Anabolic Pathways and Synthesis - Biochemistry
Card 0 of 544
The enzyme phosphoglucomutase is an enzyme responsible for the interconversion of glucose-6-phosphate and glucose-1-phosphate. In a person who is fasting, which of the following metabolic pathways is the most likely destination for glucose-6-phosphate?
The enzyme phosphoglucomutase is an enzyme responsible for the interconversion of glucose-6-phosphate and glucose-1-phosphate. In a person who is fasting, which of the following metabolic pathways is the most likely destination for glucose-6-phosphate?
From the question stem, we're told that the enzyme phosphoglucomutase is responsible for interconverting two intermediate forms of glucose, both glucose-1-phosphate and glucose-6-phosphate. We're then asked to determine the most likely metabolic pathway that glucose-6-phosphate would be used for in a fasting individual.
First, it's important to remember that in an individual that is fasting, energy resources become more scarce. Therefore, the body tries to conserve as much energy as it can in this state. Furthermore, since the brain relies mostly on glucose for its metabolism, the body tries to keep a relatively stable level of glucose in the blood. As a result, many tissues in the body switch from using glucose to instead using other energy sources, such as fatty acids or ketone bodies. In order to help ensure that blood levels of glucose remain stable, the liver increases its rate of gluconeogenesis, which generates glucose from non-sugar substrates, such as pyruvic acid, certain amino acids, and glycerol. Therefore, we would expect glucose-6-phosphate to be funneled mostly into the gluconeogenesis pathway.
Even though glucose-6-phosphate can also be diverted to other pathways, such as glycolysis, glycerogenesis, or the pentose phosphate pathway, all of these pathways result in a net consumption of glucose. In a fasting state, this is the opposite of what we would want, since blood glucose levels need to be mostly stabilized in order to ensure that nervous tissue has an adequate supply.
From the question stem, we're told that the enzyme phosphoglucomutase is responsible for interconverting two intermediate forms of glucose, both glucose-1-phosphate and glucose-6-phosphate. We're then asked to determine the most likely metabolic pathway that glucose-6-phosphate would be used for in a fasting individual.
First, it's important to remember that in an individual that is fasting, energy resources become more scarce. Therefore, the body tries to conserve as much energy as it can in this state. Furthermore, since the brain relies mostly on glucose for its metabolism, the body tries to keep a relatively stable level of glucose in the blood. As a result, many tissues in the body switch from using glucose to instead using other energy sources, such as fatty acids or ketone bodies. In order to help ensure that blood levels of glucose remain stable, the liver increases its rate of gluconeogenesis, which generates glucose from non-sugar substrates, such as pyruvic acid, certain amino acids, and glycerol. Therefore, we would expect glucose-6-phosphate to be funneled mostly into the gluconeogenesis pathway.
Even though glucose-6-phosphate can also be diverted to other pathways, such as glycolysis, glycerogenesis, or the pentose phosphate pathway, all of these pathways result in a net consumption of glucose. In a fasting state, this is the opposite of what we would want, since blood glucose levels need to be mostly stabilized in order to ensure that nervous tissue has an adequate supply.
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One of the key enzymes in the pentose phosphate pathway is glucose-6-phosphate dehydrogenase (G6PDH). This enzyme is responsible for oxidizing glucose-6-phosphate into the next intermediate in the pathway, with co-occuring production of NADPH. Which of the following is most likely to be true about the regulation of this enzyme?
One of the key enzymes in the pentose phosphate pathway is glucose-6-phosphate dehydrogenase (G6PDH). This enzyme is responsible for oxidizing glucose-6-phosphate into the next intermediate in the pathway, with co-occuring production of NADPH. Which of the following is most likely to be true about the regulation of this enzyme?
From the question stem, we are told that glucose-6-phosphate dehydrogenase oxidized glucose into another compound, and also produces a molecule of NADPH in the process. In order to determine the way in which this enzyme is likely to be regulated, it's important to consider feedback mechanics.
Since this enzyme is producing NADPH when it is turned on, we would expect this product to negatively regulate the enzyme via feedback inhibition. Moreover, since we know that 
is a reactant, we can correctly assume that having a high concentration of this will likely drive the reaction forward by turning the enzyme on. Thus, 
would be expected to allosterically activate this enzyme. Furthermore, the question stem tells us nothing about the unphosphorylated forms of these cofactors, therefore we have no way of knowing how many NADH or 
affects this enzyme, if they do at all.
From the question stem, we are told that glucose-6-phosphate dehydrogenase oxidized glucose into another compound, and also produces a molecule of NADPH in the process. In order to determine the way in which this enzyme is likely to be regulated, it's important to consider feedback mechanics.
Since this enzyme is producing NADPH when it is turned on, we would expect this product to negatively regulate the enzyme via feedback inhibition. Moreover, since we know that
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Acetyl-CoA carboxylase is essential for fatty acid synthesis. Which of the following factors regulate acetyl-CoA carboxylase?
I. Glucagon
II. Citrate
III. Palmitoyl-CoA
IV. Insulin
Acetyl-CoA carboxylase is essential for fatty acid synthesis. Which of the following factors regulate acetyl-CoA carboxylase?
I. Glucagon
II. Citrate
III. Palmitoyl-CoA
IV. Insulin
Acetyl-CoA carboxylase is essential for fatty acid synthesis, it provides malonyl-CoA, necessary for production of palmitate, a fatty acid. The enzyme is regulated via phosphorylation and dephosphorylation. Insulin activates the enzyme by dephosphorylation. Glucagon and epinephrine deactivate on the other hand the enzyme by phosphorylation (adding a phosphate group to the molecule). Citrate activates the enzyme while palmitoyl-CoA, the end product of fatty acid synthesis, inhibits it.
Acetyl-CoA carboxylase is essential for fatty acid synthesis, it provides malonyl-CoA, necessary for production of palmitate, a fatty acid. The enzyme is regulated via phosphorylation and dephosphorylation. Insulin activates the enzyme by dephosphorylation. Glucagon and epinephrine deactivate on the other hand the enzyme by phosphorylation (adding a phosphate group to the molecule). Citrate activates the enzyme while palmitoyl-CoA, the end product of fatty acid synthesis, inhibits it.
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The pentose phosphate pathway is an important metabolic pathway within cells that allows them to synthesize two essential products. What are these two products, and what do they do?
The pentose phosphate pathway is an important metabolic pathway within cells that allows them to synthesize two essential products. What are these two products, and what do they do?
The pentose phosphate pathway (PPP) is a metabolic pathway in cells that is used to generate NADPH and/or ribose-5-phosphate for use in the cell, depending on the cell's needs. NADPH is used primarily to provide reducing power for several biosynthetic reactions, but it also serves as a means to keep glutathione predominately in its reduced form in the cell. This, in turn, helps maintain a reducing environment within cells. Furthermore, ribose-5-phosphate is used as a major precursor for the synthesis of nucleotides.
NADH and FADH2 are not produced by the PPP, but rather are produced by the oxidation of glucose via the aerobic respiration pathway. These two molecules are carriers of high-energy electrons, which are used to generate ATP via the electron transport chain.
Glutathione, as mentioned previously, is not produced by the PPP; however, it does use the NADPH produced by the PPP to maintain its reduced form within the cell, which, in turn, maintains a predominately reducing environment within the cell. 2,3-bisphosphoglycerate is an intermediate of glycolysis, not the PPP. One major function of 2,3-BPG is to bind hemoglobin and reduce its affinity for O2. This allows red blood cells to have an easier time releasing O2 to tissues that are in need of it.
Fructose-2,6-bisphosphate is not a product of the PPP. Rather, it is produced from a side reaction of the glycolytic intermediate fructose-6-phosphate. Fructose-2,6-bisphosphate serves as an allosteric regulator of the enzyme fructose-1,6-bisphosphatase, which is an important regulatory enzyme for glycolysis and gluconeogenesis. Hormones such as insulin and glucagon can stimulate cells to alter their concentration of fructose-2,6-bisphosphate, which in turn regulates the activity of glycolysis and gluconeogenesis. Glycerol-3-phosphate is also not produced from the PPP. Rather, it can be produced from the phosphorylation of glycerol or from the reduction of dihydroxyacetone phosphate, an intermediate of glycolysis. It is used as the backbone for the formation of triglycerides and phospholipids.
Acetoacetate and beta-hydroxybutyrate are both ketone bodies produced not by the PPP, but from the condensation of two molecules of acetyl-CoA plus additional modifications. Generally, when the body is in a fasting state and needs to reserve blood glucose levels, ketone bodies can be produced to act as an alternative energy source, thus allowing glucose to be mostly spared.
The pentose phosphate pathway (PPP) is a metabolic pathway in cells that is used to generate NADPH and/or ribose-5-phosphate for use in the cell, depending on the cell's needs. NADPH is used primarily to provide reducing power for several biosynthetic reactions, but it also serves as a means to keep glutathione predominately in its reduced form in the cell. This, in turn, helps maintain a reducing environment within cells. Furthermore, ribose-5-phosphate is used as a major precursor for the synthesis of nucleotides.
NADH and FADH2 are not produced by the PPP, but rather are produced by the oxidation of glucose via the aerobic respiration pathway. These two molecules are carriers of high-energy electrons, which are used to generate ATP via the electron transport chain.
Glutathione, as mentioned previously, is not produced by the PPP; however, it does use the NADPH produced by the PPP to maintain its reduced form within the cell, which, in turn, maintains a predominately reducing environment within the cell. 2,3-bisphosphoglycerate is an intermediate of glycolysis, not the PPP. One major function of 2,3-BPG is to bind hemoglobin and reduce its affinity for O2. This allows red blood cells to have an easier time releasing O2 to tissues that are in need of it.
Fructose-2,6-bisphosphate is not a product of the PPP. Rather, it is produced from a side reaction of the glycolytic intermediate fructose-6-phosphate. Fructose-2,6-bisphosphate serves as an allosteric regulator of the enzyme fructose-1,6-bisphosphatase, which is an important regulatory enzyme for glycolysis and gluconeogenesis. Hormones such as insulin and glucagon can stimulate cells to alter their concentration of fructose-2,6-bisphosphate, which in turn regulates the activity of glycolysis and gluconeogenesis. Glycerol-3-phosphate is also not produced from the PPP. Rather, it can be produced from the phosphorylation of glycerol or from the reduction of dihydroxyacetone phosphate, an intermediate of glycolysis. It is used as the backbone for the formation of triglycerides and phospholipids.
Acetoacetate and beta-hydroxybutyrate are both ketone bodies produced not by the PPP, but from the condensation of two molecules of acetyl-CoA plus additional modifications. Generally, when the body is in a fasting state and needs to reserve blood glucose levels, ketone bodies can be produced to act as an alternative energy source, thus allowing glucose to be mostly spared.
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Which of the following carbohydrates cannot be continuously linearized with 
glycosidic bonds?
Which of the following carbohydrates cannot be continuously linearized with
In order to linearize using a 
linkage, there needs to be an unbound carbon on the 1 position. However, sucrose is a 
linkage and doesn't have a carbon available to linearize in the 1 position. It isn't a reducing sugar and therefore cannot be linearized. All of the other sugars have their anomeric carbon located at the 1 position and all of them are reducing sugars that can be linearized.
In order to linearize using a
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What amino acid is synthesized as a part of the initiation signal for translation with the mRNA code, UAG?
What amino acid is synthesized as a part of the initiation signal for translation with the mRNA code, UAG?
Protein translation begins by recognizing an initiation signal on the mRNA - the codon UAG. The amino acid that coded for by UAG is methionine.
Protein translation begins by recognizing an initiation signal on the mRNA - the codon UAG. The amino acid that coded for by UAG is methionine.
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Where does the pentose phosphate pathway primarily take place?
Where does the pentose phosphate pathway primarily take place?
The pentose phosphate pathway (also known as the hexose monophosphate shunt or HMS), which mainly serves to produce 
for anabolic reduction reactions and ribose-5-phosphate for nucleic acid production, takes place in the cytosol of hepatic cells.
The pentose phosphate pathway (also known as the hexose monophosphate shunt or HMS), which mainly serves to produce
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Which of the following statements is false about the human genome?
Which of the following statements is false about the human genome?
Scientists have indeed counted about 20,000 proteins coded for by the genome. Coding sequences are only about 2% or less of the genome. The definition of paralogs is genes related by duplication within a genome. Within the genome, not about 5%, but rather about 50%, of DNA sequences are repeated.
Scientists have indeed counted about 20,000 proteins coded for by the genome. Coding sequences are only about 2% or less of the genome. The definition of paralogs is genes related by duplication within a genome. Within the genome, not about 5%, but rather about 50%, of DNA sequences are repeated.
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Which of the following amino acids can be created from the carbon skeleton of oxaloacetate?
Which of the following amino acids can be created from the carbon skeleton of oxaloacetate?
From the carbon skeleton of oxaloacetate, methionine can be created. However, glutamine comes from alpha ketoglutarate, valine and leucine come from pyruvate, and histidine comes from ribose-5-phosphate.
From the carbon skeleton of oxaloacetate, methionine can be created. However, glutamine comes from alpha ketoglutarate, valine and leucine come from pyruvate, and histidine comes from ribose-5-phosphate.
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Which of the following molecules is not necessary to create glutamate from alpha-ketoglutarate?
Which of the following molecules is not necessary to create glutamate from alpha-ketoglutarate?
The reaction for the conversion of glutamine into glutamate is:
As seen in the reaction above, carbon dioxide is uninvolved.
The reaction for the conversion of glutamine into glutamate is:
As seen in the reaction above, carbon dioxide is uninvolved.
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Which of the following correctly lists the severity of damage done by mutations in DNA from most severe to least?
Which of the following correctly lists the severity of damage done by mutations in DNA from most severe to least?
When a change results in an early stop codon, nonsense mutation occurs and the protein is done being read early, often resulting in a nonfunctional protein. When a base change results into a different amino acid, this is a missense mutation. When a base change occurs but results in the same amino acid being read, this is considered a silent mutation.
When a change results in an early stop codon, nonsense mutation occurs and the protein is done being read early, often resulting in a nonfunctional protein. When a base change results into a different amino acid, this is a missense mutation. When a base change occurs but results in the same amino acid being read, this is considered a silent mutation.
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Which of of the following are the termination signals for translation?
Which of of the following are the termination signals for translation?
Just as there is an initiation codon regulating translation, there are termination codons that code for the end of translation. The three termination codons are UAA, UAG, and UGA.
A helpful mnemonic for these are the phrases:
You are annoying (UAA)
You are gross (UAG)
You go away (UGA)
Just as there is an initiation codon regulating translation, there are termination codons that code for the end of translation. The three termination codons are UAA, UAG, and UGA.
A helpful mnemonic for these are the phrases:
You are annoying (UAA)
You are gross (UAG)
You go away (UGA)
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Which of the following correctly describes the function of a signal sequence with respect to proteins?
Which of the following correctly describes the function of a signal sequence with respect to proteins?
To answer this question, it's essential to have an understanding of what a signal sequence is.
A signal sequence (also sometimes called a signal peptide) is a specific sequence of amino acids on a polypeptide that appears near the beginning of translation. When this signal sequence is present, it causes a temporary halt in the translation process. Meanwhile, another protein called a signal recognition particle (SRP) comes along and binds to the ribosome that is translating the polypeptide. Together, this polypeptide-ribosome-SRP complex is transferred from the cytosol to the surface of the endoplasmic reticulum (ER). Once there, the complex allows the polypeptide to resume synthesis, but in doing so, causes it to be synthesized into the inner lumen of the endoplasmic reticulum. Consequently, this polypeptide will go on to be modified within the ER and also the Golgi apparatus. Afterwards, it will be sent off within a vesicle, where is will either be A) secreted outside of the cell or B) incorporated into the endomembrane system of the cell (in other words, the peptide will be inserted into a membrane such as the plasma membrane, ER membrane, Golgi membrane, etc.). Lastly, it is the nuclear localization sequence (NLS) that, when added to a protein, allows it to enter the nucleus through the nuclear membrane.
To answer this question, it's essential to have an understanding of what a signal sequence is.
A signal sequence (also sometimes called a signal peptide) is a specific sequence of amino acids on a polypeptide that appears near the beginning of translation. When this signal sequence is present, it causes a temporary halt in the translation process. Meanwhile, another protein called a signal recognition particle (SRP) comes along and binds to the ribosome that is translating the polypeptide. Together, this polypeptide-ribosome-SRP complex is transferred from the cytosol to the surface of the endoplasmic reticulum (ER). Once there, the complex allows the polypeptide to resume synthesis, but in doing so, causes it to be synthesized into the inner lumen of the endoplasmic reticulum. Consequently, this polypeptide will go on to be modified within the ER and also the Golgi apparatus. Afterwards, it will be sent off within a vesicle, where is will either be A) secreted outside of the cell or B) incorporated into the endomembrane system of the cell (in other words, the peptide will be inserted into a membrane such as the plasma membrane, ER membrane, Golgi membrane, etc.). Lastly, it is the nuclear localization sequence (NLS) that, when added to a protein, allows it to enter the nucleus through the nuclear membrane.
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What are some post-translational modifications collagen goes thru before attaining its final structure?
I. The precursor collagen molecule undergoes hydroxylation of selected proline and lysine amino acids.
II. The procollagen precursor is glycosylated by the addition of galactose and glucose.
III. Procollagen has amino and carboxy procollagen extension propeptides that make it soluble.
IV. Procollagen proteinases remove extension peptides from the ends of the molecule to form collagen.
What are some post-translational modifications collagen goes thru before attaining its final structure?
I. The precursor collagen molecule undergoes hydroxylation of selected proline and lysine amino acids.
II. The procollagen precursor is glycosylated by the addition of galactose and glucose.
III. Procollagen has amino and carboxy procollagen extension propeptides that make it soluble.
IV. Procollagen proteinases remove extension peptides from the ends of the molecule to form collagen.
Procollagen has amino and carboxy procollagen extension propeptides that make it soluble. The preprocollagen undergoes both hydroxylation and glycosylation at specific aminoacid residues to form procollagen. Once secreted extracellularly, proteinases remove the extension peptides from procollagen to form the final collagen molecule.
Procollagen has amino and carboxy procollagen extension propeptides that make it soluble. The preprocollagen undergoes both hydroxylation and glycosylation at specific aminoacid residues to form procollagen. Once secreted extracellularly, proteinases remove the extension peptides from procollagen to form the final collagen molecule.
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Which of the following enzyme cofactors transfer methyl groups?
Which of the following enzyme cofactors transfer methyl groups?
Biotin moves carboxyl groups in the enzyme acetyl-CoA carboxylase. Tetrahydrofolate and S-adenylosyl methionine move methyl groups in amino acid synthesis and post-translational modifications such as DNA methylation. B12 cobalamin is a cofactor in the reactions producing succinyl-CoA and methionine, where it transfers methyl groups to complete the products.
Biotin moves carboxyl groups in the enzyme acetyl-CoA carboxylase. Tetrahydrofolate and S-adenylosyl methionine move methyl groups in amino acid synthesis and post-translational modifications such as DNA methylation. B12 cobalamin is a cofactor in the reactions producing succinyl-CoA and methionine, where it transfers methyl groups to complete the products.
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What is the role of phosphoenolpyruvate carboxykinase in carbohydrate metabolism?
What is the role of phosphoenolpyruvate carboxykinase in carbohydrate metabolism?
Gluconeogenesis is the production of glucose from other sources than carbohydrates, such as from pyruvate, amino acids, lactate and glycerol. Phosphoenolpyruvate carboxykinase converts oxaloacetate to phosphoenolpyruvate and carbon dioxide. It also produces GDP from GTP. It is regulated by hormones, such as glucagon and cortisol.
Gluconeogenesis is the production of glucose from other sources than carbohydrates, such as from pyruvate, amino acids, lactate and glycerol. Phosphoenolpyruvate carboxykinase converts oxaloacetate to phosphoenolpyruvate and carbon dioxide. It also produces GDP from GTP. It is regulated by hormones, such as glucagon and cortisol.
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Which of the following is a true statement regarding translation in eukaryotes?
Which of the following is a true statement regarding translation in eukaryotes?
Translation is a process by which polypeptides are synthesized from a mRNA transcript, which was previously synthesized from the process of transcription. During this process, tRNA acts as a carrier by bringing with it specific amino acids to the ribosome, which are then incorporated into a growing polypeptide chain.
Eukaryotic translation differs in quite a few ways from prokaryotic translation. For one thing, prokaryotic mRNA contains a Shine-Delgarno sequence, which serves as a binding site for prokaryotic ribosomes to assemble on the mRNA. This binding, in turn, helps to initiate translation in prokaryotic cells. Eukaryotic cells do not contain a Shine-Delgarno sequence.
Furthermore, in eukaryotes, translation always begins with the assembly of ribosomal subunits on mRNA in the cytosol. Therefore, translation always begins on free ribosomes in the cytosol! Sometimes, translation will also finish on free ribosomes if the resulting protein is destined to stay within the cytosol where it will serve its function. Alternatively, if the first few amino acids of the polypeptide consists of a specific "signal sequence," translation will be temporarily paused. During this time, the entire ribosome-mRNA-polypeptide complex will be translocated to the rough endoplasmic reticulum. Once attached, polypeptide synthesis will resume and the polypeptide will thread its way into the endoplasmic reticulum. As it does so, additional folding and post-translational modifications are usually done to the polypeptide for it to carry out its proper function. Generally, polypeptides that make their way through the endoplasmic reticulum are destined either to be secreted out of the cell, or to become incorporated into the endomembrane system of the cell. And finally, as polypeptides are synthesized on a ribosome, whether it is free or bound, the amino terminus (aka N-terminus) side of the polypeptide is synthesized first and the carboxy terminus (aka C-terminus) is synthesized last.
Translation is a process by which polypeptides are synthesized from a mRNA transcript, which was previously synthesized from the process of transcription. During this process, tRNA acts as a carrier by bringing with it specific amino acids to the ribosome, which are then incorporated into a growing polypeptide chain.
Eukaryotic translation differs in quite a few ways from prokaryotic translation. For one thing, prokaryotic mRNA contains a Shine-Delgarno sequence, which serves as a binding site for prokaryotic ribosomes to assemble on the mRNA. This binding, in turn, helps to initiate translation in prokaryotic cells. Eukaryotic cells do not contain a Shine-Delgarno sequence.
Furthermore, in eukaryotes, translation always begins with the assembly of ribosomal subunits on mRNA in the cytosol. Therefore, translation always begins on free ribosomes in the cytosol! Sometimes, translation will also finish on free ribosomes if the resulting protein is destined to stay within the cytosol where it will serve its function. Alternatively, if the first few amino acids of the polypeptide consists of a specific "signal sequence," translation will be temporarily paused. During this time, the entire ribosome-mRNA-polypeptide complex will be translocated to the rough endoplasmic reticulum. Once attached, polypeptide synthesis will resume and the polypeptide will thread its way into the endoplasmic reticulum. As it does so, additional folding and post-translational modifications are usually done to the polypeptide for it to carry out its proper function. Generally, polypeptides that make their way through the endoplasmic reticulum are destined either to be secreted out of the cell, or to become incorporated into the endomembrane system of the cell. And finally, as polypeptides are synthesized on a ribosome, whether it is free or bound, the amino terminus (aka N-terminus) side of the polypeptide is synthesized first and the carboxy terminus (aka C-terminus) is synthesized last.
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A researcher is analyzing a protein that is found on the plasma membrane. What can be concluded about the translation of this protein?
I. It was translated on a cytoplasmic ribosome
II. It involved the use of all three types of RNA
III. It involved a polymerase enzyme
A researcher is analyzing a protein that is found on the plasma membrane. What can be concluded about the translation of this protein?
I. It was translated on a cytoplasmic ribosome
II. It involved the use of all three types of RNA
III. It involved a polymerase enzyme
Proteins undergo translation with the help of ribosomes, which can be found in either cytoplasm or on the rough endoplasmic reticulum (rough ER). Proteins synthesized on the ribosomes in cytoplasm are destined for somewhere inside the cell. On the other hand, proteins synthesized on the rough ER are processed in the ER and Golgi apparatus and are transported to the membrane or the extracellular matrix. Since the protein in the question is found on a membrane, it must have been synthesized on the ribosomes on the rough ER.
Recall that all three types of RNA are used in translation. mRNA is the template strand used to synthesize the protein molecule. It contains the information regarding the sequence of amino acids in the protein molecule. tRNA is involved in transporting the amino acid to the growing polypeptide chain. rRNA molecules make up the ribosomes, the location of translation.
Polymerase enzymes are used in DNA replication (DNA polymerase) and transcription (RNA polymerase). They are not involved in translation.
Proteins undergo translation with the help of ribosomes, which can be found in either cytoplasm or on the rough endoplasmic reticulum (rough ER). Proteins synthesized on the ribosomes in cytoplasm are destined for somewhere inside the cell. On the other hand, proteins synthesized on the rough ER are processed in the ER and Golgi apparatus and are transported to the membrane or the extracellular matrix. Since the protein in the question is found on a membrane, it must have been synthesized on the ribosomes on the rough ER.
Recall that all three types of RNA are used in translation. mRNA is the template strand used to synthesize the protein molecule. It contains the information regarding the sequence of amino acids in the protein molecule. tRNA is involved in transporting the amino acid to the growing polypeptide chain. rRNA molecules make up the ribosomes, the location of translation.
Polymerase enzymes are used in DNA replication (DNA polymerase) and transcription (RNA polymerase). They are not involved in translation.
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Upon completion of translation, all proteins have                      starting amino acid(s) and                      ending amino acid(s).
Upon completion of translation, all proteins have                      starting amino acid(s) and                      ending amino acid(s).
Translation begins when a start codon is recognized in the mRNA molecule. The start codon is AUG, which codes for the amino acid methionine; therefore, all proteins begin with methionine. There are multiple stop codons; therefore, the ending of proteins could be different from one another.
Note that the question is asking about the state of a protein molecule after the completion of translation. A protein can undergo further processing events in the rough ER and Golgi apparatus during which the starting methionine may be cleaved; therefore, the ultimate end product of proteins might have a different starting amino acid.
Translation begins when a start codon is recognized in the mRNA molecule. The start codon is AUG, which codes for the amino acid methionine; therefore, all proteins begin with methionine. There are multiple stop codons; therefore, the ending of proteins could be different from one another.
Note that the question is asking about the state of a protein molecule after the completion of translation. A protein can undergo further processing events in the rough ER and Golgi apparatus during which the starting methionine may be cleaved; therefore, the ultimate end product of proteins might have a different starting amino acid.
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Which of the following are the same regarding prokaryotic and eukaryotic translation?
I. Location of translation of prokaryotic proteins and eukaryotic membrane proteins
II. The start codon
III. Coupling of transcription with translation
Which of the following are the same regarding prokaryotic and eukaryotic translation?
I. Location of translation of prokaryotic proteins and eukaryotic membrane proteins
II. The start codon
III. Coupling of transcription with translation
Like transcription, there are slight differences between prokaryotic and eukaryotic translation. In prokaryotes transcription and translation are coupled and occur in the cytoplasm. Recall that in eukaryotes, translation can occur either in the cytoplasm or on the rough ER. Membrane and secretory proteins are synthesized in ribosomes on the rough ER whereas the cytosolic proteins are synthesized in ribosomes in cytoplasm.
The start codon for both prokaryotic and eukaryotic translation is AUG. This codes for the amino acid methionine, which is usually the first amino acid added to a growing polypeptide chain.
As mentioned, coupling of transcription and translation only occurs in the prokaryotes. Eukaryotic transcription occurs in the nucleus and the products need to undergo post-transcriptional modification before entering the cytoplasm for translation; therefore, the two processes aren’t coupled in eukaryotes.
Like transcription, there are slight differences between prokaryotic and eukaryotic translation. In prokaryotes transcription and translation are coupled and occur in the cytoplasm. Recall that in eukaryotes, translation can occur either in the cytoplasm or on the rough ER. Membrane and secretory proteins are synthesized in ribosomes on the rough ER whereas the cytosolic proteins are synthesized in ribosomes in cytoplasm.
The start codon for both prokaryotic and eukaryotic translation is AUG. This codes for the amino acid methionine, which is usually the first amino acid added to a growing polypeptide chain.
As mentioned, coupling of transcription and translation only occurs in the prokaryotes. Eukaryotic transcription occurs in the nucleus and the products need to undergo post-transcriptional modification before entering the cytoplasm for translation; therefore, the two processes aren’t coupled in eukaryotes.
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