5.3.1.2. Messenger RNA

Messenger RNA

The messenger RNA (mRNA) is single stranded, linear basically. It only constitutes 2-5% of the total RNA.

The function of mRNA is to take the information from the DNA, which is in the nucleus, and take it to the cytoplasm, where the ribosomes are where the proteins will be synthesized with the amino acids provided by the tRNAs.

_mRNA is formed from a strand of DNA in a process called transcription. With the complementary nitrogenous bases, a template is created with the genetic information necessary for protein synthesis. The size of the mRNA depends on the size of the protein for which it carries information. After performing their function, protein synthesis, ribonuclease enzymes destroy it to prevent unnecessary protein production. When the synthesis of a particular protein is needed again, new mRNA will be created.

The information contained in the mRNA is presented in a sequence of nitrogenous bases, grouped in triplets or codons, each of which determines the binding of a certain amino acid.

The mRNA has a different structure in prokaryotes and in eukaryotes.

By The original uploader was Sverdrup at English Wikipedia (Transferred from en.wikipedia to Commons.) [Public domain], via Wikimedia Commons

mARN in eukaryotes

The messenger RNA obtained after transcription is known as primary transcribed RNA or precursor RNA or pre-RNA, which in most cases is not released from the transcription complex in a fully active form, but must undergo modifications before exerting its function (RNA processing or maturation). Among these modifications are the elimination of fragments ( splicing ), the addition of other non-coding in the DNA and the covalent modification of certain nitrogenous bases.

Eukaryotic mRNA is formed from primary transcribed RNA (pre-mRNA), which is made up of two types of alternating segments:

Exons, segments with information.
Introns, segments without information that will be deleted and do not appear in the mRNA.

The maturation of the RNA primary transcript to mRNA occurs in the nucleus, and is in the process when lost introns.

By Qef [Public domain], via Wikimedia Commons

Eukaryotic mRNA has a cap at its 5' end, formed by a nucleotide derived from guanine, which gives stability to the mRNA and allows access to the ribosome for protein synthesis. Then there is a segment without information, followed by another segment with information that usually begins with the bases A-U-G.

At the 3' end, about 200 adenine nucleotides appear, the so-called poly-A "tail", which stabilizes the molecule against exonuclease enzymes.

Eukaryotic mRNA is monocistronic, that is, it only contains information to synthesize one polypeptide chain.

mRNA in prokaryotes

The transcription and translation processes are carried out in a similar way as in eukaryotic cells. The fundamental difference is that, in prokaryotes, the messenger RNA does not undergo a maturation process and, therefore, no cap or tail is added to it or introns are removed. Also, it does not have to leave the nucleus as in eukaryotes, because in prokaryotic cells there is no defined nucleus.

The mRNA in prokaryotes is polycistronic, it contains separate information to synthesize different proteins.

Fundamental ideas about messenger RNA

Messenger RNA:

MRNA is to take the information from the DNA (transcription), which is in the nucleus, and take it to the cytoplasm, where the ribosomes will carry out the protein synthesis with the amino acids provided by the tRNAs.
Differences of mRNA in prokaryotic and eukaryotic cells:
- In eukaryotic cells:
  - mRNA needs maturation. Following transcription is obtained RNA primary transcript or precursor RNA or pre-mRNA, comprises:
    - Exons: segments with information.
    - Introns: segments with no information that are suppressed and do not appear in mature mRNA.
  - MRNA is monocistronic.
- In prokaryotic cells:
  - mRNA does not need maturation.
  - mRNA is polycistronic.

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Skip navigation Biology 2nd Baccalaureate Biology 2nd Bac. 1. Bioelements and biomolecules. Water and mineral salts 1.1. Chemical bonds in biology 1.1.1. Intramolecular bonds 1.1.1.1. Covalent bond 1.1.1.2. Ionic bond 1.1.2. Intermolecular bonds 1.1.2.1. Van der Waals forces 1.1.2.2. Hydrogen bonds 1.2. The chemical basis of life: inorganic and organic components 1.2.1. Primary bioelements 1.2.2. Secondary bioelements 1.2.3. Trace elements 1.3. The immediate principles or biomolecules 1.3.1. Water 1.3.1.1. Chemical structure of water 1.3.1.2. Properties and functions of water 1.3.2. Mineral salts 1.3.2.1. Functions of salts in solution 1.3.2.2. Colloidal solutions and dispersions 1.3.2.3. Properties of colloidal dispersions 1.3.2.4. Diffusion, osmosis and dialysis 1.3.2.4.1. Diffusion 1.3.2.4.2. Osmosis 1.3.2.4.3. Dialysis 1.4. Bibliography 2. Glucides 2.1. Glucid concept 2.2. Classification of carbohydrates 2.3. Monosaccharides 2.3.1. Trioses 2.3.1.1. Spatial isomerism or stereoisomerism 2.3.2. Tetroses 2.3.3. Pentoses 2.3.3.1. Monosaccharide cyclization 2.3.4. Hexoses 2.4. The N-glucosidic and O-glucosidic bonds 2.4.1. Substances derived from monosaccharides 2.5. Disaccharides 2.6. Polysaccharides 2.6.1. Homopolysaccharides 2.6.1.1. Reserve homopolysaccharides 2.6.1.2. Structural homopolysaccharides 2.6.2. Heteropolysaccharides 2.6.3. Heterosides 2.7. General functions of glucides 2.8. Bibliography 3. Lipids 3.1. Lipid concept 3.2. Classification of lipids 3.2.1. Fatty acids 3.2.1.1. Saturated and unsaturated fatty acids 3.2.1.2. Chemical properties of fatty acids 3.2.1.3. Physical properties of fatty acids 3.2.1.4. Fatty Acid Functions 3.2.2. Saponifiable lipids or with fatty acids 3.2.2.1. Simple lipids 3.2.2.1.1. Acylglycerides 3.2.2.1.2. Cerides 3.2.2.2. Complex lipids 3.2.2.2.1. Phospholipids 3.2.2.2.2. Glycolipids 3.2.3. Unsaponifiable lipids or without fatty acids 3.3. Lipid functions 3.4. Bibliography 4. Proteins 4.1. Introduction to proteins 4.2. Amino acids 4.2.1. Classification of amino acids 4.2.2. Properties of amino acids 4.3. The peptide bond 4.4. Protein 4.4.1. Protein structure 4.4.1.1. Primary structure of proteins 4.4.1.2. Secondary structure of proteins 4.4.1.3. Tertiary structure of proteins 4.4.1.4. Quaternary structure of proteins 4.4.2. Protein properties 4.4.3. Classification of proteins 4.4.3.1. Holoproteins 4.4.3.2. Heteroproteins 4.4.4. Protein functions 4.5. Enzymes 4.5.1. Structure of enzymes 4.5.2. The active center of enzymes 4.5.3. General Mechanism of Enzyme Catalysis 4.5.4. Regulation of enzyme activity 4.5.5. Allosteric enzymes 4.5.6. Nomenclature and classification of enzymes 4.6. The vitamins 4.6.1. Fat-soluble vitamins 4.6.2. Water soluble vitamins 4.7. Bibliography 5. Nucleotides and nucleic acids 5.1. The chemical composition of nucleic acids 5.1.1. Components of nucleic acids 5.1.2. Concept, types and functions of nucleic acids 5.1.3. Nucleosides 5.1.4. Nucleotides 5.1.4.1. Nucleotide functions 5.1.5. Nucleic acids 5.2. Deoxyribonucleic acid (DNA) 5.2.1. DNA structure 5.2.1.1. Primary structure of DNA 5.2.1.2. Secondary structure of DNA 5.2.1.3. Tertiary structure of DNA 5.2.1.3.1. Tertiary structure of DNA in prokaryotes 5.2.1.3.2. Tertiary structure of DNA in eukaryotes 5.2.1.4. Quaternary structure of DNA 5.2.2. DNA types 5.2.3. Genetic material: chromatin and chromosomes 5.2.3.1. Karyotype and karyogram 5.3. Ribonucleic acid (RNA) 5.3.1. RNA types 5.3.1.1. Transfer RNA 5.3.1.2. Messenger RNA 5.3.1.3. Ribosomal RNA 5.3.1.4. Nucleolar RNA 5.3.1.5. Small nuclear RNA 5.3.2. Functions of ribonucleic acids 5.4. Bibliography 6. Cell morphology 6.1. Cell concept 6.1.1. Cell history 6.1.2. Cell theory 6.2. Levels of cellular organization 6.2.1. General characteristics of cells 6.2.2. Prokaryotic cells 6.2.2.1. Prokaryotic cell morphology 6.2.2.2. Structure of prokaryotes 6.2.2.2.1. Bacterial capsule 6.2.2.2.2. Bacterial wall 6.2.2.2.3. Plasma membrane 6.2.2.2.4. Cytoplasm-Ribosomes-Inclusions 6.2.2.2.5. Bacterial DNA 6.2.2.2.6. Bacterial appendages 6.2.2.3. Bacteria Physiology 6.2.3. Eukaryotic cells 6.2.3.1. Animal and plant cell 6.2.3.1.1. Animal eukaryotic cell 6.2.3.1.2. Plant eukaryotic cell 6.2.3.2. Cell Evolution: Endosymbiont Theory 6.3. Size, shape and quantity 6.4. The plasma membrane 6.4.1. Chemical composition of the membrane 6.4.2. The structure of the membrane. The fluid mosaic model 6.4.3. Functions of the plasma membrane 6.4.4. Transport across the membrane 6.4.4.1. Small molecule transport 6.4.4.2. Macromolecule transport 6.4.5. Plasma membrane differentiations 6.5. The cell wall of plant cells 6.5.1. Chemical composition of the cell wall 6.5.2. Cell wall structure 6.5.3. Cell wall differentiations 6.5.4. Cell wall functions 6.6. Extracellular matrix or glucocalyx 6.7. Cytosol or hyaloplasm 6.8. The cytoskeleton 6.8.1. Microfilaments or actin filaments 6.8.2. Intermediate filaments 6.8.3. Microtubules 6.9. Cell membrane and organelle systems 6.9.1. Membrane systems 6.9.1.1. The endoplasmic reticulum 6.9.1.2. Golgi apparatus 6.9.2. Cell organelles 6.9.2.1. Lysosomes 6.9.2.2. Peroxisomes 6.9.2.3. Vacuoles 6.9.2.4. Mitochondria 6.9.2.4.1. Functions of the mitochondria 6.9.2.5. Plastids 6.9.2.5.1. Chloroplasts 6.9.2.6. Ribosomes 6.9.2.7. Centrosome 6.9.2.8. Cilia and flagella 6.10. Cell motility 6.11. The cell nucleus 6.11.1. Characteristics of the cell nucleus 6.11.2. The interphase nucleus 6.11.3. The mitotic nucleus or nucleus in division 6.12. Bibliography 7. Metabolism 7.1. Metabolism 7.1.1. Energetic Aspects of Cellular Chemical Reactions 7.2. Catabolism 7.2.1. Catabolism and obtaining energy 7.2.2. Carbohydrate catabolism 7.2.2.1. Glycolysis 7.2.2.2. Cellular respiration 7.2.2.2.1. Oxidative decarboxylation 7.2.2.2.2. Krebs cycle 7.2.2.2.3. Electron transport chain 7.2.2.2.4. Energy balance of cellular respiration 7.2.2.3. Fermentations 7.2.2.3.1. Alcoholic or ethyl fermentation 7.2.2.3.2. Lactic fermentation 7.2.2.3.3. Other types of fermentations 7.3. Anabolism 7.3.1. Autotrophic anabolism 7.3.2. Photosynthesis 7.3.2.1. Photochemical or light phase 7.3.2.1.1. Photosystems 7.3.2.1.2. Photophosphorylation 7.3.2.1.2.1. Non cyclic photophosphorylation 7.3.2.1.2.2. Cyclic photophosphorylation 7.3.2.2. Biosynthetic or dark phase 7.3.2.3. Factors influencing photosynthesis 7.3.2.4. Products of photosynthesis 7.3.3. Chemosynthesis 7.4. Bibliography 8. Cell reproduction 8.1. The cell cycle 8.1.1. Interphase 8.1.2. Cellular division 8.2. Cellular division 8.2.1. Mitosis 8.2.1.1. Prophase 8.2.1.2. Metaphase 8.2.1.3. Anaphase 8.2.1.4. Telophase 8.2.1.5. Cytokinesis 8.2.1.6. More on mitosis 8.2.2. Meiosis 8.2.2.1. Meiosis I 8.2.2.2. Meiosis II 8.2.3. Meiosis and sexual reproduction 8.2.4. Meiosis and life cycle 8.2.5. Biological importance of meiosis 8.3. Differences and similarities between mitosis and meiosis 8.4. Bibliography 9. Classical genetics 9.1. Genetics basics 9.2. Mendelian genetics 9.2.1. The method 9.2.2. Mendel's Laws 9.2.2.1. Mendel's first law or principle of uniformity in the first generation 9.2.2.2. Mendel's second law or principle of segregation 9.2.2.2.1. Backcross and test crossover 9.2.2.3. Mendel's third law or principle of independent combination 9.3. Gene interaction 9.3.1. Gene interaction between allelic genes 9.3.2. Gene interaction between non-allelic genes that influence for the same trait 9.4. Chromosomal theory of heredity 9.5. Ligation and recombination 9.6. Complex mendelism 9.6.1. Multiple allelism 9.6.1.1. Lethal genes 9.6.2. Pleiotropy 9.6.3. Expressiveness and genetic penetrance 9.7. Sex-linked inheritance 9.7.1. Y-linked inheritance 9.7.2. X-linked inheritance 9.8. Heredity influenced by sex 9.9. Bibliography 10. Molecular genetics 10.1. DNA as hereditary material 10.2. DNA replication 10.2.1. The need for DNA replication 10.2.2. First hypotheses about DNA duplication 10.2.3. Meselson and Stahl experiment 10.2.4. The sense of growth of the new strands 10.2.5. Mechanism of DNA replication 10.2.5.1. Replication in prokaryotes 10.2.5.2. Replication in eukaryotes 10.2.6. Error correction 10.2.7. Enzymes involved in replication 10.3. Gene concept 10.4. "One gene-one enzyme" theory 10.5. Transcription 10.5.1. Mechanism of transcription 10.5.1.1. Transcription in prokaryotes 10.5.1.2. Eukaryotic transcription 10.6. Translation or protein biosynthesis 10.6.1. The genetic code 10.6.2. Mechanism of translation of RNA to proteins 10.6.2.1. Translation in eukaryotes 10.7. Regulation of gene expression 10.8. Bibliography 11. Genetics and evolution 11.1. Mutations 11.2. Types of mutations 11.2.1. Gene or point mutation 11.2.2. Chromosomal or structural mutation 11.2.3. Mutation at the genomic level 11.3. Causes of mutations 11.4. Evolutionary implications of mutations 11.5. Metabolic implications of mutations 11.6. Bibliography 12. Microbiology and biotechnology 12.1. Microbiology 12.2. Viruses 12.2.1. Viral morphology 12.2.2. Viral physiology 12.2.2.1. Lytic cycle 12.2.2.2. Lysogenic cycle 12.2.2.3. Cycles of viruses of special interest 12.2.2.3.1. Flu virus life cycle 12.2.2.3.2. Life cycle of the AIDS virus 12.3. Other acellular forms 12.3.1. Viroids 12.3.2. Prions 12.4. Biotechnology 12.5. Bibliography 13. Immunology 13.1. Infection concept 13.2. Defense mechanisms against infections 13.2.1. Nonspecific mechanisms 13.2.1.1. Primary barriers: external defenses 13.2.1.2. Secondary barriers: internal defenses 13.2.2. Specific mechanisms 13.3. Immunity and immune system 13.3.1. Components of the immune system 13.3.2. Concept and nature of antigens 13.4. The immune response 13.4.1. Humoral immune response: the antibodies 13.4.1.1. Antibody-producing cells: B lymphocytes 13.4.1.2. Antibodies 13.4.1.2.1. Types of antibodies 13.4.1.2.2. Antigen-antibody reaction 13.4.1.3. Immune memory: primary and secondary responses 13.4.2. Cellular immune response: T lymphocytes 13.5. Types of immunity 13.5.1. Natural immunity 13.5.2. Artificial immunity 13.6. Immune system disorders 13.6.1. Autoimmunity 13.6.2. Hypersensitivity 13.6.3. Immunodeficiency 13.6.4. Transplants and the phenomenon of rejections 13.7. Bibliography « Previous \| Next » 5.3.1.2. Messenger RNA Messenger RNA The messenger RNA (mRNA) is single stranded, linear basically. It only constitutes 2-5% of the total RNA. The function of mRNA is to take the information from the DNA, which is in the nucleus, and take it to the cytoplasm, where the ribosomes are where the proteins will be synthesized with the amino acids provided by the tRNAs. _mRNA is formed from a strand of DNA in a process called transcription. With the complementary nitrogenous bases, a template is created with the genetic information necessary for protein synthesis. The size of the mRNA depends on the size of the protein for which it carries information. After performing their function, protein synthesis, ribonuclease enzymes destroy it to prevent unnecessary protein production. When the synthesis of a particular protein is needed again, new mRNA will be created. The information contained in the mRNA is presented in a sequence of nitrogenous bases, grouped in triplets or codons, each of which determines the binding of a certain amino acid. The mRNA has a different structure in prokaryotes and in eukaryotes. By The original uploader was Sverdrup at English Wikipedia (Transferred from en.wikipedia to Commons.) [Public domain], via Wikimedia Commons mARN in eukaryotes The messenger RNA obtained after transcription is known as primary transcribed RNA or precursor RNA or pre-RNA, which in most cases is not released from the transcription complex in a fully active form, but must undergo modifications before exerting its function (RNA processing or maturation). Among these modifications are the elimination of fragments ( splicing ), the addition of other non-coding in the DNA and the covalent modification of certain nitrogenous bases. Eukaryotic mRNA is formed from primary transcribed RNA (pre-mRNA), which is made up of two types of alternating segments: Exons, segments with information. Introns, segments without information that will be deleted and do not appear in the mRNA. The maturation of the RNA primary transcript to mRNA occurs in the nucleus, and is in the process when lost introns. By Qef [Public domain], via Wikimedia Commons Eukaryotic mRNA has a cap at its 5' end, formed by a nucleotide derived from guanine, which gives stability to the mRNA and allows access to the ribosome for protein synthesis. Then there is a segment without information, followed by another segment with information that usually begins with the bases A-U-G. At the 3' end, about 200 adenine nucleotides appear, the so-called poly-A "tail", which stabilizes the molecule against exonuclease enzymes. Eukaryotic mRNA is monocistronic, that is, it only contains information to synthesize one polypeptide chain. mRNA in prokaryotes The transcription and translation processes are carried out in a similar way as in eukaryotic cells. The fundamental difference is that, in prokaryotes, the messenger RNA does not undergo a maturation process and, therefore, no cap or tail is added to it or introns are removed. Also, it does not have to leave the nucleus as in eukaryotes, because in prokaryotic cells there is no defined nucleus. The mRNA in prokaryotes is polycistronic, it contains separate information to synthesize different proteins. Fundamental ideas about messenger RNA Messenger RNA: MRNA is to take the information from the DNA (transcription), which is in the nucleus, and take it to the cytoplasm, where the ribosomes will carry out the protein synthesis with the amino acids provided by the tRNAs. Differences of mRNA in prokaryotic and eukaryotic cells: In eukaryotic cells: mRNA needs maturation. Following transcription is obtained RNA primary transcript or precursor RNA or pre-mRNA, comprises: Exons: segments with information. Introns: segments with no information that are suppressed and do not appear in mature mRNA. MRNA is monocistronic. In prokaryotic cells: mRNA does not need maturation. mRNA is polycistronic. Licensed under the Creative Commons Attribution Share Alike License 4.0 « Previous \| Next » These pages are semi-automatically translated from the web Biology 2nd Baccalaureate. Biología de 2º de Bachillerato (biologia-geologia.com). You can make any suggestion, question, comment, ..., in our forum 2º Bachillerato Biología - Foro de biologia-geologia.com
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Messenger RNA

mARN in eukaryotes

mRNA in prokaryotes