The key difference between DNA and chromosome is the organization of their structure. DNA is a double-stranded coiled polymer composed of deoxyribonucleotides while the chromosome is a thread like structure composed of DNA molecules tightly coiled with histone proteins.
DNA and chromosomes are two different levels of structural organizations of the genetic material. DNA is a simpler structure composed of a double helix of nucleotides. In contrast, chromosomes are complex, organized structure composed of protein and DNA folded in a specific manner. Though DNA and Chromosome differ from each other in the organization of the structures, both play a major role in determining the physical and functional properties of an organism based on the hereditary material stored.
CONTENTS
1. Overview and Key Difference
2. What is DNA
3. What is Chromosome
4. Similarities Between DNA and Chromosome
5. Side by Side Comparison – DNA vs Chromosome in Tabular Form
6. Summary
What is DNA?
DNA stands for Deoxyribo Nucleic Acid. It is the main type of nucleic acid which stores genetic information. Watson and Crick first discovered and described the structure of DNA in 1953. They described the DNA as a double helical structure. The building block of DNA is the deoxyribonucleotide. Accordingly, deoxyribonucleotide has three components; namely, a nitrogenous base that includes adenine, guanine, cytosine or thymine, a deoxyribose sugar, and a phosphate group. The two polynucleotide strands join with each other by hydrogen bonds between nucleotides and make the double helix of DNA. In the formation of hydrogen bonds, adenine pairs with thymine while cytosine pairs with guanine.
Figure 01: DNA
The sequence of nucleotides in a DNA is very important. Consequently, the order of the nucleotides determines the genetic code to produce a protein. Therefore, if any mutations take place in the DNA, they can be very harmful or very useful or may not affect at all. The primary function of DNA is to store genetic material in organisms. Hence, almost all organisms store their genetic information as DNA except for a few retroviruses which store their genetic material as RNA.
What is Chromosome?
Chromosome is a complex and well-organized structure of DNA and proteins. Due to the ease of packaging inside the nucleus, DNA folds and packs with histone proteins and makes chromosomes. Histone proteins allow the efficient folding of DNA. Only the eukaryotic DNA condenses with histone proteins to form the chromosomes. The primary structure of the chromosome formation is the nucleosome. The nucleosome further coils up to form chromatin. Finally, chromatin further coils up to form chromosomes which can be observed during cell division.
Figure 02: Chromosome
Chromosomes differ based on the cellular organization of organisms. Prokaryotes have single circular chromosomes. They are condensed with histone-like proteins. In contrast, eukaryotic chromosomes are large and linear with histone proteins. Furthermore, the number of chromosomes differs from organism to organism. In humans, there are 23 pairs of chromosome, where 22 pairs are autosomes, and the 23rd pair is the sex chromosomes.
What are the Similarities Between DNA and Chromosome?
- Both DNA and Chromosome consist of carbon, hydrogen, oxygen, and nitrogen.
- Also, both have nucleotides in their structures.
- Furthermore, they contain adenine, guanine, cytosine, and thymine nucleotides.
- Moreover, DNA and Chromosome are present in both prokaryotes and eukaryotes.
- And, both store genetic material.
What is the Difference Between DNA and Chromosome?
DNA is a macromolecule composing of deoxyribonucleotides. It stores genetic information of an organism. On the other hand, the chromosome is a thread like linear structure composing of tightly coiled DNA molecules with histone proteins. Therefore, this is the key difference between DNA and chromosome. Moreover, the building block of DNA is deoxyribonucleotides while DNA and proteins are the building blocks of the chromosome. Besides, humans have a total of 46 chromosomes in a cell while a human cell contains millions of DNA molecules.
Furthermore, another difference between DNA and chromosome is that the DNA molecules are smaller than the chromosomes. Also, a further difference between DNA and chromosome is that the DNA can be visualized by gel electrophoresis and microscopy while the chromosomes can be visualized by karyotyping and microscopy.
The below illustration shows more information on the difference between DNA and chromosome.
Summary – DNA vs Chromosome
DNA and chromosomes are important structures which regulate all the bioprocesses in a living organism. In summarizing the difference between DNA and chromosome, the DNA is the simple double helical structure composing deoxyribonucleotides. Their primary function is to store genetic material. In comparison, Chromosomes are more complex organized structures of DNA. Hence, chromosomes comprise tightly coiled DNA molecules with proteins such as histones. Moreover, they are well visible during cell division through microscopy.
Reference:
1. “What Is a Chromosome? – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health. Available here
Image Courtesy:
1.”13081113544″ by Genomics Education Programme (CC BY 2.0) via Flickr
2.”156404″ by OpenClipart-Vectors (CC0) via pixabay