Molecular biology is a branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions.
The central dogma of molecular biology deals with the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein", although this is not its original meaning. It was first stated by Francis Crick in 1957, then published in 1958:
The Central Dogma. This states that once "information" has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information here means the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein.
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, proteins or non-coding RNA, and ultimately affect a phenotype. These products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) and small nuclear RNA (snRNA), the product is a functional non-coding RNA. The process of gene expression is used by all known life—eukaryotes, prokaryotes, and utilized by viruses—to generate the macromolecular machinery for life.
In molecular biology, RNA polymerase, or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template.
The Shine–Dalgarno (SD) sequence is a ribosomal binding site in bacterial and archaeal messenger RNA, generally located around 8 bases upstream of the start codon AUG. The RNA sequence helps recruit the ribosome to the messenger RNA (mRNA) to initiate protein synthesis by aligning the ribosome with the start codon. Once recruited, tRNA may add amino acids in sequence as dictated by the codons, moving downstream from the translational start site.
The peptidyl transferase center is an aminoacyltransferase ribozyme located in the large subunit of the ribosome. It forms peptide bonds between adjacent amino acids during the translation process of protein biosynthesis. It is also responsible for peptidyl-tRNA hydrolysis, allowing the release of the synthesized peptide chain at the end of translation. Peptidyl transferase activity is not mediated by any ribosomal proteins, but entirely by ribosomal RNA (rRNA). The peptidyl transferase center is a significant piece of evidence supporting the RNA World hypothesis.
The history of molecular biology begins in the 1930s with the convergence of various, previously distinct biological and physical disciplines: biochemistry, genetics, microbiology, virology and physics. With the hope of understanding life at its most fundamental level, numerous physicists and chemists also took an interest in what would become molecular biology.
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes.
In molecular biology, the 5.8S ribosomal RNA is a non-coding RNA component of the large subunit of the eukaryotic ribosome and so plays an important role in protein translation. It is transcribed by RNA polymerase I as part of the 45S precursor that also contains 18S and 28S rRNA. Its function is thought to be in ribosome translocation. It is also known to form covalent linkage to the p53 tumour suppressor protein. 5.8S rRNA can be used as a reference gene for miRNA detection. The 5.8S ribosomal RNA is used to better understand other rRNA processes and pathways in the cell.
In molecular biology, Small nucleolar RNA U6-53 is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.
In molecular biology, Small nucleolar RNA psi28S-3327 is a non-coding RNA (ncRNA) molecule which functions in the biogenesis (modification) of other small nuclear RNAs (snRNAs). This type of modifying RNA is located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a 'guide RNA'.
In molecular biology, Small nucleolar RNA snoR86 is a non-coding RNA (ncRNA) which modifies other small nuclear RNAs (snRNAs). It is a member of the H/ACA class of small nucleolar RNA that guide the sites of modification of uridines to pseudouridines. Plant snoR86 was identified in a screen of Arabidopsis thaliana.
In molecular biology, Small nucleolar RNA snoR98 is a non-coding RNA (ncRNA) which modifies other small nuclear RNAs (snRNAs). It is a member of the H/ACA class of small nucleolar RNA that guide the sites of modification of uridines to pseudouridines. Plant snoR98 was identified in a screen of Arabidopsis thaliana.
In molecular biology, SNORA17 is a member of the H/ACA class of small nucleolar RNA that guide the sites of modification of uridines to pseudouridines. Specifically, it is predicted to guide pseudouridylation of the 28S rRNA at positions U4659 and U4598. It shares the same host gene together with ACA43.
In molecular biology, Small nucleolar RNA SNORA48 is a pseudouridylation guide H/ACA box snoRNA. This snoRNA was cloned in 2004 from a HeLa cell extract immunoprecipitated with an anti-GAR1 antibody. It is predicted to guide the pseudouridylation of residue U3797 of 28S rRNA.
In molecular biology, Small nucleolar RNA SNORA74 (U19) belongs to the H/ACA class of snoRNAs. snoRNAs bind a number of proteins to form snoRNP complexes. This class is thought to guide the sites of modification of uridines to pseudouridines by forming direct base pairing interactions with substrate RNAs. Targets may include ribosomal and spliceosomal RNAs but the exact functions of many snoRNAs, including U19, are not confirmed. Co-precipitation of U19 snoRNA with RNase MRP RNA suggests that U19 may be involved in pre-rRNA processing.
In molecular biology, snoRNA U38 is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.
In molecular biology, Small nucleolar RNA SNORD83 is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA. snoRNA SNORD83 belongs to the C/D box class of snoRNAs which contain the conserved sequence motifs known as the C box (UGAUGA) and the D box (CUGA). Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs. snoRNA SNORD83 are spliced from introns 5 and 4 of the BAT1 gene in mammals.
In molecular biology, TBR5 is a member of the C/D class of snoRNA which contain the C (UGAUGA) and D (CUGA) box motifs. Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs.
In molecular biology, snoRNA Z17 is a non-coding RNA (ncRNA) molecule which functions in the biogenesis (modification) of other small nuclear RNAs (snRNAs). This type of modifying RNA is located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.
