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Winter Term -Week 1 Lecture Notes

5 Pages

Course Code
BIOL 103
Virginia K Walker

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Jan 6-12 1. Nutrition and Digestion Autotrophs • organisms which harvest light or chemical energy and stores it in carbon compounds Heterotrophs • organisms which must get complex nutrients from the environment through consuming other organisms • i.e. bread mould uses extracellular digestion Extracellular Digestion • fungi can get nutrients from dead, or alive organic matter and can even take the form of predators (athlete’s foot, mould and nematode, respectively). Therefore, fungi can be parasitic or predatory. Intracellular Digestion • i.e. Protozoa: simple ,singe cell • through phagocytosis, the organic compound/food go into the food vacuole and is digested within the cell • any undigested material is released through exocytosis Homework: know parts of digestive system • humans do not have the enzymes to break down plant material (i.e. cellulase) Cecum • pouch containing microorganisms which break down and digest cellulose • found between small and large intestine • in herbivores, the cecum is quite large (ex. horses) • rabbits eat their “night feces” the next morning to ensure maximum nutrient absorption from their food Homework: read about ruminants, pg 917 Milk • took a plasmid and inserted it with met, leu and lys • plasmid was inserted into the bacteria, so it produces cellulose and a milk protein high in those three amino acids Digestion in the Mouth • the conversion of complex organic molecules to simple ones • ex. digestive enzymes o produced in salivary gland o contains salivary amylase: breaks down starch o ~1 liter produced a day o purpose of saliva is to moisten food and begin digestion AND defensive functions iclicker o optimum PH for salivary amylase is 7 • tsetse fly o had salivary gland even though they were bloo-feeders o scientists discovered that after taking it out, the fly died after a duration of time o concluded that the salivary gland produced/contained an anticoagulant Homework: read about crops, the gizzard and the stomach (pg. 916-17) Digestion in the Stomach • contains gastric juices: HCL and pepsin. Pepsin is active in the stomach • optimum PH for HCL is 2 • pepsin is an enzyme important for hydrolyzing proteins • peptide bonds occur between the C from one amino acid, and N from the other after water is taken out (2 H’s from the amino acid with N and 1 O from the amino acid with C) • sequence of amino acids: ala-his-gly-try-thr-lys-his-ser-arg-gly-asp-his-thr-gly-gly-phe … o begins with amino terminal (left) and ends with carboxyl terminal (right) o ala-his-gly o tyr – thr-lys … • Gastric glands from cells of the stomach lining produce pepsin in an inactive form, pepsinogen, which means cells in the stomach don’t
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