Chapter 17 lecture

Chapter 17 lecture - Chapter 17: Gene to protein What is...

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Unformatted text preview: Chapter 17: Gene to protein What is genetic information? Sequence #1: Life is beautiful Sequence #2: Leaves are green What is genetic information? Sequence of four nucleotides in a DNA strand. There are ____ types of nucleotides. They are ___, ___, ___, ____. Cytosine (C), Thymine (T) Pyrimidines Adenine (A), Guanine (G) Purines Gene expression Genes determine traits. Different alleles result in different phenotypes. Gene expression The bridge between genotypes and phenotypes is proteins . Gene alleles Traits Proteins are made of sequences of amino acids. Proteins serve many biological functions inside cells. Albino phenotype is caused by a deficiency in one enzyme that catalyzes one step of a series of chemical reaction to synthesize a pigment protein, melanin. The gene that encodes for this enzyme resides on chromosome II in humans. Fig. 5-22 Primary structure Secondary and tertiary structures Quaternary structure Normal hemoglobin (top view) Primary structure Secondary and tertiary structures Quaternary structure Function Function Beta subunit Molecules do not associate with one another; each carries oxygen. Red blood cell shape Normal red blood cells are full of individual hemoglobin moledules, each carrying oxygen. 10 m Normal hemoglobin 1 2 3 4 5 6 7 Val His Leu Thr Pro Glu Glu Red blood cell shape Beta subunit Exposed hydrophobic region Sickle-cell hemoglobin Molecules interact with one another and crystallize into a fiber; capacity to carry oxygen is greatly reduced. Fibers of abnormal hemoglobin deform red blood cell into sickle shape. 10 m Sickle-cell hemoglobin Glu Pro Thr Leu His Val Val 1 2 3 4 5 6 7 Sickle-Cell Disease: A Change in Primary Structure Current hypothesis One gene one polypeptide Why not one enzyme? Why not one protein? Gene expression Gene expression , the process by which DNA directs protein synthesis, includes two stages: transcription and translation. The central dogma of biology RNA is the intermediate between genes and the proteins for which they code. Transcription is the synthesis of RNA under the direction of DNA....
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Chapter 17 lecture - Chapter 17: Gene to protein What is...

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