Regulation of Gene Expression in Prokaryotes and Eukaryotes - Genetics
Card 1 of 68
Which is a function of DNA polymerase III that occurs in the 3' to 5' direction of the template DNA strand?
Which is a function of DNA polymerase III that occurs in the 3' to 5' direction of the template DNA strand?
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DNA polymerase III has these two functions:
1. 5'-3' polymerase requiring a 3' hydroxide primer and a DNA template
2. 3'-5' exonuclease proofreading
Both DNA polymerase I and DNA polymerase III are prokaryotic only. DNA polymerase I excises RNA primers with a 5' to 3' exonuclease.
DNA polymerase III has these two functions:
1. 5'-3' polymerase requiring a 3' hydroxide primer and a DNA template
2. 3'-5' exonuclease proofreading
Both DNA polymerase I and DNA polymerase III are prokaryotic only. DNA polymerase I excises RNA primers with a 5' to 3' exonuclease.
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Which of the following describes a single genetic locus that controls more than one trait?
Which of the following describes a single genetic locus that controls more than one trait?
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The ability of a gene to affect an organism is multiple ways is called pleiotropy. During post-transcriptional modification, introns are removed from the mRNA sequence and exons are spliced together to create the desired protein product. By splicing the gene in different ways, different proteins can be produced, which will affect different traits.
Consider the sentence: The man ran on the track, but fell.
By splicing different portions of the sentence, it can take on different meanings: The man ran. The man on the track fell. The man fell. The man ran, but fell.
Where pleiotropic genes affect more than one trait, polygenic traits are affected by multiple genes. Epistatic genes are regulated by the activation of other genes.
The ability of a gene to affect an organism is multiple ways is called pleiotropy. During post-transcriptional modification, introns are removed from the mRNA sequence and exons are spliced together to create the desired protein product. By splicing the gene in different ways, different proteins can be produced, which will affect different traits.
Consider the sentence: The man ran on the track, but fell.
By splicing different portions of the sentence, it can take on different meanings: The man ran. The man on the track fell. The man fell. The man ran, but fell.
Where pleiotropic genes affect more than one trait, polygenic traits are affected by multiple genes. Epistatic genes are regulated by the activation of other genes.
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Commonly, of histones leads to the silencing of genes.
Commonly, of histones leads to the silencing of genes.
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Out of the choices, only methylation of histones is commonly associated with the silencing of genes. Proteins known as histone methyltransferases bind a methyl group to amino acids in the histone, most commonly lysine or arginine. The result is a change in chromatin structure, most commonly blocking transcription sites and preventing expression.
Acetylation of histones is often found in activated genes. Phosphorylation of histones has been seen in DNA regulation, but it is unclear whether or not this modification affects the expression of genes.
Out of the choices, only methylation of histones is commonly associated with the silencing of genes. Proteins known as histone methyltransferases bind a methyl group to amino acids in the histone, most commonly lysine or arginine. The result is a change in chromatin structure, most commonly blocking transcription sites and preventing expression.
Acetylation of histones is often found in activated genes. Phosphorylation of histones has been seen in DNA regulation, but it is unclear whether or not this modification affects the expression of genes.
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Which of the following is the correct function of the eukaryotic enzyme analogous to DNA gyrase?
Which of the following is the correct function of the eukaryotic enzyme analogous to DNA gyrase?
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Topoisomerases unwind supercoiling of DNA by breaking and rejoining DNA chains.
Topoisomerases unwind supercoiling of DNA by breaking and rejoining DNA chains.
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Glycosylases are required for which type of DNA repair?
Glycosylases are required for which type of DNA repair?
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Base excision repair (BER) requires glycosylases.
BER steps:
1. Glycosylases recognize incorrectly paired or damaged bases and 'flip' them out of the DNA chain without disrupting the phosphodiester backbone. The N-glycosidic bond of the flipped base is cleaved, leaving an AP site (site without a base).
2. AP site is removed by AP endonucleases and an AP lyase.
3. DNA polymerase I (prokaryotes) or DNA polymerase beta (humans) replaces the gap with a new base and DNA ligase seals the strand.
Base excision repair (BER) requires glycosylases.
BER steps:
1. Glycosylases recognize incorrectly paired or damaged bases and 'flip' them out of the DNA chain without disrupting the phosphodiester backbone. The N-glycosidic bond of the flipped base is cleaved, leaving an AP site (site without a base).
2. AP site is removed by AP endonucleases and an AP lyase.
3. DNA polymerase I (prokaryotes) or DNA polymerase beta (humans) replaces the gap with a new base and DNA ligase seals the strand.
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Which of the following is a DNA control element?
Which of the following is a DNA control element?
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DNA control elements are contained within the DNA helix.
DNA control elements:
1. TATA box: 25-35 basepairs (bps) upstream from start site, determines site of transcription and directs RNA polymerase II binding
2. Proximal promoter elements: 200 bps upstream of start and are roughly 20bps long
3. Enhancers are short regions of DNA that can be 50-1500bp long. They can be bound by activators to increase transcription. Can be far from the site of transcription and still be functional
NOT DNA control elements:
Transcription factors: bind to DNA control elements to influence transcription but are not considered control elements themselves.
Transcriptional repressors and activators: proteins coded by one gene that act to regulate transcription
DNA control elements are contained within the DNA helix.
DNA control elements:
1. TATA box: 25-35 basepairs (bps) upstream from start site, determines site of transcription and directs RNA polymerase II binding
2. Proximal promoter elements: 200 bps upstream of start and are roughly 20bps long
3. Enhancers are short regions of DNA that can be 50-1500bp long. They can be bound by activators to increase transcription. Can be far from the site of transcription and still be functional
NOT DNA control elements:
Transcription factors: bind to DNA control elements to influence transcription but are not considered control elements themselves.
Transcriptional repressors and activators: proteins coded by one gene that act to regulate transcription
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What type of chemical modification occurs when DNA is damaged by ultraviolet light?
What type of chemical modification occurs when DNA is damaged by ultraviolet light?
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Ultraviolet light causes thymine dimers in DNA.
Ultraviolet light causes thymine dimers in DNA.
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Alternative splicing can result in which of the following?
Alternative splicing can result in which of the following?
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Alternative splicing can:
1. Retain/remove exons.
2. Retain/remove introns.
3. Truncate/extend at 5' or 3' ends.
4. Have mutually exclusive exons (one or the other, but never both).
Alternative splicing can:
1. Retain/remove exons.
2. Retain/remove introns.
3. Truncate/extend at 5' or 3' ends.
4. Have mutually exclusive exons (one or the other, but never both).
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Correctly order the 3 steps that initiate DNA transcription.
I. Catalysis of phosphodiester bond linkage
II. Polymerase binding to promoter sequence
III. DNA melting
Correctly order the 3 steps that initiate DNA transcription.
I. Catalysis of phosphodiester bond linkage
II. Polymerase binding to promoter sequence
III. DNA melting
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The correct order of the processes that initiate transcription are as follows:
1. Polymerase binds to promoter sequence. At this point, the DNA is still bound together.
2. Polymerase melts DNA near transcription site. Hydrogen bonds are broken, opening the DNA.
3. Polymerase catalyzes phosphodiester bond linkage of initial 2 rNTPs (ribonucleotide triphosphates).
The correct order of the processes that initiate transcription are as follows:
1. Polymerase binds to promoter sequence. At this point, the DNA is still bound together.
2. Polymerase melts DNA near transcription site. Hydrogen bonds are broken, opening the DNA.
3. Polymerase catalyzes phosphodiester bond linkage of initial 2 rNTPs (ribonucleotide triphosphates).
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Which of the following is a step performed by RNA polymerase during the elongation process of DNA transcription?
Which of the following is a step performed by RNA polymerase during the elongation process of DNA transcription?
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During elongation, RNA polymerase advances in the 3'-5' direction down the template, melting and adding rNTPs to growing RNA
During elongation, RNA polymerase advances in the 3'-5' direction down the template, melting and adding rNTPs to growing RNA
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The lac operon in E. coli bacteria is a widely used example of an inducible operon. In order for the operon to be expressed, must be bound to the activator and must be bound to the repressor.
The lac operon in E. coli bacteria is a widely used example of an inducible operon. In order for the operon to be expressed, must be bound to the activator and must be bound to the repressor.
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The lac operon expresses enzymes used to break down lactose. It would be a pointless waste of energy to make those enzymes if there is no lactose present, or if there was glucose present — as glucose is a preferable source of energy to E. coli. High concentrations of cAMP signify low levels of glucose. cAMP binds to CAP, the activator of the lac operon, allowing CAP to bind to the promoter and then bind RNA polymerase to begin transcription. However, in the absence of lactose, there is also a repressor protein present that will block RNA polymerase from binding to the promoter. Lactose binds to the repressor and inactivates it, causing it to detach from the promoter and allow RNA polymerase to bind. Therefore, the expression of the lac operon is induced by the presence of cAMP and lactose.
The lac operon expresses enzymes used to break down lactose. It would be a pointless waste of energy to make those enzymes if there is no lactose present, or if there was glucose present — as glucose is a preferable source of energy to E. coli. High concentrations of cAMP signify low levels of glucose. cAMP binds to CAP, the activator of the lac operon, allowing CAP to bind to the promoter and then bind RNA polymerase to begin transcription. However, in the absence of lactose, there is also a repressor protein present that will block RNA polymerase from binding to the promoter. Lactose binds to the repressor and inactivates it, causing it to detach from the promoter and allow RNA polymerase to bind. Therefore, the expression of the lac operon is induced by the presence of cAMP and lactose.
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An autosome is .
An autosome is .
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By definition, an autosome is any chromosome that is not a sex chromosome. Humans have a diploid genome that consists of 22 pairs of autosomal chromosomes, and one special pair of chromosomes (which is nonautosomal) that determines gender (two X chromosomes = female, one X and one Y chromosome = male).
By definition, an autosome is any chromosome that is not a sex chromosome. Humans have a diploid genome that consists of 22 pairs of autosomal chromosomes, and one special pair of chromosomes (which is nonautosomal) that determines gender (two X chromosomes = female, one X and one Y chromosome = male).
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What does the processing of mRNA ensure?
What does the processing of mRNA ensure?
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The purpose of mRNA processing is to protect it from degradation during its transport to cytosol. It does not involve introns or uracil. In addition, this concept has nothing to do with being double-stranded or single-stranded. Also, since the question states mRNA is being processed, it would imply that this takes place in a eukaryotic organism and hence, simultaneous transcription and translation is not possible.
The purpose of mRNA processing is to protect it from degradation during its transport to cytosol. It does not involve introns or uracil. In addition, this concept has nothing to do with being double-stranded or single-stranded. Also, since the question states mRNA is being processed, it would imply that this takes place in a eukaryotic organism and hence, simultaneous transcription and translation is not possible.
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Which of the following describes a single genetic locus that controls more than one trait?
Which of the following describes a single genetic locus that controls more than one trait?
Tap to reveal answer
The ability of a gene to affect an organism is multiple ways is called pleiotropy. During post-transcriptional modification, introns are removed from the mRNA sequence and exons are spliced together to create the desired protein product. By splicing the gene in different ways, different proteins can be produced, which will affect different traits.
Consider the sentence: The man ran on the track, but fell.
By splicing different portions of the sentence, it can take on different meanings: The man ran. The man on the track fell. The man fell. The man ran, but fell.
Where pleiotropic genes affect more than one trait, polygenic traits are affected by multiple genes. Epistatic genes are regulated by the activation of other genes.
The ability of a gene to affect an organism is multiple ways is called pleiotropy. During post-transcriptional modification, introns are removed from the mRNA sequence and exons are spliced together to create the desired protein product. By splicing the gene in different ways, different proteins can be produced, which will affect different traits.
Consider the sentence: The man ran on the track, but fell.
By splicing different portions of the sentence, it can take on different meanings: The man ran. The man on the track fell. The man fell. The man ran, but fell.
Where pleiotropic genes affect more than one trait, polygenic traits are affected by multiple genes. Epistatic genes are regulated by the activation of other genes.
← Didn't Know|Knew It →
Commonly, of histones leads to the silencing of genes.
Commonly, of histones leads to the silencing of genes.
Tap to reveal answer
Out of the choices, only methylation of histones is commonly associated with the silencing of genes. Proteins known as histone methyltransferases bind a methyl group to amino acids in the histone, most commonly lysine or arginine. The result is a change in chromatin structure, most commonly blocking transcription sites and preventing expression.
Acetylation of histones is often found in activated genes. Phosphorylation of histones has been seen in DNA regulation, but it is unclear whether or not this modification affects the expression of genes.
Out of the choices, only methylation of histones is commonly associated with the silencing of genes. Proteins known as histone methyltransferases bind a methyl group to amino acids in the histone, most commonly lysine or arginine. The result is a change in chromatin structure, most commonly blocking transcription sites and preventing expression.
Acetylation of histones is often found in activated genes. Phosphorylation of histones has been seen in DNA regulation, but it is unclear whether or not this modification affects the expression of genes.
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Which of the following is the correct function of the eukaryotic enzyme analogous to DNA gyrase?
Which of the following is the correct function of the eukaryotic enzyme analogous to DNA gyrase?
Tap to reveal answer
Topoisomerases unwind supercoiling of DNA by breaking and rejoining DNA chains.
Topoisomerases unwind supercoiling of DNA by breaking and rejoining DNA chains.
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Which is a function of DNA polymerase III that occurs in the 3' to 5' direction of the template DNA strand?
Which is a function of DNA polymerase III that occurs in the 3' to 5' direction of the template DNA strand?
Tap to reveal answer
DNA polymerase III has these two functions:
1. 5'-3' polymerase requiring a 3' hydroxide primer and a DNA template
2. 3'-5' exonuclease proofreading
Both DNA polymerase I and DNA polymerase III are prokaryotic only. DNA polymerase I excises RNA primers with a 5' to 3' exonuclease.
DNA polymerase III has these two functions:
1. 5'-3' polymerase requiring a 3' hydroxide primer and a DNA template
2. 3'-5' exonuclease proofreading
Both DNA polymerase I and DNA polymerase III are prokaryotic only. DNA polymerase I excises RNA primers with a 5' to 3' exonuclease.
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RNA primers are removed by which of the following exonucleases?
RNA primers are removed by which of the following exonucleases?
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5'-3' exonuclease removal of primers by DNA polymerase I.
DNA polymerase I is prokaryotic only, it degrades RNA primer and fills in the gap with DNA.
5'-3' exonuclease removal of primers by DNA polymerase I.
DNA polymerase I is prokaryotic only, it degrades RNA primer and fills in the gap with DNA.
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Which DNA repair mechanism removes DNA damage caused by ultraviolet light?
Which DNA repair mechanism removes DNA damage caused by ultraviolet light?
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Nucleotide excision repair (NER) is used to repair thymine dimers, which are caused by ultraviolet damage. It also repairs bulky DNA adducts caused by carcinogens.
Nucleotide excision repair (NER) is used to repair thymine dimers, which are caused by ultraviolet damage. It also repairs bulky DNA adducts caused by carcinogens.
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Glycosylases are required for which type of DNA repair?
Glycosylases are required for which type of DNA repair?
Tap to reveal answer
Base excision repair (BER) requires glycosylases.
BER steps:
1. Glycosylases recognize incorrectly paired or damaged bases and 'flip' them out of the DNA chain without disrupting the phosphodiester backbone. The N-glycosidic bond of the flipped base is cleaved, leaving an AP site (site without a base).
2. AP site is removed by AP endonucleases and an AP lyase.
3. DNA polymerase I (prokaryotes) or DNA polymerase beta (humans) replaces the gap with a new base and DNA ligase seals the strand.
Base excision repair (BER) requires glycosylases.
BER steps:
1. Glycosylases recognize incorrectly paired or damaged bases and 'flip' them out of the DNA chain without disrupting the phosphodiester backbone. The N-glycosidic bond of the flipped base is cleaved, leaving an AP site (site without a base).
2. AP site is removed by AP endonucleases and an AP lyase.
3. DNA polymerase I (prokaryotes) or DNA polymerase beta (humans) replaces the gap with a new base and DNA ligase seals the strand.
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