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Transcription—A molecular view

By: HWC, Views: 3329

Transcription, as related to genomics, is the process of making an RNA copy of a gene's DNA sequence. This copy, called messenger RNA (mRNA), carries the gene's protein information encoded in DNA. During transcription, a DNA molecule is copied into RNA molecules that are then used to translate...

Major Elements in Biological Molecules: Proteins

By: HWC, Views: 7156

Proteins are chains of amino acids linked by peptide bonds. The 20 different amino acids used to make all proteins differ only in their side chains, and the properties of these side chains account for the great diversity of protein structure and function. Collagen is an example of how a prote...

Gastrin (gastric emptying) & Secretin (buffering gastric acid)

By: HWC, Views: 7261

• Gastrin also binds to the smooth muscle cells in the stomach causing: • Increased gastric motility. • Opening of pyloric sphincter. • Increased gastric emptying. • The intestinal phase of digestion begins as chyme enters the duodenum. • The chyme's acidity can damage int...

DNA Replication Factory and Protein

By: HWC, Views: 7255

DNA (deoxyribose nucleic acid) carries all the genetic information needed to re-create itself and to pass on the characteristics of the organism. The “factory” model of DNA replication hypothesizes a specific nuclear structure in which the molecular machinery for replication forks are brou...

Digestive chemicals - types & enzymes

By: HWC, Views: 7725

• Chemical digestion breaks down food as it moves through the digestive tract. • Using enzymes and other digestive chemicals, the process reduces food particles into nutrient molecules that can be absorbed. • Most chemical digestion is done by the actions of digestive enzymes. • O...

Secondary and tertiary levels of protein structure Animation

By: HWC, Views: 1659

Amino acid sequence dictates a protein's final shape. The presence of certain amino acids favors a pattern of hydrogen bonding that causes part of the polypeptide chain to coil and twist into an alpha helix. The presence of other amino acids enables hydrogen bonding between strand like re...

Miller's reaction chamber experiment Animation

By: HWC, Views: 1320

A simple diagram of Stanley Miller and Harold Urey's experimental apparatus. The lower portion of the apparatus was filled with water. The upper portion was filled with a mixture of gases that simulated the earth's early atmosphere. Examples are methane, ammonia, hydrogen and carbon dioxide. ...

Stomach peristalsis & Enterogastric reflex

By: HWC, Views: 7155

• Food enters, distending the stomach. • Stretch receptors activate enteric reflexes that promote peristaltic movements. • These movements, called mixing waves, begin to mix the food with stomach secretions. • Mixing waves force the digesting food (chyme) toward and through the pylo...

Role of the urinary system - acidosis and alkalosis

By: HWC, Views: 7966

• Tubular cells of the proximal convoluted tubule and collecting tubules can alter filtrate pH and therefore blood pH. • These cells can affect blood pH with two coupled mechanisms: • Reabsorption of bicarbonate ions. • Secretion of hydrogen ions. • The reabsorption of bicarbonate...