E. coli?

A) E. coli can be grown in the laboratory.

B) E. coli normally lives in the guts of humans and other vertebrates.

C) E. coli stores genetic information in the form of DNA.

D) E. coli is a model eukaryote.

D) E. coli is a model eukaryote.

Which subatomic particle is found in the nucleus of a hydrogen atom?

A) a neutron plus a proton

B) a neutron only

C) an electron only

D) a proton only

D) a proton only

The atomic weight of an atom is its mass relative to that of what?

A) Hydrogen

B) Carbon

C) Water

D) Oxygen

A) Hydrogen

On the basis of mass, which is most abundant in a living bacterial cell?

A) Inorganic Ions

B) Fatty Acids

C) Proteins

D) Water

D) Water

Covalent bonds are formed by the sharing of electrons. In the cell, how are covalent bonds broken?

A) By energetic molecular collisions with protons

B) By energy provided by the electrical force across membranes

C) By energetic molecular collisions with negative ions.

D) By enzyme catalysis that is specific for a protein and its substrate

D) By enzyme catalysis that is specific for a protein and its substrate

Which of the following would most likely interact by forming an ionic bond?

A) The enzyme hexokinase and its substrate glucose

B) Two strands of DNA

C) Fatty acid chain and inorganic phosphate

D) ATP and magnesium cations

D) ATP and magnesium cations

How do protein, nucleic acid, and polysaccharide molecules polymerize (grow in length)?

A) by hydrolysis reactions

B) by oxidation reaction

C) by condensation reactions

D) by van der Waals reaction

C) by condensation reactions

Protein molecules that have a quaternary structure will always have two or more of which of the following?

A) different primary structures

B) disulfide bonds

C) polypeptides

D) α helices and β sheets

C) polypeptides

What does the primary structure of a protein refer to?

A) the locations of the peptide bonds that form the protein’s backbone

B) the overall three-dimensional shape of the protein

C) the linear amino acid sequence of the protein

D) the structure that forms first as the protein folds into its most stable form.

C) the linear amino acid sequence of the protein

True or False: Chaperone proteins provide the energy needed for a protein to fold into the correct conformation.

False

Enzymes alter the speed of a reaction without affecting the overall energy (thermodynamics) of its reactants or products. Enzymes accomplish this by doing which of the following?

A) reducing the activation energy of a reaction

B) supplying the activation energy for a reaction

C) elimination the activation energy for a reaction

D) increasing the activation energy for a reaction

A) reducing the activation energy of a reaction

All of the following are true concerning enzymes except which statement?

A) They can bring reactants togethr in the proper orientation for chemistry to occur.

B) They usually require an input of energy from ATP for activation.

C) They can form covalent bonds with their substrates

D) They can change the shape of substrates to increase the rate of a particular reaction.

B) They usually require an input of energy from ATP for activation.

What determines the specificity an antibody has for its antigen?

A) polypeptide loops in its variable domains

B) polypeptide loops of its light chain

C) the location of its disulfide bonds

D) its Y-shaped, bivalent structure

A) polypeptide loops in its variable domains

When are chromosomes in their most compact form?

A) during interphase

B) during mitosis

C) during replication

D) during gene expression

B) during mitosis

Which statement is true about the association of histone proteins and DNA?

A) Histone proteins form hydrogen bonds with the nucleotide bases of DNA.

B) Each Histone protein has a deep grove int whoch a DNA double helix tightly fits

C) Histone proteins have a high proportion of negatively charged amino acids, which bind tightly to the positively charged DNA backbone.

D) Histone proteins have a high proportion of positively charged amino acids, which bind tightly to the negatively charged DNA backbone.

D) Histone proteins have a high proportion of positively charged amino acids, which bind tightly to the negatively charged DNA backbone.

Where is heterochromatin not commonly located?

A) centromeres

B) the Human X chromosome

C) gene-poor chromosomal regions

D) chromosomal regions carrying genes that encode ribosomal proteins

D) chromosomal regions carrying genes that encode ribosomal proteins

Consider the process that a cell uses to replicate its double-stranded DNA before undergoing cell division. Which statement describes the DNA in the resulting daughter cells?

A) One daughter cell recieves the DNA strands that were originally in the parent cell, while the other daughter recieves the newly synthesized strands.

B) Each strand of DNA in the daughter cells contain a mix of both newly replicated and parent DNA.

C) The daughter cells recieve only newly synthesized DNA; the parent cell keeps the original DNA.

D) The double helix in each daughter cell consists of one parent strand and one newly synthesized strand.

D) The double helix in each daughter cell consists of one parent strand and one newly synthesized strand.

When is homologous recombination, which can flawlessly repair double-strand DNA breaks, most likely to occur?

A) before DNA is replicated, to avoid propagating the error

B) when the breaks are overlooked by the fast-acting mismatch repair system

C) whenever a double-strand break is detected

D) after the cell’s DNA has been replicated

D) after the cell’s DNA has been replicated

DNA mismatch repair typically corrects what percentage of replication errors?

A) 1%

B) 50%

C) 100%

D) 99%

D) 99%

Which of the following best defines a mutation?

A) mistake created by faulty mismatch repair

B) harmful change in a DNA sequence

C) change in DNA sequence that causes a change in an amino acid in a protein

D) permanent change in a DNA sequence

D) permanent change in a DNA sequence