Tag: molecular biology

Quizzes (15) Questions (122)

Questions Related to molecular biology

Multiple choice bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

All RNA except .......... is made from DNA.

  1. tRNA

  2. mRNA

  3. rRNA

  4. cDNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

cDNA or complementary DNA is the DNA synthesized from a single-stranded RNA template in a reaction catalysed by reverse transcriptase enzyme. This cDNA is naturally produced by retroviruses where RNA acts as the genetic material. It is also used to clone eukaryotic genes in prokaryotes.

Remaining tRNA, mRNA and rRNA are synthesised from DNA through the process of transcription using RNA polymerase enzyme.
So, the correct option is 'cDNA'.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

Genome is the complete complement of  __________ including all ___________ and the inter genetic regions.

  1. DNA and RNA

  2. DNA and genes

  3. RNA and genes

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A genome is an organism's complete set of DNA, including all of its genes in the genetic regions.
So, the correct option is 'DNA and genes'
Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

DNA is a polymer of a

  1. Glucose

  2. Amino acid

  3. Nucleotide

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since, they are composed of simpler units called as nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase either guanine (G), adenine (A), thymine (T), or cytosine (C) as well as a monosaccharide sugar called as deoxyribose and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. According to base pairing rules (A with T and C with G), hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA. So, nuclotides are building blocks of DNA and not glucose or aminoacid. Thus, the correct answer is option C.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

The diameter of DNA molecule is

  1. $10 \mathring{A}$
  2. $100 \mathring{A}$
  3. $200 \mathring{A}$
  4. $20 \mathring{A}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
DNA is made of two ("duplex DNA") dextrogyre (like a screw, right- handed) helical chains or strands ("the double helix"), coiled around an axis to form a double helix of $20 \mathring{A}$ of diameter. The two strands are antiparallel. The general appearance of the polymer shows a periodicity of $3.4 \mathring{A}$, corresponding to the distance between 2 bases, and another one of $34 \mathring{A}$, corresponding to one helix turn.
So, the correct answer is "$20 \mathring{A}$".
Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

As the base sequence present on one strand of DNA decides the base sequence of other strand, this is considered as _____.

  1. Descending strand

  2. Leading strand

  3. Lagging strand

  4. Complimentary strand
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Because the two strands of DNA are complementary, the sequence of one strand dictates the sequence of the other. This property is known as complementarity.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

The basis of life (secret of life) is

  1. Lipid

  2. Protein

  3. Nucleic acid

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

All the bio-molecules are important for life but as per the question the nucleic acids stand out, because they only have genetic information coded in them and can pass on this information to next generation of cells. So, nucleic acid plays a significant role  in the basis of life. 

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

UAG is triplet nitrogen base on m RNA. What will be the corresponding triplet on the coding strand?       

  1. TAG

  2. UAG

  3. ATC

  4. TUA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • In DNA transcription, the coding strand is the DNA strand whose base sequence corresponds to the base sequence of the RNA transcript produced (although with thymine replaced by uracil).
  •  It is this strand which contains codons, while the non-coding strand contains anticodons.
  •  Hence, UAG is triplet nitrogen base on m RNA, TAG will be the corresponding triplet on the coding strand. 
  •  So, the correct answer is 'TAG'.
Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

In eukaryotes basic structural unit made of histone and DNA 

  1. Nucleosome

  2. Nucleolus

  3. Chromosome

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

In eukaryotes DNA is tightly bound to histones which form a DNA protein particles called nucleosome. Each nucleosome contains 2 copies of each $H _{2A},H _{2B}.H _{3}$ and $H _{4}$ histone protein bounded on 146 BP of DNA.Each nucleosome bead is linked to next nucleosome bead by linker DNA.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

The transforming substance in Griffith's experiment is 

  1. protein

  2. DNA

  3. mRNA

  4. polysaccharide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The transforming principle in Griffith's experiment is DNA. Griffith conducted an experiment in 1928. In this experiment he chose two strains of Stephylococcus pneumoniae bacteria. One of them was a smooth strain which was virulent and the other one was a rough strain which was non-virulent. The smooth strains caused pneumonia when they were injected to the mice, and the rough strains did not cause pneumonia in mice. Griffith heat killed the smooth strain bacteria and injected them into mice and he observed that pneumonia was not caused in them. He mixed the heat killed smooth strain and rough strain and injected the mixture into mice and this mixture caused pneumonia in mice. When he tested the blood of the mice, he saw both rough and smooth strains of bacteria. This implied that some factor from the dead smooth bacterial strain had taken entry into the rough strains and converted them into smooth strains. He called this factor as Transforming principle.

Later in 1944 scientists, Avery, MacLeod, and McCarty conducted an experiment to find out what the transforming principle was, They selected DNA, Proteins and RNA. They eliminated proteins by adding proteases and the strains were able to perform the transformation, they eliminated RNA with RNase the strains were still able to perform the transformation, they eliminated DNA with DNase and now the smooth strains lost the ability to transform Rough strains and hence it was proved that the DNA was the transforming principle. 
Therefore the right option is option B, DNA.