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Frataxin
Frataxin is a protein that in humans is encoded by the ''FXN'' gene. It is located in the mitochondrion and Frataxin mRNA is mostly expressed in tissues with a high metabolic rate. The function of frataxin is not clear but it is involved in assembly of iron-sulfur clusters. It has been proposed to act as either an iron chaperone or an iron storage protein. Reduced expression of frataxin is the cause of Friedreich's ataxia. Structure X-ray crystallography has shown that human frataxin consists of a β-sheet that supports a pair of parallel α-helices, forming a compact αβ sandwich. Frataxin homologues in other species are similar, sharing the same core structure. However, the frataxin tail sequences, extending from the end of one helix, diverge in sequence and differ in length. Human frataxin has a longer tail sequence than frataxin found in bacteria or yeast. It is hypothesized that the purpose of the tail is to stabilize the protein. Like most mitochondrial protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedreich's Ataxia
Friedreich's ataxia (FRDA) is a rare, inherited, autosomal recessive neurodegenerative disorder that primarily affects the nervous system, causing progressive damage to the spinal cord, peripheral nerves, and cerebellum, leading to impaired muscle coordination (''ataxia''). The condition typically manifests in childhood or adolescence, with initial symptoms including difficulty walking, loss of balance, and poor coordination. As the disease progresses, it can also impact speech, vision, and hearing. Many individuals with Friedreich's ataxia develop scoliosis, diabetes, and hypertrophic cardiomyopathy, a serious heart condition that is a leading cause of mortality in patients. Friedreich's ataxia is caused by mutations in the ''FXN'' gene, which result in reduced production of frataxin, a protein essential for mitochondrial function, particularly in iron-sulfur cluster biogenesis. The deficiency of frataxin disrupts cellular energy production and leads to oxidative stress, co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trinucleotide Repeat Expansion
A trinucleotide repeat expansion, also known as a triplet repeat expansion, is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide repeat disorder. These are labelled in dynamical genetics as dynamic mutations. Triplet expansion is caused by slippage during DNA replication, also known as "copy choice" DNA replication. Due to the repetitive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized. If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of repeats. However, if the loop out structure is formed on the parent strand, a decrease in the number of repeats occurs. It appears that expansion of these repeats is more common than reduction. Generally, the larger the expansion the more likely they are to cause disease or i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rate (mathematics)
In mathematics, a rate is the quotient of two quantities, often represented as a fraction. If the divisor (or fraction denominator) in the rate is equal to one expressed as a single unit, and if it is assumed that this quantity can be changed systematically (i.e., is an independent variable), then the dividend (the fraction numerator) of the rate expresses the corresponding rate of change in the other ( dependent) variable. In some cases, it may be regarded as a change to a value, which is caused by a change of a value in respect to another value. For example, acceleration is a change in velocity with respect to time ''Temporal rate'' is a common type of rate ("per unit of time"), such as speed, heart rate, and flux. In fact, often ''rate'' is a synonym of rhythm or frequency, a count per second (i.e., hertz); e.g., radio frequencies or sample rates. In describing the units of a rate, the word "per" is used to separate the units of the two measurements used to calculate th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligonucleotide
Oligonucleotides are short DNA or RNA molecules, oligomers, that have a wide range of applications in genetic testing, Recombinant DNA, research, and Forensic DNA, forensics. Commonly made in the laboratory by Oligonucleotide synthesis, solid-phase chemical synthesis, these small fragments of nucleic acids can be manufactured as single-stranded molecules with any user-specified sequence, and so are vital for artificial gene synthesis, polymerase chain reaction (PCR), DNA sequencing, molecular cloning and as Fluorescence in situ hybridization, molecular probes. In nature, oligonucleotides are usually found as small RNA molecules that function in the regulation of gene expression (e.g. microRNA), or are degradation intermediates derived from the breakdown of larger nucleic acid molecules. Oligonucleotides are characterized by the Nucleic acid sequence, sequence of nucleotide residues that make up the entire molecule. The length of the oligonucleotide is usually denoted by "Monomer, -m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R-loop
An R-loop is a three-stranded nucleic acid structure, composed of a DNA:RNA hybrid and the associated non-template single-stranded DNA. R-loops may be formed in a variety of circumstances and may be tolerated or cleared by cellular components. The term "R-loop" was given to reflect the similarity of these structures to D-loops; the "R" in this case represents the involvement of an RNA moiety (chemistry), moiety. In the laboratory, R-loops can be created by transcription of DNA sequences (for example those that have a high GC content) that favor annealing of the RNA behind the progressing RNA polymerase. At least 100bp of DNA:RNA hybrid is required to form a stable R-loop structure. R-loops may also be created by the Nucleic acid hybridization#Hybridization, hybridization of mature mRNA with double-stranded DNA under conditions favoring the formation of a DNA-RNA hybrid; in this case, the intron regions (which have been Splicing (genetics), spliced out of the mRNA) form single-stra ... [...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 eukaryotes and many eukaryotic 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 I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Splicing (genetics)
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcription (biology), transcript is transformed into a mature messenger RNA (Messenger RNA, mRNA). It works by removing all the introns (non-coding regions of RNA) and ''splicing'' back together exons (coding regions). For nuclear genes, nuclear-encoded genes, splicing occurs in the cell nucleus, nucleus either during or immediately after Transcription (biology), transcription. For those eukaryotic transcription, eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translation (biology), translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs). There exist self-splicing introns, that is, ribozymes that can catalyze their own excision from their parent RNA molecule. The process of transcription, spli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenetic
In biology, epigenetics is the study of changes in gene expression that happen without changes to the DNA sequence. The Greek prefix ''epi-'' (ἐπι- "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in addition to" the traditional (DNA sequence based) genetic mechanism of inheritance. Epigenetics usually involves a change that is not erased by cell division, and affects the regulation of gene expression. Such effects on cellular and physiological traits may result from environmental factors, or be part of normal development. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Further, non-coding RNA sequences have been shown to play a key role in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurodegenerative
A neurodegenerative disease is caused by the progressive loss of neurons, in the process known as neurodegeneration. Neuronal damage may also ultimately result in their death. Neurodegenerative diseases include amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple system atrophy, tauopathies, and prion diseases. Neurodegeneration can be found in the brain at many different levels of neuronal circuitry, ranging from molecular to systemic. Because there is no known way to reverse the progressive degeneration of neurons, these diseases are considered to be incurable; however research has shown that the two major contributing factors to neurodegeneration are oxidative stress and inflammation. Biomedical research has revealed many similarities between these diseases at the subcellular level, including atypical protein assemblies (like proteinopathy) and induced cell death. These similarities suggest that therapeut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics ( phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are associated with specific signs and symptoms. A disease may be caused by external factors such as pathogens or by internal dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergy, allergies, and autoimmune disorders. In humans, ''disease'' is often used more broadly to refer to any condition that causes pain, Abnormality (behavior), dysfunction, distress (medicine), distress, social problems, or death to the person affected, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injury in humans, injuries, disability, disabilities, Disorder (medicine) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species. Some yeast species have the ability to develop multicellular characteristics by forming strings of connected budding cells known as pseudohyphae or false hyphae, or quickly evolve into a Multicellular organism, multicellular cluster with specialised Organelle, cell organelles function. Yeast sizes vary greatly, depending on species and environment, typically measuring 3–4 micrometre, μm in diameter, although some yeasts can grow to 40 μm in size. Most yeasts reproduce asexual reproduction, asexually by mitosis, and many do so by the asymmetric division process known as budding. With their single-celled growth habit, yeasts can be contrasted with Mold (fungus), molds, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
