Consider the following statements : 1. DNA is much larger than RNA with millions of nucleotides. 2. DNA is self-replicating, unlike RNA. 3. DNA is synthesized from RNA. Which of the following statements given above is/are correct?
Consider the following statements : 1. DNA is much larger than RNA with millions of nucleotides. 2. DNA is self-replicating, unlike RNA. 3. DNA is synthesized from RNA. Which of the following statements given above is/are correct? Correct Answer 1 and 2 only
The correct answer is 1 and 2 only.
Key Points
- A DNA molecule in a human chromosome can be up to 250 million nucleotide pairs long; in contrast, most RNAs are no more than a few thousand nucleotides long, and many are considerably shorter. Hence, statement 1 is correct.
- DNA is a self-replicating molecule where its component parts, nucleotides, have specific chemical interactions that allow for the design of self-assembled structures. Hence, statement 2 is correct.
- RNA is synthesized from a portion of one strand of DNA, which acts as a template. Hence, statement 3 is not correct.
- This process is called transcription.
- All RNA molecules are derived from the information permanently stored in DNA except the RNA genome of certain viruses.
Additional Information
- Humans have 46 chromosomes that contain all of the genetic information, and there are over 25,000 genes in the human genome.
- Genes are composed of DNA and it is predicted that there are over 3 billion base pairs in the human genome.
- DNA (deoxyribonucleic acid) is the genomic material in cells that contains the genetic information used in the development and functioning of all known living organisms.
- DNA, along with RNA and proteins, is one of the three major macromolecules that are essential for life.
- Most of the DNA is located in the nucleus, although a small amount can be found in mitochondria (mitochondrial DNA).
- Within the nucleus of eukaryotic cells, DNA is organized into structures called chromosomes.
- The complete set of chromosomes in a cell makes up its genome; the human genome has approximately 3 billion base pairs of DNA arranged into 46 chromosomes.
- The information carried by DNA is held in the sequence of pieces of DNA called genes.
- DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds.
- These two strands run in opposite directions to each other and are therefore anti-parallel.
- Attached to each sugar is one of four types of molecules called nucleobases (bases).
- It is the sequence of these four bases along the backbone that encodes information.
- The sequence of these bases comprises the genetic code, which subsequently specifies the sequence of the amino acids within proteins.
- Ribonucleic acid(RNA) is a molecule similar to DNA.
- An RNA strand has a backbone made of alternating sugar (ribose) and phosphate groups.
- Attached to each sugar is one of four bases--adenine (A), uracil (U), cytosine (C), or guanine (G).
- Different types of RNA exist in the cell: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).
- The chemical structure of RNA is very similar to that of DNA: each nucleotide consists of a nucleobase a ribose sugar, and a phosphate group.
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Differences between DNA and RNA:
| DNA | RNA |
| DNA is usually double-stranded, has two separate strands that are connected | RNA molecules are single-stranded and can adopt very complex three-dimensional structures. |
| DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom) | RNA contains the sugar ribose |
| DNA is much larger than RNA with millions of nucleotides. | RNA is smaller with hundreds of nucleotides. |
| DNA is self-replicating. | RNA is synthesized from DNA. |
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Feb 20, 2025