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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Maxam Gilbert Sequncing - Meiosis
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Maturing face
(trans face; Golgi). The outermost membrane in a Golgi stack from where proteins processed in the Golgi exit for various cellular destinations.
Maturity onset iabetes of the young (MODY)
A rare variant of type 2 diabetes mellitus that arises due to mutations in genes involved in insulin secretion such as the glucokinase gene on chromosome7.
Maxam-Gilbert sequencing
The chemical method for determining the nucleotide sequence of DNA involving specific chemical reagents that cleaves the nucleic acid strand at one end of the four bases. The fragments generated are separated by electrophoresis and the sequence determined based on the fragment size.
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Maximum likelihood (phylogeny, alignment)
The most likely outcome (tree or alignment) given a probabilistic model of evolutionary change in DNA sequences.
Maximum parsimony
The minimum number of evolutionary steps required to generate the observed variation in a set of sequences by comparing a number of steps in all possible phylogenetic trees.
MBP vector
An expression vector used for the purification of proteins expressed via the vector. The gene to be expressed is fused to the gene coding for the maltose binding protein (MBP) and the fusion protein purified by column chromatography.
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Mc Ardle’s disease (glycogen storage disease type V)
An uncommon, autosomal recessive, glycogen storage disease that arises due to a deficiency of myophosphorylase. The disease shows a male preponderance with symptoms of pain, cramps and myoglobinuria following strenuous exercise. Glycogen content is abnormally elevated in muscle and serum creating kinase is increased. Blood lactate fails to increase after ischaemic exercise test. Avoidance of strenuous muscular exercise is recommended.
McClintock, Barbara
(1902-1992) A geneticist awarded the Nobel Prize in Medicine in 1983 for her pioneering work on transposable elements (jumping genes) in maize. Originally called controlling elements, the mobile genetic elements were later identified as transposons. The transposons play an important role in generation of genetic diversity. They are used as gene delivery systems and for gene mapping.
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Mcm proteins
Proteins that bind to origin recognition complexes in eukaryotic DNA during early G1. These proteins are involved in the formation of the pre-replication complex.
MDA
1. Multiple drop array. See microdroplet array. 2. malondialdehyde, one of the end products of free radical-induced lipid peroxidation.
MDR protein
See multidrug resistance protein.
Mean
In statistics, the arithmetic average; the sum of all measurements or values in a sample divided by the sample size.
Media
See culture medium; medium.
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Median
An average that divides a distribution into two halves when the given values are arranged in as ascending/descending order.
Median effective dose (ED50)
The dose of a drug predicted by statistical techniques to produce a characteristic effect in 50 per cent of the subjects to whom the dose is administered. It is the most frequently used standardised dose by means of which the potencies of drugs are compared.
Mediator
A protein complex that mediates interaction between the activator protein, RNA polymerase and general transcription factors during eukaryotic transcription.
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Medical bioinformatics
Linking clinical data to patient gene profiling. This includes haplotyping, genotyping, population genomics, gene expression profiling, for use in diagnosis, prognosis and therapeutic stratification of patients.
Medium
(pl: media). A term used in tissue culture for the liquid or solidified formulation upon which cells, tissues or organs develop. See culture medium.
Medium formulation
In tissue culture, the specific formula for the culture medium. It commonly contains macroelements and microelements (high and low salt), vitamins, growth regulators, a carbohydrate source (sucrose of glucose), substances such as amino acids or complex growth factors. Media may be liquid or solidified with agar. The pH is adjusted to 5-6 and the solution is sterilised by filtration or autoclaving. While some media formulations are specific for the kind of cells or tissues that can be maintained, others are very general.
Mega (M)
SI prefix, 106.
Megabase (Mb)
Unit of length for DNA fragments equal to 1 million nucleotides and approximately equivalent 1cM. 106 bp of DNA.
Megabase cloning
The cloning of very large DNA fragments. See cloning.
Megabecquerel (SI unit, MBq)
106Bq or 27.027 μCi.
Megadalton (MDa)
106 daltons. See dalton.
Megakaryocyte
A large myeloid cell with a Multilobed nucleus that remains in the bone marrow. It buds off platelets from cytoplasmic processes.
Megaloblast
A large, nucleated immature immature precursor of abnormal erythrocytes.
Megaloblastic anaemia
A condition characterised by low red blood cell count and large, immature, nucleated cells (megaloblasts) in the blood.
Meiosis
The process of cell division of diploid cells (2n) to form haploid (n) cells. In the first division, homologous chromosomes crossover and recombine, exchanging genetic material before moving away from each other into separate daughter nuclei (reduction division). These new nuclei divide by mitosis to produce for haploid nuclei. The products of meiosis mature to form germ cells. Meiosis is an important source of variability through recombination.
Meiotic product(s)
See Gametes.
MEK
An intermediate in the ras signal transduction pathway. Phosphorylation of MEK by raf activates MEK which in turn phosphorylates a MAP kinase.
Melanin
Pigment produced by specialised epidermal cells called melanocytes. This pigment is responsible for sin colour.
Melanocytes
A cell that produces melanin which is responsible for the pigmentation of the skin and hair.
Melanoma
a malignant tumour derived from cells that synthesise melanin.
Mello, Craig
An American scientist who was awarded the 2006 Nobel Prize in Physiology or Medicine together with Andrew Fire for elucidating the mechanism of RNA interference and gene silencing by double-stranded RNA which as important implications in biology and medicine.
Melting
The breakage of hydrogen bonds holding double-strand DNA together by heating. Melting converts double-stranded DNA to the single-stranded state. Also called denaturation.
Melting temperature (Tm)
The temperature at which the two strands of a DNA or a DNA-RNA molecule separate into single strands (denature). It is the midpoint of the temperature range over which DNA is denatured. It is characteristic of each DNA species and gives an indication of its base composition. DNA preparations rich in G:C base pairs are more resistant denaturation that A:T rich DNA because there are three hydrogen bonds between G and C, but only two between A and T.
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- Dictionary of Bioinformatics, Biotechnology, Biochemistry Part 4
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