DNA, RNA, and Proteins - MCAT Biological and Biochemical Foundations of Living Systems
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Choose the transcript created if RNA polymerase transcribes the following template strand.
5'-ACTTGCAGGCC-3'
Choose the transcript created if RNA polymerase transcribes the following template strand.
5'-ACTTGCAGGCC-3'
When transcribing from a template strand, here are a few things to remember:
1. RNA polymerase reads the strand in the 3' to 5' direction.
2. In the RNA transcript, thymine is replaced with uracil.
In order to double check, make sure that the two strands are complementary when antiparallel to one another.
Template: 5'-ACTTGCAGGCC-3'
Transcript: 3'-UGAACGUCCGG-5'
When transcribing from a template strand, here are a few things to remember:
1. RNA polymerase reads the strand in the 3' to 5' direction.
2. In the RNA transcript, thymine is replaced with uracil.
In order to double check, make sure that the two strands are complementary when antiparallel to one another.
Template: 5'-ACTTGCAGGCC-3'
Transcript: 3'-UGAACGUCCGG-5'
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The base sequence of one strand of tRNA is v. What is the corresponding sequence of DNA?
The base sequence of one strand of tRNA is v. What is the corresponding sequence of DNA?
Both tRNA and DNA are complementary to mRNA, meaning that they will have the exact same sequence in the exact same direction with only one distinction: tRNA will use uracil where DNA uses thymine.
The given tRNA strand is 5'-AGUCGAUCUAGC-3'.
The corresponding DNA strand will be 5'-AGTCGATCTAGC-3'.
Both tRNA and DNA are complementary to mRNA, meaning that they will have the exact same sequence in the exact same direction with only one distinction: tRNA will use uracil where DNA uses thymine.
The given tRNA strand is 5'-AGUCGAUCUAGC-3'.
The corresponding DNA strand will be 5'-AGTCGATCTAGC-3'.
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The concept of genomic imprinting is important in human genetics. In genomic imprinting, a certain region of DNA is only expressed by one of the two chromosomes that make up a typical homologous pair. In healthy individuals, genomic imprinting results in the silencing of genes in a certain section of the maternal chromosome 15. The DNA in this part of the chromosome is "turned off" by the addition of methyl groups to the DNA molecule. Healthy people will thus only have expression of this section of chromosome 15 from paternally-derived DNA.
The two classic human diseases that illustrate defects in genomic imprinting are Prader-Willi and Angelman Syndromes. In Prader-Willi Syndrome, the section of paternal chromosome 15 that is usually expressed is disrupted, such as by a chromosomal deletion. In Angelman Syndrome, maternal genes in this section are deleted, while paternal genes are silenced. Prader-Willi Syndrome is thus closely linked to paternal inheritance, while Angelman Syndrome is linked to maternal inheritance.
Figure 1 shows the chromosome 15 homologous pair for a child with Prader-Willi Syndrome. The parental chromosomes are also shown. The genes on the mother’s chromosomes are silenced normally, as represented by the black boxes. At once, there is also a chromosomal deletion on one of the paternal chromosomes. The result is that the child does not have any genes expressed that are normally found on that region of this chromosome.
Histones are proteins that can interact with some sequences of DNA to help it coil into a more manageable arrangement within the nucleus. If the DNA-histone interaction is mediated primarily by intermolecular bonds, which of the following is likely true of histones?
The concept of genomic imprinting is important in human genetics. In genomic imprinting, a certain region of DNA is only expressed by one of the two chromosomes that make up a typical homologous pair. In healthy individuals, genomic imprinting results in the silencing of genes in a certain section of the maternal chromosome 15. The DNA in this part of the chromosome is "turned off" by the addition of methyl groups to the DNA molecule. Healthy people will thus only have expression of this section of chromosome 15 from paternally-derived DNA.
The two classic human diseases that illustrate defects in genomic imprinting are Prader-Willi and Angelman Syndromes. In Prader-Willi Syndrome, the section of paternal chromosome 15 that is usually expressed is disrupted, such as by a chromosomal deletion. In Angelman Syndrome, maternal genes in this section are deleted, while paternal genes are silenced. Prader-Willi Syndrome is thus closely linked to paternal inheritance, while Angelman Syndrome is linked to maternal inheritance.
Figure 1 shows the chromosome 15 homologous pair for a child with Prader-Willi Syndrome. The parental chromosomes are also shown. The genes on the mother’s chromosomes are silenced normally, as represented by the black boxes. At once, there is also a chromosomal deletion on one of the paternal chromosomes. The result is that the child does not have any genes expressed that are normally found on that region of this chromosome.
Histones are proteins that can interact with some sequences of DNA to help it coil into a more manageable arrangement within the nucleus. If the DNA-histone interaction is mediated primarily by intermolecular bonds, which of the following is likely true of histones?
DNA is acidic, and thus has a generally negative charge in aqueous conditions (consider what this means for the electrophoresis pattern of DNA in an agarose gel). Because the interaction has to be tight to coil DNA effectively, it must be a dipole interaction. Dipole interactions are relatively strong intermolecular forces. Covalent forces, however, are intramolecular and much more permanent than dipole interactions.
Acidic DNA has a negativecharge, which will be drawn to a basic histone with a positive charge.
DNA is acidic, and thus has a generally negative charge in aqueous conditions (consider what this means for the electrophoresis pattern of DNA in an agarose gel). Because the interaction has to be tight to coil DNA effectively, it must be a dipole interaction. Dipole interactions are relatively strong intermolecular forces. Covalent forces, however, are intramolecular and much more permanent than dipole interactions.
Acidic DNA has a negativecharge, which will be drawn to a basic histone with a positive charge.
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Which class of upstream DNA element is responsible for increasing transcription of target genes?
Which class of upstream DNA element is responsible for increasing transcription of target genes?
An enhancer is a cis-acting element that is responsible for activating or increasing expression of a target gene. An insulator is a boundary element between inactive and active domains of DNA. Both activators and repressors are trans-acting (protein) factors that modulate gene expression.
An enhancer is a cis-acting element that is responsible for activating or increasing expression of a target gene. An insulator is a boundary element between inactive and active domains of DNA. Both activators and repressors are trans-acting (protein) factors that modulate gene expression.
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Which of the following cell organelles is responsible for making proteins?
Which of the following cell organelles is responsible for making proteins?
Ribisomes are the protein creators within the cell. Ribisomes use a process called translation (via the use of mRNA) to form proteins.
The Golgi apparatus and rough endoplasmic reticulum are involved in protein modification and packaging. Lysosomes are involved in detoxification.
Ribisomes are the protein creators within the cell. Ribisomes use a process called translation (via the use of mRNA) to form proteins.
The Golgi apparatus and rough endoplasmic reticulum are involved in protein modification and packaging. Lysosomes are involved in detoxification.
Compare your answer with the correct one above
Choose the transcript created if RNA polymerase transcribes the following template strand.
5'-ACTTGCAGGCC-3'
Choose the transcript created if RNA polymerase transcribes the following template strand.
5'-ACTTGCAGGCC-3'
When transcribing from a template strand, here are a few things to remember:
1. RNA polymerase reads the strand in the 3' to 5' direction.
2. In the RNA transcript, thymine is replaced with uracil.
In order to double check, make sure that the two strands are complementary when antiparallel to one another.
Template: 5'-ACTTGCAGGCC-3'
Transcript: 3'-UGAACGUCCGG-5'
When transcribing from a template strand, here are a few things to remember:
1. RNA polymerase reads the strand in the 3' to 5' direction.
2. In the RNA transcript, thymine is replaced with uracil.
In order to double check, make sure that the two strands are complementary when antiparallel to one another.
Template: 5'-ACTTGCAGGCC-3'
Transcript: 3'-UGAACGUCCGG-5'
Compare your answer with the correct one above
The base sequence of one strand of tRNA is v. What is the corresponding sequence of DNA?
The base sequence of one strand of tRNA is v. What is the corresponding sequence of DNA?
Both tRNA and DNA are complementary to mRNA, meaning that they will have the exact same sequence in the exact same direction with only one distinction: tRNA will use uracil where DNA uses thymine.
The given tRNA strand is 5'-AGUCGAUCUAGC-3'.
The corresponding DNA strand will be 5'-AGTCGATCTAGC-3'.
Both tRNA and DNA are complementary to mRNA, meaning that they will have the exact same sequence in the exact same direction with only one distinction: tRNA will use uracil where DNA uses thymine.
The given tRNA strand is 5'-AGUCGAUCUAGC-3'.
The corresponding DNA strand will be 5'-AGTCGATCTAGC-3'.
Compare your answer with the correct one above
The concept of genomic imprinting is important in human genetics. In genomic imprinting, a certain region of DNA is only expressed by one of the two chromosomes that make up a typical homologous pair. In healthy individuals, genomic imprinting results in the silencing of genes in a certain section of the maternal chromosome 15. The DNA in this part of the chromosome is "turned off" by the addition of methyl groups to the DNA molecule. Healthy people will thus only have expression of this section of chromosome 15 from paternally-derived DNA.
The two classic human diseases that illustrate defects in genomic imprinting are Prader-Willi and Angelman Syndromes. In Prader-Willi Syndrome, the section of paternal chromosome 15 that is usually expressed is disrupted, such as by a chromosomal deletion. In Angelman Syndrome, maternal genes in this section are deleted, while paternal genes are silenced. Prader-Willi Syndrome is thus closely linked to paternal inheritance, while Angelman Syndrome is linked to maternal inheritance.
Figure 1 shows the chromosome 15 homologous pair for a child with Prader-Willi Syndrome. The parental chromosomes are also shown. The genes on the mother’s chromosomes are silenced normally, as represented by the black boxes. At once, there is also a chromosomal deletion on one of the paternal chromosomes. The result is that the child does not have any genes expressed that are normally found on that region of this chromosome.
Histones are proteins that can interact with some sequences of DNA to help it coil into a more manageable arrangement within the nucleus. If the DNA-histone interaction is mediated primarily by intermolecular bonds, which of the following is likely true of histones?
The concept of genomic imprinting is important in human genetics. In genomic imprinting, a certain region of DNA is only expressed by one of the two chromosomes that make up a typical homologous pair. In healthy individuals, genomic imprinting results in the silencing of genes in a certain section of the maternal chromosome 15. The DNA in this part of the chromosome is "turned off" by the addition of methyl groups to the DNA molecule. Healthy people will thus only have expression of this section of chromosome 15 from paternally-derived DNA.
The two classic human diseases that illustrate defects in genomic imprinting are Prader-Willi and Angelman Syndromes. In Prader-Willi Syndrome, the section of paternal chromosome 15 that is usually expressed is disrupted, such as by a chromosomal deletion. In Angelman Syndrome, maternal genes in this section are deleted, while paternal genes are silenced. Prader-Willi Syndrome is thus closely linked to paternal inheritance, while Angelman Syndrome is linked to maternal inheritance.
Figure 1 shows the chromosome 15 homologous pair for a child with Prader-Willi Syndrome. The parental chromosomes are also shown. The genes on the mother’s chromosomes are silenced normally, as represented by the black boxes. At once, there is also a chromosomal deletion on one of the paternal chromosomes. The result is that the child does not have any genes expressed that are normally found on that region of this chromosome.
Histones are proteins that can interact with some sequences of DNA to help it coil into a more manageable arrangement within the nucleus. If the DNA-histone interaction is mediated primarily by intermolecular bonds, which of the following is likely true of histones?
DNA is acidic, and thus has a generally negative charge in aqueous conditions (consider what this means for the electrophoresis pattern of DNA in an agarose gel). Because the interaction has to be tight to coil DNA effectively, it must be a dipole interaction. Dipole interactions are relatively strong intermolecular forces. Covalent forces, however, are intramolecular and much more permanent than dipole interactions.
Acidic DNA has a negativecharge, which will be drawn to a basic histone with a positive charge.
DNA is acidic, and thus has a generally negative charge in aqueous conditions (consider what this means for the electrophoresis pattern of DNA in an agarose gel). Because the interaction has to be tight to coil DNA effectively, it must be a dipole interaction. Dipole interactions are relatively strong intermolecular forces. Covalent forces, however, are intramolecular and much more permanent than dipole interactions.
Acidic DNA has a negativecharge, which will be drawn to a basic histone with a positive charge.
Compare your answer with the correct one above
Which class of upstream DNA element is responsible for increasing transcription of target genes?
Which class of upstream DNA element is responsible for increasing transcription of target genes?
An enhancer is a cis-acting element that is responsible for activating or increasing expression of a target gene. An insulator is a boundary element between inactive and active domains of DNA. Both activators and repressors are trans-acting (protein) factors that modulate gene expression.
An enhancer is a cis-acting element that is responsible for activating or increasing expression of a target gene. An insulator is a boundary element between inactive and active domains of DNA. Both activators and repressors are trans-acting (protein) factors that modulate gene expression.
Compare your answer with the correct one above
Which of the following cell organelles is responsible for making proteins?
Which of the following cell organelles is responsible for making proteins?
Ribisomes are the protein creators within the cell. Ribisomes use a process called translation (via the use of mRNA) to form proteins.
The Golgi apparatus and rough endoplasmic reticulum are involved in protein modification and packaging. Lysosomes are involved in detoxification.
Ribisomes are the protein creators within the cell. Ribisomes use a process called translation (via the use of mRNA) to form proteins.
The Golgi apparatus and rough endoplasmic reticulum are involved in protein modification and packaging. Lysosomes are involved in detoxification.
Compare your answer with the correct one above
An important part of creating DNA primers when performing a PCR or other quantitative analysis is the melting point of the primer. Which set of primers would most likely work well together as the forward and reverse primers of a PCR?
An important part of creating DNA primers when performing a PCR or other quantitative analysis is the melting point of the primer. Which set of primers would most likely work well together as the forward and reverse primers of a PCR?
The melting point of a strand of DNA can be predicted by the bases that make it up. Cytosine and guanine have three hydrogen bonds to each other, so they bond more strongly than adenine and thymine's two hydrogen bonds. This means that strands containing the same amount of Cs and Gs would work best together. There is only answer choice in which both strands have the same amount of Cs and Gs (or Ts and As).
The melting point of a strand of DNA can be predicted by the bases that make it up. Cytosine and guanine have three hydrogen bonds to each other, so they bond more strongly than adenine and thymine's two hydrogen bonds. This means that strands containing the same amount of Cs and Gs would work best together. There is only answer choice in which both strands have the same amount of Cs and Gs (or Ts and As).
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Which piece of DNA has the lowest melting point?
Note: only one strand is shown
Which piece of DNA has the lowest melting point?
Note: only one strand is shown
Cytosine and guanine bond more strongly to each other than adenine and guanine because they have three hydrogen bonds as opposed to two. Therefore, a piece of DNA with a high concentration of Ts and As will have a low melting point. The correct choice has 8 Ts and As, while the rest have less than that.
Cytosine and guanine bond more strongly to each other than adenine and guanine because they have three hydrogen bonds as opposed to two. Therefore, a piece of DNA with a high concentration of Ts and As will have a low melting point. The correct choice has 8 Ts and As, while the rest have less than that.
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Which of the following will be the complimentary pairing of this coded gene during transcription?
3’ GCTAGC 5’
Which of the following will be the complimentary pairing of this coded gene during transcription?
3’ GCTAGC 5’
During transcription, a complimentary RNA strand is constructed from a DNA template. It is important to realize that in RNA, the nucleotide base uracil is used instead of thymine as a complementary pair with adenine. The complementary strand is constructed 5’ to 3’ , but is lined up anti-parallel to the original strand.
During transcription, a complimentary RNA strand is constructed from a DNA template. It is important to realize that in RNA, the nucleotide base uracil is used instead of thymine as a complementary pair with adenine. The complementary strand is constructed 5’ to 3’ , but is lined up anti-parallel to the original strand.
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Which segment of DNA would have the highest melting point when paired with its complimentary strand?
Which segment of DNA would have the highest melting point when paired with its complimentary strand?
DNA nucleotide base pairs are held together by hydrogen bonding. Cytosine and guanine are held together by three hydrogen bonds, where adenine and thymine are held together by only two. Increased hydrogen bonding within a strand of DNA will increase the melting point. The DNA segment with the most guanine-cytosine base pairs will have the highest melting point.
DNA nucleotide base pairs are held together by hydrogen bonding. Cytosine and guanine are held together by three hydrogen bonds, where adenine and thymine are held together by only two. Increased hydrogen bonding within a strand of DNA will increase the melting point. The DNA segment with the most guanine-cytosine base pairs will have the highest melting point.
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Human chromosomes are divided into two arms, a long q arm and a short p arm. A karyotype is the organization of a human cell’s total genetic complement. A typical karyotype is generated by ordering chromosome 1 to chromosome 23 in order of decreasing size.
When viewing a karyotype, it can often become apparent that changes in chromosome number, arrangement, or structure are present. Among the most common genetic changes are Robertsonian translocations, involving transposition of chromosomal material between long arms of certain chromosomes to form one derivative chromosome. Chromosomes 14 and 21, for example, often undergo a Robertsonian translocation, as below.
A karyotype of this individual for chromosomes 14 and 21 would thus appear as follows:
Though an individual with aberrations such as a Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages.
The principal chemical component of chromosomes is nucleic acid, though proteins are also important elements. Which of the following is true of nucleic acids?
Human chromosomes are divided into two arms, a long q arm and a short p arm. A karyotype is the organization of a human cell’s total genetic complement. A typical karyotype is generated by ordering chromosome 1 to chromosome 23 in order of decreasing size.
When viewing a karyotype, it can often become apparent that changes in chromosome number, arrangement, or structure are present. Among the most common genetic changes are Robertsonian translocations, involving transposition of chromosomal material between long arms of certain chromosomes to form one derivative chromosome. Chromosomes 14 and 21, for example, often undergo a Robertsonian translocation, as below.
A karyotype of this individual for chromosomes 14 and 21 would thus appear as follows:
Though an individual with aberrations such as a Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages.
The principal chemical component of chromosomes is nucleic acid, though proteins are also important elements. Which of the following is true of nucleic acids?
Guanine-cytosine pairing forms three hydrogen bonds, instead of the two bonds formed by adenine and thymine. The other choices are all tempting, but subtly wrong. RNA contains uracil, DNA is the main storage form for information, mRNA is directly translated by tRNA, and ribosomes are important in the synthesis of proteins. It is worth noting that the 2' hydroxyl group of RNA's pentose sugar backbone is lost in DNA, which increases the stability and allows DNA to serve as a stable storage medium.
Guanine-cytosine pairing forms three hydrogen bonds, instead of the two bonds formed by adenine and thymine. The other choices are all tempting, but subtly wrong. RNA contains uracil, DNA is the main storage form for information, mRNA is directly translated by tRNA, and ribosomes are important in the synthesis of proteins. It is worth noting that the 2' hydroxyl group of RNA's pentose sugar backbone is lost in DNA, which increases the stability and allows DNA to serve as a stable storage medium.
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Which of the following options include degenerate codons?
Which of the following options include degenerate codons?
The term "degenerate codons" refers to codons with different nucleotide base sequences that specify the same amino acid. In the provided examples, two codons (UCU and UCA) both specify serine, indicating this is the correct answer.
The term "degenerate codons" refers to codons with different nucleotide base sequences that specify the same amino acid. In the provided examples, two codons (UCU and UCA) both specify serine, indicating this is the correct answer.
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The codons GGU, GGA, GGC, and GGG all code for the same amino acid, glycine. What biological term is used to describe this phenomenon?
The codons GGU, GGA, GGC, and GGG all code for the same amino acid, glycine. What biological term is used to describe this phenomenon?
Degeneracy refers to the fact that more than one codon can code for the same amino acid. These codons generally differ in their third or "wobble" base. Degeneracy explains how there can be a total of sixty-four possible codons corresponding to only twenty amino acids.
Degeneracy refers to the fact that more than one codon can code for the same amino acid. These codons generally differ in their third or "wobble" base. Degeneracy explains how there can be a total of sixty-four possible codons corresponding to only twenty amino acids.
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Pick the reason that is least likely to explain why two purines will never be seen attached to each other in a DNA helix.
Pick the reason that is least likely to explain why two purines will never be seen attached to each other in a DNA helix.
DNA strands are composed of millions of nucleotides. As a result, it would be virtually impossible to find a single strand that did not have all four nucleotides.
Nucleotides combine in purine-pyrimidine pairs due to the sterically appropriate fit of the bases, as well as the preferred combination of hydrogen bonds between the two nucleotides. As a result, two purines would not be seen combined. This is due to both being too large when together, and the incorrect hydrigen bonding between their functional groups.
DNA strands are composed of millions of nucleotides. As a result, it would be virtually impossible to find a single strand that did not have all four nucleotides.
Nucleotides combine in purine-pyrimidine pairs due to the sterically appropriate fit of the bases, as well as the preferred combination of hydrogen bonds between the two nucleotides. As a result, two purines would not be seen combined. This is due to both being too large when together, and the incorrect hydrigen bonding between their functional groups.
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A sequence of DNA is written below.
5'-AGCCGTAAG-3'
What will be the squence of the strand created from this one by DNA polymerase during replication?
A sequence of DNA is written below.
5'-AGCCGTAAG-3'
What will be the squence of the strand created from this one by DNA polymerase during replication?
Remember that DNA polymerase builds the new strand by reading the original DNA strand in a 3' to 5' direction. The newly formed strand will be read 5' to 3' and will have nucleotides that are complementary to the original strand.
Remember that DNA polymerase builds the new strand by reading the original DNA strand in a 3' to 5' direction. The newly formed strand will be read 5' to 3' and will have nucleotides that are complementary to the original strand.
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In 2013, scientists linked a cellular response called the unfolded protein response (UPR) to a series of neurodegenerative diseases, including such major health issues as Parkinson’s and Alzheimer’s Disease. According to their work, the unfolded protein response is a reduction in translation as a result of a series of enzymes that modify a translation initiation factor, eIF2, as below:
In the above sequence, the unfolded protein sensor binds to unfolded protein, such as the pathogenic amyloid-beta found in the brains of Alzheimer’s Disease patients. This sensor then phosphorylates PERK, or protein kinase RNA-like endoplasmic reticulum kinase. This leads to downstream effects on eIF2, inhibition of which represses translation. It is thought that symptoms of neurodegenerative disease may be a result of this reduced translation.
During translation, the genetic code is used to convert a sequence of nitrogenous bases in mRNA to an amino acid sequence. Which of the following is true of the genetic code?
I. More than one codon sequence codes for a single amino acid
II. The most 5' position of the codon on mRNA is the wobble position
III. Each codon sequence only codes for one amino acid
In 2013, scientists linked a cellular response called the unfolded protein response (UPR) to a series of neurodegenerative diseases, including such major health issues as Parkinson’s and Alzheimer’s Disease. According to their work, the unfolded protein response is a reduction in translation as a result of a series of enzymes that modify a translation initiation factor, eIF2, as below:
In the above sequence, the unfolded protein sensor binds to unfolded protein, such as the pathogenic amyloid-beta found in the brains of Alzheimer’s Disease patients. This sensor then phosphorylates PERK, or protein kinase RNA-like endoplasmic reticulum kinase. This leads to downstream effects on eIF2, inhibition of which represses translation. It is thought that symptoms of neurodegenerative disease may be a result of this reduced translation.
During translation, the genetic code is used to convert a sequence of nitrogenous bases in mRNA to an amino acid sequence. Which of the following is true of the genetic code?
I. More than one codon sequence codes for a single amino acid
II. The most 5' position of the codon on mRNA is the wobble position
III. Each codon sequence only codes for one amino acid
The genetic code is unambiguous, because each codon only codes for one amino acid. It is also degenerate, so that each amino acid can be coded for by multiple codons. Choice 2 is incorrect, as the most 3' position on the mRNA is the wobble position.
The genetic code is unambiguous, because each codon only codes for one amino acid. It is also degenerate, so that each amino acid can be coded for by multiple codons. Choice 2 is incorrect, as the most 3' position on the mRNA is the wobble position.
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