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| 1 | |
RNA and DNA are different because of |
| | A) | one base, uracil. |
| | B) | their sugar component. |
| | C) | their phosphate group. |
| | D) | their sugar component and one base, uracil. |
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| 2 | |
Each DNA molecule is composed of the same three parts: a sugar, a phosphate group, and a nitrogenous base; this makes it consistent between and among species. It is also variable, however, because |
| | A) | of all the possible combinations of bases. |
| | B) | it can contain one of two pentose sugars. |
| | C) | of the combination of different sugars and bases. |
| | D) | of all of the different phosphate groups. |
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| 3 | |
Watson and Crick found the X-ray pattern of DNA to be significant because it allowed them to create a model of the molecule based on |
| | A) | simple mathematical calculations. |
| | B) | application of Chargaff’s rules. |
| | C) | the visible hydrogen bonds in the X-ray diffraction pattern. |
| | D) | the shape, which appeared to be a helix maintained by hydrogen bonding, mathematical measurements, and the application of Chargaff’s rules. |
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| 4 | |
A molecule of DNA is two linked, anti-parallel strands that spiral about one another. Adenine pairs with thymine, and guanine with cytosine. But how is this molecule held together? |
| | A) | The sugar backbones are covalently bonded to each other. |
| | B) | The complementary bases are held together by hydrogen bonds. |
| | C) | The phosphate groups form ionic bonds with each other. |
| | D) | The bases are hydrogen bonded to the base above and below them in their own strand, as well as the complementary base in the other strand. |
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| 5 | |
DNA replication requires the separation of the two strands of a DNA molecule. An enzyme called __________ unwinds the molecule. Then, each strand __________ for complementary base pairing of free nucleotides. The nucleotides on the template strand hydrogen bond with the nucleotides on the newly synthesized strand to form daughter helices. |
| | A) | DNA polymerase; serves as a template |
| | B) | helicase; leaves the nucleus |
| | C) | helicase; serves as a template |
| | D) | DNA polymerase; leaves the nucleus |
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| 6 | |
What does semiconservative mean? |
| | A) | It means that the old DNA is not lost during replication; once the new DNA is made, the old DNA it is stored in the nucleus for replication in the future. |
| | B) | It means that the new strand of DNA is made from free nucleotides that are in the nucleus as a result of the old DNA strand being broken down. |
| | C) | It means that some of the old DNA is kept, but only that parts that are not worn out. |
| | D) | The old DNA is not lost during replication; it becomes part of each new DNA molecule. |
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| 7 | |
Mistakes in replication are rare because of |
| | A) | the proofreading abilities of DNA polymerase. |
| | B) | the proofreading abilities of helicase. |
| | C) | the checkpoints in replication, which discard replicated strands that contain errors. |
| | D) | the cell contains checkpoint proteins that digest strands that contain errors. |
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| 8 | |
mRNA is a transcript of a gene, transcribed into RNA from a DNA molecule. This mRNA carries the genetic code of the DNA molecule in __________ called codons which correspond to __________. |
| | A) | four bases (A,C,G, and U); four different amino acids. |
| | B) | two base units; amino acids, the subunits of protein. |
| | C) | single base units; four different amino acids. |
| | D) | three-letter base units; amino acids, the subunits of protein |
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| 9 | |
During RNA transcription, RNA polymerase __________. Then, the RNA (mRNA in this example) is processed through the addition of a __________, which stabilize(s) the molecule. |
| | A) | unzips a DNA molecule completely and adds DNA nucleotides in a transcript of the RNA template; cap and poly-A tail |
| | B) | opens a DNA helix just slightly and adds RNA nucleotides in a transcript of the DNA template; cap and a poly-A tail |
| | C) | unzips a DNA molecule completely and adds RNA nucleotides in a transcript of the DNA template; stop codon |
| | D) | unzips a DNA helix just slightly and adds DNA nucleotides in a transcript of the RNA template; stop codon |
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| 10 | |
A mature mRNA molecule contains |
| | A) | introns and exons, the introns running in between the exons. |
| | B) | introns only, the exons are removed via alternative splicing. |
| | C) | continuous exons only, the introns are removed via primary-mRNA splicing. |
| | D) | introns or exons depending on which protein product is produced; alternative splicing makes this possible. |
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| 11 | |
This type of RNA is functional in the cytoplasm, where it moves amino acids to the ribosomes, where they bond to form a protein. |
| | A) | None of these answers is correct. |
| | B) | rRNA |
| | C) | mRNA |
| | D) | tRNA |
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| 12 | |
This type of RNA joins with proteins to form the two subunits of ribosomes. |
| | A) | rRNA |
| | B) | mRNA |
| | C) | tRNA |
| | D) | None of these answers is correct. |
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| 13 | |
This type of RNA carries genetic information from DNA to the cytoplasm for protein synthesis. |
| | A) | tRNA |
| | B) | rRNA |
| | C) | None of these answers is correct. |
| | D) | mRNA |
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| 14 | |
For a polypeptide to be synthesized, all of the components for the process must first be assembled during __________. This process gathers a small ribosomal unit, mRNA, initiator tRNA and a large ribosomal unit for protein synthesis. One amino acid is added a time during __________, and a protein increases in length. |
| | A) | unwinding; translocation |
| | B) | initiation; elongation |
| | C) | elongation; termination |
| | D) | the preparatory reaction; translocation |
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| 15 | |
Which representation of the steps of gene expression is in the correct order? |
| | A) | mRNA processing → DNA → tRNA to mRNA → mRNA + ribosomes → elongation → protein modifaction → initiation → termination |
| | B) | initiation → DNA → mRNA → mRNA processing → mRNA + ribosomes → tRNA to mRNA → elongation → protein modification → termination |
| | C) | DNA → mRNA → mRNA processing → mRNA + ribosomes → tRNA to mRNA → initiation → elongation → protein modification → termination |
| | D) | initiation → termination → DNA → mRNA processing → mRNA → mRNA + ribosomes → elongation → protein modification → termination |
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| 16 | |
A change in a single DNA base pair can lead to |
| | A) | a dysfunctional protein. This change alters the amino acid sequence of the protein, which can lead to changes in the shape of the protein. |
| | B) | a missing protein. If a stop codon is created in place of an amino acid, a protein might not be made at all. |
| | C) | no observable change. A single base pair alteration does not change the amino acid sequence because of the redundancy of the codons. |
| | D) | All of these are possible results of a change in a single DNA base pair. |
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| 17 | |
Huntington disease is caused by which mutation? |
| | A) | triplet repeat |
| | B) | frameshift |
| | C) | missense |
| | D) | silent |
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| 18 | |
There are several types of chromosomal mutations, each with its own associated influence on an individual. An individual who inherits a normal chromosome from one parent and a chromosome with a deletion from another parent __________, and a syndrome might result. |
| | A) | has three alleles for each trait |
| | B) | has chromosomal segments in the opposite direction from normal |
| | C) | has repeated chromosomal segments |
| | D) | no longer has a pair of alleles for each trait |
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| 19 | |
There are several types of chromosomal mutations, each with its own associated influence on an individual. When a chromosomal segment is repeated in the same chromosome or in a nonhomologous chromosome, __________. This is termed as _________. |
| | A) | the resulting chromosome is shorter than it was and is missing alleles; deletion |
| | B) | the resulting chromosome is longer than it was and has multiple copies of an allele; duplication |
| | C) | the resulting chromosome contains portions that are joined in the opposite direction than normal; inversion |
| | D) | the resulting chromosome is longer than it was and has multiple copies of an allele; frameshift mutation |
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| 20 | |
________ is the exchange of chromosomal segments between two nonhomologous chromosome and __________. |
| | A) | Duplication; can produce healthy individuals, but if the exchange breaks an allele into two pieces, an individual can inherit one copy of certain alleles and three copies of others |
| | B) | Inversion; can result in recombinant chromosomes with duplicated and deleted segments if inverted chromosomes cross-over |
| | C) | Translocation; can produce healthy individuals, but if the exchange breaks an allele into two pieces, an individual can inherit one copy of certain alleles and three copies of others |
| | D) | Deletion; can result in recombinant chromosomes with duplicated and deleted segments if inverted chromosomes cross-over |
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