How do rna and dna differ in structure and function

The molecules also differ in their functions. DNA serves as the master blueprint of proteins for the cell, while the various forms of RNA serve multiple purposes including helping protein synthesis and serving some enzymatic functions. Rogan T.

Sep 22, In terms of structure the key differences are: A different sugar molecule occurs on the backbone of the molecule. However, both can occur in either form. Purine and Pyrimidine bases are equal in number. There is no proportionality in between the number of Purine and Pyrimidine bases. DNA is susceptible to UV damage. Hydrogen bonds are formed between complementary nitrogen bases of the opposite strands A-T, C-G.

Base pairing through hydrogen bonds, occurs in the coiled parts. DNA is found in the nucleus of a cell and in mitochondria. The small grooves in the helix also serve as protection, providing minimal space for enzymes to attach. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels. Facebook Facebook Twitter Twitter. Updated February 02, Used to transfer the genetic code from the nucleus to the ribosomes to make proteins.

RNA is used to transmit genetic information in some organisms and may have been the molecule used to store genetic blueprints in primitive organisms. Structural Features B-form double helix. DNA is a double-stranded molecule consisting of a long chain of nucleotides. A-form helix. RNA usually is a single-strand helix consisting of shorter chains of nucleotides.

Composition of Bases and Sugars deoxyribose sugar phosphate backbone adenine, guanine, cytosine, thymine bases ribose sugar phosphate backbone adenine, guanine, cytosine, uracil bases Propagation DNA is self-replicating. The small grooves in the helix also serve as protection, providing minimal space for enzymes to attach.

RNA is not stable under alkaline conditions, plus the large grooves in the molecule make it susceptible to enzyme attack. Several specific cases have been shown to be involved in transcriptional gene silencing, and the activation of critical regulators of development and differentiation: these exerted their regulatory roles by interfering with transcription factors or their co-activators, though direct action on DNA duplex, by regulating adjacent protein-coding gene expression, by mediating DNA epigenetic modifications, etc.

This is known to occur in the case of retroviruses, such as HIV, as well as in eukaryotes, in the case of retrotransposons and telomere synthesis. Post-transcriptional modification is a process in cell biology by which, primary transcript RNA is converted into mature RNA. This process is vital for the correct translation of the genomes of eukaryotes as the human primary RNA transcript that is produced as a result of transcription contains both exons, which are coding sections of the primary RNA transcript and introns, which are the non coding sections of the primary RNA transcript.

The cap and tail protect the mRNA from enzyme degradation and aid its attachment to the ribosome. In addition, iii introns non-coding sequences are spliced out of the mRNA and exons coding sequences are spliced together. The mature mRNA transcript will then undergo translation A protein is a molecule that performs reactions necessary to sustain the life of an organism. One cell can contain thousands of proteins. Following transcription, translation is the next step of protein biosynthesis.

In translation, mRNA produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or a polypeptide, that will later fold into a protein. Ribosomes read mRNA sequence in a ticker tape fashion three bases at a time, inserting the appropriate amino acid encoded by each three-base code word or codon into the appropriate position of the growing protein chain.

This process is called mRNA translation. Each amino acid is encoded by a sequence of three successive bases. Some specialized codons serve as punctuation points during translation. The methionine codon AUG , serves as the initiator codon signaling the first amino acid to be incorporated. All proteins thus begin with a methionine residue, but this is often removed later in the translational process.

The completed polypeptide chain then folds into a functional three-dimensional protein molecule and is transferred to other organelles for further processing or released into cytosol for association of the newly completed chain with other subunits to form complex multimeric proteins.

Protein translation. Post-translational modification is the chemical modification of a peptide that takes place after its translation. They represent one of the later steps in protein biosynthesis for many proteins. During protein synthesis, 20 different amino acids can be incorporated in order to form a polypeptide. In addition, enzymes may remove amino acids from the amino end of the protein, or even cut the peptide chain in the middle.

This amino acid is usually taken off during post-translational modification. Other modifications, like phosphorylation, are part of common mechanisms for controlling the behavior of a protein, for instance activating or inactivating an enzyme. See also: Inside a cell external link. Home Learn! DNA 1. DNA transcription 1.

Regions of DNA in the human genome, ranging from 0. Approximately half of all gene promoters have CpG islands that when methylated lead to transcriptional silencing. Aberrant DNA methylation patterns have been described in various human malignancies.

In particular, global hupomethylation has been implicated in the earlier stages of carcinogenesis, whereas hypermethylation of tumour suppressor genes has been implicated in cancer progression 3. DNA hypomethylating agents are used for the treatment of certain haematological malignancies. Histone modifications: Histones are proteins around which DNA winds to form nucleosomes.

Nucleosome is the basic unit of DNA packaging within the nucleus and consists of base pairs of genomic DNA wrapped twice around a highly conserved histone octamer, consisting of 2 copies each of the core histones H2A, H2B, H3 and H4.

The histone tails may undergo many posttranslational chemical modifications, such as acetylation, methylation, phosphorylation, ubiquitylation, and sumoylation. Histone modifications act except for chromatin condention and transcriptional repression in various other biological processes including gene activation and DNA repair 4.

Epigenetic Modifications 2. Untranslated regions: Untranslated regions UTRs are nucleotide stretches that flank the coding region and are not translated into amino acids. These regions are part of the primary transcript and remain after the splicing of exons into the mRNA. As such UTRs are exonic regions. Several functional roles have been attributed to the untranslated regions, including mRNA stability, mRNA localization, and translational efficiency.

Coding regions begin with the start codon and end with a stop codon. This tail promotes export from the nucleus, translation, and stability of mRNA 13 , The structure of an mRNA 3. RNA interference in mammalian cells Designer siRNAs are now widely used in the laboratory to down-regulate specific proteins whose function is under study.

Non protein coding RNAs a. More than one thousand miRNAs are currently known for the human genome, and each of them has the ability to down regulate the expression of possibly thousands of protein coding genes Alternative pathways non-canonical Drosha independent pathways: As mentioned above, most miRNAs either originate form their own transcription units or derive from the exons or introns of other genes 33 and require both Drosha and Dicer for cleavage in their maturation.

It was recently shown however first in Droshophila 33 and later in mammals 34 that short hairpin introns, called mirtrons can be alternative sources of miRNAs. Although there are several differences between mammalian and invertebrate mirtrons, both are Drosha independent.

Mirtrons are short introns with hairpin potential that can be spliced and debranched into pre-miRNA mimics and then enter the canonical pathway. Importantly, the Ago catalytic function for the miR biogenesis was shown in Ago2 homozygous mutants that were found to have loss of miR and died shortly after their birth with anemia