Eukaryotic Transcriptional Gene Regulation Quiz

PDF page 658: To start transcription, general transcription factors must first bind to a specific area on the DNA called the TATA box and then recruit RNA polymerase to that location. In addition, other areas on the DNA called enhancer regions help augment transcription. Transcription factors can bind to enhancer regions to increase or prevent transcription.

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 659: The Science Practice Challenge Questions contain additional test questions for this section that will help you prepare for the AP exam. These questions address the following standards: [APLO 3.18] Like prokaryotic cells, the transcription of genes in eukaryotes requires the actions of an RNA polymerase to bind to a sequence upstream of a gene to initiate transcription. However, unlike prokaryotic cells, the eukaryotic RNA polymerase requires other proteins, or transcription factors, to facilitate transcription initiation. Transcription factors are proteins that bind to the promoter sequence and other regulatory sequences to control the transcription of the target gene. RNA polymerase by itself cannot initiate transcription in eukaryotic cells. Transcription factors must bind to the promoter region first and recruit RNA polymerase to the site for transcription to be established. The activity of transcription factors can regulate differential gene expression in cells, resulting in the development of different cell products and functions. For example, scientists have found that primary sexual characteristics is regulated by several genes Figure 16.9. In the fruit fly Drosophila, the slx gene determines sex. This gene is expressed when the organism has two copies of the X chromosome. The gene product for slx binds to the mRNA of the tra gene and regulates its splicing. In the presence of slx, tra is spliced into its female form and influences the expression of dsx and fru to result in female sexual characteristics. In the absence of slx, tra is spliced into its male form and male sexual characteristics result.

PDF page 659: The Science Practice Challenge Questions contain additional test questions for this section that will help you prepare for the AP exam. These questions address the following standards: [APLO 3.18] Like prokaryotic cells, the transcription of genes in eukaryotes requires the actions of an RNA polymerase to bind to a sequence upstream of a gene to initiate transcription. However, unlike prokaryotic cells, the eukaryotic RNA polymerase requires other proteins, or transcription factors, to facilitate transcription initiation. Transcription factors are proteins that bind to the promoter sequence and other regulatory sequences to control the transcription of the target gene. RNA polymerase by itself cannot initiate transcription in eukaryotic cells. Transcription factors must bind to the promoter region first and recruit RNA polymerase to the site for transcription to be established. The activity of transcription factors can regulate differential gene expression in cells, resulting in the development of different cell products and functions. For example, scientists have found that primary sexual characteristics is regulated by several genes Figure 16.9. In the fruit fly Drosophila, the slx gene determines sex. This gene is expressed when the organism has two copies of the X chromosome. The gene product for slx binds to the mRNA of the tra gene and regulates its splicing. In the presence of slx, tra is spliced into its female form and influences the expression of dsx and fru to result in female sexual characteristics. In the absence of slx, tra is spliced into its male form and male sexual characteristics result.

PDF page 660: genes on a cell-by-cell basis without any involvement of sex hormones (which circulate throughout the entire body). The primary sex-determination gene is Sex lethal (Sxl), which is transcribed only when the X/A ratio (the X chromosome-to-autosome ratio) equals or exceeds 1. As females have two X chromosomes and males have one, Sxl is transcribed only in females (see the figure, left part). Sxl is a splicing repressor and binds to its target, the primary RNA of the transformer (tra) gene, which undergoes differential splicing depending on the presence (female) or absence (male) of Sxl, yielding a protein-coding tra mRNA only in females. The Tra protein binds to the primary RNAs of doublesex (dsx) and fruitless (fru). In females, Tra promotes splicing to occur near its binding site, whereas in males it uses an alternative, default splice site. The dsx primary RNA thus produces female-specific mRNA and malespecific mRNA, both of which encode functional Dsx proteins, DsxF and DsxM, respectively. The presence (female) and absence (male) of Tra similarly results in female-type fru mRNA and male-type fru mRNA, but here, only the maletype fru mRNA encodes a functional protein.

PDF page 660: genes on a cell-by-cell basis without any involvement of sex hormones (which circulate throughout the entire body). The primary sex-determination gene is Sex lethal (Sxl), which is transcribed only when the X/A ratio (the X chromosome-to-autosome ratio) equals or exceeds 1. As females have two X chromosomes and males have one, Sxl is transcribed only in females (see the figure, left part). Sxl is a splicing repressor and binds to its target, the primary RNA of the transformer (tra) gene, which undergoes differential splicing depending on the presence (female) or absence (male) of Sxl, yielding a protein-coding tra mRNA only in females. The Tra protein binds to the primary RNAs of doublesex (dsx) and fruitless (fru). In females, Tra promotes splicing to occur near its binding site, whereas in males it uses an alternative, default splice site. The dsx primary RNA thus produces female-specific mRNA and malespecific mRNA, both of which encode functional Dsx proteins, DsxF and DsxM, respectively. The presence (female) and absence (male) of Tra similarly results in female-type fru mRNA and male-type fru mRNA, but here, only the maletype fru mRNA encodes a functional protein.

PDF page 660: genes on a cell-by-cell basis without any involvement of sex hormones (which circulate throughout the entire body). The primary sex-determination gene is Sex lethal (Sxl), which is transcribed only when the X/A ratio (the X chromosome-to-autosome ratio) equals or exceeds 1. As females have two X chromosomes and males have one, Sxl is transcribed only in females (see the figure, left part). Sxl is a splicing repressor and binds to its target, the primary RNA of the transformer (tra) gene, which undergoes differential splicing depending on the presence (female) or absence (male) of Sxl, yielding a protein-coding tra mRNA only in females. The Tra protein binds to the primary RNAs of doublesex (dsx) and fruitless (fru). In females, Tra promotes splicing to occur near its binding site, whereas in males it uses an alternative, default splice site. The dsx primary RNA thus produces female-specific mRNA and malespecific mRNA, both of which encode functional Dsx proteins, DsxF and DsxM, respectively. The presence (female) and absence (male) of Tra similarly results in female-type fru mRNA and male-type fru mRNA, but here, only the maletype fru mRNA encodes a functional protein.

PDF page 660: genes on a cell-by-cell basis without any involvement of sex hormones (which circulate throughout the entire body). The primary sex-determination gene is Sex lethal (Sxl), which is transcribed only when the X/A ratio (the X chromosome-to-autosome ratio) equals or exceeds 1. As females have two X chromosomes and males have one, Sxl is transcribed only in females (see the figure, left part). Sxl is a splicing repressor and binds to its target, the primary RNA of the transformer (tra) gene, which undergoes differential splicing depending on the presence (female) or absence (male) of Sxl, yielding a protein-coding tra mRNA only in females. The Tra protein binds to the primary RNAs of doublesex (dsx) and fruitless (fru). In females, Tra promotes splicing to occur near its binding site, whereas in males it uses an alternative, default splice site. The dsx primary RNA thus produces female-specific mRNA and malespecific mRNA, both of which encode functional Dsx proteins, DsxF and DsxM, respectively. The presence (female) and absence (male) of Tra similarly results in female-type fru mRNA and male-type fru mRNA, but here, only the maletype fru mRNA encodes a functional protein.

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 661: Genes are organized to make the control of gene expression easier. The promoter region is immediately upstream of the coding sequence. This region can be short (only a few nucleotides in length) or quite long (hundreds of nucleotides long). The longer the promoter, the more available space for proteins to bind. This also adds more control to the transcription process. The length of the promoter is gene-specific and can differ dramatically between genes. Consequently, the level of control of gene expression can also differ quite dramatically between genes. The purpose of the promoter is to bind transcription factors that control the initiation of transcription. Within the promoter region, just upstream of the transcriptional start site, resides the TATA box. This box is simply a repeat of thymine and adenine dinucleotides (literally, TATA repeats). RNA polymerase binds to the transcription initiation complex, allowing transcription to occur. To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box. Binding of TFIID recruits other transcription factors, including TFIIB, TFIIE, TFIIF, and TFIIH to the TATA box. Once this complex is assembled, RNA polymerase can bind to its upstream sequence. When bound along with the transcription factors, RNA polymerase is phosphorylated. This releases part of the protein from the DNA to activate the transcription initiation complex and places RNA polymerase in the correct orientation to begin transcription; DNA-bending protein brings the enhancer, which can be quite a distance from the gene, in contact with transcription factors and mediator proteins (Figure 16.10).

PDF page 661: In addition to the general transcription factors, other transcription factors can bind to the promoter to regulate gene transcription. These transcription factors bind to the promoters of a specific set of genes. They are not general transcription factors that bind to every promoter complex, but are recruited to a specific sequence on the promoter of a specific gene. There are hundreds of transcription factors in a cell that each bind specifically to a particular DNA sequence motif. When transcription factors bind to the promoter just upstream of the encoded gene, it is referred to as a cis-acting element, because it is on the same chromosome just next to the gene. The region that a particular transcription factor binds to is called the transcription factor binding site. Transcription factors respond to environmental stimuli that cause the proteins to find their binding sites and initiate transcription of the gene that is needed.