anonymous
  • anonymous
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Biology
  • Stacey Warren - Expert brainly.com
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schrodinger
  • schrodinger
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
- State the central dogma of molecular biology. - Outline research that determined that DNA is the genetic material. - What are Chargaff's rules? One Medal For Each Question !
anonymous
  • anonymous
Dont copy and paste please.
anonymous
  • anonymous
How did Griffith's research, coupled with the work of Avery and his colleagues demonstrate that DNA, not protein is the genetic material Griffith's research established that a then-unkown molecule in a lethal strain of bacteria could transform non-lethal bacteria making them able to kill mice. Avery et el. added enzymes that destroyed either proteins or DNA to the mixtures that Griffith used in his experiments. In Avery's experiments, mice died only from bacterial solutions mixed with enzymes that destroyed proteins. Mice did not die from bacterial solutions mixed with enzymes that destroyed DNA. These experiments showed that DNA, Not protein, changed bacteria from non-lethal to lethal.  How did the Hershey-Chase blender experiments confirm Griffith's results? The Hershey-Chase blender experiment used radioactive sulphur to label the protein coats of one batch of bacteriophages and used radioactive phosphorous to label the DNA of another batch of bacteriophages. Both batches of viruses were allowed to infect bacteria. The solutions were separately blended at high speed to separate viral protein coats from bacterial cells. Radioactive bacteria were only found in the batches that had been infected by phages with radioactively labelled DNA. The protein labelled phages did not transmit radioactivity to the bacteria they had infected. These experiments confirmed that DNA, not protein is the genetic material.  What are the components of DNA and it's three dimensional structure? The components of a DNA molecule are nucleotides. These are composed of a deoxyribose sugar bonded to a phosphate and a nucleotide base (adenine, thymine, cytosine, or guanine). The three dimensional structure of DNA is a double helix.  What evidence enabled Watson and Crick to decipher the structure of DNA? The evidence included Rosalind Franklins x-ray diffraction photo of a crystal of DNA, plus Erwin Chargaff's work that showed that DNA contains equal amounts of adenine and thymine and equal amounts of cytosine and guanine.  What is the relationship between a gene and a protein? A gene is a strand of DNA that encodes a protein.  What are the two main stages in protein synthesis? Transcription and translation  What are the three types of RNA, and how does each contribute to protein synthesis? Messenger RNA (mRNA) carries the DNA instructions for building the protein, Transfer RNA (tRNA) carries the appropriate amino acid to the ribosome, and Ribosomal RNA (rRNA) is the major component of a ribosome, the structure that reads codons on the mRNA and assembles amino acids into polypeptides.  What happens during each stage of transcription? Initiation, Elongation of the RNA molecule, and Termination. During initiation enzymes unzip the DNA and RNA polymerase binds. During elongation, RNA polymerase reads the DNA strand and adds complimentary nucleotides to the growing RNA strand. During termination, synthesis of the RNA molecule ends and the DNA molecule reforms.  Where in the cell does transcription occur? Transcription occurs in the nucleus  What is the role of RNA polymerase in transcription? RNA polymerase uses the DNA template to bind additional RNA bases into the growing chain of RNA being transcribed.  What are the roles of the promoter and terminator sequence in transcription? The promoter signals the start of a gene, and the terminator signals the end of a gene. RNA polymerase recognizes the promoter and terminator, thus, starts and stops transcription at the correct signals  How is mRNA modified before it leaves the nucleus of a eukaryotic cell? A cap is added to the 5' end of the mRNA molecule A poly-A-tail is added to the 3'end Introns are removed and exons are spiced together.  What happens in each stage of translation? Initiation (ribosomal subunit binds to initiator codon), elongation of the polypeptide, and termination (release of the last tRNA from the ribosome, signified by a stop codon).  where in the cell does translation occur? Translation occurs at ribosomes, which are either free in the cytoplasm or attached to the rough e.r.  How are polypeptides modified after translation Polypeptides have to be folded into proteins; sometimes amino acids are cut out of the chain, and sometimes multiple polypeptides join together.  What is a mutation? A mutation is a change in the DNA sequence of a cell  What is recombinant DNA? Recombinant DNA is the combined DNA from 2 or more organisms.  What is the function of DNA? Some of it encodes the cell's RNA and proteins.  List the differences between RNA and DNA RNA nucleotides contain ribose; DNA nucleotides contain deoxyribose. RNA has the nitrogrenous base uracil, which behaves similarly to the thymine in DNA. RNA can be single-stranded; DNA is double-stranded. RNA can catalyze chemical reactions.  Define and distinguish between transcription and translation. Where in the eukaryotic cell does each process occur? Transcription copies the information encoded in a DNA base sequence into the complimentary language of mRNA. Once transcription is complete and mRNA is processed, the cell is ready to translate the mRNA message into a sequence of amino acids that builds a protein. Transcription occurs in the nucleus, and translation occurs in ribosomes in the cytoplasm.  Why were P32 and S35 chosen in the Hershey-Chase experiment? Nucleic acids contain large amounts of phosphorus and no sulphur, whereas proteins contain sulphur and no phosphorus.  What component of the nucleotide is responsible for the absorption of UV light. How is this technique important in the analysis of nucleic acids. The nitrogenous bases of nucleic acids absorb UV light maximally at wavelengths of 254 to 260nm. Using this technique can determine the presence and concentration of nucleic acids in a mixture. UV absorption is greater in single-stranded molecules than in double-stranded structures. Applying denaturing agents can determine whether a nucleic acid is single or double stranded.  What is the hyperchromic effect? How is it measured? What does Tm imply? A hyperchromic effect is the increased absorption of UV light as double-stranded DNA (or RNA) is converted to single-stranded DNA. The change in absorption is significant, with a structure of higher G-C content melting at a higher temperature than A-T nucleic acid. The Tm is the point on the profile (temperature) at which half of the sample is denatured.  Compare conservative, semi-conservative and dispersive modes of DNA replication. In the conservative mode, the original double helix remains as a complete unit and the new DNA double helix is produced as a singe unit. The old DNA is completely conserved. In the semi-conservative mode, each daughter strand is composed of one old DNA strand and on new DNA strand. In the dispersive mode, the original DNA strand is broken into pieces and the new DNA in the daughter strand is interspersed among the old pieces.  What are the requirements for in vitro synthesis of DNA under the direction of DNA polymerase I The in vitro replication requires a DNA template, a primer to give a double-stranded portion, a divalent cation (Mg2+) and all four of the doxyribonuclease triphosphates; dATP, dCTP, dTTP and dGTP.  The basic structure of a nucleotide Base, sugar and phosphate  The classic Hershey-Chase (1952) experiment that offered evidence in support of DNA being the genetic material in bacteriophages made use of what two components? Phosphorus and Sulphur  Reverse transcriptase is an enzyme found in association with retroviral activity. It has the property of: Synthesis of DNA from an RNA template.  What are the two major components of the Tobacco Mosaic Virus? RNA and protein  In the structure of double-stranded DNA what kind of bonds hold one complimentary strand to the other. Hydrogen  Regarding the structure of DNA, the covalently arranged combination of a deoxyribose and nitrogen is called a Nucleoside  In the classic Hershey-Chase experiment, why was the pellet radioactive in the centrifuge tube that contained bacteria viruses, which had been grown on a medium containing 32 P? The bacteria were in the pellet, and many contained the radioactive viral dna  If 15% of the nitrogenous bases in a sample of DNA from a particular organism is thymine, what percentage should be cytosine? 35%  In an analysis of the nucleotide composition of double-stranded DNA to see which bases are equivalent in concentration, which of the following would be true? A+C=G+T  Which of the following clusters of terms accurately describes DNA as it is generally viewed to exist in prokaryotes and eukaryotes? Double-stranded, antiparallel, (A+T)/(C+G)=variable,(A+G)/(C+T)=1.0  Briefly define transformation and describe the relationship between the phenomenon of transformation and the discovery that DNA is the genetic material in bacteria. Transformation is the process whereby one organism is genetically altered by exposure to DNA from another organism. Since DNA can carry heritable traits from one organism to another, it must be the genetic material.  Can RNA be the genetic material? yes , tobacco mosaic virus  Describe four major functions of DNA in a cell. Replication Transcription Translation Mutagenesis  If the GC content of a DNA molecule is 60%, wha are the molar percentages of the four bases (G,C,T,A)? G=30%, C=30%, A=20%, T=20%  Explain how and why the following circumstances influence characteristics of temperature-induced DNA melting. a. Percentage of GC base Pairs b. Urea (forms hydrogen bonds with bases) c. Sodium chloride (neutralizes negatively charged phosphate's), a) GC pairs are composed of three hydrogen bonds and require more energy (heat) to separate that AT pairs. b) Urea competes for hydrogen bonds; thus, the bases pair with urea rather than with each other. This weakens the complimentary associations that are required to hold the dna helix together; thus, less heat is required for melting. c) Sodium chloride associates with and neutralizes the strong negative charges on the phosphates. The phosphates do not repel each other with the sodium ion present; thus, the double stranded structure requires more energy to melt.  Assume that the molar percentage of thymine in a double-stranded DNA is 20. What are the percentages of the four bases G.C,T,A? If the DNA is single stranded, would you change your answer? T=20, A=20,G=30,C=30. Chargaff's rule does not apply to single-stranded DNA(viral) genomes or any type of RNA genome.  The base content of a sample of DNA is as follows: A=31%,G=31%,T=19%,C=19%. What conclusions can be drawn from this information? The sample of DNA is single stranded  What does it mean to say that double-stranded nucleic acids are antiparallel? The C -5' to C-3' orientations run in opposite directions.  List three forms of DNA. B-DNA, A-DNA and Z-DNA  Considering the central dogma of molecular biology, what three general properties are ascribed to DNA? Storage and expression of information, variation through mutation  At what proximate wavelengths do DNA, RNA and proteins maximally absorb light? DNA/RNA absorb light maximally at 260nm, proteins absorb light maximally at 280nm.  List two major differences between RNA and DNA at the level of the nucleotide. ribose in RNA, deoxyribose in DNA; uracil in RNA replaces thymine in DNA  In 1869, A Swiss chemist isolated an acid substance from cell nuclei that he called nuclein. It turned out that this substance contain the hereditary material. What substance had Meischer discovered? Meischer was the first to isolate and chemically characterize DNA.  Experiments conducted in the 1920's by Griffith involving the bacterium diplococcus pneunmoniae demonstrated that a substance from one bacterial strain could genetically transform other bacterial strains. What was the name of the substance capable of such transformation and who finally determined its identity. DNA was determined by Avery et al.(1944)  Name the pyrimidine's and the purines in DNA Pyrimidine- cytosine, uracil, thymine Purines- adenosine, guanine.  During the polymerization of nucleic acids, covalent bonds are formed between neighbouring nucleotides. Which carbons are involved in such bonds. DNA polymers are built from individual nucleotides by linking the phosphate of one nucleotide to the 3' carbon of the neighbouring nucleotide and the 5' carbon of the sugar deoxyribose.  Suppose that the dinucleotide were cleaved with the enzyme spleen diesterase, which breaks the covalent bond connectin the phosphate to c-5'. After such cleavage, to which nucleoside is the phosphate now attached? Deoxyadenosine (DNAa)  What is meant by the term anti-parallel? The opposite orientation of the two complimentary strands of deoxyribonucleic acid, 5'to 3' and 3' to 5'.  In ribose the 2'carbon has an OH to it. True or False True  DNA has no sulphur and proteins have no phosphorus. True/False. True  The transforming principle discovered by Griffith is RNA, True/False False  G and C are present in both DNA and RNA. True/False True  Hershey-Chase used labelled DNA and protein to determine that DNA is the genetic material in bacteria. True/False False  Avery et al. 1944 determined that DNA is the genetic material in bacteriophage. True/False False  In 1953, Watson and Crick published a paper that described the structure of DNA. True/False True  Deoxyribonuclease is an enzyme that adds 3' hydroxyl groups to RNA. True/False False  When considering the structure of DNA, we would say that complimentary strands are antiparallel. True/False True  In RNA, uracil is present instead of thymine. True/False True  Which of the following terms accurately describes the replication of DNA in vivo. Semi-discontinuous  DNA polymerase III add nucleotides: To the 3'end of the RNA primer.  DNA polymerase I is thought to add nucleotides: In the place of the primer RNA after it is removed.  Which cluster of terms accurately reflects the nature of DNA replication in prokaryotes? Fixed point of initiation, bidirectional, semi-conservative.  The discontinuous aspect of replication of DNA in vivo is caused by. The 5' to 3' polarity restriction.  Okazaki Fragment. Single short stranded stretches of DNA on the lagging strand.  Lagging Strand The side of the replication fork where synthesis is discontinuous  Bidirectional From the point of initiation, replication occurs in both directions along the DNA.  What enzyme functions to unwind the DNA? Helicase  What enzyme functions to deal with supercoils in DNA? Gyrases/Topisomerases  What enzyme functions to couple newly synthesized fragments of DNA? DNA ligase  List at least four enzymes known to be involved in the replication of DNA in bacteria? Helicase - unwinds a portion of the double helix. RNA primase - attaches RNA primers to the replicating strands DNA polymerase III- binds to the 5'-3' strand in order to bring nucleotides and create the daughter leading strand. Exonuclease - DNA pol I, finds and removes the RNA primers. DNA Ligase - Adds phosphates in the remaining caps of the phosphate-sugar backbone. Nucleases - Remove wrong nucleotides from the daughter strand.  What structural circumstance in DNA sets up the requirement for its semidiscontinuous nature of replication? 5'-3' polarity restrictions of DNA synthesis and the anti parallel orientation of the DNA strands in DNA.  As unwinding of the helix ocdurs during DNA replication, tension is created ahead of the replication fork. Describe the nature of this tension and state the manner in which this tension is resolved. Supercoiling and DNA gyrase.  The complex of proteins that is involved in the replication of DNA is called a: Replisome  What protein is responsible for the initial step in unwinding the DNA helix during replication of the bacterial chromosome. DnaA  During DNA replication, what is the function of RNA primase? RNA primase provides a free 3'-OH group which DNA polymerase depends upon.  What three models were suggested to originally describe the nature of DNA replication? Conservative Semi conservative Dispersive  Meselson and Stahl determined that DNA replication in E.coli is semiconservative. What additive did they initially supply to the medium in order to distinguish new from old DNA? Nitrogen N 15 .  What primary ingredients, coupled with DNA polymerase I are needed for the in vitro synthesis of DNA? dNTP, DNA template, primer DNA or RNA, Mg2+  DNA replication in vivo requires a primer with a free 3"-OH end. What molecular species provides this 3' end, and how is it provided? The free 3'end is provided by an RNA primer, which is provided by the enzyme activity of RNA primase.  DNA replication occurs in the 5'-3' end direction, that is new nucleoside triphosphates are added to the 3' end. True/False True  DNA replicates conservatively, which means that one of two daughter double helices is old and the other is new. True/False False  DNA strand replication begins with an RNA primer. True/False True  In general, DNA replicates semi-conservatively and bi-directionally. True/False True  In ligase-deficient strains of E.coli, DNA and chromosomal replication is unaltered because ligase is not involved in DNA replication. True/False False  During replication, primase adds a DNA primer to RNA. True/False False  DNA polymerase III is an enzyme that adds nucleotides to the 3' end of each growing DNA strand. True/False True  An endonuclease is involved in removing bases sequentially from one end of DNA or the other. True/False False  What roles do restriction enzymes, vectors and host cells play in recombinant DNA studies? Enzymes- known as restriction endonucleases cut DNA at specific sites and often yield cohesive ends for interaction with DNA molecules cut with the same class of enzymes. A vector may be a plasmid, bacteriophage or cosmid that receives through ligation, pieces of foreign DNA. The recombinant vector can transform a host cell (bacterium, yeast) and be amplified in number.  Although many cloning applications involve introducing recombinant DNA into bacterial host cells, many other cell types are also used as hosts for recombinant DNA. Why? Bacteria are prokaryotes' and do not process transcripts. Bacterial artificial chromosomes and yeast artificial chromosomes are vectors that can be used to clone larger fragments. Plasmids are small and can only accept (25kb) of DNA fragments.  Restriction sites are palindromic; that is, they read the same in the 5' to 3' direction on each strand of DNA. What is the advantage of having restriction sites organized in this way? Palindromic - Symmetrical sequencing which reads the same on both strands of the DNA when read in the 5' to 3' direction. The advantage to this is that each restriction enzyme recognizes its particular restriction site and cuts the DNA in a characteristic cleavage pattern. In order for both strands to be protected by methylation, the sequence must be read in the same in both directions on the double helix.  In a typical PCR reaction, describe what is happening in stages occurring at temperature ranges a) 90-95 C b) 50-70 C and c) 70-75C. a). 90-95C - DNA is denatured, heat separates ends then each strand is annealed to short, complimentary primers. b). 50-70C - Decrease of temperature allows the binding if the primers (hybridization/annealing) to the denatured single-stranded target DNA. c).70-75C - DNA polymerase uses the primers as a starting point to synthesize new DNA strands by adding nucleotides to the ends of the primers in a 5'-3' direction.  Words such as mom, dad, liveevil might have special significance when considering the fundamental tools of recombinant DNA technology. What term would be used to describe such words in the context of recombinant DNA technology? Palindromic  Restriction endonucleases are especially useful if the generate sticky ends. What makes an end sticky? Single-stranded complimentary tails  Which of the following would you expect to be especially useful characteristics of cloning vectors? High copy number and antibiotic resistant gene(s).  Some vectors such as pUC18 and others of the pUC series contain a large number of restriction enzyme sites clustered in one region. What term is given to this advantageous arrangement of restriction sites? Polylinker  One of the primary reasons for the necessity of generating a large number of clones in a eukaryotic genomic library is that.. Each vector can take up only a very small fraction the eukaryotic DNA.  Assume a circular plasmid is 3200 base pairs in length and has restriction sites at the following locations: 400, 700, 1400,2600. Give the expected sizes of the restriction fragments following complete digestion. 300, 700, 1000, 1200.  The PCR (polymerase chain reaction) protocol that is currently used in laboratories was facilitated by the discovery of a bacterium called Thermus Aquaticus in a hot spring inside Yellowstone National Park, Wyoming. This organism contains a heat-stable form of DNA polymerase known as TAQ polymerase, which continues to function even after it has been heated to 95 C. Why would such a heat-stable polymerase be beneficial in PCR? Each cycle includes a hot denaturation phase (95C), which separates the hydrogen bonds that hold the strands of the template DNA together.  What is recombinant DNA technology? What are some safety issues related to recombinant DNA technology? Recombinant DNA is a form of artificial DNA which is engineered through the combination or insertion of one or more DNA strands, thereby combining DNA sequences which would not normally occur together. 1. Natural process of transduction and transformation may cause unintended effects which could spiral out of control. 2. Increase risk of accidental release of dangerous altered organisms that are more virulent and more resistant to treatment.  What is a cDNA molecule? A DNA copy of an RNA molecule.  What might be a reasonable function of restriction endonucleases in a bacterium, distinct from their use by molecular biologists? Restrict or prevent viral infections by degrading invading viral nucleic acids.  What is meant by the designation EcoRI One of the first endonuclease enzyme isolated from strains of E.coli.  Nucleic acid blotting is commonly used in molecular biology. Two types, Southern blots and Northern blots, involve gel electrophoresis and a filter that holds the nucleic acid. Briefly describe the procedure of Blotting in this context and differentiate between southern and northern blots. In a southern blot the DNA to be probed is cut with a restriction enzyme(s), then the fragments are separated by gel electrophoresis. Alkali treatment of the gel denatures the DNA which is then blotted onto the filter. A labelled probe (RNA/DNA) is then hybridised to complimentary fragments on the filter. In a northern blot, RNA is separated in the gel and probed with the labelled DNA.  Assume that you have cut DNA with the restriction enzyme HindIII. You separate the fragments on an agarose gel and stain the DNA with ethidium bromide. You notice that the intensity of the strain is less in the bands that have migrated closer to the positive pole. Give an explanation for this finding. Since the smaller fragments migrate toward the positive pole, away from the origin, they bind less stain than the larger fragments near the origin.  Over the years, sophisticated plasmid vectors have been developed for use in recombinant DNA technology. What useful features have been introduced in particularly useful vectors? Small size to allow large inserts, high copy number, large numbers of unique restriction sites (polylinkers), variety of selection schemes (pigmented colonies, antibiotic resistance).  List, in order, the steps usually followed in producing recombinant DNA molecules in a plasmid vector. Isolation of DNA (foreign and plasmid) Digestion of DNA's with an appropriate restriction endonuclease. Ligation of fragment Transformation of host cells.  What advantage does pUC18 have in terms of recombinant DNA technology? Small size, high copy number, polylinker in lacz gene.  What term is used to refer to the process in which DNA can be introduced into host bacterial cells? Transformation  Under ideal conditions, how many copies of all the sequences of the host genome should be represented in a genomic library? At least one should be represented. Typically, library construction includes a several-fold greater number of clones than necessary for one representative of each fragment in order to increase likelihood of cloning difficult fragments and stochastic loss.  What is the specific application of reverse transcriptase in the preparation of cDNA? Synthesis of DNA to form an RNA-DNA duplex.  In the polymerase chain reaction, what is the purpose of the initial high temperature? What is the purpose of the cooling in the second step? Purpose of initial high temperature is to denature the target (template) DNA. Purpose of the cooling in the second step is the annealing of the primer to the target.  In what way are specific DNA sequences of the template amplified in the polymerase chain reaction? In other words, how does one target the target? Oligonucleotide primers hydrogen bond to specific sections; primers are then extended.  Of what advantage is it to have a polylinker region (multiple unique restriction sites) embedded in the LacZ component in pUC18? An insert of DNA in the polylinker inactivates the LacZ component and allows identification of recombinant plasmids under proper genetic and environmental conditions.  Assume that one conducted a typical cloning experiment using pUC18, transformed an appropriate host bacterial strain (one carrying the lacZ complementing region), and plated the bacteria on an appropriate xgal medium. Blue and white colonies appeared. Which of the two types of colonies, blue or white, would most likely contain the recombinant pUC18? The white colonies because of insertional activation of lacZ component.  When cloning a gene using typical restriction endonucleases, how does the restriction endonuclease recognize genes in the genome? Restriction endonucleases do not recognize functional regions I the genome (genes). They can only recognize relatively short DNA sequences, which have no relationship to functionality.  Below are four processes common to most cloning experiments. Place the components in the order in which they would most likely occur during a cloning experiment. Cutting DNA with restriction enzymes. Ligating DNA fragments. Transforming Plating bacteria on selective medium  A common term for a plasmid or other DNA element that serves as a cloning vehicle is vector. T/F True  Restriction endonucleases typically recognize palindromic DNA sequences and often generate sticky ends or single-stranded DNA overhangs at cut sites. T/F True  In general, the main goal of cloning is to include as many different genes as possible in a single cloning vector. T/F False  The main purpose of a probe is its insertion in plasmid DNA. T/F False  To isolate a bacterium with a plasmid that carries a desired DNA fragment cloned within the ampicillin resistance gene, we should grow bacteria in a medium that contains ampicillin. T/F False  Some restriction endonucleases are capable of producing blunt ends, while others can generate sticky ends. T/F True  In recombinant DNA technology, a YAC is an enzyme isolated from a large south American four legged mammal. T/F False  Reverse transcriptase is often used as the heat-stable enzyme in PCR. T/F False  In a typical PCR, primers are used to cleave specific regions of the DNA template. T/F False  A restriction map provides the location of sites cleaved by restriction enzymes. T/F True  During a PCR, heat is provided to inactivate the polymerase enzyme. T/F False  pUC18 is a common YAC. T/F False  In recombinant DNA technology, YAC, ddNTP's and pUC18 have identical uses. T/F False  In a PCR, primers are complimentary to stretches of DNA with which the anneal. T/F True  What is the name given to the three bases in a messenger RNA that bind to the anticodon of tRNA to specify an amino acid replacement in a protein? codon  An intron is a section of.. RNA that is removed during RNA processing  The genetic code is fairly consistent among all organisms. The term often used to describe such consistency in the code is Universal  Which of the following sets of two terms relates most closely to split genes? introns; exons  Significant in the deciphering of the genetic code was the discovery of the enzyme polynucleotide phosphorylase. What was this enzyme used for? The manufacture of synthetic RNA for cell free systems.  1964, Nirenberg and Leder used the triplet binding assay to determine specific codon assignments. A complex of which of the following components was trapped in the nitrocellulose filter? Charged tRNA, RNA triplet and ribosome  What is the initiator triplet in both prokaryotes and eukaryotes? What amino acid is recruited by this triplet? AUG- Methionine  Select three post transcriptional modifications often seen in the maturation of mRNA in eukaryotes. 5'capping and a 3' poly-A-tail addition, splicing  The genetic code is said to be a triplet, meaning that: There are three bases in mRNA that code for an amino acid  When scientists were attempting to determine the structure of the genetic code, Crick and coworkers found that when three base additions or three base deletions occurred in a singe gene, the wild-type phenotype was sometimes restored. These data supported the hypothesis that: The code is a triplet  When examining the genetic code, it is apparent that: There can be more than one codon for a particular amino acid  The relationship between a gene and a messenger RNA is that: mRNA's are made from genes  Introns are known to contain termination codons (UAA, UGA, or UAG), yet these codons do not interrupt the coding of a particular protein. Why? Introns are removed from mRNA before translation  It has been recently determined that the gene for Duchenne Muscular Distrophy (DMD) is over 2000kb in length; However, the mRNA produced by this gene is only about 17kb long. What is the likely cause of this discrepancy? The introns have been spliced out during mRNa processing @dna.com

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DangerousJesse
  • DangerousJesse
Hey, you would get far more responses if you asked these one at a time. Mind starting a new topic?
anonymous
  • anonymous
What topic do you have in mind
DangerousJesse
  • DangerousJesse
I meant asking a new question, with only one of these questions in it.
anonymous
  • anonymous
okay
anonymous
  • anonymous
Well why is DNA replication said to be semi conservative?

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