Molecular Biology - SAT Subject Test in Biology
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Which organic compound serves as stored energy for living things?
Which organic compound serves as stored energy for living things?
Lipids make up the bulk of fat in animal tissues and thus stores energy.
Lipids make up the bulk of fat in animal tissues and thus stores energy.
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Plants often have a waxy covering on the outside of their leaves to prevent water loss. This waxy covering probably contains mostly which organic compound?
Plants often have a waxy covering on the outside of their leaves to prevent water loss. This waxy covering probably contains mostly which organic compound?
Major lipid groups include fats, steroids, and waxes. Because the question references a "waxy covering," we know that the plant covering must be composed of lipids.
Major lipid groups include fats, steroids, and waxes. Because the question references a "waxy covering," we know that the plant covering must be composed of lipids.
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Which of the following macromolecules are composed of long chains of amino acids?
Which of the following macromolecules are composed of long chains of amino acids?
By process of elimination, lipids and fats cannot be the correct answer-they are synonymous (lipids are also known as fats). Carbohydrates, eg sugars and starches are composed only of carbon, hydrogen, and oxygen. Nucleic acids contribute to DNA and RNA structure and function. The correct answer is proteins, made of long chains of amino acids-amino acids are sometimes called the "building blocks" of proteins.
By process of elimination, lipids and fats cannot be the correct answer-they are synonymous (lipids are also known as fats). Carbohydrates, eg sugars and starches are composed only of carbon, hydrogen, and oxygen. Nucleic acids contribute to DNA and RNA structure and function. The correct answer is proteins, made of long chains of amino acids-amino acids are sometimes called the "building blocks" of proteins.
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Which of the following is not involved in DNA synthesis?
Which of the following is not involved in DNA synthesis?
Uracil is a base utilized in RNA synthesis, whereas adenine, cytosine, guanine, and thymine are utilized in DNA synthesis.
Uracil is a base utilized in RNA synthesis, whereas adenine, cytosine, guanine, and thymine are utilized in DNA synthesis.
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Nucleic acids carry the information of what your cells will do. An example of a nucleic acid would be which of the following?
Nucleic acids carry the information of what your cells will do. An example of a nucleic acid would be which of the following?
Examples of nucleic acids include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Because DNA is not an answer choice, we know that the correct answer in this problem must be RNA. Cellulose is a carbohydrate, asparagine is an amino acid, and carbon is an element.
Examples of nucleic acids include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Because DNA is not an answer choice, we know that the correct answer in this problem must be RNA. Cellulose is a carbohydrate, asparagine is an amino acid, and carbon is an element.
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Asparagine is an example of an amino acid. If you put asparagine and other amino acids together in a chain, you would get what organic compound?
Asparagine is an example of an amino acid. If you put asparagine and other amino acids together in a chain, you would get what organic compound?
Amino acids are the building blocks of proteins, so when they are put together in a chain, you will get a protein.
Amino acids are the building blocks of proteins, so when they are put together in a chain, you will get a protein.
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Which of the following macromolecules is made up of amino acids?
Which of the following macromolecules is made up of amino acids?
A macromolecule made of amino acids is a protein. Lactase, the enzyme that aids in lactose digestion, is the only protein on the list. Sucrose and glucose are carbohydrates. Deoxyribonucleic acid is DNA, a nucleic acid. Triglycerides are a type of lipid.
Note: You can identify an enzyme (which is a protein) by the fact that its name ends in "-ase."
A macromolecule made of amino acids is a protein. Lactase, the enzyme that aids in lactose digestion, is the only protein on the list. Sucrose and glucose are carbohydrates. Deoxyribonucleic acid is DNA, a nucleic acid. Triglycerides are a type of lipid.
Note: You can identify an enzyme (which is a protein) by the fact that its name ends in "-ase."
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What type of mutation will code for an amino acid but not the correct or desired amino acid?
What type of mutation will code for an amino acid but not the correct or desired amino acid?
By definition, a missense mutation will still code for an amino acid, but not the desired amino acid. Silent mutations will have a different base pair, but due to the redundancy of genetic code, it will still code for the desired mutation. Nonsense mutations code for an amino acid that leads to a stop codon, which terminates the translation of mRNA into protein. Insertions and deletions result in a shifted reading frame and typically are detrimental.
By definition, a missense mutation will still code for an amino acid, but not the desired amino acid. Silent mutations will have a different base pair, but due to the redundancy of genetic code, it will still code for the desired mutation. Nonsense mutations code for an amino acid that leads to a stop codon, which terminates the translation of mRNA into protein. Insertions and deletions result in a shifted reading frame and typically are detrimental.
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Many enzymes have sites on them where the binding of specific molecules will increase or decrease the activity of the enzyme. What is the name of this type of site?
Many enzymes have sites on them where the binding of specific molecules will increase or decrease the activity of the enzyme. What is the name of this type of site?
The correct answer is "allosteric site." A molecule that binds to an enzyme's allosteric site induces a conformational change in the enzyme, decreasing or increasing the affinity of the enzyme’s binding sites to the substrate. The binding site binds and orients the substrate. The catalytic site lowers the activation energy of the reaction. The binding site and the catalytic site together make up the active site. Cofactors are parts of certain enzymes and are required for those enzymes to function.
The correct answer is "allosteric site." A molecule that binds to an enzyme's allosteric site induces a conformational change in the enzyme, decreasing or increasing the affinity of the enzyme’s binding sites to the substrate. The binding site binds and orients the substrate. The catalytic site lowers the activation energy of the reaction. The binding site and the catalytic site together make up the active site. Cofactors are parts of certain enzymes and are required for those enzymes to function.
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In eukaryotes, translation of mRNA into a polypeptide is performed by what type of ribosome if the polypeptide is to be secreted from the cell?
In eukaryotes, translation of mRNA into a polypeptide is performed by what type of ribosome if the polypeptide is to be secreted from the cell?
The correct answer is a ribosome bound to the rough endoplasmic reticulum. The rough endoplasmic reticulum is covered with bound ribosomes, giving it its “rough” appearance. Proteins that are to be secreted from the cell are translated by ribosomes in the rough ER before moving through the Golgi apparatus and eventually ending up in a vesicle to be secreted from the cell. There are no ribosomes found in the nucleus, bound to smooth ER, or bound to the plasma membrane.
The correct answer is a ribosome bound to the rough endoplasmic reticulum. The rough endoplasmic reticulum is covered with bound ribosomes, giving it its “rough” appearance. Proteins that are to be secreted from the cell are translated by ribosomes in the rough ER before moving through the Golgi apparatus and eventually ending up in a vesicle to be secreted from the cell. There are no ribosomes found in the nucleus, bound to smooth ER, or bound to the plasma membrane.
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Disulfide bonds can add stability to the structure of a protein. The formation of disulfide bonds occurs in the formation of what level of protein structure?
Disulfide bonds can add stability to the structure of a protein. The formation of disulfide bonds occurs in the formation of what level of protein structure?
The correct answer is "tertiary." Translation is a process performed by ribosomes to link amino acids together in a chain, and the order of the amino acids is based on a code from mRNA. The order of the amino acids in the chain is the primary structure. The secondary structure is the folding in that chain, mainly based on hydrogen bonds between parts of the chain and the surrounding water molecules. The tertiary structure is the actual three-dimensional structure of the protein. Disulfide bonds are covalent bonds between cysteine residues and are stronger than hydrogen bonds and give a stable, three-dimensional structure to what was originally just a chain of amino acids.
The correct answer is "tertiary." Translation is a process performed by ribosomes to link amino acids together in a chain, and the order of the amino acids is based on a code from mRNA. The order of the amino acids in the chain is the primary structure. The secondary structure is the folding in that chain, mainly based on hydrogen bonds between parts of the chain and the surrounding water molecules. The tertiary structure is the actual three-dimensional structure of the protein. Disulfide bonds are covalent bonds between cysteine residues and are stronger than hydrogen bonds and give a stable, three-dimensional structure to what was originally just a chain of amino acids.
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Which of the following answer choices describes a difference between DNA and RNA?
Which of the following answer choices describes a difference between DNA and RNA?
There are generally considered to be three major differences between DNA and RNA. 1) DNA has a main sugar of deoxyribose and RNA has a main sugar of ribose, 2) RNA uses uracil instead of thymine, and 3) RNA is almost exclusively a single-stranded nucleic acid. Further, DNA is generally the template that an organism uses to create RNA (except in specific organisms which use reverse transcriptase and use RNA to create DNA).
There are generally considered to be three major differences between DNA and RNA. 1) DNA has a main sugar of deoxyribose and RNA has a main sugar of ribose, 2) RNA uses uracil instead of thymine, and 3) RNA is almost exclusively a single-stranded nucleic acid. Further, DNA is generally the template that an organism uses to create RNA (except in specific organisms which use reverse transcriptase and use RNA to create DNA).
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What are the three types of RNA most important to polypeptide formation?
What are the three types of RNA most important to polypeptide formation?
The main three types of RNA necessary to create a polypeptide are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). snRNA is also important and can help modify the primary mRNA transcript, but it is only found in eukaryotes and is not absolutely essential to polypeptide formation. Micro RNA (miRNA) is also useful for post-transcriptional modification, but plays a minor role when compared to mRNA/tRNA/rRNA.
The main three types of RNA necessary to create a polypeptide are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). snRNA is also important and can help modify the primary mRNA transcript, but it is only found in eukaryotes and is not absolutely essential to polypeptide formation. Micro RNA (miRNA) is also useful for post-transcriptional modification, but plays a minor role when compared to mRNA/tRNA/rRNA.
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Which of the following nucleic acid types encodes the amino acid sequence of a polypeptide?
Which of the following nucleic acid types encodes the amino acid sequence of a polypeptide?
mRNA, or messenger RNA, carries genetic information from DNA into a three-letter code that encodes the amino acid sequence of a polypeptide (protein).
DNA contains the genetic instructions for structure and development of living things and stores genetic information over the long term.
tRNA, or transfer RNA, brings amino acids to ribosomes during translation of RNA to protein.
rRNA, or ribosomal RNA, is a component of ribosomes along with ribosomal proteins. Ribosomes are the cell organelles responsible for translating mRNA to protein.
snRNA, or small nuclear RNA, forms complexes with proteins used in RNA processing. snRNA is found only in eukaryotes.
mRNA, or messenger RNA, carries genetic information from DNA into a three-letter code that encodes the amino acid sequence of a polypeptide (protein).
DNA contains the genetic instructions for structure and development of living things and stores genetic information over the long term.
tRNA, or transfer RNA, brings amino acids to ribosomes during translation of RNA to protein.
rRNA, or ribosomal RNA, is a component of ribosomes along with ribosomal proteins. Ribosomes are the cell organelles responsible for translating mRNA to protein.
snRNA, or small nuclear RNA, forms complexes with proteins used in RNA processing. snRNA is found only in eukaryotes.
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What is the dividing structure that separates transcription from translation in a eukaryotic cell?
What is the dividing structure that separates transcription from translation in a eukaryotic cell?
The nuclear envelope separates transcription from translation in a eukaryotic cell. Translation cannot occur until transcription is finished, which is the opposite of what occurs in a prokaryotic cell. In eukaryotic cells, transcription occurs in the nucleus where mRNA will be produced. Once mRNA is produced, it will exit the nucleus through pores and then proceed to be translated into protein in the cytoplasm.
The nuclear envelope separates transcription from translation in a eukaryotic cell. Translation cannot occur until transcription is finished, which is the opposite of what occurs in a prokaryotic cell. In eukaryotic cells, transcription occurs in the nucleus where mRNA will be produced. Once mRNA is produced, it will exit the nucleus through pores and then proceed to be translated into protein in the cytoplasm.
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The lac operon is an inducible operon. Which of the following best describes this type of operon?
The lac operon is an inducible operon. Which of the following best describes this type of operon?
With an inducible system, the operon is off, meaning its repressor is active, or actively repressing the system from turning on. Inducible operons are opposite to a repressible operon, which is always on until it is repressed.
With an inducible system, the operon is off, meaning its repressor is active, or actively repressing the system from turning on. Inducible operons are opposite to a repressible operon, which is always on until it is repressed.
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The trp operon is a repressible operon. Which of the following best describes this type of operon?
The trp operon is a repressible operon. Which of the following best describes this type of operon?
With a repressible system, the operon is on, meaning the repressor is inactive. Repressible operons are the opposite of inducible operons, which are always off until their repressor is inactivated.
With a repressible system, the operon is on, meaning the repressor is inactive. Repressible operons are the opposite of inducible operons, which are always off until their repressor is inactivated.
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At what point does transcription occur in relation to gene expression?
At what point does transcription occur in relation to gene expression?
Transcription is the first process of gene expression and happens before translation.
Transcription is the first process of gene expression and happens before translation.
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What happens when one of the three codons of UAG, UAA, or UGA reach the A site on a ribosome that is helping facilitate translation?
What happens when one of the three codons of UAG, UAA, or UGA reach the A site on a ribosome that is helping facilitate translation?
UAG, UAA, and UGA are stop codons so when they enter the A site of a ribosome they will initiate the termination of translation.
UAG, UAA, and UGA are stop codons so when they enter the A site of a ribosome they will initiate the termination of translation.
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Given the partial sequence of a single DNA strand shown below, what will be the sequence of the complementary strand that is produced during DNA replication?
3' - ATCGAAGTGC - 5'
Given the partial sequence of a single DNA strand shown below, what will be the sequence of the complementary strand that is produced during DNA replication?
3' - ATCGAAGTGC - 5'
The question specifies that this is DNA replication. U (uracil) is found only in RNA and T (thymine) is found only in DNA. In DNA, A (adenine) pairs with T (thymine) and G (guanine) pairs with C (cytosine) so the complementary strand will have "A" where the original has "T," "G" where the original has "C," "C" where the original has "G" and "T" where the original has "A."
DNA strands run antiparallel, so the 3' end on the new strand will go opposite the 5' end on the original and vice versa. In this case, that means the complementary strand will run from 5' to 3' to read 5' - TAGCTTCACG - 3'. This sequence is shown in bold below:
5' - TAGCTTCACG - 3'
3' - ATCGAAGTGC - 5'
The question specifies that this is DNA replication. U (uracil) is found only in RNA and T (thymine) is found only in DNA. In DNA, A (adenine) pairs with T (thymine) and G (guanine) pairs with C (cytosine) so the complementary strand will have "A" where the original has "T," "G" where the original has "C," "C" where the original has "G" and "T" where the original has "A."
DNA strands run antiparallel, so the 3' end on the new strand will go opposite the 5' end on the original and vice versa. In this case, that means the complementary strand will run from 5' to 3' to read 5' - TAGCTTCACG - 3'. This sequence is shown in bold below:
5' - TAGCTTCACG - 3'
3' - ATCGAAGTGC - 5'
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