6a. The two strands of a DNA molecule can be separated by the application of hea
ID: 150773 • Letter: 6
Question
6a. The two strands of a DNA molecule can be separated by the application of heat and without breaking any covalent bonds. However, every unique DNA molecule "melts" at a different temperature. In this context, Tm(melting temperature) is the point at which two strands separate, or become denatured. Write out the order of the DNA sequences listed below according to relative melting temperatures (from lowest T to highest Tm). Assume that they all begin as stable double-stranded DNA molecules. [3 pts B. C. TATTGTCT GACTCCTO BAD From lowest T to highest T 6b. Explain your answer for 6a.(4 pts] 7. Prokaryotes and eukaryotes carry out transcription using very similar machinery, but there are also distinct differences 7a. Circle the components below that are present in eukaryotes but NOT in bacteria 3 pts RNA Polymerase Promoter Enhancer Splicing 5' Cap Poly (A) Tail Mediator TATA box Terminator Sigma Factor 7b. When a region of DNA that contains the genetic information for a protein is isolated from a bacterial cell and inserted into a eukaryotic cell in a proper position between a promoter and a terminator, the resulting cell usually produces the correct protein. But when the experiment is done in the reverse direction (eukaryotic DNA into a bacterial cel), the correct protein is often not produced even though transcription is carried out. The absence of which of the componentls) in 7a in bacteria may explain this observation? [4 pts)Explanation / Answer
Answer- (6a) Correct sequence for Tm of dna sequences is
B<A< C < D
answer(6b) This sequence is seen because melting point depend on bond as bond between guanine and cytosine is triple bonded while between adenine and thiamine has double bond between them . So (D) option contain maximum number of guanine and cytosine pair and (B) contain least number so (D) has highest Tm and (A) has lowest .
Answer7- following are differnce between prokaryotic and eukaryotic transcription,
a) Eukaryotic transcription takes place in nucleus while prokaryotic transcription takes place in cytoplasm.
b) both transcription and translation occur together in prokaryote while these occur differently at different place in eukaryotes .
c) prokaryotes have only one type of RNA polymerase while eukaryotes have three type of RNA polymerase.
Answer 7a- Componets present in eukaryotes but not in bacteria
a) splicing- spicing of post transcribed RNA occur only in eukaryotes, in this only coding seques are retained and non coding sequences are removed.
b) Capping - at 5' end of newly transcribed mRNA guanosine nucleotide is added in eukaryotes , this donot occur in bacteria.
c) Tailing - poly adenylic acid added at 3' end in mRNA in eukaryotes, this is absent in bacteria.
d)Tata box - Contain sequences from where transcription start present in eukaryotes, absent in bacteria.
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