Biology

Molecular Biology and Genetics

985 Questions

Molecular biology and genetics explore the structure and function of DNA, RNA, genetic mutations, and heredity. Understanding these building blocks of life is essential for most biology examinations. Review these practice questions to test your molecular genetics knowledge.

DNA structure and basesGenetic mutationsNucleic acids compositionDNA sequencing and replication

Molecular Biology and Genetics Questions

Multiple choice

Match the following.

 
Column - I Column - II
A. NhaA family 1. Belongs to the ion transporter superfamily
B. NhaB family 2. Consists of a single protein of 64 amino acyl residues in length with 2 transmembrane segments
C. XanPHol family 3. Contains a number of bacterial sodium-proton antiporter proteins

  1. A - 1, B - 2, C - 3

  2. A - 3, B - 1, C - 2

  3. A - 2, B - 3, C - 1

  4. A - 2, B - 1, C - 3

  5. A - 3, B - 2, C - 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Correct answer. NhaA family contains a number of bacterial sodium-proton antiporter proteins. NhaB family belongs to the ion transporter superfamily. XanPHol family consists of a single protein of 64 amino acyl residues in length with 2 transmembrane segments.  

Multiple choice

Assertion (A): The G-quadruplexes are formed in nucleic acids by sequences that are rich in guanine. Reason (R): The interaction between G5 and G21 is a 90-degree turn between the G-qudruplex and duplex motifs.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct. The G-quadruplexes are formed in nucleic acids by sequences that are rich in guanine. The interaction between G5 and G21 is a 90-degree turn between the G-qudruplex and duplex motifs.

Multiple choice

Which of the following statements is/are correct about anti-thrombin aptamers?

P. These are G-quadruplex-bearing polynucleotides. Q. They show poor affinity and specificity against thrombin. R. They are bound to the exosite I of thrombin majorly via their two TT loops through polar and hydrophobic interactions.

  1. Only P

  2. Only Q

  3. Only R

  4. Only P and Q

  5. Only Q and R
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct. They are bound to the exosite I of thrombin majorly via their two TT loops through polar and hydrophobic interactions.

Multiple choice

Which of the following identical sequences occur(s) within nucleic acid sequences, peptide sequences, protein structures and carbohydrates across different species?

  1. Conserved sequences

  2. International Nucleotide Sequence Database Collaboration

  3. Linguistic sequence complexity

  4. Sequence hypothesis

  5. Nucleic acid sequence
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct. Conserved sequences are identical sequences that occur within nucleic acid sequences, peptide sequences, protein structures and polysaccharides across species or within different molecules, produced by the same organism.

Multiple choice

Which of the following is a polymer identical to DNA or RNA but differing in the composition of its backbone?

  1. Glycol nucleic acid

  2. In silico PCR

  3. Locked nucleic acid

  4. Nucleic acid analogue

  5. UCbase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct. Glycol nucleic acid is a polymer identical to DNA or RNA but differing in the composition of its backbone. DNA and RNA have a deoxyribose and ribose sugar backbone, respectively. GNA's backbone is composed of repeating glycol units linked by phosphodiester bonds.

Multiple choice

Assertion (A): Purines are complementary only with pyrimidines, where pyrimidine-pyrimidine pairing is energetically unfavorable. Reason (R): The molecules are too far apart for H-bonding to be formed.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Purines can hydrogen bond only with pyrimidines, where pyrimidine-pyrimidine pairing is energetically unfavorable because the molecules are too far apart for H-bonding to be formed. Thus, this option is correct.

Multiple choice

Which of the following statements about nucleic acid metabolism is/are incorrect?

A. Nucleotide preparation is an anabolic mechanism involving the chemical reaction of phosphate, pentose sugar and nitrogenous base. B. In purine synthesis, phosphoribosyl pyrophosphate is turned into inosine triphosphate. C. Both synthesis and degradation reactions require enzymes.

  1. Only A

  2. Only B

  3. Only C

  4. Only A and B

  5. Only A and C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct. In purine synthesis, phosphoribosyl pyrophosphate is turned into inosine monophosphate.

Multiple choice

Which of the following exists between two nucleotides in RNA molecules that do not follow Watson-Crick base pair rules?

  1. Wobble base pair
  2. Hoogsteen base pair
  3. UCbase

  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct. Wobble base pair is a pairing between two nucleotides in RNA molecules that do not follow Watson-Crick base pair rules. The four main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A) and hypoxanthine-cytosine (I-C).

Multiple choice

Match the following.

 
Column – I Column – II
A. Peptide nucleic acid 1. Modified RNA nucleotide synthesised by the group of Jesper Wengel
B. Locked nucleic acid 2. Artificial genetic polymer invented by Albert Eschenmoser
C. Threose nucleic acid 3. Artificially synthesised polymer similar to DNA or RNA invented by Peter E. Nielsen

  1. A - 1, B - 2, C - 3

  2. A - 3, B - 1, C - 2

  3. A - 2, B - 3, C - 1

  4. A - 2, B - 1, C - 3

  5. A - 3, B - 2, C - 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because all nucleic acids are correctly matched. Peptide nucleic acid is an artificially synthesised polymer similar to DNA or RNA invented by Peter E. Nielsen. A locked nucleic acid is a modified RNA nucleotide synthesised by the group of Jesper Wengel. Threose nucleic acid is an artificial genetic polymer invented by Albert Eschenmoser.