Bacterial cells can take up the amino acid tryptophan (Trp) from their surroundings, or, if there is an insufficient external supply, they can synthesize tryptophan from other small molecules. The trp repressor is a bacterial gene regulatory protein that represses the transcription of genes that code for the enzymes required […]

Niremberg used the enzyme polynuclotide phosphorylase to assemble RNA with random sequences in the absence of a template. Suppose they added the enzyme to a solution of 90% GTP and 10% UTP, and then used the cell-free system of protein synthesis to make peptides according to the sequences in their […]

The free energy for the oxidation of glucose to co2 and water is-686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as twelve NADH could be formed. […]

1) The Drosophila alleleby determines the mutant phenotype blistery wings and thewild type allele by+ determines normal wings.At another gene, the allele ss determines the mutantphenotype spineless bristles and the wild type alleless+ determines spiny bristles. A female flythat is heterozygous for both genes is crossed with a male that […]