The genome of eukaryotes consists of genes derived from

both archaebacteria and bacteria.

In contrast to animal cells, yeast or bacterial cell cultures can be grown on fairly simple media without the need to add amino acids or various vitamins and hormones. This is primarily because animal cells

come from organisms that have specialized cell types.

Which of the following is a high-resolution light microscope technique for detecting interactions between proteins?

FRET (fluorescence resonance energy transfer)

Transmission electron microscopy is used to

observe subcellular organelles and macromolecules.

Chloroplasts are thought to have originated from endosymbiosis of _______ by a large host cell.

photosynthetic eubacteria such as cyanobacteria

Chymotrypsin, trypsin, elastase, and thrombin are all grouped together as members of the serine protease family because each

uses the same catalytic mechanism involving the same key amino acids.

Which of the following is not true of coenzymes?

Chemically, they are branched amino acids.

Lipids with unsaturated fatty acids

decrease the fluidity of membranes.

decreasing the activation energy.

Enzymes affect the transition state of a chemical reaction by

a. binding to the substrate(s). b. providing a surface on which the reactions converting substrate to product can occur more rapidly. c. altering the conformation of the substrate(s) to approach that of the transition state.

All of the following are ways in which enzyme activity can be regulated except

by modulation of intracellular sucrose concentrations.

Passive transport across a membrane refers to

transport in the energetically favorable direction.

About 50% of the mass of most biological membranes consists of lipids and about 50% consists of proteins. Therefore,

the membranes contain more molecules of lipid than of protein.

Whereas small uncharged molecules can diffuse through the hydrophobic core of a phospholipid bilayer, a larger polar substance such as glucose must enter cells by binding to

carrier proteins that facilitate the passage of specific molecules across membranes.

The lock-and-key and induced-fit models are two alternative models that can explain how enzymes and substrates interact. These two models can be distinguished from each other according to changes in the

shape as the substrate and enzyme bind.

In the fluid mosaic model of biological membrane structure, transmembrane proteins are

embedded nearly randomly in the lipid bilayer.

Under aerobic conditions, the NADH formed during glycolysis

provides additional energy by donating its electrons to the electron transport chain.

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Cell bio practice

Question	Answer
An E. coli cell under well-defined laboratory conditions divides about every	20 minutes.
How many genes does an E. coli have?	4,300
The original atmosphere of Earth is thought to have been rich in	CO2, N2, H2, H2S, and CO
The genome of eukaryotes consists of genes derived from	both archaebacteria and bacteria.
Solid tissues in animals include epithelial tissue, _______ tissue, nervous tissue, and muscle.	connective
In fluorescence microscopy, the immediate source of the light detected is light that has been _______ the sample.	emitted by
The feature that most clearly separates eukaryotes from prokaryotes is the presence of _______ in eukaryotic cells.	a nucleus
What is the theoretical diffraction limit of resolution of a light microscope used to look at a sample through oil?	0.22 μm
What is the smallest number of ultracentrifugation steps needed to separate nuclei from ribosomes in a cellular lysate?	1
In contrast to animal cells, yeast or bacterial cell cultures can be grown on fairly simple media without the need to add amino acids or various vitamins and hormones. This is primarily because animal cells	come from organisms that have specialized cell types.
Which of the following is a high-resolution light microscope technique for detecting interactions between proteins?	FRET (fluorescence resonance energy transfer)
Which of the following are the most commonly used mammals for genetic studies?	Mice
Which of the following is not a unicellular eukaryote? a. Saccharomyces cerevisiae b. Paramecium c. Archaebacteria d. Chlamydomonas	Archaebacteria
Transmission electron microscopy is used to	observe subcellular organelles and macromolecules.
The original cell was thought to have arisen from the enclosure of self-replicating _______ by a phospholipid membrane.	RNA
The source of the atmospheric oxygen necessary for the development of oxidative metabolism is thought to have been	photosynthesis.
Approximately how many doublings can normal human fibroblasts undergo in culture?	50 to 100
Embryonic stem cells are different from primary cell cultures or permanent cell lines derived from a tissue in that they are capable of	generating many cell types.
Chloroplasts are thought to have originated from endosymbiosis of _______ by a large host cell.	photosynthetic eubacteria such as cyanobacteria
Bacteriophages are	viruses that infect bacteria.
Molecules that are partly water-soluble and partly water-insoluble are	amphipathic.
Transport across biological membranes is speeded by what class of biological molecules?	Proteins
Chymotrypsin, trypsin, elastase, and thrombin are all grouped together as members of the serine protease family because each	uses the same catalytic mechanism involving the same key amino acids.
Which of the following classes of amino acids is buried within the folded structure of the protein?	Nonpolar
Which of the following is not true of coenzymes?	Chemically, they are branched amino acids.
Lipids with unsaturated fatty acids	decrease the fluidity of membranes.
Phospholipids consist of a 3-carbon core to which fatty acids and a phosphate group are linked. The most common 3-carbon core is	glycerol.
Enzymes act by	decreasing the activation energy.
Which of the following is not one of the four major classes of organic molecules in the cell?	Water
Enzymes affect the transition state of a chemical reaction by	a. binding to the substrate(s). b. providing a surface on which the reactions converting substrate to product can occur more rapidly. c. altering the conformation of the substrate(s) to approach that of the transition state.
Coenzymes are chemically related to	vitamins.
All of the following are ways in which enzyme activity can be regulated except	by modulation of intracellular sucrose concentrations.
What is the effect of a β barrel on the permeability of a membrane?	It increases permeability
Passive transport across a membrane refers to	transport in the energetically favorable direction.
What is the major carbohydrate-storage molecule in plants?	Starch
Proteins must have more than one _______ to have a quaternary structure.	polypeptide chain
The most abundant molecule in cells is	water
Introducing a double bond into a fatty acid has the effect of putting a(n) _______ into the conformation of the molecule.	kink
How many common amino acids are there?	20
The three-dimensional structure of a protein is analyzed most definitively by	X-ray crystallography.
About 50% of the mass of most biological membranes consists of lipids and about 50% consists of proteins. Therefore,	the membranes contain more molecules of lipid than of protein.
Cholesterol, a membrane lipid in animals, has a chemical structure similar to	estradiol
A disulfide bond is formed between _______ residues.	cysteine
The α (alpha) helix is an example of which level of protein structure?	Secondary
Whereas small uncharged molecules can diffuse through the hydrophobic core of a phospholipid bilayer, a larger polar substance such as glucose must enter cells by binding to	carrier proteins that facilitate the passage of specific molecules across membranes.
The lock-and-key and induced-fit models are two alternative models that can explain how enzymes and substrates interact. These two models can be distinguished from each other according to changes in the	shape as the substrate and enzyme bind.
In the fluid mosaic model of biological membrane structure, transmembrane proteins are	embedded nearly randomly in the lipid bilayer.
The end product of the anaerobic metabolism of glucose may be any of the following except	methanol.
Under aerobic conditions, the NADH formed during glycolysis	provides additional energy by donating its electrons to the electron transport chain.
In plants, the molecule that captures energy from sunlight is	chlorophyll
Which of the following is a key molecule in the electron transport chain in mitochondria?	Cytochrome c
Gluconeogenesis normally starts from	a. amino acids. b. glycerol. c. lactate.
Each photocenter in a chloroplast consists of hundreds of antenna pigment molecules that absorb light and transfer energy to a reaction center	chlorophyll.
Animal cells can synthesize glucose (gluconeogenesis) from all of the following except	fatty acids.
The ATP synthases of mitochondria and chloroplasts are examples of _______ proteins in which polypeptide rotation provides a mechanical coupling to ATP synthesis.	motor
What is the major site of energy production in the form of ATP in human cells?	The inner mitochondrial membrane
In humans, how many amino acids must be taken up in the diet?	9
The role of cytochrome c in the electron transport chain is to	transfer electrons from complex III to complex IV.
Because fatty acids are synthesized by the stepwise addition of acetyl CoA derivatives, they differ in length by units of _______ carbon(s).	2
Antimetabolite chemotherapy succeeds as a treatment for childhood leukemia because	cancer cells are fast growing.
Which statement correctly describes the difference between the proton gradient across the inner mitochondrial membrane and the proton gradient across the thylakoid membrane of chloroplasts?	The first creates an electrochemical gradient, while the second is largely a chemical gradient.
What is the change in free energy (ΔG) for the hydrolysis of ATP to ADP and Pi in the cell?	–12 kcal/mol
The carbon skeletons of amino acids are derived from	intermediates in glycolysis and the citric acid cycle.
Together, glycolysis and the citric acid cycle directly generate two molecules of ATP and two molecules of GTP. Most of the energy derived from the oxidation of glucose comes from the oxidation of the _______ generated from _______.	NADH; the citric acid cycle
The Calvin cycle is involved in the synthesis of _______ from _______.	glucose; carbon dioxide
All organisms can utilize _______ as a nitrogen source.	ammonia
What are the energetic consequences of coupling a reaction with a +ΔG to one with a larger –ΔG?	A ΔG that is favorable overall and drives the reaction with a +ΔG in the forward direction
Nucleotide chains are elongated in the 5′-to-3′ direction. The 5′ and 3′ refer to the chemical positions on the	ribose or deoxyribose.
In polysaccharide biosynthesis, the activated metabolic intermediate of glucose is	UDP-glucose.
The electrochemical gradient across the mitochondrial inner membrane drives the import of all of the following except	cytochrome c.
Light is captured by _______ different photosystems associated with the thylakoid membranes of chloroplasts.	two
How many carbons does the acetate group of acetyl CoA have?	2
What is the net yield of ATP molecules per molecule of glucose from the process of glycolysis?	2
Which of the following correctly outlines the process of RNA interference, beginning with a double-stranded RNA molecule?	Cleavage by Dicer; association with RISC; unwinding of siRNA; pairing with target mRNA; mRNA cleavage
Transgenic plants are easier to produce than transgenic animals because	plants can be grown more easily from single cultured cells into which recombinant DNA has been introduced
The characterization of restriction endonucleases was a key step in the development of recombinant DNA technology. What is the function of these enzymes?	Cleavage of DNA at specific sequences
Which of the following techniques is used to inactivate a gene by altering the DNA that encodes it?	Homologous recombination
The CRISPR/Cas system is a fast and powerful method to introduce mutations into cellular genomes via homologous recombination to study the function of genes and the proteins they encode. Which of the following are necessary reagents for CRISPR/Cas?	Mutant copy of target gene, guide RNA, and Cas9
Which of the following terms refers to a collection of clones that contain all the genomic or mRNA sequences of a particular cell type?	Recombinant DNA library
The enzyme that synthesizes DNA using RNA templates is called	reverse transcriptase.
The SDS in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of a protein is used to	denature the protein and give it an overall negative charge.
Which of the following is not necessary in a plasmid vector to facilitate successful cloning?	IRES (internal ribosomal entry site)
What technique would you use to determine if the level of a specific mRNA had been increased in response to an inducer?	Northern blotting
The two strands of DNA in the double helix are held together by	hydrogen bonds between the bases of each strand.
A restriction enzyme with a four-base recognition site would cleave DNA with a statistical frequency of once every	256 base pairs.
The process by which proteins are made from RNA templates is called	translation.
Which of the following correctly describes a cDNA molecule?	A DNA copy of an RNA sequence synthesized by the enzyme reverse transcriptase
Which of the following serves as an adaptor between amino acids and mRNA during translation?	tRNA
Which of the following correctly represents the distinction between the terms “genotype” and “phenotype”?	The genotype is the genetic composition of an organism, whereas the phenotype is its physical appearance.
All of the following are examples of cloning vectors except a. plasmids. b. cosmids. c. yeast artificial chromosomes (YACs). d. bacteriophages.	bacteriophages.
Transgenic mice carry a foreign gene	in all of their cells.
How many molecules would be produced from two molecules of DNA following five rounds of PCR amplification?	64
Bioinformatics is	a field of biology that is focused on developing the computational methods to analyze and extract useful biological information from the sequences of DNA.
The eukaryote Caenorhabditis elegans has been used especially in the study of	animal development.
Which of the following organisms has the highest percentage of its genome used to encode protein?	Haemophilus influenza
A collection of all the RNAs that are expressed at any given time in a cell are referred to as the	transcriptome.
In 2001, two groups of researchers announced their successful completion of draft sequences of the human genome. Which of the following statements about these draft sequences is true?	Both groups presented draft sequences that cover only the euchromatin portion of the genome.
As an example of synthetic biology, the pharmaceutical company Sanofi developed a therapeutic treatment for malaria. Which of the following was the strategy?	Develop a new yeast strain that produces artemsinic acid
The main difference between the genomes of the bacteria Haemophilus influenzae and E. coli is that	the genome of E. coli is approximately three times the size of the H. influenzae genome.
Humans have about 21,000 genes that encode proteins. It is estimated that due to alternative splicing and protein modifications, these genes can give rise to how many different proteins?	100,000
Which of the following methods can accurately quantify the amount of mRNA expressed in a given cell or tissue sample?	DNA microarray and RNA-seq
An estimated 40% of the human genome contains proteins related to proteins that are also present in a diverse number of other species. These proteins are involved in which of the following cellular processes?	a. Replication b. Transcription c. Translation
All of the following are methods that allow scientists to investigate protein-protein interactions. Which method utilizes gene expression as the detection component?	Yeast two-hybrid
Neandertals are thought to be our closest evolutionary relatives, having diverged from humans 300,000 to 400,000 years ago, and their genome has been sequenced. Which of the following statements about humans and Neandertals is false?	The Neandertal genome was surprisingly GC-rich.
Experimentally, you discover that in addition to stimulating the G protein, the epinephrine receptor can also directly stimulate glycogen synthase, bypassing the intermediate proteins. This would be an example of	a feedforward relay.
The plant Arabidopsis thaliana contains significantly more genes than either C. elegans or Drosophila. Which of the following statements is true?	The large number of genes results from duplication of large segments of the Arabidopsis genome
Two-dimensional gel electrophoresis is not an acceptable method to protein-protein interactions. Which of the following statements best describe the reason why?	The SDS-PAGE gel denatures all the proteins, preventing any quaternary interactions.
In RNAi screens, siRNAs are incubated with cells in culture to assess functional consequences of the targeted gene. Which of the following statements is true in regards to the siRNA and its action?	The siRNA is homologous to and binds the mRNA leading to degradation of the mRNA.
Which of the following is the first step in next-generation sequencing?	The DNA sample is fragmented into smaller pieces.
Which of the following methods would best be used to determine posttranslational modifications to a protein, such as phosphorylation?	Tandem mass spectrometry
In exerting its biological activity on cells, epi binds to a cell surface receptor, which activates a G protein, which then activates cAMP-dependent protein kinase, then phos kinase, then gly synthase, which then breaks down glu. This is an example of	a signaling pathway
Which of the following molecular biology methods would best be used to directly determine the relative level of all mRNAs in a given cell or tissue?	DNA microarray
Which of the following statements about exons is false?	An exon may contain sequences for small nucleolar RNAs.
Extensive digestion of chromatin with micrococcal nuclease was found to yield particles called nucleosome core particles that appear as beads when viewed by electron microscopy. Which of the following is not found in the nucleosome core particle?	One molecule of H1 protein
The ENCODE project revealed that as much as 75% of the genome in humans is actually transcribed into RNA. Most of this is non-protein coding RNA. Which of the following include two new classes of noncoding RNA discovered by the ENCODE project?	MicroRNA and lncRNA
Partial digestion of chromatin with micrococcal nuclease was found to yield DNA fragments approximately 200 base pairs long. What accounts for this phenomenon?	This result suggests that the binding of proteins to DNA in chromatin protects regions of DNA from nuclease digestion.
The human genome contains only 20,000 to 25,000 actual gene sequences, yet the human genome can produce up to 100,000 gene products. Which of the following processes accounts for this difference?	Alternative splicing
The percentage of the average human gene that encodes proteins is approximately	3%
Which of the following describe centromeric sequences in humans?	c. It consists of 171 base-pair A/T-rich α-satellite DNA, spanning 1–5 million base pairs.
Which of the following describe centromeric sequences in humans?	It consists of 171 base-pair A/T-rich α-satellite DNA, spanning 1–5 million base pairs.
In dogs, the Fgf4 gene encodes a protein that regulates bone growth and in its normal chromosomal location, Fgf4 yields dogs with long legs. Which of the following statements best explains the mechanism leading to a short-legged phenotype in dogs?	The Fgf4 gene is retrotransposed into the middle of a LINE that contains mutated regulatory sequences that give abnormal expression of Fgf4.
The function of telomeres is	to ensure chromosome replication and maintenance.
If a human gene is found to contain five introns, the mature mRNA encoded by that gene would have how many exons?	There could be multiple mRNAs that contain between one and six introns.
Which of the following statements about introns in the yeast Saccharomyces cerevisiae is true?	A small percentage of S. cerevisiae genes contain introns, and these introns are usually located near the beginning of the gene.
Even though the complete genome is significantly smaller than humans, the flowering plant Arabidopsis thaliana has about _______ genes, about the same number as humans have.	26,000
In the chromatin around centromeres, nucleosomes are present that have a unique structure in which the core protein _______ is replaced by _______ and this variant of the nucleosome is required for protein assembly at the kinetochore.	histone H3; CENP-A
The human genome is distributed among _______ chromosomes.	23
A centromere is a region of the chromoso me that	plays a critical role in ensuring the correct distribution of duplicated chromosomes to daughter cells during mitosis.
Which of the following statements about introns is true?	They are part of a gene, but they are absent from the corresponding mRNA.
Which of the following transposable elements accounts for ~21% of the human genome?	Long interspersed elements (LINEs)
Which of the following statements about LINEs is false?	Mutations induced by LINEs are exclusively harmful.
Which of the following statements best describe the mechanism of action of miRNAs in blocking expression of proteins?	The single-stranded miRNA, in association with the RISC complex, bind to the complementary sequence in the 3′ UTR of mRNAs, blocking translation and inducing degradation of the mRNA.
A pseudogene is a	gene that arose through gene duplication, but by acquiring mutations became nonfunctional.
A mutation in the leucine zipper of a transcription factor would directly prevent	interaction with other transcription factors in forming hetero- and homodimers.
Which of the following is not involved in relieving transcriptional repression imposed by chromatin?	DNA methylation
The lac operon in E. coli is regulated by lactose, which	inactivates a repressor of transcription.
E. coli preferentially utilizes glucose for energy. However, in the absence of glucose, genes that can metabolize alternative sugars are activated. Low glucose	elevates cAMP through adenylyl cyclase that binds to and activates CAP to effectively increase transcription rates of genes that metabolize alternative sugars.
Which of the following best describes the ability of an enhancer to mediate transcription from very distant sites?	Looping of the DNA can occur, allowing the transcription factor to get into the proximity of the RNA polymerase.
Which of the following is not involved in the tissue-specific expression of the immunoglobin (Ig) heavy-chain gene?	RNA polymerase II
Suppose that a gene has three exons and two introns in the following order:	5′-exon 2 – exon 1-3′
Which of the following both stabilizes and increases the efficiency of translation of an mRNA?	Addition of a 7-methylguanosine cap
Which of the following statements about transcription of ribosomal RNA is false?	TBP binds the TATA sequences in the promoter of the ribosomal gene.
Which of the following statements about transcriptional termination in prokaryotes is false?	The ribosome comes to a UAA, UAG, or UGA stop codon and transcription ceases.
Which of the following is not an example of a transcription factor DNA-binding domain?	Acidic
Which of the following experimental approaches is least likely to be used in identifying transcription factor binding sites?	Northern blotting
Which of the following is not part of the transcription complex?	RFC
A yeast mutant shows decreased expression of the 5.8S rRNA, the 5S rRNA, and protein-encoding mRNAs. In which of the following might the mutation lie?	TATA-binding protein (TBP)
A ribozyme is defined as an enzyme	in which an RNA molecule is responsible for the catalytic activity.
In prokaryotes, σ factors are necessary for	specific binding to certain promoters.
According to the central dogma of molecular biology, transcription of genetic information occurs via	DNA-dependent RNA synthesis.
Which of the following statements about cis-acting elements is true?	a. They are specific DNA sequences that control the transcription of adjacent genes. b. Various proteins specifically recognize and bind to these cis-acting sequences. c. They are utilized by both prokaryotes and eukaryotes.
Glucose repression (or catabolite repression) is mediated by several positive transcriptional control mechanisms. Which of the following is not one of those mechanisms?	cAMP-activated CAP transcribes genes that metabolize lactose.
A reporter gene is used to	identify regulatory sequences from the upstream regions of other genes.
Which of the following statements about translational initiation is false?	a. In prokaryotes, ribosomes often bind the mRNA and can scan 5′ or 3′ until recognizing a Shine-Dalgarno sequence.
Protein phosphatases	catalyze the removal of phosphate residues from proteins.
The primary function of rRNAs in the ribosome is	to catalyze peptide bond formation.
Which of the following is not a common lipid modification to proteins?	Glycosylation
Which of the following is not associated with translational regulation?	Autolytic degradation of the mRNA by folding back on itself
A proteasome is a	multisubunit protease complex that degrades proteins marked for destruction.
The initiator codon in prokaryotes is	recognized via the Shine-Dalgarno sequence.
The function of aminoacyl tRNA synthetases is to	covalently attach amino acids to their corresponding tRNA molecules.
Which of the following statements regarding tRNAs is false?	tRNAs differ in sequence only at the anticodon.
The proteins shaped like a “double chamber” that are involved in protein folding are called	chaperonin proteins.
The first amino acid of eukaryotic polypeptides is	methionine.
Ferritin expression is stimulated by iron because iron	stimulates the dissociation of a translational inhibitor from the ferritin mRNA.
The half-lives of proteins in the cell vary widely, ranging from	minutes to days.
Antibiotics are medications that inhibit the growth of bacteria. Many target the process of protein synthesis in the bacterial cell. In the developing of an antibiotic, which of the following would be an effective strategy or target for the drug?	a. Inhibition of translational initiation b. Induction of premature polypeptide chain termination c. Inhibition of aminoacyl tRNA binding
Which of the following statements about the attachment of amino acids to tRNAs is false?	The amino acid is first joined to AMP, forming an aminoacyl AMP intermediate.
Which of the following is an example of posttranslational modification?	a. Glycosylation b. Proteolysis c. Palmitoylation
Signal sequences are sequences of hydrophobic amino acids that target membrane translocation. Signal sequences are found	at the amino terminus of the secreted protein.
Which of the following processes does not require the assistance of chaperones?	Protein transport into the nucleus
Which of the following statements about translational regulation of ferritin is false?	The iron response element is a unique sequence of amino acids near the amino terminus of the growing polypeptide.
cAMP activates cAMP-dependent protein kinase by	binding regulatory subunits and inducing their release from the catalytic subunits.

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