Many crystal structures of DNA are in an A-DNA form. Identified at the same time as B-DNA by Rosalind Franklin, A-DNA is an alternative DNA structure that often appears when the molecule is dehydrated. Z-DNA is thought to play a role in regulating gene expression and may be produced in the wake of DNA processing enzymes, like DNA polymerase. Canonical, “classic” DNA is called B-DNA. While the structure of DNA you will see above – and in any biology textbook you might care to open – has a right-handed helix, DNA molecules with left-handed helices also exist. Other forms of both DNA and RNA exist that subvert the classical structures of these nucleic acids. The structure we have described in this article is certainly the most common form of DNA, but it isn’t the whole story. Other cytoplasmic ribosomes are bound to the endoplasmic reticulum, a membranous structure that helps process proteins and export them from the cell 5. Ribosomes are formed in an area of the nucleus called the nucleolus, before being exported to the cytoplasm, where some ribosomes float freely. rRNA, as previously mentioned, is found as part of ribosomes. If it receives the correct signal from the ribosome, it will then hunt down amino acid subunits in the cytoplasm and bring them to the ribosome to be built into proteins 5. tRNA, like mRNA, is a free-roaming molecule that moves around the cytoplasm. The fragments are then shuttled around the cell as needed, moved along by the cell’s internal transport system, the cytoskeleton. ![]() mRNA is made in the nucleus, with each mRNA fragment copied from its relative piece of DNA, before leaving the nucleus and entering the cytoplasm. The three types of RNA are found in different locations. We can identify five key categories where DNA and RNA differ: What are the key differences between DNA and RNA? RNA is more resistant to damage from UV light than DNA. RNA’s larger helical grooves mean it is more easily subject to attack by enzymes.ĭNA is vulnerable to damage by ultraviolet light. RNA, containing a ribose sugar, is more reactive than DNA and is not stable in alkaline conditions. RNA forms in the nucleolus, and then moves to specialised regions of the cytoplasm depending on the type of RNA formed.ĭue 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 shares Adenine (‘A’), Guanine (‘G’) and Cytosine (‘C’) with DNA, but contains Uracil (‘U’) rather than Thymine.Īdenine and Thymine pair (A-T) Cytosine and Guanine pair (C-G)Īdenine and Uracil pair (A-U) Cytosine and Guanine pair (C-G)ĭNA is found in the nucleus, with a small amount of DNA also present in mitochondria. The bases in DNA are Adenine (‘A’), Thymine (‘T’), Guanine (‘G’) and Cytosine (‘C’). RNA contains ribose sugar molecules, without the hydroxyl modifications of deoxyribose. The sugar in DNA is deoxyribose, which contains one less hydroxyl group than RNA’s ribose. A large RNA molecule might only be a few thousand base pairs long. RNA molecules are variable in length, but much shorter than long DNA polymers. A chromosome, for example, is a single, long DNA molecule, which would be several centimetres in length when unravelled. RNA sometimes forms a secondary double helix structure, but only intermittently.ĭNA is a much longer polymer than RNA. RNA strands are shorter than DNA strands. RNA only has one strand, but like DNA, is made up of nucleotides. Each nucleotide contains a phosphate, a 5-carbon sugar molecule and a nitrogenous base. ![]() These strands are made up of subunits called nucleotides. RNA converts the genetic information contained within DNA to a format used to build proteins, and then moves it to ribosomal protein factories.ĭNA consists of two strands, arranged in a double helix. It is a blueprint for all genetic information contained within an organism. RNA – A comparison chartĭNA replicates and stores genetic information. These include the two molecules’ functions, their structure, their average length, the sugar (DNA contains deoxyribose and RNA contains ribose) and base molecules (RNA contains uracil rather than thymine) they contain, their location and their reactivity to enzymes and ultraviolet light. There are several differences that separate DNA from RNA.
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