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Unlike prokaryotic chromosomes, eukaryotic chromosomes are linear. As you’ve learned, the enzyme DNA pol can add nucleotides only in the 5' to 3' direction. In the leading strand, synthesis continues until the end of the chromosome is reached. On the lagging strand, DNA is synthesized in short stretches, each of which... |
have a better quality of life as they grow older. In 2010, scientists found that telomerase can reverse some age-related conditions in mice. This may have potential in regenerative medicine. Telomerase-deficient mice were used in these studies; these mice have tissue atrophy, stem cell depletion, organ system failure,... |
they are not they may result in a mutation, which is defined as a permanent change in a DNA sequence. A mutation can be passed to daughter cells through DNA replication and cell division. There are several types of DNA mutations, including substitution, deletion, insertion, and translocation. Mutations in repair genes... |
Biological systems have multiple processes that increase genetic variation. 6.2 The student can construct explanations of phenomena based on evidence produced through scientific practices. 3.28 The student is able to construct an explanation of the multiple processes that increase variation within a population. DNA re... |
-term continuing association of some of the replication proteins with the new daughter strand after replication has completed. Figure 14.18 In mismatch repair, the incorrectly added base is detected after replication. The mismatch repair proteins detect this base and remove it from the newly synthesized strand by nucle... |
of natural reactions taking place within the body. Mutations may have a wide range of effects. Some mutations are not expressed; these are known as silent mutations. Point mutations are those mutations that affect a single base pair. The most common nucleotide mutations are substitutions, in which one base is replaced... |
ic cancer, colon cancer, and colorectal cancer. Mutations can affect either somatic cells or germ cells. If many mutations accumulate in a somatic cell, they may lead to problems such as the uncontrolled cell division observed in cancer. If a mutation takes place in germ cells, the mutation will be passed on to the nex... |
result of chemical reactions taking place naturally without exposure to any external agent telomerase enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends telomere DNA at the end of linear chromosomes topoisomerase enzyme that causes underwinding or o... |
The model for DNA replication suggests that the two strands of the double helix separate during replication, and each strand serves as a template from which the new complementary strand is copied. In conservative replication, the parental DNA is conserved, and the daughter DNA is newly synthesized. The semi-conservati... |
RNA template and extending one end of the chromosome. DNA polymerase can then extend the DNA using the primer. In this way, the ends of the chromosomes are protected. 14.6 DNA Repair DNA polymerase can make mistakes while adding nucleotides. It edits the DNA by proofreading every newly added base. Incorrect bases are ... |
a. cytoplasmic rRNA b. mitochondrial DNA c. nuclear chromosomal DNA d. nuclear mRNA 4. The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding of what? a. Radioactive phages were found in the pellet. b. Radioactive cells were found in the supernatant. c. Rad... |
leading strand d. primer 22. Which of the following does the enzyme primase synthesize? a. DNA primer b. Okazaki fragments c. phosphodiester linkage d. RNA primer 23. The ends of the linear chromosomes are maintained by what? a. DNA polymerase b. helicase c. primase d. telomerase 24. What is the difference in the rate... |
. frameshift copying b. portions of prokaryotic chromosomes that can be transferred from one organism to another c. areas of eukaryotic chromosomes that are equivalent to the origin of replication in E. coli d. portions of eukaryotic chromosomes that replicate independent of the parent chromosome 26. What type of body ... |
be used to identify different species. b. The amount of adenine, thymine, guanine, and cytosine varies from species to species and is found in equal quantities. They do not vary between individuals of the same species and can be used to identify different species. c. The amount of adenine and thymine is equal to guani... |
sulfur and DNA was labeled with radioactive phosphorous. Phosphorous is found in DNA, so it will be tagged by radioactive phosphorous. b. Protein was labeled with radioactive phosphorous and DNA was labeled with radioactive sulfur. Phosphorous is found in DNA, so it will be tagged by radioactive phosphorous. c. Protei... |
Sanger’s sequencing is a chain termination method that is used to generate DNA fragments that terminate at different points using dye-labeled dideoxynucleotides. DNA is separated by electrophoresis on the basis of size. The DNA sequence can be read out on an electropherogram generated by a laser scanner. b. Frederick ... |
chromosomes. Prokaryotes pack their chromosomes by super coiling, managed by DNA gyrase. Eukaryote chromosomes are wrapped around histone proteins that could form heterochromatin, which is not present in prokaryotes. the 5’ to 3’ direction and adds nucleotides only in the 5’ to 3’ direction. The leading strand is synt... |
access to the DNA is always from the 5’ end. This results in pieces of DNA being replicated in a discontinuous fashion. b. Replication of the leading strand occurs in the direction away from the replication fork in short stretches of DNA, since access to the DNA is always from the 5’ end. This results in pieces of DNA... |
Explain why half of DNA is replicated in a discontinuous fashion. 584 Chapter 14 | DNA Structure and Function a. Helicase separates the DNA strands at the origin and DNA ligase in DNA replication. a. DNA polymerase I removes the RNA primers from the developing copy of DNA. DNA ligase seals the ends of the new segment,... |
, the DNA strands will not be joined together at the beginning of replication. c. Helicase separates the DNA strands at the origin of replication. Topoisomerase breaks and reforms DNA’s sugar backbone ahead of the replication fork, thereby increasing the pressure. Single-stranded binding proteins prevent reforming of D... |
otes. Prokaryotes have a single origin of replication and use five types of polymerases, while eukaryotes have multiple sites of origin and use fourteen polymerases. Telomerase is absent in eukaryotes. DNA pol I is the primer remover in prokaryotes, while in eukaryotes it is RNase H. DNA pol III performs strand elongat... |
atch repair corrects the errors after the replication is completed by excising the incorrectly added nucleotide and adding the correct base. Any mutation in the mismatch repair enzyme would lead to more temporary damage. 51. A mutation has occurred in the DNA and in the mRNA for a gene. Discuss which would have a more ... |
heritable information. d. Phages were the primary source of heritable information. 55. Which piece of evidence supports that the material Miescher discovered was DNA? a. The precipitate contained sulfur. b. The precipitate contained oxygen. c. The precipitate contained phosphorus. d. The precipitate contained protein.... |
diffraction methods to demonstrate the helical nature of DNA, while Rosalind Franklin formulated the double stranded structural model of DNA. d. Watson and Crick used X-ray diffraction methods to demonstrate the helical nature of DNA, while Rosalind Franklin formulated the double stranded structural model of DNA. 58. ... |
antiparallel to each other. d. DNA is composed of nucleotides, consisting of a 5 carbon sugar, a phosphate, and a nitrogenous base. DNA is a double helical structure in which complementary base pairing occurs. Adenine pairs with cytosine and guanine pairs with thymine. Adenine and cytosine form three hydrogen bonds an... |
specific to the four different ddNTPS’s. d. A DNA sample is denatured by heating and then put into four tubes. A primer, DNA polymerase and all four nucleotides are added. Limited quantities of one of the four deoxynucleotides (dNTPs) are added to each tube respectively. Each one of them carries a specific fluorescent... |
the population. a. Xeroderma Pigmentosa patients cannot employ the nucleotide excision repair mechanism. When these patients are exposed to UV light, thymine dimers are formed and they are not able to repair this defect. These dimers distort the structure of DNA and cause them to have a high risk of contracting skin c... |
a population. a. Substitution mutations may cause a different amino acid to be placed at a specific location, causing small changes in the protein. Frameshift mutations usually cause multiple amino acid changes, increasing chances that a new protein will form, leading to radically different characteristics in the offs... |
protein polymers. Briefly explain: • • • the relationship between the structure of polymeric DNA and the information stored the relationship between the interactions between base pairs on complementary strands of the double helix and Chargaff’s observation on the relative abundance of nucleotides in DNA the meaning of... |
increase variation within populations of bacteria and archaebacteria by the following: a. b. c. transferring DNA among different species transferring free DNA across the cell membrane without energy expenditure transferring DNA between different strains of the same species of bacteria d. phagocytosis of bacteriophages... |
sequencing makes termination technology very rapid and relatively inexpensive. All babies born in the U.S. are currently screened by statemandated tests for several genetic conditions. The number of conditions tested ranges from 29 (GA and KS) to 59 (IL and MS). It is proposed that whole-genome sequencing should be ma... |
lowering the metabolic performance from generation to generation. As described in the Evolution Connection in this chapter of the text, a fossil fingertip found in a Siberian cave revealed an evolutionary link between Neanderthals and Denisovans. Fossils from 28 individuals were located in the “pit of bones,” Sima de ... |
Currently, we can perform tests for many genetic diseases, but these tests create ethical and legal issues. For example, would you want to be tested for a debilitating genetic disease if there was the possibility insurance companies could use that information to deny you coverage? Fortunately, the Genetic Information ... |
a triplet code, with each RNA codon consisting of three consecutive nucleotides that specify one amino acid or the release of the newly formed polypeptide chain; for example, the mRNA codon CAU specifies the amino acid histidine. The code is degenerate; that is, some amino acids are specified by more than one codon, l... |
features support the concept of common ancestry for all organisms. Living systems store, retrieve, transmit and respond to information essential to life processes. Heritable information provides for continuity of life. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 15 | Genes a... |
decoding of one molecule to another is performed by specific proteins and RNAs. Because the information stored in DNA is so central to cellular function, it makes intuitive sense that the cell would make mRNA copies of this information for protein synthesis, while keeping the DNA itself intact and protected. The copyi... |
of three nucleotides caused an extra amino acid to be inserted during translation, the integrity of the rest of the protein was maintained. Figure 15.4 The deletion of two nucleotides shifts the reading frame of an mRNA and changes the entire protein message, creating a nonfunctional protein or terminating protein syn... |
to synthesize proteins from amino acids. If there is an error in this process, the correct proteins will not be made to build important body tissue or perform vital functions thus leading to hereditary and age-related diseases. d. Translation is the process Golgi bodies use to synthesize proteins from amino acids. If ... |
this might correspond to the amount of DNA in these fruits’ cell nuclei. Read about the technique of DNA isolation to understand how each step in the isolation protocol helps liberate and precipitate DNA. Hypothesis: Hypothesize whether you would be able to detect a difference in DNA quantity from similarly sized stra... |
? Connection for AP® Courses During transcription, the enzyme RNA polymerase moves along the DNA template, reading nucleotides in a 3′ to 5′ direction, with U pairing with A and C with G, and assembling the mRNA transcript in a 5′ to 3′ direction. In prokaryotes, mRNA synthesis is initiated at a promoter sequence on th... |
(and in eukaryotes) requires the DNA double helix to partially unwind in the region of mRNA synthesis. The region of unwinding is called a transcription bubble. Transcription always proceeds from the same DNA strand for each gene, which is called the template strand. The mRNA product is complementary to the template s... |
role; the two α-subunits are necessary to assemble the polymerase on the DNA; the β-subunit binds to the ribonucleoside triphosphate that will become part of the nascent “recently born” mRNA molecule; and the β' binds the DNA template strand. The fifth subunit, σ, is involved only in transcription initiation. It confe... |
affected. b. RNA polymerase will not be able to attach. c. RNA polymerase will bind upstream of the promoter sequence. d. RNA polymerase will bind downstream of the promoter sequence. Elongation and Termination in Prokaryotes The transcription elongation phase begins with the release of the σ subunit from the polymera... |
polymerase, induces enough instability for the core enzyme to break away and liberate the new mRNA transcript. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 15 | Genes and Proteins 603 Upon termination, the process of transcription is complete. By the time termination occurs, ... |
, transcription in eukaryotes is more complex than transcription in prokaryotes. First, transcription in eukaryotes involves one of three types of RNA polymerase, depending on the gene being transcribed. Second, the initiation of transcription involves the binding of several transcription factors to complex promoters w... |
template on its own, eukaryotes require several other proteins, called transcription factors, to first bind to the promoter region and then help recruit the appropriate polymerase. The Three Eukaryotic RNA Polymerases The features of eukaryotic mRNA synthesis are markedly more complex those of prokaryotes. Instead of ... |
nucleus. This polymerase transcribes a variety of structural RNAs that includes the 5S pre-rRNA, transfer pre-RNAs (pre-tRNAs), and small nuclear pre- RNAs. The tRNAs have a critical role in translation; they serve as the adaptor molecules between the mRNA template and the growing polypeptide chain. Small nuclear RNAs... |
' cap and 3' poly-A tail are also added. A scientist splices a eukaryotic promoter in front of a bacterial gene and inserts the gene in a bacterial chromosome. Would you expect the bacterium to transcribe the gene? a. b. Initially the bacterium will not transcribe it, but will transcribe after 5’ capping. It will not t... |
the recruitment of RNA polymerase II. The processes of bringing RNA polymerases I and III to the DNA template involve slightly less complex collections of transcription factors, but the general theme is the same. Eukaryotic transcription is a tightly regulated process that requires a variety of proteins to interact wi... |
aryotic promoters and other gene regulatory sequences may evolve as well. For instance, consider a gene that, over many generations, becomes more valuable to the cell. Maybe the gene encodes a structural protein that the cell needs to synthesize in abundance for a certain function. If this is the case, it would be bene... |
polymerase accomplishes elongation and termination. Although the enzymatic process of elongation is essentially the same in eukaryotes and prokaryotes, the DNA template is more complex. When eukaryotic cells are not dividing, their genes exist as a diffuse mass of DNA and proteins called chromatin. The DNA is tightly ... |
(or GTP) cap and a 3′ poly-A tail are added to protect mature mRNA from degradation and allow its export from the nucleus. Pre-mRNAs also undergo splicing, in which introns are removed and exons are reconnected. Exons can be reconnected in different sequences, a phenomenon referred to as alternative gene splicing, whi... |
intervening sequences that do not specify the appropriate amino acids. In rare cases, the mRNA transcript can be “edited” after it is transcribed. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 15 | Genes and Proteins 611 RNA Editing in Trypanosomes The trypanosomes are a group... |
the evolutionary reason for this additional step in pre-mRNA processing? One possibility is that the mitochondria, being remnants of ancient prokaryotes, have an equally ancient RNAbased method for regulating gene expression. In support of this hypothesis, edits made to pre-mRNAs differ depending on cellular condition... |
the 1970s who expected that pre-mRNAs would specify protein sequences without further processing, as they had observed in prokaryotes. The genes of higher eukaryotes very often contain one or more introns. These regions may correspond to regulatory sequences; however, the biological significance of having many introns... |
. b. Mutations in the spliceosome recognition sequence at each end of an exon, or in the proteins and RNAs that make up the spliceosome, may occur. Mutations may also add new spliceosome recognition sites. c. Mutations in the spliceosome recognition sequence at each end of an intron, or in the proteins and RNAs that ma... |
acids for protein synthesis. Most of the tRNAs and rRNAs in eukaryotes and prokaryotes are first transcribed as a long precursor molecule that spans multiple rRNAs or tRNAs. Enzymes then cleave the precursors into subunits corresponding to each structural RNA. Some of the bases of pre-rRNAs are methylated; that is, a ... |
peptide. Each amino acid is carried to the ribosome by attaching to a specific molecule of tRNA. A tRNA molecule often is depicted as a cloverleaf, with an anticodon on one end, and the amino acid attachment site at the other. Amino-acid charging enzymes ensure that the correct amino acid is attached to the correct tRN... |
16][APLO 4.22][APLO 3.6] The synthesis of proteins consumes more of a cell’s energy than any other metabolic process. In turn, proteins account for more mass than any other component of living organisms (with the exception of water), and proteins perform virtually every function of a cell. The process of translation, o... |
hair loss. b. Lack of protein in the diet can weaken the immune system, thus leading to hair loss. c. Due to lack of protein in the diet, energy will be lost, thus leading to hair loss. d. Lack of protein in the diet will lead to breakage of disulfide bonds between proteins, thus leading to hair loss. Ribosomes Even b... |
on the mRNA template and add the corresponding amino acid to the polypeptide chain. Therefore, tRNAs are the molecules that actually “translate” the language of RNA into the language of proteins. Of the 64 possible mRNA codons—or triplet combinations of A, U, G, and C—three specify the termination of protein synthesis... |
eukaryotes. Here we’ll explore how translation occurs in E. coli, a representative prokaryote, and specify any differences between prokaryotic and eukaryotic translation. Initiation of Translation Protein synthesis begins with the formation of an initiation complex. In E. coli, this complex involves the small 30S ribo... |
the 5' to 3' direction, searching for the AUG start codon. Many eukaryotic mRNAs are translated from the first AUG, but this is not always the case. According to Kozak’s rules, the nucleotides around the AUG indicate whether it is the correct start codon. Kozak’s rules state that the following consensus sequence must ... |
RNAs nonspecifically. Elongation proceeds with charged tRNAs entering the A site and then shifting to the P site followed by the E site with each single-codon “step” of the ribosome. Ribosomal steps are induced by conformational changes that advance the ribosome by three bases in the 3' direction. The energy for each s... |
the protein chain Chloramphenicol would directly affect: 1. tRNA binding to the ribosome 2. Ribosome assembly 3. Growth of the protein chain a. Tetracycline would directly affect tRNA binding to the ribosome. Chloramphenicol would affect the growth of the protein chain. b. Tetracycline would directly affect ribosome a... |
ria or chloroplasts (in plants). Once the protein reaches its cellular destination, the signal sequence is usually clipped off. Many proteins fold spontaneously, but some proteins require helper molecules, called chaperones, to prevent them from aggregating during the complicated process of folding. Even if a protein i... |
C, G), and the polypeptide alphabet (20 amino acids). The Central Dogma describes the flow of genetic information in the cell from genes to mRNA to proteins. Genes are used to make mRNA by the process of transcription; mRNA is used to synthesize proteins by the process of translation. The genetic code is degenerate be... |
capping, 3' polyadenylation, and intron splicing are exported from the nucleus to the cytoplasm. Pre-rRNAs and pretRNAs may be processed by intramolecular cleavage, splicing, methylation, and chemical conversion of nucleotides. Rarely, RNA editing is also performed to insert missing bases after an mRNA has been synthe... |
Protein d. RNA 6. Which molecule in the central dogma can be compared to a disposable photocopy of a book kept on reserve in the This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 15 | Genes and Proteins 625 library? 5S rRNA? a. DNA b. mRNA c. Protein d. tRNA a. polymerase I b. pol... |
a transcript in the cytoplasm d. 3’-end of a transcript in the cytoplasm 17. Which pre-mRNA processing step is important for initiating translation? a. poly-A tail b. RNA editing c. splicing d. 7-methylguanosine cap 18. Where are the RNA components of ribosomes synthesized? a. cytoplasm b. endoplasmic reticulum c. nuc... |
200 commonly occurring amino acids instead of 20. Given what you know about the genetic code, what would be the shortest possible codon length? Explain. 24. The peptide bond synthesis in prokaryotic translation is catalyzed by: a. a ribosomal protein b. a cytoplasmic protein c. mRNA itself d. ribosomal RNA 25. What wo... |
these subunits, denoted α, α, β, and β ’, comprise the polymerase core enzyme. The fifth subunit, σ, is involved only in transcription initiation. The polymerase comprised of all five subunits is called the holoenzyme. In prokaryotes the polymerase is composed of four polypeptide subunits, two of which are identical. ... |
template. In rho-independent termination, when the polymerase encounters a region rich in C-G nucleotides, the mRNA creates a hairpin loop that causes polymerase to stall. d. Rho-dependent termination is controlled by rho protein and the polymerase stalls near the end of the gene at a run of G nucleotides on the DNA t... |
predict how alternative splicing may lead to an economy of genes? Do you need a different gene for every protein that the cell can produce? a. Alternative splicing can lead to the synthesis of several polypeptides from a single gene. b. Alternative splicing can lead to the synthesis of several forms of mRNA from a sin... |
by its anticodon. Which codon in the mRNA would the tRNA recognize: the one specified by its anticodon or the one that matches the modified amino acid it carries? a. exporting the mRNA across the nuclear a. The anticodon will match the codon in mRNA. b. c. d. membrane importing the mRNA across the nuclear membrane b. ... |
The enzyme reverse transcriptase transcribes the DNA straight into the protein molecules. d. The enzyme reverse transcriptase transcribes DNA to RNA, then again to DNA. There is no protein synthesis. 47. Radioactive deoxythymidine triphosphate is supplied to the protist Euglena. After an interval of time, the cells ar... |
-alanine-asparagine-leucine-valine 3. Serine-alanine-asparagine (-stop) c. 1. Serine-alanine-asparagine-leucine-valine 2. Serine-alanine-asparagine (-stop) 3. Serine-alanine-asparagine-leucine-valine d. 1. Serine-alanine-asparagine-leucine-valine 2. Serine-arginine-asparagine-leucine-valine 3. Serine-alanine-asparagine... |
, Nirenberg and Matthaei conducted a series of experiments to better understand the flow of genetic information from gene to protein. They discovered that in solutions containing the contents of ruptured E. coli bacterial cells from which DNA had been removed, polymers containing only one repeating amino acid, phenylal... |
ana’s findings, calculate the relative distributions of the following ratios of concentrations of RNA triplet sequences from mixtures in which the relative concentrations of guanine and cytosine, G:C, are 5:1. Ratio Relative Probabilities GGC:GGG GCG:GGG CGG:GGG GCC:GGG CGC:GGG CCG:GGG CCC:GGG Table 15.2 C. Based on th... |
to white. A. You have a uv-c lamp, culture plates, and growth chambers at 23 °C and 37 °C. You also have available known haploid strains that are (ade-2,+,+), where + denotes the wild type. Design a plan to determine the rate of uv-c-induced mutations in nutrient-containing plates inoculated with yeast. Earth's ozone ... |
exposure has the following values for an incubation time of 1 to 8: 0.58, 0.43, 0.38, 0.35, 0.49, 0.42, 0.32, 0.59, 0.45, with a standard deviation of 0.10. A 30 second exposure has the following values for an incubation time of 1 to 8: 0.33, 0.17, 0.12, 0.08, 0.11, 0.12, 0.09, 0.11, 0.14, with a standard deviation of... |
blanks with the letter corresponding to the correct term. a. amino acid b. tRNA c. DNA d. transcription e. mRNA f. translation g. protein h. RNA polymerase i. rRNA Within the cytoplasm, __ is synthesized from __ bound to __ in a sequence that corresponds to information provided by __. This process is called __. Within... |
range conditions that are suitable for an organism. Refine the question posed in part B, taking this result into account. 56. Only a fraction of DNA encodes proteins. The noncoding portion of a gene is referred to as the intron. The intron fraction depends upon the gene. Introns are rare in prokaryotic and mitochondri... |
Regulation 16.3: Eukaryotic Epigenetic Gene Regulation 16.4: Eukaryotic Transcriptional Gene Regulation 16.5: Eukaryotic Post-transcriptional Gene Regulation 16.6: Eukaryotic Translational and Post-translational Gene Regulation 16.7: Cancer and Gene Regulation Introduction Most people know that regular exercise is imp... |
in a given cell. Even the type of chromosome a gene is located on, like whether it is a sex chromosome or not, can determine its expression pattern, as can mutations or changes in DNA sequence and other external factors. In prokaryotes, gene expression is regulated primarily at the level of transcription, when DNA is ... |
spatial and temporal scales. 3.18 The student is able to describe the connection between the regulation of gene expression and observed differences between different kinds of organisms. For a cell to function properly, necessary proteins must be synthesized at the proper time. All cells control or regulate the synthes... |
expression is regulated, we must first understand how a gene codes for a functional protein in a cell. The process occurs in both prokaryotic and eukaryotic cells, just in slightly different manners. Prokaryotic organisms are single-celled organisms that lack a cell nucleus, and their DNA therefore floats freely in th... |
.1. The regulation of gene expression is discussed in detail in subsequent modules. Differences in the Regulation of Gene Expression of Prokaryotic and Eukaryotic Organisms Prokaryotic organisms Eukaryotic organisms Lack nucleus Contain nucleus DNA is found in the cytoplasm DNA is confined to the nuclear compartment RN... |
the human protein will be unrelated. Think About It How does controlling gene expression alter the overall protein level in the cell? 16.2 | Prokaryotic Gene Regulation In this section, you will explore the following question: • What are operons and what are the roles of activators, inducers, and repressors in regulat... |
questions. A learning objective merges required content with one or more of the seven science practices. Big Idea 3 Enduring Understanding 3.B Living systems store, retrieve, transmit and respond to information essential to life processes. Expression of genetic information involves cellular and molecular mechanisms. E... |
tryptophan availability is low, the switch controlling the operon is turned on, transcription is initiated, the genes are expressed, and tryptophan is synthesized. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 16 | Gene Regulation 641 Figure 16.3 The five genes that are needed... |
be able to break down tryptophan. b. The cell will gradually produce more tryptophan over time. c. The cell would not be able to make tryptophan. d. The cell would make tryptophan when it was not needed. 642 Chapter 16 | Gene Regulation Catabolite Activator Protein (CAP): An Activator Regulator Just as the trp operon ... |
lactose from the local environment. CAP binds to the operator sequence upstream of the promoter that initiates transcription of the lac operon. However, for the lac operon to be activated, two conditions must be met. First, the level of glucose must be very low or non-existent. Second, lactose must be present. Only wh... |
Yes Watch an animated tutorial (http://openstaxcollege.org/l/lac_operon) about the workings of lac operon here. The E. coli bacteria can have several mutations that affect the lac operon system. One mutation inhibits the ability of RNA polymerase to bind to the lac operon. How would this affect the cell? a. The cell w... |
contain DNA that is not expressed. On the other hand, histone acetylation results in loose packing of nucleosomes, allowing transcription factors to bind to DNA. Acetylated nucleosomes contain DNA that may be expressed. Information presented and the examples highlighted in the section support concepts outlined in Big ... |
Chapter 16 | Gene Regulation Figure 16.6 DNA is folded around histone proteins to create (a) nucleosome complexes. These nucleosomes control the access of proteins to the underlying DNA. When viewed through an electron microscope (b), the nucleosomes look like beads on a string. (credit “micrograph”: modification of w... |
8 depicts modifications to histone proteins and DNA). These tags are not permanent, but may be added or removed as needed. They are chemical modifications (phosphate, methyl, or acetyl groups) that are attached to specific amino acids in the protein or to the nucleotides of the DNA. The tags do not alter the DNA base s... |
configuration, the RNA polymerase and transcription factors do not have access to the DNA and transcription cannot occur (Figure 16.7). Think About It In females, one of the two X chromosomes is inactivated during embryonic development because of epigenetic changes to the chromatin. What impact do you think these chan... |
student is able to describe the connection between the regulation of gene expression and observed differences between different kinds of organisms 3.B.1 Gene regulation results in differential gene expression, leading to cell specialization 650 Science Practice Learning Objective Essential Knowledge Science Practice L... |
in female sexual characteristics. In the absence of slx, tra is spliced into its male form and male sexual characteristics result. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 16 | Gene Regulation 651 Figure 16.9 In Drosophila melanogaster, the sex is determined by a series o... |
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