Regulation of energy metabolism can occur at the gene level, where enzymes needed for energy metabolic pathways are either transcribed, or their transcription inhibited. A well-studied example is the Lac Operon which can be seen in E. coli bacteria. The Lac Operon is characterized by an operator which is essentially an on/off switch that controls […]
Three sequences of nucleotides called a codon on the mRNA code for amino acids. There are 64 codons. Sixty-one of them code for amino acids including AUG which is a start codon corresponding to methionine. Three codons are referred to as STOP codons. Stop codons terminate translation of mRNA. The stop codons are UGA, UAA, […]
The DNA contains the code for making all proteins. In order for proteins to be synthesized, the code on the DNA for making the protein of interest must be transcribed. Imagine trying to make a cake (the protein) that you have never made before. Consider that the book with the recipe is in a rare […]
Mechanical digestion of protein starts in the mouth with the break down of protein into smaller pieces aided by the biting and crushing action of teeth. Protein then travels to the stomach via the esophagus where chemical digestion starts. Cells lining the stomach secretes hydrochloric acid (HCL) and pepsinogen, a proenzyme into the stomach. Cells […]
The word gluconeogenesis means the creation (genesis) of glucose from new (neo) sources. Under normal circumstances, carbohydrates are broken down to release glucose. However, under special circumstances such as limited availability of carbohydrates, other molecules such as fatty acids, amino acids and pyruvate are converted to glucose. This is important for humans, as we store […]
During periods of fasting the pancreas secretes the hormone glucagon which tells the liver cells to breakdown glucose into its individual glucose molecules. Epinephrine, another hormone tells the muscle cells to do the same thing. Steps in Glycogenolysis Glycogen phosphorylase cleaves α (1, 4) bonds at the non-reducing ends of glucose chains and catalyze transfer […]
