Biology

Molecular Biology and Genetics

717 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

Nuclear DNA is isolated and sheared into pieces of constant size. The DNA is denatured and then slowly renatured. The first sequence to renature would be

  1. higly repetitive in frequency

  2. localized in the nucleolus

  3. globin genes

  4. unique in frequency

  5. all the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Repetitive DNA will renature at low C0t values. The fast renaturation of the repetitive DNA is because of the avalability of numerous complementary sequences.

Multiple choice

Identify the incorrect statement.

  1. Eukaryotic genetic material is DNA.

  2. All bacteriophages only contain DNA as their genetic material.

  3. Retroviruses are single stranded RNA viruses having reverse transcriptase.

  4. There are mainly animal viruses containing DNA as their genetic material.

  5. Plant viruses usually contain RNA as their genetic material.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome.

Multiple choice

The nucleosomes

  1. contain only DNA and non histone proteins

  2. have a core of histones with DNA wound around

  3. contain histones that are a family of small, negatively charged proteins

  4. contain histones that cannot be displaced by chromatin remodelling complexes

  5. containing DNA itself provides energy for its folding
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The basic repeating structural (and functional) unit of chromatin is the nucleosome, which contains nine histone proteins and about 166 base pairs of DNA.

Multiple choice

Where is Ramachandran's plot used?

  1. Determination of the structure of nucleic acids

  2. Determination of orientation of groups in amino acids

  3. Determination of the structure of proteins

  4. Determination of the structure of DNA

  5. Determination of the structure of carbohydrates

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 
 

Multiple choice

The two strands of the DNA molecule are held together by:

  1. phosphate bond

  2. amino bond

  3. hydrogen bond

  4. nitrogen bond
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA's double helix structure is maintained by hydrogen bonds between complementary base pairs on opposite strands. Adenine pairs with thymine (2 hydrogen bonds), and guanine pairs with cytosine (3 hydrogen bonds). These bonds are strong enough to hold the strands together but weak enough to separate during DNA replication and transcription.

Multiple choice

A molecule of ATP is structurally similar to a molecule of

  1. RNA molecule

  2. DNA molecule

  3. amino acid

  4. fatty acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ATP (Adenosine Triphosphate) is structurally similar to RNA molecules because both contain a ribose sugar (not deoxyribose like DNA) and the nitrogenous base adenine. ATP can be considered a modified RNA nucleotide with three phosphate groups instead of one. DNA contains deoxyribose sugar, amino acids and fatty acids are completely different molecular structures.

Multiple choice

Products of adenine and guanine metabolism are excreted by humans as

  1. ammonia

  2. urea

  3. uric acid

  4. allantoin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Adenine and guanine are purines. In humans, purine metabolism end products are excreted as uric acid. Ammonia is excreted by aquatic animals. Urea is the excretory product of amino acid metabolism (urea cycle). Allantoin is further breakdown of uric acid in some mammals but not in humans.

Multiple choice

Prokaryotic genetic system has :

  1. DNA and histone

  2. DNA and no histone

  3. No DNA and histone

  4. No DNA and no histone

  5. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Prokaryotes do not contain DNA packing histones.

Multiple choice

Purines are generally abbreviated as:

  1. R

  2. Y

  3. C

  4. U
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In single-letter nucleotide notation, R stands for purines (A and G), while Y stands for pyrimidines (C and T/U). C and U represent specific bases, not base categories.

Multiple choice

Which of the following statement is true?

  1. DNA is non-polar due to the highly charged phosphate backbone.

  2. DNA is polar due to the highly charged phosphate backbone.

  3. DNA is polar due to the highly charged sugar backbone.

  4. DNA is non-polar due to the highly charged sugar backbone.

  5. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA is polar due to highly charged phosphate backbone.