Single base mutations

F4. Filosa, S., Cai, W., Galanello, R., Cao, A., De Mattia, D Schettini, F., and Martini, G., A novel single-base mutation in the glucose 6-phosphate dehydrogenase gene is associated with chronic non-spherocytic haemolytic anaemia. Hum. Genet. 94,560-562 (1994),... 

K19. Kashi, H Mukai, T., Hirono, A., Fujii, H., Miwa, S and Hori, K Human aldolase A deficiency associated with a hemolytic anemia Thermolabile aldolase due to a single base mutation. Proc. Natl. Acad. Sci. U.S.A. 84,8623-8627 (1987). 

Obviously, if there is even a single base mutation in the target DNA, the... 

Because approximately 2/3 of all mutations leading to these diseases are insertions or deletions, differences in single-base mutations (i.e., mis-sense or nonsense mutations) would not be the most likely explanation, excluding choice C and choice . 

Zhang, Y, Coyne, M.Y, WUl, S.G., Levenson, C.H., and Kawasaki, E.S., Single-base mutational analysis of cancer and genetic diseases using membrane bound modified oligonucleotides. Nucleic Acid Res., 19(14), 3929-3933, 1991. 

Tapprich WE, Dahlberg AE (1990) A single base mutation at position 2,661 in E. coli 23S ribosomal RNA affects the binding of ternary complex to the ribosome. EMBO J 9 2649—2655 Tarun Jr SZ, Sachs AB (1996) Association of the yeast poly(A) tail binding protein with translation initiation factor eIE-4G. EMBO J 15 7168-7177... 

Table 5.15. Effects of Some Hypothetical Single-Base Mutations on the Biological Activity of the...

A single-base mutation resulting in an amino-acid change that may not alter the biological activity of the protein because the amino-acid replacement is in a noncriticai position and also resembles the normal amino-acid also a silent mutation... 

A lethal single-base mutation in which a serine residue essential for enzyme activity is replaced by phenylalanine to give an enzymatically inactive product... 

Molecular defects that give rise to dysfibrinogenemias are commonly caused by single base mutations that lead to the substitution of a single amino acid. Other mutations can give rise to a stop codon, resulting in a... 

More selective detection of single-base mutations can be achieved by replacing a nudeobase with a fluorophore (Figure 4.2.6). We envisaged that this forced intercalation of fluorophores or fluorescent base surrogates should enable the detection... 

One of the main motivations of using synthetic DNA for cellular engineering seems to be at odds with the random nature of directed evolution. Traditionally, PCR-based methods have been used to create sequence diversity, inspired by the fact that mutations in nature commonly arise from errors in DNA replication. PCR-based methods are preferred when there is no prior knowledge about where mutations are likely to influence the traits of interest, but are limited in that the sequence diversity that results is restricted and biased. With single base mutations per codon - a common assumption with most protocols - only 5.7 amino acids are accessible per position on average, and in most cases, the resulting set of amino acids does not accurately represent the spectrum of physicochemical properties of naturally-occurring residues [76]. 

The simplest change that can be made in a protein is the replacement of a single amino acid, usually by a single-base mutation in its gene. Such a change may influence the pharmacological characteristics or the production efficiency of a protein drug. Several such proteins, sometimes referred to as luteins , have been constructed successfully. 

Most of the mutations shown result in a missense effect, with a different amino acid being incorporated into the same site in a protein. This may or may not have an effect depending upon its location. Some single-base mutations are harmless because of the degeneracy of the genetic code, whereby more than one triplet code exists for all amino acids except tryptophan and methionine. Choice a contains two mutations, one degenerate and the other missense. 

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