1.
DNA located in the nucleus of a cell provides the genetic information required to build proteins in a cell. However, proteins are made outside the nucleus. Which statement best explains how the genetic instructions for protein synthesis are delivered outside the nucleus?
Correct Answer
D. The genetic information is transferred out of the nucleus by RNA.
Explanation
DNA contains the genetic instructions for building proteins, but proteins are synthesized outside the nucleus in the cytoplasm. The transfer of this information is done by messenger RNA (mRNA), which is created during a process called transcription. The mRNA carries a copy of the genetic instructions from the DNA in the nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. This ensures that the instructions from the DNA can be translated into a sequence of amino acids to form proteins.
2.
Which of the following is a nucleotide found in DNA?
Correct Answer
D. Deoxyribose + pHospHate group + cytosine
Explanation
The correct answer is deoxyribose + phosphate group + cytosine. This is because DNA is made up of nucleotides, which consist of a sugar molecule (in this case deoxyribose), a phosphate group, and a nitrogenous base. Cytosine is one of the four nitrogenous bases found in DNA, along with adenine, guanine, and thymine. Uracil is found in RNA, not DNA.
3.
In a DNA molecule, what base is paired with cytosine?
Correct Answer
B. Guanine
Explanation
Cytosine is one of the four nitrogenous bases found in DNA. It forms a complementary base pair with guanine through hydrogen bonding. This means that in a DNA molecule, cytosine is always paired with guanine. Thymine, adenine, and uracil are the other three bases, but they do not pair with cytosine in DNA.
4.
Because of base pairing in DNA, the percentage of
Correct Answer
B. Pyrimidines in DNA is about equal to the percentage of purines.
Explanation
The answer is that pyrimidines in DNA are about equal to the percentage of purines. This is because of base pairing in DNA. Adenine pairs with thymine (a pyrimidine), and guanine pairs with cytosine (a purine). The base pairing rule states that the amount of adenine will be equal to the amount of thymine, and the amount of guanine will be equal to the amount of cytosine. Therefore, the percentage of pyrimidines (thymine and cytosine) will be about equal to the percentage of purines (adenine and guanine).
5.
A strand of DNA is made up of the bases CATAGCGTA. What is the complementary base sequence on the other strand of DNA?
A) CATAGCGTA B) UTATCUCAT C) GTATCGCAT D) CAUAGCCUA
Correct Answer
C. GTATCGCAT
Explanation
The complementary base sequence of DNA is formed by pairing specific bases. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Therefore, to find the complementary base sequence, we need to replace each base with its complementary base. In the given sequence CATAGCGTA, we can see that each base is already paired with its complementary base (C pairs with G, A pairs with T). Thus, the complementary base sequence is GTATCGCAT.
6.
DNA replication results in two DNA molecules,
A) each with two new strands. B) one with two new strands and the other with two original strands. C) each with one new strand and one original strand. D) each with two original strands.
Correct Answer
C. Each with one new strand and one original strand
Explanation
During DNA replication, the double-stranded DNA molecule unwinds and separates into two strands. Each original strand serves as a template for the synthesis of a new complementary strand. This results in two DNA molecules, each consisting of one original strand and one newly synthesized strand. Therefore, the correct answer is "each with one new strand and one original strand."
7.
What takes place during replication?
A) the information in a molecule of DNA is copied before cell division occurs B) information from mRNA is used to make proteins C) mRNA makes a copy of the DNA template D) rRNA reads the information from mRNA to make proteins
Correct Answer
A. The information in a molecule of DNA is copied before cell division occurs
Explanation
During replication, the information in a molecule of DNA is copied before cell division occurs. This process ensures that each new cell receives an identical copy of the genetic material, allowing for the transmission of genetic information from one generation to the next. Replication involves the unwinding of the DNA double helix, the separation of the DNA strands, and the synthesis of new complementary strands using each original strand as a template. This results in two identical DNA molecules, each consisting of one original strand and one newly synthesized strand.
8.
What is the job of DNA polymerase?
A) It translates the mRNA while it proofreads for mutations. B) It transforms DNA into RNA by breaking the hydrogen bonds. C) It makes a complimentary strand of DNA and then proofreads it. D) It makes a complimentary strand of RNA and then proofreads it.
Correct Answer
C. It makes a complimentary strand of DNA and then proofreads it.
Explanation
DNA polymerase is responsible for making a complimentary strand of DNA during DNA replication. It adds nucleotides to the growing DNA strand, using the existing DNA strand as a template. Additionally, DNA polymerase has a proofreading function, which allows it to detect and correct errors or mutations that may occur during replication. This ensures the accuracy of the newly synthesized DNA strand.
9.
Genes are sections of DNA that contain instructions for assembling.
Correct Answer
C. Proteins
Explanation
Genes are sections of DNA that contain instructions for assembling proteins. Proteins are essential molecules that perform various functions in the body, such as building and repairing tissues, regulating chemical reactions, and serving as enzymes and hormones. Therefore, it is correct to say that genes contain instructions for assembling proteins. Purines and pyrimidines, on the other hand, are types of nitrogenous bases that make up the building blocks of DNA and RNA, while nucleosomes are structures formed by DNA wrapped around histone proteins.
10.
RNA contains the sugar
A) ribose. B) deoxyribose. C) glucose. D) lactose.
Correct Answer
A. Ribose
Explanation
RNA contains the sugar ribose. Ribose is a 5-carbon sugar that is a component of RNA molecules. It is different from deoxyribose, which is the sugar found in DNA. Glucose and lactose are different types of sugars, but they are not found in RNA.
11.
Unlike DNA, RNA contains
Correct Answer
B. Uracil
Explanation
RNA contains uracil instead of thymine. Thymine is one of the four nitrogenous bases found in DNA, but it is replaced by uracil in RNA. This difference in bases is due to a chemical modification during the process of transcription, where DNA is used as a template to synthesize RNA. Uracil pairs with adenine in RNA, just like thymine pairs with adenine in DNA. This distinction between thymine in DNA and uracil in RNA is crucial for the proper functioning of these two types of nucleic acids in various cellular processes.
12.
How many types of RNA are involved in protein synthesis?
Correct Answer
B. 3
Explanation
There are three types of RNA involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). mRNA carries the genetic information from DNA to the ribosomes, where protein synthesis occurs. tRNA helps in translating the mRNA sequence into amino acids and brings them to the ribosomes. rRNA is a structural component of ribosomes and plays a crucial role in protein synthesis. Therefore, the correct answer is 3.
13.
Which cell structures are involved in protein synthesis?
Correct Answer
B. Ribosomes
Explanation
Ribosomes are the cell structures involved in protein synthesis. They are responsible for translating the genetic information from the DNA into proteins. Ribosomes can be found in all types of cells, including prokaryotic and eukaryotic cells. They are composed of RNA and proteins and are found either free in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes play a crucial role in the process of protein synthesis by reading the mRNA and assembling the amino acids into a polypeptide chain. Therefore, the correct answer is ribosomes.
14.
During protein synthesis, genetic material is transferred from _____.
Correct Answer
B. DNA to RNA to proteins
Explanation
During protein synthesis, genetic material is transferred from DNA to RNA to proteins. This process is known as transcription and translation. Transcription occurs in the nucleus where DNA is used as a template to synthesize RNA molecules. The RNA molecules then undergo translation in the cytoplasm, where they are used as instructions to assemble amino acids into proteins. This sequential transfer of genetic information from DNA to RNA to proteins is a fundamental process in all living organisms.
15.
Which of the following are copied from DNA?
Correct Answer
B. MRNA, tRNA, and rRNA
Explanation
mRNA, tRNA, and rRNA are all copied from DNA. mRNA is transcribed from DNA and carries the genetic information from the nucleus to the ribosomes for protein synthesis. tRNA is also transcribed from DNA and is responsible for bringing the amino acids to the ribosomes during protein synthesis. rRNA is transcribed from DNA and is a major component of ribosomes, where protein synthesis occurs. Therefore, all three molecules are involved in the process of gene expression and are directly copied from DNA.
16.
During transcription, what base pairs with adenine?
Correct Answer
A. Uracil
Explanation
During transcription, adenine base pairs with uracil. This is because in RNA, uracil replaces thymine, which is found in DNA. Adenine and uracil form a complementary base pair, meaning they bind together through hydrogen bonding. This pairing is crucial for the transcription process, where the DNA sequence is copied into RNA.
17.
What is produced during transcription?
A) RNA molecules B) DNA molecules C) RNA polymerase D) proteins
Correct Answer
A. RNA molecules
Explanation
During transcription, RNA molecules are produced. Transcription is the process in which the DNA sequence is used as a template to synthesize a complementary RNA molecule. This RNA molecule carries the genetic information from the DNA to the ribosomes, where it is used as a template for protein synthesis. Therefore, RNA molecules are the product of transcription.
18.
What is produced during translation?
A) RNA molecules B) DNA molecules C) RNA polymerase D) proteins
Correct Answer
D. Proteins
Explanation
During translation, proteins are produced. Translation is the process in which the genetic information encoded in RNA molecules is used to synthesize proteins. This process occurs in the ribosomes, where transfer RNA (tRNA) molecules bring the correct amino acids according to the codons on the messenger RNA (mRNA) molecule. The ribosomes then catalyze the formation of peptide bonds between the amino acids, resulting in the production of proteins.
19.
Which type of molecule transcribes the information from a DNA molecule to a molecule that carries the information to a ribosome?
Correct Answer
C. MRNA
Explanation
mRNA (messenger RNA) is the type of molecule that transcribes the information from a DNA molecule to a molecule that carries the information to a ribosome. mRNA is synthesized during the process of transcription, where it copies the genetic information from DNA and carries it to the ribosome for protein synthesis. This process is essential for gene expression and the production of proteins in cells. tRNA (transfer RNA) carries amino acids to the ribosome during protein synthesis, rRNA (ribosomal RNA) forms the structure of ribosomes, and dRNA (deoxyribonucleic acid) is another term for DNA.
20.
How many codons are needed to specify three amino acids?
Correct Answer
A. 3
Explanation
Three codons are needed to specify three amino acids because each codon codes for a specific amino acid. In the genetic code, there are 64 possible codons, and each codon corresponds to one of the 20 amino acids used to build proteins. Therefore, if we need to specify three different amino acids, we would require three codons, each coding for a different amino acid.
21.
What happens during the process of translation?
Correct Answer
B. The cell uses information from messenger RNA to produce proteins.
Explanation
During the process of translation, the cell uses information from messenger RNA to produce proteins. Messenger RNA is synthesized from DNA in a process called transcription, and it carries the genetic code from the DNA to the ribosomes in the cytoplasm. The ribosomes then read the mRNA sequence and use it as a template to assemble amino acids in the correct order, forming a protein molecule. This process is essential for gene expression and protein synthesis in cells.
22.
During translation, the type of amino acid that is added to the protein chain depends on the
Correct Answer
D. Codon on the mRNA and the anticodon on the tRNA to which the amino acid is attached.
Explanation
During translation, the type of amino acid that is added to the protein chain depends on both the codon on the mRNA and the anticodon on the tRNA to which the amino acid is attached. The codon on the mRNA determines the specific amino acid that needs to be added, while the anticodon on the tRNA ensures that the correct amino acid is brought to the ribosome. This process ensures that the protein chain is built with the correct sequence of amino acids according to the genetic code.
23.
Where does transcription occur?
Correct Answer
C. Nucleus
Explanation
Transcription is the process by which genetic information in DNA is copied into RNA. It occurs in the nucleus of a cell. This is where the DNA is located, and transcription takes place in order to produce mRNA molecules that can then be used for protein synthesis. The cytoplasm is where translation occurs, not transcription. The ribosome is involved in translation, not transcription. The nucleolus is responsible for the production of ribosomes, not transcription.
24.
Where does translation occur?
Correct Answer
B. Ribosome
Explanation
Translation occurs in the ribosome. The ribosome is a cellular organelle that is responsible for protein synthesis. During translation, the ribosome reads the messenger RNA (mRNA) and uses it as a template to assemble a sequence of amino acids, which then form a protein. This process takes place in the cytoplasm of the cell. The ribosome acts as the site where the mRNA is decoded and the protein is synthesized, making it the correct answer.
25.
The mRNA sequence ACU codes for the amino acid Thr. A mutation occurs, and the resulting mRNA sequence is AUU. What amino acid will replace Thr?
Correct Answer
C. Ile
Explanation
The mRNA sequence ACU codes for the amino acid Thr (Threonine). However, due to a mutation, the sequence changes to AUU. In the genetic code, AUU codes for the amino acid Ile (Isoleucine). Therefore, Ile will replace Thr in the resulting protein.
26.
Persons A and B have similar mRNA sequences with the exception of 1 nucleotide.
Person A: AUGGUUACUAAGGGCUGA
Person B: AUGGUUACUGAGGGCUGA
Use the genetic code chart to determine how this difference affects the sequence of amino acids in the resulting protein.
A) Lys in Person A is replaced with Glu in Person B. B) Phe in Person A is replaced with Leu in Person B. C) Persons A and B have identical amino acid sequences. D) A stop codon is generated in Person B and not in Person A.
Correct Answer
A. Lys in Person A is replaced with Glu in Person B.
Explanation
The mRNA sequence of Person A is "AUGGUUACUAAGGGCUGA" and the mRNA sequence of Person B is "AUGGUUACUGAGGGCUGA". The only difference between the two sequences is the presence of a "U" nucleotide in Person A and a "G" nucleotide in Person B at the 9th position. Using the genetic code chart, we can determine that the codon "UAC" in Person A codes for the amino acid Lysine (Lys), while the codon "GAC" in Person B codes for the amino acid Glutamic Acid (Glu). Therefore, the correct answer is that Lys in Person A is replaced with Glu in Person B.
27.
This molecule below is an example of the monomer of a protein. What is this molecule called?
Correct Answer
A. Amino acid
Explanation
The molecule shown in the question is an example of an amino acid. Amino acids are the building blocks of proteins and are composed of an amino group, a carboxyl group, and a side chain. They are linked together through peptide bonds to form proteins. Carbohydrates are composed of sugars, fatty acids are the building blocks of lipids, and nucleic acids are the building blocks of DNA and RNA. Therefore, the correct answer is amino acid.