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Question
Answer the following question in your own words.
Describe the structure of the DNA molecule.
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Solution
- All organisms have the same DNA structure. Watson and Crick modelled DNA in 1953. In this model, two parallel nucleotide threads coil around each other. A ‘double helix’ describes this arrangement. Like a coiled ladder, its construction is flexible.
- The DNA strands include many tiny ‘nucleotide’ molecules. Four nitrogenous bases are adenine, guanine, cytosine, and thymine. Cytosine and thymine are pyrimidines and adenine and guanine are purines.
- A nitrogenous base, phosphoric acid, and sugar molecule form the nucleotide.
- Four types of nitrogenous bases equal four types of nucleotides.
- DNA has a chain of nucleotides. Each ladder rail is constructed of alternately connected sugar and phosphoric acid molecules, like the DNA molecule's two threads. Every ladder step is two nitrogenous bases connected by hydrogen bonds. Adenine always connects with thymine, cytosine with guanine.
Structure of DNA
DNA (Watson and Crick’s Model)
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RELATED QUESTIONS
Correct the following statement by changing the underlined word:
Nitrogen bonds are present between the complementary nitrogenous bases of DNA.
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Multiple Choice Question:
Place the following event of translation in the correct sequence
i. Binding of met-tRNA to the start codon.
ii. Covalent bonding between two amino acids.
iii. Binding of second tRNA.
iv. Joining of small and large ribosome subunits.
New nucleotides are added and a new complementary strand of DNA is formed with the help of enzyme DNA polymerase.
How is the structure of DNA organized?
Match the Column I with Column II and select the correct option.
| List-I | List-II | ||
| i. | Ribozyme | a. | Lac operon |
| ii. | Friedrich Miescher | b. | DNS as genetic material |
| iii. | Alfred Hershey and Martha Chase | c. | Catalytic RNA molecule |
| iv. | Francois-Jacob | d. | DNA is acidic substance |
Which of the following is not a component of a nucleotide?
Write the functions of DNA.
Expand the abbreviation - DNA.
