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

Frame shift mutation refers to the type of gene mutations created by a deletion or insertion in a DNA sequence, which shifts the reading frame sequence.

Which of the following mutagenic agents intercalate in the DNA causing frameshift mutation?

  1. Nitrous acid

  2. Benzo[a]pyrene

  3. Dimethylnitrosamine

  4. Aflatoxin

  5. Ultraviolet light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Benzo[a]pyrene, found in smoke is a mutagenic agent that intercalates in the DNA causing frameshift mutation.

Multiple choice

The International Nucleotide Sequence Database (INSD) consists of

  1. DNA Data Bank of Japan
  2. European Nucleotide Archive
  3. GenBank
  4. PROSITE
  5. VectorBase

  1. 1, 2 and 3

  2. 1, 3 and 5

  3. 2, 3 and 4

  4. 2, 4 and 5

  5. 3, 4 and 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Correct answer. The International Nucleotide Sequence Database Collaboration (INSDC) consists of a joint effort to collect and disseminate databases containing DNA and RNA sequences. It consists of the following databases: DNA Data Bank of Japan (Japan), GenBank (USA) and the European Nucleotide Archive (UK).

Multiple choice

Phosphorus is a structural element in

  1. proteins

  2. cytochrome

  3. carbohydrates

  4. DNA

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

Phosphorus is a key structural component of DNA and RNA. DNA (deoxyribonucleic acid) is a nucleic acid, and its backbone contains phosphate groups which contain phosphorus. Proteins contain nitrogen but no phosphorus in their basic structure. Cytochrome is a protein, and carbohydrates contain carbon, hydrogen, and oxygen only.

Multiple choice

Which of these is not a type of mutation resulting in only single nucleotide base changes in a gene's DNA sequence?

  1. Frameshift mutation

  2. Silent mutation

  3. Point mutation

  4. Missense mutation

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

Insertion and deletion mutations add or remove one or more DNA bases. Insertion and deletion mutations cause frameshift mutations which change the grouping of nucleotide bases into codons. This results in a shift of reading frame during protein translation.

Multiple choice

Which type of mutation can cause such type of changes in a DNA base sequence?

A mutation in a DNA sequence GTA CCT AGG forms a new sequence reading as GTAT CCT AGG before its rearrangement by our body to the triplet codon format reading as GTA TCC TAG.

  1. Frameshift mutation

  2. Point mutation

  3. Nonsense mutation

  4. Silent mutation

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

A frameshift mutation is generally much more serious and will cause a change all the way down a DNA sequence making each codon a different sequence not just in one point or base like a point mutation that would only slightly change the sequence of a single codon. For example consider our DNA sequence is GTA CCT AGG. In a frameshift mutation a whole base would be added somewhere in that sequence making it look something like GTAT CCT AGG. Since it is impossible though to have 4 bases in a codon our body would automatically shift every letter down one even to the next codon in the sequence. In the end the final product would look something like GTA TCC TAG (with the left over G being the first base in the next codon and so on).

Multiple choice

Which type of mutation will result in the formation of an AT base pair in the mutant from a GC base pair?

  1. Specific mispairing

  2. Directed mutation

  3. Transversion mutation

  4. Conditional mutation

  5. Transition mutation
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

It is a point mutation involving substitution of one base pair for another by replacement of one purine by another purine and of one pyrimidine by another pyrimidine but without change in the purine-pyrimidine orientation. Here the GC base pair is changed to AT that is the purine G is substituted by another purine adenine and the pyrimidine C is substituted by another pyrimidine thymine. So it is a transition type of mutation. Hydroxylating agents can make such type of transition mutation.