|
Sphinx (gene)
In molecular biology, ''Sphinx'' (''spx'') is a long non-coding RNA found in ''Drosophila''. It is expressed in the brain, within the antennal lobe and inner antennocerebral tract. It is involved in the regulation of male courtship behaviour, this may be via olfactory neuron mediated regulation. Sphinx may act as a negative regulator of target genes. It is a chimeric gene, originating from a retroposed sequence of the ATP synthase chain F gene from chromosome 2 to chromosome 4. Nearby sequences were recruited to form an intron and an exon of this chimeric gene. See also * Long noncoding RNA Long non-coding RNAs (long ncRNAs, lncRNA) are a type of RNA, generally defined as transcripts more than 200 nucleotides that are not translated into protein. This arbitrary limit distinguishes long ncRNAs from small non-coding RNAs, such as mic ... References {{reflist Non-coding RNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Biology
Molecular biology is the 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 study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retroposon
Retroposons are repetitive DNA fragments which are inserted into chromosomes after they had been reverse transcribed from any RNA molecule. Difference between retroposons and retrotransposons In contrast to retrotransposons, retroposons never encode reverse transcriptase (RT) (but see below). Therefore, they are non-autonomous elements with regard to transposition activity (as opposed to transposons). Non-long terminal repeat (LTR) retrotransposons such as the human LINE1 elements are sometimes falsely referred to as retroposons. However, this depends on the author. For example, Howard Temin published the following definition: Retroposons encode RT but are devoid of long terminal repeats (LTRs), for example long interspersed elements (LINEs). Retrotransposons also feature LTRs and retroviruses, in addition, are packaged as viral particles (virions). Retrosequences are non-autonomous elements devoid of RT. They are retroposed with the aid of the machinery of autonomous element ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the exome. History The term ''exon'' derives from the expressed region and was coined by American biochemist Walter Gilbert in 1978: "The notion of the cistron… must be replaced by that of a transcription unit containing regions which will be lost from the mature messengerwhich I suggest we call introns (for intragenic regions)alternating with regions which will be expressedexons." This definition was originally made for protein-coding transcripts that are spliced before being translated. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intron
An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e. a region inside a gene."The notion of the cistron .e., gene... must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger – which I suggest we call introns (for intragenic regions) – alternating with regions which will be expressed – exons." (Gilbert 1978) The term ''intron'' refers to both the DNA sequence within a gene and the corresponding RNA sequence in RNA transcripts. The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. Introns are found in the genes of most organisms and many viruses and they can be located in both protein-coding genes and genes that function as RNA (noncoding genes). There are four main types of introns: tRNA introns, group I introns, group II introns, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 4
Chromosome 4 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 4 spans more than 186 million base pairs (the building material of DNA) and represents between 6 and 6.5 percent of the total DNA in cells. Genomics The chromosome is ~191 megabases in length. In a 2012 paper, 775 protein-encoding genes were identified on this chromosome.Chen LC, Liu MY, Hsiao YC, Choong WK, Wu HY, Hsu WL, Liao PC, Sung TY, Tsai SF, Yu JS, Chen YJ (2012) Decoding the disease-associated proteins encoded in the human chromosome 4. J Proteome Res 211 (27.9%) of these coding sequences did not have any experimental evidence at the protein level, in 2012. 271 appear to be membrane proteins. 54 have been classified as cancer-associated proteins. Genes Number of genes The following are some of the gene count estimates of human chromosome 4. Because researchers use different approaches to genome annotation their predictions of the number of genes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 2
Chromosome 2 is one of the twenty-three pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second-largest human chromosome, spanning more than 242 million base pairs and representing almost eight percent of the total DNA in human cells. Chromosome 2 contains the HOXD homeobox gene cluster. Chromosomes Humans have only twenty-three pairs of chromosomes, while all other extant members of Hominidae have twenty-four pairs. It is believed that Neanderthals and Denisovans had twenty-three pairs. Human chromosome 2 is a result of an end-to-end fusion of two ancestral chromosomes.It has been hypothesized that Human Chromosome 2 is a fusion of two ancestral chromosomes by Alec MacAndrew; accessed 18 May 2006.< ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and 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 noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP Synthase
ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). It is classified under ligases as it changes ADP by the formation of P-O bond (phosphodiester bond). ATP synthase is a molecular machine. The overall reaction catalyzed by ATP synthase is: * ADP + Pi + 2H+out ATP + H2O + 2H+in The formation of ATP from ADP and Pi is energetically unfavorable and would normally proceed in the reverse direction. In order to drive this reaction forward, ATP synthase couples ATP synthesis during cellular respiration to an electrochemical gradient created by the difference in proton (H+) concentration across the inner mitochondrial membrane in eukaryotes or the plasma membrane in bacteria. During photosynthesis in plants, ATP is synthesized by ATP synthase using a proton gradient created in the thylakoid lumen through the thylakoid membrane and into the chloroplast stro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimeric Gene
Chimeric genes (literally, made of parts from different sources) form through the combination of portions of two or more coding sequences to produce new genes. These mutations are distinct from fusion genes which merge whole gene sequences into a single reading frame and often retain their original functions. Formation Chimeric genes can form through several different means. Many chimeric genes form through errors in DNA replication or DNA repair so that pieces of two different genes are inadvertently combined.Rogers, RL, Bedford, T and Hartl DL. "Formation and Longevity of Chimeric and Duplicat Genes in ''Drosphila''". ''Genetics''. 181: 313-322. Chimeric genes can also form through retrotransposition where a retrotransposon accidentally copies the transcript of a gene and inserts it into the genome in a new location. Depending on where the new retrogene appears, it can recruit new exons to produce a chimeric gene. Finally, ectopic recombination, when there is an exchange ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Non-coding RNA
Long non-coding RNAs (long ncRNAs, lncRNA) are a type of RNA, generally defined as transcripts more than 200 nucleotides that are not translated into protein. This arbitrary limit distinguishes long ncRNAs from small non-coding RNAs, such as microRNAs (miRNAs), small interfering RNAs (siRNAs), Piwi-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs), and other short RNAs. Long intervening/intergenic noncoding RNAs (lincRNAs) are sequences of lncRNA which do not overlap protein-coding genes. Long non-coding RNAs include intergenic lincRNAs, intronic ncRNAs, and sense and antisense lncRNAs, each type showing different genomic positions in relation to genes and exons. Abundance In 2007 a study found only one-fifth of transcription across the human genome is associated with protein-coding genes, indicating at least four times more long non-coding than coding RNA sequences. Large-scale complementary DNA (cDNA) sequencing projects such as FANTOM reveal the complexity of this t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regulation Of Gene Expression
Regulation of gene expression, or gene regulation, includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA). Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from Transcriptional regulation, transcriptional initiation, to RNA processing, and to the post-translational modification of a protein. Often, one gene regulator controls another, and so on, in a gene regulatory network. Gene regulation is essential for viruses, prokaryotes and eukaryotes as it increases the versatility and adaptability of an organism by allowing the cell to express protein when needed. Although as early as 1951, Barbara McClintock showed interaction between two genetic loci, Activator (''Ac'') and Dissociator (''Ds''), in the color f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is a compact structure, and the axon and dend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
