Question 18 (3 points) Several differences between DNA and RNA allow the cell to differentiate between the two
molecules, ensuring that transcription and translation occur appropriately. Which is one of the
properties of RNA that differentiates it from DNA?
A. RNA includes phosphate groups instead of nitrogenous groups.
B. RNA is double stranded instead of single stranded.
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C. RNA contains uracil (U) instead of thymine (1).
D. RNA contains cytosine (C) instead of guanine (G).
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Explanation:

Comparison

DNA

RNA

Full Name

Deoxyribonucleic Acid 

Ribonucleic Acid

Function

DNA replicates and stores genetic information. It is a blueprint for all genetic information contained within an organism

RNA converts the genetic information contained within DNA to a format used to build proteins, and then moves it to ribosomal protein factories. 

Structure

DNA consists of two strands, arranged in a double helix. These strands are made up of subunits called nucleotides. Each nucleotide contains a phosphate, a 5-carbon sugar molecule and a nitrogenous base.

RNA only has one strand, but like DNA, is made up of nucleotides. RNA strands are shorter than DNA strands. RNA sometimes forms a secondary double helix structure, but only intermittently. 

Length

DNA is a much longer polymer than RNA. A chromosome, for example, is a single, long DNA molecule, which would be several centimetres in length when unravelled.

RNA molecules are variable in length, but much shorter than long DNA polymers. A large RNA molecule might only be a few thousand base pairs long. 

Sugar

The sugar in DNA is deoxyribose, which contains one less hydroxyl group than RNA’s ribose. 

RNA contains ribose sugar molecules, without the hydroxyl modifications of deoxyribose.

Bases

The bases in DNA are Adenine (‘A’), Thymine (‘T’), Guanine (‘G’) and Cytosine (‘C’).

RNA shares Adenine (‘A’), Guanine (‘G’) and Cytosine (‘C’) with DNA, but contains Uracil (‘U’) rather than Thymine.

Base Pairs

Adenine and Thymine pair (A-T)

Cytosine and Guanine pair (C-G)  

Adenine and Uracil pair (A-U)

Cytosine and Guanine pair (C-G)        

Location

DNA is found in the nucleus, with a small amount of DNA also present in mitochondria.

RNA forms in the nucleolus, and then moves to specialised regions of the cytoplasm depending on the type of RNA formed. 

ReactivityDue to its deoxyribose sugar, which contains one less oxygen-containing hydroxyl group, DNA is a more stable molecule than RNA, which is useful for a molecule which has the task of keeping genetic information safe.RNA, containing a ribose sugar, is more reactive than DNA and is not stable in alkaline conditions. RNA’s larger helical grooves mean it is more easily subject to attack by enzymes.Ultraviolet (UV) SensitivityDNA is vulnerable to damage by ultraviolet light. RNA is more resistant to damage from UV light than DNA.