Molecular Genetics Review

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| By MrsJanisse
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Molecular Genetics Review - Quiz

There are so many ways in which we can put our knowledge of genetics to good use. The most effective way, for example, is that we can look at our heredity to see if our parents or someone else in generations further up suffering from a disease makes us more likely to develop it ourselves! It’s an amazing scientific innovation, and today we’ll be seeing how much you know about molecular genetics!


Questions and Answers
  • 1. 

    Select the CORRECT statement about DNA and RNA:

    • A.

      DNA is a single strand; RNA is a double strand.

    • B.

      DNA contains thymine; so does RNA.

    • C.

      DNA and RNA are both found in the cytosol.

    • D.

      Thymine is absent in RNA, but is present in DNA.

    • E.

      RNA is the main component in ribosomes, tRNA and mRNA.

    Correct Answer
    D. Thymine is absent in RNA, but is present in DNA.
    Explanation
    Thymine (T) is one of the four nitrogenous bases found in DNA, but it is not found in RNA. Instead, RNA uses uracil (U) as a complementary base to adenine (A). This is a key difference between DNA and RNA base pairing.

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  • 2. 

    The sequence of DNA 3'-ACCGTTACC-5' would be transcribed as follows:

    • A.

      TGGCAATCC

    • B.

      5'-UGGCAAAUG-3'

    • C.

      TCCUAAUGG

    • D.

      UGGCAAUGG

    Correct Answer
    B. 5'-UGGCAAAUG-3'
    Explanation
    The given sequence of DNA, 3'-ACCGTTACC-5', would be transcribed into its complementary RNA sequence. In RNA, the base thymine (T) is replaced by uracil (U). Therefore, the complementary RNA sequence would be 5'-UGGCAAAUG-3'.

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  • 3. 

    5' and 3' refer to:

    • A.

      Numbered carbon atoms in any molecule with at least 5 carbons.

    • B.

      The direction of the DNA strand.

    • C.

      Bond formation between adjacent nucleotides in the DNA molecule.

    • D.

      The carbon atoms which have a phosphate and a carboxyl group attached respectively.

    Correct Answer
    B. The direction of the DNA strand.
    Explanation
    The terms "5'" and "3'" refer to the directionality of the DNA strand. DNA is made up of nucleotides, and each nucleotide has a sugar molecule with a phosphate group attached at the 5' carbon and a hydroxyl group attached at the 3' carbon. The numbering system is used to indicate the order in which the nucleotides are linked together in the DNA strand. The 5' end is where the phosphate group is located, and the 3' end is where the hydroxyl group is located. This directionality is important for DNA replication and transcription processes.

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  • 4. 

    Which enzyme is incorrectly paired with its function?           

    • A.

      Helicase - the DNA molecule "unzipping".

    • B.

      Gyrase - relieves tension in the unzipping DNA strand

    • C.

      DNA polymerase III - adds DNA nucleosides to a DNA template

    • D.

      RNA polymerase - adds RNA nucleosides to a growing rRNA strand

    Correct Answer
    D. RNA polymerase - adds RNA nucleosides to a growing rRNA strand
    Explanation
    mRNA strand, not rRNA.

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  • 5. 

    The leading strand and the lagging strand have  roles in:            

    • A.

      Transcription

    • B.

      Translation

    • C.

      DNA replication

    • D.

      Both A and B

    • E.

      All of a, b and c

    Correct Answer
    C. DNA replication
    Explanation
    The leading strand and the lagging strand have roles in DNA replication. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments. These strands work together to replicate the DNA molecule during cell division.

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  • 6. 

    The molecule(s) that does not act to make a new DNA molecule is/are:  

    • A.

      RNA polymerase

    • B.

      Helicase

    • C.

      Gyrase

    • D.

      SSBs

    • E.

      Primase

    • F.

      All of a, b, c and d are involved in DNA replication

    Correct Answer
    A. RNA polymerase
    Explanation
    RNA polymerase is not involved in DNA replication. RNA polymerase is responsible for transcribing DNA into RNA during the process of transcription, not for making a new DNA molecule. DNA replication involves enzymes such as helicase, gyrase, SSBs, and primase, which are responsible for unwinding the DNA helix, relieving DNA supercoiling, stabilizing single-stranded DNA, and synthesizing RNA primers, respectively. Therefore, the correct answer is RNA polymerase.

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  • 7. 

    Using the enclosed table of messenger RNA codons, select the NUMBER of CORRECT statements about the following sequence of RNA bases:                         AUG AAG AAA GGU UGA CAC UCU             (i)  It is a normal polypeptide since it starts off with a methionine.             (ii)  The polypeptide is six amino acids long.             (iii) The sequence of amino acids could be altered by a point mutation in the third codon, AAA, to AAG.             (iv)  The sequence of amino acids shown above would constitute a large polypeptide.             (v)  The polypeptide includes a molecule of lysine. The number of correct statements above is:

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    • E.

      You have to look this up and figure out what the answer is!

    Correct Answer
    E. You have to look this up and figure out what the answer is!
    Explanation
    i) is true. ii) find the stop codon, then count how many amino acids would be made.
    iii) Consult the code. If the mutation is silent (does not change the resulting amino acid), no change in the sequence will occur.
    iv) false - this is a very short sequence, but most polypeptides are hundreds of amino acids long.
    v) consult the code to figure out which amino acids will result.

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  • 8. 

    All the following are mutagens (can cause mutations), EXCEPT:

    • A.

      X-rays

    • B.

      Gamma rays

    • C.

      Dideoxynucleotides

    • D.

      UV rays

    • E.

      Chemicals that mimic nucleotide bases

    Correct Answer
    C. Dideoxynucleotides
    Explanation
    Dideoxynucleotides are not mutagens because they are not capable of causing mutations. Dideoxynucleotides are modified versions of nucleotides that lack a 3' hydroxyl group, which is necessary for DNA chain elongation during DNA replication. These modified nucleotides are commonly used in DNA sequencing techniques, but they do not have the ability to induce mutations in DNA. Therefore, dideoxynucleotides do not belong to the category of mutagens.

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  • 9. 

    Select the  INCORRECT statement about a eukaryotic DNA molecule:

    • A.

      It has an anti-parallel arrangement

    • B.

      It replicates in a semi-conservative manner.

    • C.

      The new DNA molecule formed after replication contains 50% of the original template.

    • D.

      It can consist of several thousand nucleotides.

    • E.

      It is found associated with a protein, haptitone.

    Correct Answer
    E. It is found associated with a protein, haptitone.
    Explanation
    It is associated with histone

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  • 10. 

    During translation, a transfer RNA (tRNA) molecule is associated with:

    • A.

      An amino acid molecule, a DNA molecule, and a ribosome.

    • B.

      An amino acid, a messenger RNA molecule and a ribosome.

    • C.

      A nucleolus, mRNA and DNA

    • D.

      RRNA molecule, DNA molecule, and a phosphate

    • E.

      An amino acid, rRNA and DNA

    Correct Answer
    B. An amino acid, a messenger RNA molecule and a ribosome.
    Explanation
    see protein synthesis, translation

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  • 11. 

    For which processes is RFLP required?

    • A.

      DNA fingerprinting

    • B.

      PCR

    • C.

      Sanger dideoxy sequencing

    • D.

      Both a and c

    Correct Answer
    D. Both a and c
    Explanation
    RFLP (Restriction Fragment Length Polymorphism) is a technique used in DNA fingerprinting and Sanger dideoxy sequencing. In DNA fingerprinting, RFLP helps to analyze and compare the unique patterns of DNA fragments, while in Sanger dideoxy sequencing, it is used to determine the sequence of nucleotides in a DNA fragment. Therefore, both processes require the use of RFLP. PCR (Polymerase Chain Reaction) is a different technique that amplifies specific DNA sequences and does not involve RFLP.

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  • 12. 

    Which biotechnology method most closely resembles natural DNA replication?        

    • A.

      RFLP

    • B.

      DNA fingerprinting

    • C.

      Cloning

    • D.

      PCR

    • E.

      Sanger Dideoxy sequencing

    Correct Answer
    D. PCR
    Explanation
    PCR (Polymerase Chain Reaction) is the biotechnology method that most closely resembles natural DNA replication. PCR is a technique used to amplify a specific segment of DNA, just like DNA replication in living cells. It involves the use of DNA polymerase enzyme to synthesize new strands of DNA using the existing DNA as a template. This process mimics the natural DNA replication process, where DNA polymerase replicates the DNA molecule by adding complementary nucleotides to the template strand. Therefore, PCR is the method that closely resembles natural DNA replication.

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  • 13. 

    Post transcriptional modificiations DO NOT include:

    • A.

      Adding a 5' methyl cap

    • B.

      Cutting out exons

    • C.

      Adding a poly adenylated tail to the 5' end

    • D.

      Cutting out introns

    • E.

      Adding a poly adenylated tail to the 3' end

    • F.

      More than one of these is a correct answer

    Correct Answer
    F. More than one of these is a correct answer
    Explanation
    read each one carefully...make sure you know what introns and exons are, and to what end the methyl cap is being added.

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  • Current Version
  • Jan 10, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Dec 20, 2011
    Quiz Created by
    MrsJanisse

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