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Spores of Riccia sorocarpa still associated in tetrads following meiosis. The tetrad is the four spores produced after meiosis of a yeast or other Ascomycota, Chlamydomonas or other alga, or a plant. After parent haploids mate, they produce diploids. Under appropriate environmental conditions, diploids sporulate and undergo meiosis.
In molecular biology, a guanine tetrad (also known as a G-tetrad or G-quartet) is a structure composed of four guanine bases in a square planar array. [1] [2] They most prominently contribute to the structure of G-quadruplexes, where their hydrogen bonding stabilizes the structure.
Depending on the direction of the strands or parts of a strand that form the tetrads, structures may be described as parallel or antiparallel. G-quadruplex structures can be computationally predicted from DNA or RNA sequence motifs, [ 11 ] [ 12 ] but their actual structures can be quite varied within and between the motifs, which can number ...
A homotetramer is a protein complex made up of four identical subunits which are associated but not covalently bound. [3] Conversely, a heterotetramer is a 4-subunit complex where one or more subunits differ. [4] Examples of homotetramers include: enzymes like beta-glucuronidase (pictured) export factors such as SecB from Escherichia coli [5]
(The tertiary structure of a protein consists of the way a polypeptide is formed of a complex molecular shape. This is caused by R-group interactions such as ionic and hydrogen bonds, disulphide bridges, and hydrophobic & hydrophilic interactions. Protein tertiary structure is the three-dimensional shape of a protein.
Protein before and after folding Results of protein folding. Protein folding is the physical process by which a protein, after synthesis by a ribosome as a linear chain of amino acids, changes from an unstable random coil into a more ordered three-dimensional structure. This structure permits the protein to become biologically functional. [1]
The SC protein scaffold stabilizes the physical pairing of homologous chromosomes by polymerizing between them during meiotic prophase. [2] During synapsis, autosomes are held together by the synaptonemal complex along their whole length, whereas for sex chromosomes , this only takes place at one end of each chromosome.
However, because water is a polar molecule this process of simple diffusion is relatively slow, and in tissues with high water permeability the majority of water passes through aquaporin. [ 4 ] [ 5 ] The 2003 Nobel Prize in Chemistry was awarded jointly to Peter Agre for the discovery of aquaporins [ 6 ] and Roderick MacKinnon for his work on ...