Central dogma - AP Biology
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What is the role of DNA ligase?
What is the role of DNA ligase?
DNA ligase joins the sugar-phosphate backbone of DNA strands through catalyzing the formation of phosphodiester bonds. The nicks in the backbone arise from Okazaki fragments and the action of topoisomerase.
DNA ligase joins the sugar-phosphate backbone of DNA strands through catalyzing the formation of phosphodiester bonds. The nicks in the backbone arise from Okazaki fragments and the action of topoisomerase.
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What is the result of a silent mutation?
What is the result of a silent mutation?
As the name suggests, silent mutations are point mutations that actually have no visible effect on the protein. This is due to the degeneracy of the genetic code. Several codons actually insert the same amino acid. It is possible to mutate a codon so that it actually inserts the same amino acid. For example, if the codon UCU were mutated to UCG, it will still recruit the amino acid serine.
The other answers describe other types of mutations. Missense mutations are point mutations that result in the swapping of one amino acid for another. Nonsense mutations cause early termination. Frameshift mutations shift the reading frame of the codon sequence, severely altering the protein composition.
As the name suggests, silent mutations are point mutations that actually have no visible effect on the protein. This is due to the degeneracy of the genetic code. Several codons actually insert the same amino acid. It is possible to mutate a codon so that it actually inserts the same amino acid. For example, if the codon UCU were mutated to UCG, it will still recruit the amino acid serine.
The other answers describe other types of mutations. Missense mutations are point mutations that result in the swapping of one amino acid for another. Nonsense mutations cause early termination. Frameshift mutations shift the reading frame of the codon sequence, severely altering the protein composition.
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Which of the following describes abortive initiation?
Which of the following describes abortive initiation?
Abortive initiation is the process by which RNA polymerase starts short cycles of RNA synthesis. During abortive initiation, RNA polymerase releases short RNA strands before the initiation complex leaves the promoter sequence. Abortive initiation is a common process in both eukaryotes and prokaryotes.
Abortive initiation is the process by which RNA polymerase starts short cycles of RNA synthesis. During abortive initiation, RNA polymerase releases short RNA strands before the initiation complex leaves the promoter sequence. Abortive initiation is a common process in both eukaryotes and prokaryotes.
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If a DNA sequence is mutated from AGCTAA to AGCCTAA, what kind of mutation has occurred?
If a DNA sequence is mutated from AGCTAA to AGCCTAA, what kind of mutation has occurred?
An insertion mutation is a mutation due to an additional nucleotide base pair being added to a DNA sequence. In this case, a cytosine nucleotide has been inserted.
An insertion mutation is a mutation due to an additional nucleotide base pair being added to a DNA sequence. In this case, a cytosine nucleotide has been inserted.
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If a DNA sequence is mutated from AGCTAA to AGCAAA, what type of mutation has occurred?
If a DNA sequence is mutated from AGCTAA to AGCAAA, what type of mutation has occurred?
A substitution mutation occurs when a base pair is exchanged for a different base pair. In this case, a thymine nucleotide has been substituted for an adenine nucleotide.
A substitution mutation occurs when a base pair is exchanged for a different base pair. In this case, a thymine nucleotide has been substituted for an adenine nucleotide.
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If a DNA sequence experiences an insertion mutation, what consequence may this have on the DNA sequence?
If a DNA sequence experiences an insertion mutation, what consequence may this have on the DNA sequence?
An insertion mutation that occurs where an amount of nucleotides that is not a multiple of three is added to a DNA sequence will shift the reading frame.
An insertion mutation that occurs where an amount of nucleotides that is not a multiple of three is added to a DNA sequence will shift the reading frame.
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If a DNA sequence is mutated from TCCGGA to TCGGA, what type of mutation has occurred?
If a DNA sequence is mutated from TCCGGA to TCGGA, what type of mutation has occurred?
A deletion mutation occurs when a base pair is removed from the DNA sequence. In this case, a cytosine nucleotide has been deleted.
A deletion mutation occurs when a base pair is removed from the DNA sequence. In this case, a cytosine nucleotide has been deleted.
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Which of the following represents a step necessary to create the lagging strand, but not the leading strand, during DNA replication?
Which of the following represents a step necessary to create the lagging strand, but not the leading strand, during DNA replication?
Okazaki fragments are only produced, and subsequently joined together, in the lagging strand to allow for replication in the opposite direction as replication fork movement. The leading strand, however, allows for continual replication.
All other choices reflect aspects of DNA replication for both the leading and lagging strands.
Okazaki fragments are only produced, and subsequently joined together, in the lagging strand to allow for replication in the opposite direction as replication fork movement. The leading strand, however, allows for continual replication.
All other choices reflect aspects of DNA replication for both the leading and lagging strands.
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Which one of the following proteins is found in the nucleus of eukaryotic cells?
Which one of the following proteins is found in the nucleus of eukaryotic cells?
Helicase, gyrase, and DNA polymerase are all used in the process of DNA replication, which takes place in the nucleus. Helicase is responsible for "unzipping" DNA, separating its two strands and unwinding the double-helix. Gyrase is responsible for relaxing the DNA strands and relieving tensions during unwinding. DNA polymerase synthesizes the the new DNA strands by recruiting nitrogenous bases.
Helicase, gyrase, and DNA polymerase are all used in the process of DNA replication, which takes place in the nucleus. Helicase is responsible for "unzipping" DNA, separating its two strands and unwinding the double-helix. Gyrase is responsible for relaxing the DNA strands and relieving tensions during unwinding. DNA polymerase synthesizes the the new DNA strands by recruiting nitrogenous bases.
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Frameshift mutations _________.
Frameshift mutations _________.
Frameshift mutations involve the insertion or deletion of a nucleotide in a DNA sequence, changing the reading frame of the entire nucleotide sequence after the mutation. As a result, every subsequent codon is also affected, creating a change in the organism's phenotype.
Oftentimes, this results in a premature stop codon, which causes the protein product to be shorter than an unaffected polypeptide.
Frameshift mutations involve the insertion or deletion of a nucleotide in a DNA sequence, changing the reading frame of the entire nucleotide sequence after the mutation. As a result, every subsequent codon is also affected, creating a change in the organism's phenotype.
Oftentimes, this results in a premature stop codon, which causes the protein product to be shorter than an unaffected polypeptide.
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Point mutations __________.
Point mutations __________.
Point mutations replace a single nucleotide for a different one. This can change a certain codon to code for a different amino acid (missense), the same amino acid (silent), or lead to a stop codon (nonsense). Nonsense mutations are the most severe type of point mutation, as they will cause early termination of the protein.
Point mutations replace a single nucleotide for a different one. This can change a certain codon to code for a different amino acid (missense), the same amino acid (silent), or lead to a stop codon (nonsense). Nonsense mutations are the most severe type of point mutation, as they will cause early termination of the protein.
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How many copies of DNA would you have after ten replication cycles if you start with four copies?
How many copies of DNA would you have after ten replication cycles if you start with four copies?
This is really just a math equation. We need to double the amount of DNA each time it goes through a replication cycle.
Begin: 4
Cycle 1: 8
Cycle 2: 16
Cycle 3: 32
Cycle 4: 64
Cycle 5: 128
Cycle 6: 256
Cycle 7: 512
Cycle 8: 1024
Cycle 9: 2048
Cycle 10: 4096
After ten cycles, we would have 4096 copies from our original 4.
A shortcut calculation would be 
.
This is why PCR amplification is so effective.
This is really just a math equation. We need to double the amount of DNA each time it goes through a replication cycle.
Begin: 4
Cycle 1: 8
Cycle 2: 16
Cycle 3: 32
Cycle 4: 64
Cycle 5: 128
Cycle 6: 256
Cycle 7: 512
Cycle 8: 1024
Cycle 9: 2048
Cycle 10: 4096
After ten cycles, we would have 4096 copies from our original 4.
A shortcut calculation would be
This is why PCR amplification is so effective.
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Select the complementary strand of DNA for the following DNA segment.
5'-ACTTGACT-3'
Select the complementary strand of DNA for the following DNA segment.
5'-ACTTGACT-3'
The complementary strand will be going in the opposite direction (3'-5'). As a result, you will need to flip the direction in order for it to be complementary to the original strand. When pairing bases, remember that guanine (G) and cytosine (C) are paired with one another, and adenine (A) and thymine (T) are paired.
5'-ACTTGACT-3' Switch the direction.
3'-TCAGTTCA-5' Find the complement pairs.
5'-AGTCAAGT-3'
The complementary strand will be going in the opposite direction (3'-5'). As a result, you will need to flip the direction in order for it to be complementary to the original strand. When pairing bases, remember that guanine (G) and cytosine (C) are paired with one another, and adenine (A) and thymine (T) are paired.
5'-ACTTGACT-3' Switch the direction.
3'-TCAGTTCA-5' Find the complement pairs.
5'-AGTCAAGT-3'
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Which of the following statements is true concerning DNA replication?
Which of the following statements is true concerning DNA replication?
DNA polymerase always reads DNA strands in the 3'-to-5' direction, creating a complimentary 5'-to-3' strand. As a result, the parent strand oriented in the 3'-to-5' can be replicated seamlessly, but the strand that is unraveled in the 5'-to-3' direction will require multiple attachment points for DNA polymerase so that the whole strand can be replicated in the reverse direction.
These multiple segments of replication are called Okazaki fragments, and can only be found on the lagging strand, which is replicated more slowly.
DNA polymerase always reads DNA strands in the 3'-to-5' direction, creating a complimentary 5'-to-3' strand. As a result, the parent strand oriented in the 3'-to-5' can be replicated seamlessly, but the strand that is unraveled in the 5'-to-3' direction will require multiple attachment points for DNA polymerase so that the whole strand can be replicated in the reverse direction.
These multiple segments of replication are called Okazaki fragments, and can only be found on the lagging strand, which is replicated more slowly.
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Which of the following proteins is responsible for the fusing of Okazaki fragments?
Which of the following proteins is responsible for the fusing of Okazaki fragments?
Okazaki fragments are found on the lagging strand during replication. Because these fragments will not be attached together following strand synthesis, a protein is required to combine the fragments. DNA ligase will follow DNA polymerase on the lagging strand, and combine the fragments in order to create a complete strand.
DNA polymerase is responsible for recruiting and joining nucleotides in the 3'-to-5' direction, but cannot fuse Okazaki fragments on the lagging strand. Primase lays down an RNA primer to recruit DNA polymerase prior to replication. Helicase unwinds the DNA helix in order to expose the template strands. RNA polymerase is involved in transcription, and plays no active role in DNA replication.
Okazaki fragments are found on the lagging strand during replication. Because these fragments will not be attached together following strand synthesis, a protein is required to combine the fragments. DNA ligase will follow DNA polymerase on the lagging strand, and combine the fragments in order to create a complete strand.
DNA polymerase is responsible for recruiting and joining nucleotides in the 3'-to-5' direction, but cannot fuse Okazaki fragments on the lagging strand. Primase lays down an RNA primer to recruit DNA polymerase prior to replication. Helicase unwinds the DNA helix in order to expose the template strands. RNA polymerase is involved in transcription, and plays no active role in DNA replication.
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What is the function of the single-strand binding protein during DNA replication?
What is the function of the single-strand binding protein during DNA replication?
Single-strand binding protein (SSB) binds the newly separated DNA strands to ensure that it does not reanneal during replication. This keeps the strands separate so that replication can occur.
All of the other answers describe the functions of other proteins. Primase synthesizes the RNA primers, which helps to recruit DNA polymerase. The structural basis for the replication of the leading and lagging strands ensures that replication follows the same rate on both strands.
Single-strand binding protein (SSB) binds the newly separated DNA strands to ensure that it does not reanneal during replication. This keeps the strands separate so that replication can occur.
All of the other answers describe the functions of other proteins. Primase synthesizes the RNA primers, which helps to recruit DNA polymerase. The structural basis for the replication of the leading and lagging strands ensures that replication follows the same rate on both strands.
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What is the purpose topoisomerase during DNA replication?
What is the purpose topoisomerase during DNA replication?
DNA topoisomerases are the cell's solution to the "winding" problem. The double helical nature of DNA results in tension during the replication process that would interfere with the process. DNA topoisomerases cut the phosphate backbone to relieve this tension, and allow DNA to replicate properly.
DNA topoisomerases are the cell's solution to the "winding" problem. The double helical nature of DNA results in tension during the replication process that would interfere with the process. DNA topoisomerases cut the phosphate backbone to relieve this tension, and allow DNA to replicate properly.
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A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.
A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.
The primary function of the ribosomes bound to the rough endoplasmic reticulum is to synthesize proteins for transport to the cell exterior or extracellular matrix. These ribosomes produce polypeptides that are packaged into vesicles by the Golgi apparatus and transported to the membrane. The vesicle then fuses with the membrane, either releasing proteins out of the cell or incorporating them into the cell membrane.
Nuclear ribosomes synthesize replication and transcription proteins into the nucleus, while cytoplasmic ribosomes produce cytoplasmic proteins.
The primary function of the ribosomes bound to the rough endoplasmic reticulum is to synthesize proteins for transport to the cell exterior or extracellular matrix. These ribosomes produce polypeptides that are packaged into vesicles by the Golgi apparatus and transported to the membrane. The vesicle then fuses with the membrane, either releasing proteins out of the cell or incorporating them into the cell membrane.
Nuclear ribosomes synthesize replication and transcription proteins into the nucleus, while cytoplasmic ribosomes produce cytoplasmic proteins.
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Which enzymes are necessary to produce recombinant DNA?
Which enzymes are necessary to produce recombinant DNA?
Recombinant DNA technology involves combining genes from two sources, such as different species, into a single molecule.
Applying restriction enzymes to DNA will cleave the DNA into fragments, which can be isolated for specific genes. Ligase can then be used to fuse the fragments together into a full recombinant gene.
Topoisomerase is responsible for relieving tension in the winding of the DNA helix. DNA polymerase synthesizes new DNA from individual nucleotides, but would not be useful in fusing two types of DNA together.
Recombinant DNA technology involves combining genes from two sources, such as different species, into a single molecule.
Applying restriction enzymes to DNA will cleave the DNA into fragments, which can be isolated for specific genes. Ligase can then be used to fuse the fragments together into a full recombinant gene.
Topoisomerase is responsible for relieving tension in the winding of the DNA helix. DNA polymerase synthesizes new DNA from individual nucleotides, but would not be useful in fusing two types of DNA together.
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What is the purpose of polymerase chain reaction (PCR)?
What is the purpose of polymerase chain reaction (PCR)?
Polymerase chain reaction, or PCR, is commonly used in laboratories to increase the amount of a small biological sample. Given a small sample of DNA, the process replicates the sample to make numerous identical copies. These copies can then be studied directly, used to make protein products, or incorporated into genetic modification.
Other laboratory techniques can be used to achieve the results given by the other answer options.
Polymerase chain reaction, or PCR, is commonly used in laboratories to increase the amount of a small biological sample. Given a small sample of DNA, the process replicates the sample to make numerous identical copies. These copies can then be studied directly, used to make protein products, or incorporated into genetic modification.
Other laboratory techniques can be used to achieve the results given by the other answer options.
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