Question

In order for a gene to be expressed, it must be transcribed into RNA, which is done by RNA polymerase. RNA polymerase resembles DNA polymerase because they both use a single strand of DNA as their template, they both need a pool of nucleoside triphosphates to incorporate into the growing nucleic acid strand, and they both always synthesize nucleic acids in the 5’ to 3’ direction (both read their DNA template strands in the 3’ to 5’ direction). They differ in a few ways too. RNA polymerase synthesizes RNA using nucleoside triphosphates, while DNA polymerase synthesizes DNA using deoxynucleoside triphosphates; in RNA, uridine is substituted for thymidine. The final product of RNA polymerase is single-stranded, while DNA is famously double-stranded, so that the new strand synthesized by DNA polymerase remains base-paired to its complementary template strand. Another difference is where synthesis begins: DNA replication begins at origins of replication, while transcription begins at promoters. To a first approximation, a promoter is a region of DNA with a sequence that is recognized by proteins which can bind to it, thereby recruiting RNA polymerase. A promoter is a stretch of DNA which says to RNA polymerase "start transcription here". Finally, unlike DNA polymerase, RNA polymerase is able to unwind DNA on its own to create a short region of single-stranded DNA to use as a template, and it does not require a double-stranded region to elongate: in other words, it can add the first few complementary RNA nucleotides all by itself. We will first consider transcription in the bacterium E. coli (a prokaryote). Promoters in E. coli (and also in eukaryotes) do not have an exact fixed DNA sequence, but they do often have a consensus sequence: in other words, a favored nucleotide for each position. In general, the closer a promoter adheres to the consensus sequence, the "stronger" a promoter it will be: transcription initiates more often at a strong promoter than at a weak one, leading to the production of more RNA. A promoter in E. coli usually has 2 small blocks of consensus sequence separated by 15-19 random nucleotides: the first has a consensus sequence of TTGACA and the second has a consensus sequence of TATAAT, with the preferred spacing being 17 nucleotides. As is always the case, the DNA sequence is given in the 5’ to 3’ direction (unless otherwise noted). Remember that DNA is double-stranded: it is also conventional to give the DNA sequence of only one strand, generally NOT the template strand (the one which is actually being "read" by RNA polymerase), but instead the one that will most closely resemble the RNA product of transcription, which is variously referred to as the sense strand, coding strand, or RNA-like strand. Promoters are directional, in that the way they are oriented sends RNA polymerase off in the correct direction to transcribe the gene, which is thus referred to as being "downstream". The first consensus sequence is called the "-35 element" because the beginning of it lies about 35 nucleotides upstream of where RNA polymerase will place the first RNA nucleotide (the "+1" position); the second consensus sequence is correspondingly called the "-10 element" because the beginning of it lies about 10 nucleotides upstream of where transcription begins. a. Draw a double-stranded region of DNA containing a promoter in the space below; for the regions outside the promoter, you can just use double lines as before, but within the promoter use the consensus sequence of bases. Use "N" for the unspecified nucleotides in the spacer region, and also in the region downstream of the -10 element until you reach the first nucleotide that will be incorporated into RNA, which should be designated with an "X". NB: there is no "0" position; counting goes straight from -1 to +1. Your drawing should look something like this: -----------------NNNX------------------ -----------------NNNX------------------ Be sure to label the 5’ and 3’ ends of each strand, and provide the correct complementary sequence for the consensus sequences.

Name: 1 in order for a gene to be expressed it must be transcribed into rna which is done by rna polymerase rna polymerase resembles dna polymerase because they both use a single strand of dna as 29447
Uploaded: 2022-05-15T13:24:10-08:00
Duration: 1 min 30 s
Channel: Suman K
Description: 1 in order for a gene to be expressed it must be transcribed into rna which is done by rna polymerase rna polymerase resembles dna polymerase because they both use a single strand of dna as 29447

They differ in a few ways too. RNA polymerase synthesizes RNA using nucleoside triphosphates, while DNA polymerase synthesizes DNA using deoxynucleoside triphosphates; in RNA, uridine is substituted for thymidine. The final product of RNA polymerase is single-stranded, while DNA is famously double-stranded, so that the new strand synthesized by DNA polymerase remains base-paired to its complementary template strand. Another difference is where synthesis begins: DNA replication begins at origins of replication, while transcription begins at promoters. To a first approximation, a promoter is a region of DNA with a sequence that is recognized by proteins which can bind to it, thereby recruiting RNA polymerase. A promoter is a stretch of DNA which says to RNA polymerase "start transcription here".

Finally, unlike DNA polymerase, RNA polymerase is able to unwind DNA on its own to create a short region of single-stranded DNA to use as a template, and it does not require a double-stranded region to elongate: in other words, it can add the first few complementary RNA nucleotides all by itself.

We will first consider transcription in the bacterium E. coli (a prokaryote). Promoters in E. coli (and also in eukaryotes) do not have an exact fixed DNA sequence, but they do often have a consensus sequence: in other words, a favored nucleotide for each position. In general, the closer a promoter adheres to the consensus sequence, the "stronger" a promoter it will be: transcription initiates more often at a strong promoter than at a weak one, leading to the production of more RNA. A promoter in E. coli usually has 2 small blocks of consensus sequence separated by 15-19 random nucleotides: the first has a consensus sequence of TTGACA and the second has a consensus sequence of TATAAT, with the preferred spacing being 17 nucleotides. As is always the case, the DNA sequence is given in the 5’ to 3’ direction (unless otherwise noted). Remember that DNA is double-stranded: it is also conventional to give the DNA sequence of only one strand, generally NOT the template strand (the one which is actually being "read" by RNA polymerase), but instead the one that will most closely resemble the RNA product of transcription, which is variously referred to as the sense strand, coding strand, or RNA-like strand. Promoters are directional, in that the way they are oriented sends RNA polymerase off in the correct direction to transcribe the gene, which is thus referred to as being "downstream". The first consensus sequence is called the "-35 element" because the beginning of it lies about 35 nucleotides upstream of where RNA polymerase will place the first RNA nucleotide (the "+1" position); the second consensus sequence is correspondingly called the "-10 element" because the beginning of it lies about 10 nucleotides upstream of where transcription begins.

a. Draw a double-stranded region of DNA containing a promoter in the space below; for the regions outside the promoter, you can just use double lines as before, but within the promoter use the consensus sequence of bases. Use "N" for the unspecified nucleotides in the spacer region, and also in the region downstream of the -10 element until you reach the first nucleotide that will be incorporated into RNA, which should be designated with an "X". NB: there is no "0" position; counting goes straight from -1 to +1. Your drawing should look something like this:
-----------------NNNX------------------
-----------------NNNX------------------
Be sure to label the 5’ and 3’ ends of each strand, and provide the correct complementary sequence for the consensus sequences.

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Biology for AP Courses

Julianne Zedalis, John Eggebrecht

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Solved by Expert Suman K

05/15/2022

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Use "N" for the unspecified nucleotides in the spacer region and designate the first nucleotide that will be incorporated into RNA with an "X". Show more…

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In order for a gene to be expressed, it must be transcribed into RNA, which is done by RNA polymerase. RNA polymerase resembles DNA polymerase because they both use a single strand of DNA as their template, they both need a pool of nucleoside triphosphates to incorporate into the growing nucleic acid strand, and they both always synthesize nucleic acids in the 5’ to 3’ direction (both read their DNA template strands in the 3’ to 5’ direction). They differ in a few ways too. RNA polymerase synthesizes RNA using nucleoside triphosphates, while DNA polymerase synthesizes DNA using deoxynucleoside triphosphates; in RNA, uridine is substituted for thymidine. The final product of RNA polymerase is single-stranded, while DNA is famously double-stranded, so that the new strand synthesized by DNA polymerase remains base-paired to its complementary template strand. Another difference is where synthesis begins: DNA replication begins at origins of replication, while transcription begins at promoters. To a first approximation, a promoter is a region of DNA with a sequence that is recognized by proteins which can bind to it, thereby recruiting RNA polymerase. A promoter is a stretch of DNA which says to RNA polymerase "start transcription here". Finally, unlike DNA polymerase, RNA polymerase is able to unwind DNA on its own to create a short region of single-stranded DNA to use as a template, and it does not require a double-stranded region to elongate: in other words, it can add the first few complementary RNA nucleotides all by itself. We will first consider transcription in the bacterium E. coli (a prokaryote). Promoters in E. coli (and also in eukaryotes) do not have an exact fixed DNA sequence, but they do often have a consensus sequence: in other words, a favored nucleotide for each position. In general, the closer a promoter adheres to the consensus sequence, the "stronger" a promoter it will be: transcription initiates more often at a strong promoter than at a weak one, leading to the production of more RNA. A promoter in E. coli usually has 2 small blocks of consensus sequence separated by 15-19 random nucleotides: the first has a consensus sequence of TTGACA and the second has a consensus sequence of TATAAT, with the preferred spacing being 17 nucleotides. As is always the case, the DNA sequence is given in the 5’ to 3’ direction (unless otherwise noted). Remember that DNA is double-stranded: it is also conventional to give the DNA sequence of only one strand, generally NOT the template strand (the one which is actually being "read" by RNA polymerase), but instead the one that will most closely resemble the RNA product of transcription, which is variously referred to as the sense strand, coding strand, or RNA-like strand. Promoters are directional, in that the way they are oriented sends RNA polymerase off in the correct direction to transcribe the gene, which is thus referred to as being "downstream". The first consensus sequence is called the "-35 element" because the beginning of it lies about 35 nucleotides upstream of where RNA polymerase will place the first RNA nucleotide (the "+1" position); the second consensus sequence is correspondingly called the "-10 element" because the beginning of it lies about 10 nucleotides upstream of where transcription begins. a. Draw a double-stranded region of DNA containing a promoter in the space below; for the regions outside the promoter, you can just use double lines as before, but within the promoter use the consensus sequence of bases. Use "N" for the unspecified nucleotides in the spacer region, and also in the region downstream of the -10 element until you reach the first nucleotide that will be incorporated into RNA, which should be designated with an "X". NB: there is no "0" position; counting goes straight from -1 to +1. Your drawing should look something like this: -----------------NNNX------------------ -----------------NNNX------------------ Be sure to label the 5’ and 3’ ends of each strand, and provide the correct complementary sequence for the consensus sequences.