Bio ch. 18, 20, 21 – Flashcards

What does the operon model attempt to explain? a) how genes move between homologous regions of DNA b) horizontal transmission of plant viruses c) the mechanism of viral attachment to a host cell d) bacterial resistance to antibiotics e) the coordinated control of gene expression in bacteria

A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA: repressor a) promoter b) operon c) inducer d) corepressor

A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes: a) repressor b) promoter c) inducer d) corepressor e)operon

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, which of the following would be likely? a) Three structural genes will no longer be expressed. b)Beta galactosidase will be produced. c) RNA polymerase will no longer transcribe permease. e)The operon will no longer be inducible. f)The cell will continue to metabolize but more slowly

Muscle cells and nerve cells in one species of animal owe their differences in structure to having different chromosomes. a) having unique ribosomes. b) having different genes expressed. c) using different genetic codes. d) having different genes

Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA? a)83% b)46% c)1.5% d)13% e)32%

Two potential devices that eukaryotic cells use to regulate transcription are DNA methylation and histone amplification. histone amplification and DNA acetylation. DNA amplification and histone methylation. DNA methylation and histone modification. DNA acetylation and methylation.

In eukaryotes, general transcription factors are required for the expression of specific protein-encoding genes. usually lead to a high level of transcription even without additional specific transcription factors. bind to sequences just after the start site of transcription. bind to other proteins or to a sequence element within the promoter called the TATA box. inhibit RNA polymerase binding to the promoter and begin transcribing

This binds to a site in the DNA far from the promoter to stimulate transcription: terminator enhancer activator repressor promoter

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains also specific for binding. In general, which of the following would you expect many of them to be able to bind? protein-based hormones tRNA repressors other transcription factors ATP

Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell? enzymatic shortening of the poly(A) tail methylation of C nucleotides removal of one or more exons methylation of histones removal of the 5' cap

Which of the following best describes siRNA? a molecule, known as Dicer, that can degrade other mRNA sequences a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor

Which of the following describes the function of an enzyme known as Dicer? It chops up single-stranded DNAs from infecting viruses. It degrades single-stranded mRNA. It trims small double-stranded RNAs into molecules that can block translation. It degrades mRNA with no poly(A) tail. It degrades single-stranded DNA.

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to pseudogenes, which interfere with gene expression in adults. histone proteins changing shape during embryonic development. identical genes that generate many copies of the ribosomes needed for fetal globin production. nonidentical genes that produce different versions of globins during development. the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced

The process of cellular differentiation is a direct result of differential gene expression. differences in cellular genomes. cell division. apoptosis. morphogenesis.

A cell that remains entirely flexible in its developmental possibilities is said to be totipotent. differentiated. genomically equivalent. epigenetic. determined.

In animals, embryonic stem cells differ from adult stem cells in that embryonic stem cells have fewer genes than adult stem cells. embryonic stem cells are totipotent, and adult stem cells are pluripotent. embryonic stem cells are pluripotent, and adult stem cells are totipotent. embryonic stem cells have more genes than adult stem cells. embryonic stem cells are localized to specific sites within the embryo, whereas adult stem cells are spread throughout the body

Differentiation of cells is not easily reversible because it involves changes in the nucleotide sequence of genes within the genome. frameshift mutations and inversions. excision of some coding sequences. changes in chromatin structure that make certain regions of the genome more accessible. chemical modifications of histones and DNA methylation.

n most cases, differentiation is controlled at which level? translation post-translational activation of the proteins transcription replication of the DNA nucleosome formation

The MyoD protein is a target for other proteins that bind to it. magnifies the effects of other muscle proteins. is a transcription factor that binds to and activates the transcription of muscle-related genes. can promote muscle development in all cell types. was used by researchers to convert differentiated muscle cells into liver cells.

Which of the following statements describes proto-oncogenes? Their normal function is to suppress tumor growth They are produced by somatic mutations induced by carcinogenic substances. They are underexpressed in cancer cells They can code for proteins associated with cell growth. They are introduced to a cell initially by retroviruses.

Tumor suppressor genes are frequently overexpressed in cancerous cells. often encode proteins that stimulate the cell cycle. can encode proteins that promote DNA repair or cell-cell adhesion. are cancer-causing genes introduced into cells by viruses. all of the above

The incidence of cancer increases dramatically in older humans because as we age, normal cell division inhibitors cease to function. proteasomes become more active with age. tumor-suppressor genes are no longer able to repair damaged DNA. the Ras protein is more likely to be hyperactive after age sixty. the longer we live, the more mutations we accumulate.

Forms of the ras protein found in tumors usually cause which of the following? cell-to-cell adhesion to be nonfunctional DNA replication to stop growth factor signaling to be hyperactive DNA replication to be hyperactive cell division to cease

Which of the following can contribute to the development of cancer? random spontaneous mutations transposition mutations caused by X-rays chromosome translocations all of the above

One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Which of the following best describes this phenomenon? inherited predisposition to mutation embryonic or fetal cancer inherited inability to repair UV-induced mutation inherited cancer taking a few years to be expressed susceptibility to chemical carcinogens

How is a physical map of the genome of an organism achieved? using very high-powered microscopy using recombination frequency using restriction enzyme cutting sites using DNA fingerprinting via electrophoresis using sequencing of nucleotides

Which of the following most correctly describes a shotgun technique for sequencing a genome? cloning large genome fragments into very large vectors such as YACs, followed by sequencing genetic mapping followed immediately by sequencing physical mapping followed immediately by sequencing cloning several sizes of fragments into various size vectors, ordering the clones, and then sequencing them cloning the whole genome directly, from one end to the othe

What is bioinformatics? a series of search programs that allow a student to identify who in the world is trying to sequence a given species a technique using 3D images of genes in order to predict how and when they will be expressed a procedure that uses software to order DNA sequences in a variety of comparable ways a software program available from NIH to design genes a method that uses very large national and international databases to access and work with sequence information

Bioinformatics can be used to scan sequences for probable genes looking for start and stop sites for transcription and for translation, for probable splice sites, and for sequences known to be found in other known genes. Such sequences containing these elements are called cDNA. multigene families. proteomes. short tandem repeats. expressed sequence tags

A microarray known as a GeneChip, with most now known human protein coding sequences, has recently been developed to aid in the study of human cancer by first comparing two - three subsets of cancer subtypes. What kind of information might be gleaned from this GeneChip to aid in cancer prevention? information on cancer epidemiology in the U.S. or elsewhere. evidence that might suggest how best to treat a person's cancer with chemotherapy. information about whether or not a patient has this type of cancer prior to treatment. data that could alert patients to what kind of cancer they were likely to acquire. information about which parent might have provided a patient with cancer-causing genes.

Why is it unwise to try to relate an organism's complexity with its size or number of cells? A single-celled organism, such as a bacterium or a protist, still has to conduct all the complex life functions of a large multicellular organism. A very large organism may be composed of very few cells or very few cell types. A single-celled organism that is also eukaryotic, such as a yeast, still reproduces mitotically. A simple organism can have a much larger genome. A complex organism can have a very small and simple genome.

Fragments of DNA have been extracted from the remnants of extinct wooly mammoths, amplified, and sequenced. These can now be used to understand the evolutionary relationships among members of related taxa. appreciate the reasons why mammoths went extinct introduce into relatives, such as elephants, certain mammoth traits. clone live wooly mammoths. study the relationships among wooly mammoths and other wool-producers

Which of the following is a representation of gene density? C. elegans has ~20,000 genes. Humans have 2,900 Mb per genome. Humans have ~25,000 genes in 2,900 Mb. Fritillaria has a genome 40 times the size of a human. Humans have 27,000 bp in introns.

Which of the following is a major distinction between a transposon and a retrotransposon? A transposon is related to a virus and a retrotransposon is not. A transposon moves via a DNA intermediate and a retrotransposon via an RNA intermediate. A transposon always leaves a copy of itself at its original position and a retrotransposon does not. The positioning of a transposon copy is transient while that of a retrotransposon is permanent. A retrotransposon always uses the copy-paste mechanism, while a transposon uses cut and paste mechanism.

Multigene families include two or more nearly identical genes or genes sharing nearly identical sequences. A classical example is the set of genes for globin molecules, including genes on human chromosomes 11 and 16. How might identical and obviously duplicated gene sequences have gotten from one chromosome to another? by deletion followed by insertion by normal mitotic recombination between sister chromatids by normal meiotic recombination by chromosomal translocation by transcription followed by recombination

Multigene families include two or more nearly identical genes or genes sharing nearly identical sequences. A classical example is the set of genes for globin molecules, including genes on human chromosomes 11 and 16. Several of the different globin genes are expressed in humans, but at different times in development. What mechanism could allow for this? differential translation of mRNAs intron activation exon shuffling differential gene regulation over time pseudogene activation

When does exon shuffling occur? during splicing of DNA as an alternative splicing pattern in post-transcriptional processing as the result of faulty DNA repair as an alternative cleavage or modification post-translationally during mitotic recombination

What does the field often called "evo-devo" study? whether or not there are specific genes controlling development whether the pattern of human development evolved early or late whether or not development is an evolutionary process whether or not all animals have developmental regulation how developmental processes have evolved

Bioinformatics includes all of the following except use of mathematical tools to make sense of biological systems. analyzing protein interactions in a species. using computer programs to align DNA sequences. development of computer-based tools for genome analysis. using molecular biology to provide biological information to a system so that it gets expressed

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to cut the plasmid with enzyme X and then insert the gene into the plasmid. insert the fragments cut with X directly into the plasmid without cutting the plasmid. cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid. cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X. cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

What is the enzymatic function of restriction enzymes? to join nucleotides during replication to add new nucleotides to the growing strand of DNA to repair breaks in sugar-phosphate backbones to join nucleotides during transcription to cleave nucleic acids at specific sites

How does a bacterial cell protect its own DNA from restriction enzymes? reinforcing the bacterial DNA structure with covalent phosphodiester bonds adding histones to protect the double-stranded DNA using DNA ligase to seal the bacterial DNA into a closed circle adding methyl groups to adenines and cytosines forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics.Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in all four types of broth. the nutrient broth only. the nutrient broth, the ampicillin broth, and the tetracycline broth. the nutrient broth and the tetracycline broth only. the ampicillin broth and the nutrient broth.

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using DNA ligase to put together fragments of the DNA that codes for a particular polypeptide. RNA polymerase to transcribe the gene. reverse transcriptase to reconstruct the gene from its mRNA. a restriction enzyme to cut the gene into shorter pieces. DNA polymerase to reconstruct the gene from its polypeptide product.

The DNA fragments making up a genomic library are generally contained in DNA-RNA hybrids radioactive eukaryotic cells recombinant plasmids of bacteria. recombinant viral RNA. individual wells

How does a genomic library differ from a cDNA library? The genomic library contains only the genes that can be expressed in the cell. A genomic library contains only noncoding sequences, whereas a cDNA library contains only coding sequences. A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase. A genomic library varies, dependent on the cell type used to make it, whereas the content of a cDNA library does not. The genomic library can be replicated but not transcribed.

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. 2, 1, 4 3, 4, 2 3, 4, 1, 2 1, 3, 2, 4 2, 3, 4

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates. the nematode is a good animal model for trying out cures for viral illness. it allows research on a group of organisms we do not usually care much about. it allows researchers to use the sequence to build a "better" nematode, resistant to disease. a sequence that is found to have no introns in the nematode genome is likely to have acquired the introns from higher organisms.

Which of the following is used to make complementary DNA (cDNA) from RNA? DNA ligase restriction enzymes gene cloning reverse transcriptase gel electrophoresis

DNA ligase gel electrophoresis restriction enzymes reverse transcriptase gene cloning

Which of the following separates molecules by movement due to size and electrical charge? gene cloning reverse transcriptase restriction enzymes DNA ligase gel electrophoresis

Dideoxyribonucleotide chain-termination is a method of synthesizing DNA. digesting DNA. sequencing DNA. separating DNA fragments. cloning DNA

DNA microarrays have made a huge impact on genomic studies because they dramatically enhance the efficiency of restriction enzymes. allow the expression of many or even all of the genes in the genome to be compared at once. can be used to eliminate the function of any gene in the genome. allow physical maps of the genome to be assembled in a very short time. can be used to introduce entire genomes into bacterial cells.

RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of mRNA. For which of the following might it more possibly be useful? to raise the concentration of a desired protein to decrease the production from a harmful gain-of-function mutated gene to destroy an unwanted allele in a homozygous individual to form a knockout organism that will not pass the deleted sequence to its progeny to raise the rate of production of a needed digestive enzyme

Which of the following is most closely identical to the formation of twins? cell cloning therapeutic cloning use of adult stem cells organismal cloning embryo transfer

In 1997, Dolly the sheep was cloned. Which of the following processes was used? separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate use of mitochondrial DNA from adult female cells of another ewe replication and dedifferentiation of adult stem cells from sheep bone marrow isolation of stem cells from a lamb embryo and production of a zygote equivalent

Which of the following is true of embryonic stem cells but not of adult stem cells? They can provide enormous amounts of information about the process of gene regulation. They can differentiate into many cell types. They can continue to replicate for an indefinite period. One aim of using them is to provide cells for repair of diseased tissue. They make up the majority of cells of the tissue from which they are derived.

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation? Cloning to produce embryonic stem cells may lead to great medical benefits for many. No embryos would be destroyed in the process of therapeutic cloning. A clone that lives until the blastocyst stage does not yet have human DNA. Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells. Cloning to produce stem cells relies on a different initial procedure than reproductive cloning.

Genetically engineered plants are able to fix nitrogen themselves. are banned throughout the world. include a transgenic rice plant that can help prevent vitamin A deficiency. are more difficult to engineer than animals. are being rapidly developed, but traditional plant breeding programs are still the only method used to develop new plants.

Which uses reverse transcriptase to make cDNA followed by amplification? Northern blotting Southern blotting Eastern blotting Western blotting RT-PCR