CB final exam
Even though DNA polymerase has a proofreading function it still introduces errors in the newly synthesized strand at a rate of 1 per 107 nucleotides. To what degree the mismatch repair system decreases the error rate arising from DNA replication?
100-fold
If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively?
16 protons; 19 neutrons; 16 electrons
How many replication forks are formed when an origin of replication is opened?
2
Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input?
2 ATP, 2 NADH
During glycolysis, the number of ATP consumed (per glucose molecule) is ___, while the number produced is ___
2, 4
The number of ATP molecules that could be synthesized from the energy released by the transfer of two electrons from NADH to molecular oxygen is
2.5
Modern eukaryotes depend on mitochondria to generate most of the cell's ATP. How many molecules of ATP can a single molecule of glucose generate?
30
There are 90 naturally occurring elements on the earth, __________ of which compose 96% of the mass of living organisms.
4
Figure 7-3 shows a ribose sugar. The part of the ribose sugar where a new ribonucleotide will attach in an RNA molecule is pointed to by arrow
4 (3')
Which of the following DNA strands can form a DNA duplex by pairing with itself at each position?
5' AAGCGCTT 3'
Export of RNA from the nucleus requires the RNA to have which characteristic(s)?
5' cap and poly-A tail
Figure 19-24 diagrams one of the Mendel's experiments using the round and wrinkled seed traits. If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of a wrinkle-seeded plants, how many round-seeded plants would you expect to obtain in the next generation?
50%
Which of the following represents a symport transporter protein?
A
Which of the following statements about cancer is FALSE?
A mutation in even a single cancer critical gene is sufficient to convert a normal cell into a cancer cell
Which of the following would be able to cross a protein free lipid bilayer most rapidly?
A steroid hormone (nonpolar, large)
Which of the following descriptions best matches the function of a kinase?
An enzyme that catalyzes the addition of phosphate groups to other molecules
In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated?
At the end of G2.
Which of the labels in the following figure shows a nucleosome core particle?
B
Sort the following from a low to a high contribution to the total mass of an E. coli bacterium. Your answer would be a four-letter string composed of letters A to D only, e.g. DCBA. (A) Water;(B) Sugars; (C) Proteins; (D) Nucleic acids
BDCA
Microtubules extend from organizing centers in the cell. Which is an example of an organizing center?
Basal body of a cilium
Which of the following processes that happen inside a cell DOES NOT normally require the consumption of free energy by the cell?
diffusion of small molecules within cell
Which of the following statements is TRUE?
disulfide bonds stabilize but don't change a protein's final conformation
Cells in the G0 state
do not divide
DNA replication is considered semi-conservative because
each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand
A mutant with a small haplotype block surrounding it likely arose
earlier in the evolution of the organism
The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that
energy can be extracted in usable amounts
Cells that are specialized for the secretion of proteins are likely to have which of the following features?
enlarged ER
The concentration of mitotic cyclin (M cyclin)
falls toward the end of M phase as a result of ubiquitylation and degradation
The food molecule whose breakdown generates most of the energy for a majority of animal cells is
glucose
Which of the following are examples of isomers?
glucose & galactose
Hemopoietic stem cells in the bone marrow produce all of the following specialized cells EXCEPT
heart muscle cells
which of the following statements is true regarding cellular metabolism?
heat released by an animal cells as part of its metabolic processes comes from the bond energies
When an organism has inherited two nonidentical alleles, it is said to be
heterozygous
When activated, a G-protein has a structure that
is bound to GTP
It is a model organism used to study various cellular processes such as regulation of the eukaryotic cell cycle. Mutants are available for every gene in its exceptionally small genome. It can live indefinitely in either haploid or a diploid state. Which of the following describes this organism?
it is a fungus
RNA in cells differs from DNA in that
it is single-stranded and can fold up into a variety of structures
Enzymes that add a phosphate group to a switch protein are called
kinases
Which of the following is NOT a feature commonly observed in α helices?
left handedness
Noncoding RNAs include all of the following EXCEPT
mRNA
A transcriptional regulator that activates expression of additional transcriptional regulators that induce production of a particular cell type or organ is called a
master regulator
The proton flow through the transmembrane H+ carrier of ATP synthase results in
mechanical rotation that is converted into the chemical-bond energy of ATP
Cadherins
mediate cell-cell attachments through homophilic interactions
In the terms of structure, if cytoplasmic intermediate filaments are described as ropes, nuclear lamins could be best described as
mesh
The kinetochores of sister chromatids in meiosis I attach to
microtubules from the same spindle pole.
A loss-of-function mutant will always be dominant if the
mutant form of the protein interferes with the wild type version.
Which of the following statements is TRUE?
non polar amino acids tend to be found in interior of proteins.
An oncogene is different from a tumor suppressor gene in that
oncogenes have mutations causing increased activity of the protein.
The four products of human germ-cell meiosis each contain _____ copy(ies) of each gene.
one
Which of the endocytic pathways involves the ingestion of large particles or microorganisms and is performed mainly by specialized cells?
phagocytosis
Which of the following is true regarding energy production and storage in plants and animals?
plan seeds often contain large amounts of fats and starch
The control of a gene products levels or activity after transcription has taken place called
post-translational control
Long noncoding RNA (IncRNA) can function as a(n)
protein scaffold
Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is a/an
proto-oncogene
Fibroblasts organize the collagen of the extracellular matrix by
pulling the collagen into sheets or cables after it has been secreted.
The DNA from two different species can often be distinguished by a difference in the
ratio of A + T to G + C
Aromatic carbon compounds such as benzene are planar and very stable. Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside. This characteristic is caused by electron
resonance
Microtubules are inherently unstable unless they are
stabilized by a (+) end attachment.
What can happen if heterochromatin spreads inappropriately into an area with active genes?
the active genes can become silenced
Progression through the cell cycle requires a cyclin to bind to Cdk because
the binding of a cyclin to Cdk is required for Cdk enzymatic activity
Which of the following statements is true regarding reactions involving oxidation and reduction?
the carbon atom is more oxidized in form aldehyde (CH2O) than in methanol (CH3OH)
Initiator proteins bind to replication origins and disrupt hydrogen bonds between the two DNA strands being coupled which of the factors below does not contribute to the relative ease of strand separation by initiator proteins?
the rxn can occur at RT
In a DNA double helix,
the two DNA strands run antiparallel
Scientists discover more than ten thousand new species of living organisms every year. What is shared between all of these organisms?
their genome contains at least 1000 genes
Mitochondria and chloroplasts are thought to have evolved from free-living aerobic bacteria that were engulfed by an ancestral anaerobic cell and established a mutually bene!cial (symbiotic) relationship with it. Which of the following statements is NOT true about these organelles?
they are both in all eukaryotes
The information in an mRNA molecule is converted into protein sequence using
three consecutive bases, with no overlap between triplets
Both multicellular plants and animals have
tissues composed of multiple different cell types.
MicroRNAs block the expression of a specific gene product by binding to the mRNA and inhibiting
translation
Proteins that are fully translated in the cytosol do not end up in
transport vesicles
One of the two types of GTP-binding proteins, often called G-proteins, are membrane bound. These are the
trimeric GTP-binding proteins
Which of the following is a mobile electron carrier in the electron-transport chain?
ubiquinone
A single nondisjunction event during meiosis
will result in the production of two normal gametes if it occurs during meiosis II.
Is it possible for a hydrogen bond to form between two sugars?
yes, the partial negative on the oxygen of an -OH group can be attracted to the partial positive of the hydrogen on another -OH group.
ΔG measures the change of free energy in a system as it converts reactant (Y) into product (X). When [Y] = [X], ΔG is equal to
∆G⦁
When an action potential excites a muscle ell, where do the calcium ions come from?
Both the extracellular space and the sarcoplasmic reticulum
The biosynthetic pathway for the two amino acids E and H is shown schematically in Figure 4-33. You are able to show that E inhibits enzyme V, and H inhibits enzyme X. Which biosynthetic product is most likely the inhibitor of enzyme T?
C
The major products of the citric acid cycle are
CO2 and NADH
Which of the following ions has a cytosolic concentration so that a flood of this ion into the cell can be used as a signal for cell processes like fertilization?
Ca2+
How do calcium ions stimulate contraction in nonmuscle cells and smooth muscle cells?
Calcium ions bind to troponin and lead to a conformational change in tropomyosin that expose the myosin binding sites on the actin filament.
In oxidative phosphorylation in mitochondria, high-energy electrons are transferred to the electron-transport chain from activated carriers like NADH. Stage 1 of photosynthesis also uses an electron-transport chain to pump protons and make ATP. In this case where do the high-energy electrons come from?
Chlorophyll
Which of the choices below represents the correct way to repair the mismatch shown in Figure 6-25?
Choice A
Which of the following molecules is NOT found in plants?
Collagen
Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?
Conversion of pyruvate to acetyl CoA
Which motor protein is an ATPase, has two globular heads, moves toward the (-) end of a microtubule, and generally interacts with cargo via an adaptor protein?
Cytoplasmic dynein
Which of the following is a difference between the mechanisms of DNA polymerase and RNA polymerase?
DNA polymerase needs a base-paired 3'-OH for a polymerization reaction to occur; RNA polymerase can polymerize two nucleotides without a base-paired 3' -OH
If the genome of the bacterium E. coli requires about 20 minutes to replicate itself, how can the genome of the fruit fly Drosophila be replicated in only 3 minutes?
Drosophila DNA contains more origins of replication than E. coli DNA
What is the initiating event in meiotic homologous recombination?
Formation of a double-strand break
Which of the following is a covalent modification that occurs mainly in the ER?
Formation of disulfide bonds
Which of the following is NOT an intracellular signaling protein activated by an RTK?
G-protein
Which of the following is a function of the protein component of chromosomes?
It packages the DNA strands
Which of the following is NOT used as source of energy by a transmembrane pump to actively transport a solute?
K+
What is the fermentation product produced in an anerobic muscle cell?
Lactic acid
You prepare bacterial cell extracts by lysing the cells and removing insoluble debris via centrifugation. These extracts provide the proteins required for DNA replication. Your DNA template is a small, double-stranded circular piece of DNA (a plasmid) with a single origin of replication and a single replication termination site. The termination site is on the opposite side of the plasmid from the origin. What part of the DNA replication process would be most directly affected if a strain of bacteria lacking DNA ligase were used to make the cell extracts?
Lagging strand completion
Which of the following is a cell type in humans that uses voltage-gated ion channels?
Muscle cells
Which of the following motor proteins has one head domain, moves along actin toward the plus end, and is found in all cell types?
Myosin-I
NADH contains a high-energy bond that, when cleaved, donates a pair of electrons to the electron-transport chain, what are the immediate products of this bond cleavage?
NAD+ + H-
Which of the following represents an "activated" carrier molecule?
NADH
If cells were undergoing glycolysis but could not carry out fermentation, what product would build up in the cytosol?
NADH and pyruvate
Which of the following has the lowest electron affinity?
NADH dehydrogenase complex
The classic experiments conducted by Meselson and Staphl used isotopes of which element to distinguish newly synthesized DNA from parental DNA?
Nitrogen
What type of cell response would take the longest amount of time (on the scale of minutes to hours) to execute?
One that involves a change in gene expression
Which of the following cell types is responsible for removing matrix for renewal in bone tissue?
Osteoclasts
The type of bond that holds together neighboring subunits in a single strand of DNA is a
Phosphodiester bond
Which of the following statements about the endoplasmic reticulum (ER) is FALSE?
Proteins to be delivered to the ER lumen are synthesized on the smooth ER
Which of the following statement is FLASE?
RNA polymerase adds bases in a 3' to 5' direction, DNA polymerase adds bases in a 5' to 3' direction
Why does RNA polymerase make more mistakes than DNA polymerase?
RNA polymerase does not have proofreading activity
What recognizes the stop codons in an mRNA?
Release factor
Telomeres serve as caps protecting the ends of linear chromosomes which of the following is FALSE regarding the replication of telomeric sequence?
The leading strand doubles back on itself to form a primer for the lagging strand
Which of the following statements about plant cell walls is TRUE?
The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall
Which of the following events does NOT usually occur during interphase?
The nuclear envelop breaks down
Which of following statements correctly explains what it means for DNA replication to be bidirectional?
The replication forks formed at the origin move in opposite direction
Which of the following factors DO NOT influence the length of a covalent bond?
The tendency of atoms to fill outer electron shells
How do the intermediate filament proteins keratin, vimentin, and neurofilaments differ from each other?
They are different at the head and tail domains that are exposed at the surface.
How do the high-energy electrons of activated carriers contribute to forming the high-energy phosphate bonds of ATP?
They are used by the electron-transport chain to make a proton gradient
What is the function of nucleolus?
To assemble ribosomal RNA and proteins into ribosomes
The process of gene expression always involves which process(es) described in the central dogma?
Transcription
Which of the following is the main point of control for regulating gene expression levels?
Transcription
Which of the following is a difference between transporters and channels?
Transporters can facilitate both active or passive transport of solutes; channels facilitate only passive transport.
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?
Triacylglycerol
What is the force that drives plant cell growth?
Turgor pressure
Both budding yeast and the bacteria E. coli are unicellular life forms. Which of the following statements explains why budding yeast can undergo sexual reproduction while E. coli cannot?
Unlike E. coli, budding yeast can alternate between a diploid state and a haploid state.
How is an electrical signal converted to a chemical signal at a nerve terminal?
Voltage-gated Ca2+ channels are activated and the influx of Ca2+ triggers the release of neurotransmitters
Which statement about carbon bonds is true?
When C is covalently bound to 3 or 2 other atoms, these bonds are arranged in a single plane in space.
Which of the following is NOT good direct evidence that the cell-cycle control system is conserved through billions of years of divergent evolution?
Yeast cells have only one Cdk, whereas humans have many Cdks
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 conformational changes is coupled to ATP hydrolysis
Transplanting the nucleus of an epithelial cell into an egg call lacking genetic information leads to the formation of
a normally developing embryo
Protein structures have several different levels of organization. The primary structure of a protein is its amino acid sequence. The secondary and tertiary structures are more complicated. Consider the definitions below and select the one that best fits the term "protein domain."
a protein segment that folds independently
In an enzymatic reaction involving NADH or NADPH, reduction of a substrate accompanies the oxidation of these carrier molecules to NAD+ or NADP+, respectively. What else typically happens in such a reaction?
a proton is taken up by substrate that is being reduced
A gene is the information required to make an RNA or protein product, a(n) _______ is a variant version of a particular gene.
allele
How do tRNAs become attached to the correct amino acid?
aminoacyl -tRNA synthetases
Tight junctions
are formed from claudins and occludins
The world of prokaryotes is divided into two domains (bacteria and archaea), each as different from each other as from eukaryotes. Select the observable characteristic that BEST separates archaea from bacteria.
are found in extremely harsh environments
Cells, compared with the extracellular fluid
are slightly negatively charged
Hemidesmosomes are important for
attaching epithelial cells to the extracellular matrix.
Steroid hormones trigger transcription of target genes by
binding to nuclear receptors that act as transcription factors for specific genes.
Figure 3-20 is an energy diagram for the reaction X→Y. Which equation below provides the correct calculation for the amount of free-energy change when X is converted to Y?
c-a
Induced pluripotent stem (iPS) cells
can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues
A pluripotent cell
can give rise to all the tissues and cell types in the body.
Choose the phrase that best completes this sentence: Microtubules __________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.
can rapidly recognize
Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?
cell division
Which one of the following structures provides a selective barrier to the prokaryotic cell?
cell membrane
The nucleus, an organelle found in eukaryotic cells, confines the __________, keeping them separated from other components of the cell.
chromosomes
Which of the following is NOT a feature commonly observed in β sheets?
coiled coil patterns
The structural feature of DNA that hints at the mechanism for its replication is the
complimentary base pairing
Operons
contain a cluster of genes transcribed as a dingle mRNA
Select the option that correctly finishes the following statement: A cell's genome
contains all of a cell's DNA
Which of the following is not an organelle in Eukaryotic cells?
cytoskeleton because it's not enclosed in a separate membrane.
Which of the following statements about the cytoskeleton is TRUE?
Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end
A sodium-potassium antiport maintains the extracellular concentration of sodium at levels that are about 20-30 times higher than inside the cells. What directly supplies the energy for maintaining the gradient?
ATP hydrolysis drives the function of the pump
Which of the following would you NOT expect to find in a bacterial cell?
ATP production in mitochondria
Stage two of photosynthesis (or the light-independent reactions) uses which input molecules to produce organic food molecules?
ATP, NADH, CO2
Which of the following depicts the correct order of steps involved in nitric oxide (NO) signaling to trigger smooth muscle relaxation?
Acetylcholine receptor activation -- activation of NO synthetase -- NO diffusion into neighboring cells -- activation of guanylyl cyclase -- cGMP production
The active form of a monomeric GTP-binding protein is the
GTP-bound form
What performs the function of bacterial sigma factor in eukaryotes?
General transcription factors
The relationship between the nucleic acid sequence over a stretch of DNA and the order of amino acids in the resulting protein is referred to as the
Genetic
If a lactose and glucose are both available to a bacterial cell, which carbon source(s) will be used?
Glucose
Which of the following chemicals do you NOT expect to be readily dissolved in water?
Hexane
In which direction, and on which strands does DNA replication proceed from a replication origin on a chromosome?
In both directions, on both strands
Where are chloroplast proteins translated?
In both the cytosol and the chloroplast
Which of the following contributes to genetic reassortment during meiosis?
Independent assortment and crossing-over during meiosis I
Which of the cytoskeletal structures are made up of protein subunits that are fibrous?
Intermediate filaments
Which of the following statements describes the mitochondrial matrix?
It contains enzymes required for the oxidation of fatty acids
Cytochrome c oxidase catalyzes the reaction that reduces molecular oxygen (two oxygen atoms) to two water molecules. The electrons are added sequentially, and during the process cytochrome c oxidase must bind the oxygen tightly in the active site. Why?
Superoxide radicals are formed as an intermediate, and are dangerous to the cell.
Which of the following is found only in eukaryotic genomes, and not in prokaryotic genomes?
Telomeres
Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2?
The cell would enter M phase under conditions when normal cells wound not.
Steps 7 and 10 of glycolysis result in substrate-level phosphorylation. Which of the following best describes this process?
The energy derived from substrate oxidation is coupled to the conversion of ADP to ATP
What determines the position of the cleavage furrow of the dividing cell?
The interpolar microtubules send signals to form a cleavage furrow between the poles
Calcium ion release triggers all of the following biological processes EXCEPT
action potential transmission along an axon
Which of the following functional groups are nonpolar?
alkyl
Lysozyme is an enzyme that specifically recognizes bacterial polysaccharides, which renders it an effective antibacterial agent. Into what classification of enzymes does lysozyme fall?
hydrolase
Lysosomes contain ______ enzymes that can break down diverse macromolecules, cell parts, and microorganisms
hydrolytic
The pH of an aqueous solution is an indication of the concentration of available protons. However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a/an __________ ion.
hydronium
If one end of a DNA strand has a phosphate group on it, the chemical group on the other end must be
hydroxyl
A housekeeping gene is a gene whose cellular function is
important for processes found in all cell types
Imagine the reaction A → B with a negative ΔG value under experimental conditions. Which of the following statements is true about this reaction?
increase concentration of B molecules would increase delta G value (toward more positive values)
The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by
inhibiting cyclin transcription
