A base-pair substitution is the replacement of one nucleotide and its partner with another pair of nucleotides. Some substitutions are called silent mutations because, owing to the redundancy of the genetic code, they have no effect on the encoded protein. In other words, a change in a base pair may […]

Gregor Mendel used pea plants to study heredity in a series of experiments. Mendel worked by carefully observing and recording traits in successive generations of plants. Knowledge about DNA and chromosomes came later. This lab will apply genetic laws to human inheritance using Punnett squares. Recall that DNA is wound […]

Biology: Visual System Actions for ‘5. Visual System’ Subscribe Hide Description It’s easy to get swamped in details about the visual system. (This animation may help.) Discuss the visual pathways that originate in the retina and “ascend” to the visual cortex via the thalamus. In this week’s resources the retina […]

1. Phenylketonuria-Individuals with this disorder are unable to produce the enzyme responsible for the conversion of the amino acid phenylalanine to the amino acid tyrosine. Because tyrosine is needed in the production of melanin, PKU sufferers are very blond and fair -skinned. Phenylalanine is present in protein and in the […]