Bio notes - Bio Lecture 1 What is Life 1 All life a Composed of 1 or more cells b Has growth and development c ATP based metabolism d Has

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Bio Lecture 1 What is Life? 1. All life a. Composed of 1 or more cells b. Has growth and development c. ATP based metabolism d. Has homeostasis i. The maintenance of stable internal environment e. Has DNA based heredity i. Tells how to build cells, materials and to metabolize like parents f. Sensitivity to stimuli Early Earth 1. Most agree that there was lots H 2 but no O 2 a. This made it a reducing atmosphere which favored formative of organic molecules with C-C and C-H bonds b. Lots of heat, lightening, and radiation provided energy to make organic molecules c. Problem with scenario: no O 2 meant no ozone layer and high UV would cause organics to break down 2. Some believe life may have evolved at deep sea vents a. Right reactants and conditions exist there b. Ancient bacteria live around deep sea vents Bio Lecture 2 1. 1 st unequivocal fossils are 2.5 billion years old 2. But there are 3.5 billion year old fossils; stromalolites a. Formed by colonies of cyanobacteria 3. Believed that there is now no evolution of new life forms from the inanimate a. Because life would be out-competed by existing life forms b. Today life evolves from pre-existing life 4. All life requires energy, C and H sources a. Some prokaryotes make own organic molecules= photosynthetic or chemoautotrophic b. Some use existing molecules c. The early photosynthetic organisms split H 2 S as H source and waste product was organic +S 2 d. Methanogens use H 2 and CO 2 gases and give off CH 4 i. Exist today in sewage, garbage dumps, swamps, and cow rumen 1. Methane from cows contribute to greenhouse effect ii. One type lives in 185°F water at deep sea vents with pressure 245X greater than sea level e. No early prokaryotes used or produced O 2 and none present Appearance of Aerobic Life 1. ~2.7 billion years ago a new cyanobacteria evolved from H 2 S splitters that could split H 2 O a. Both types used sunlight to split molecules b. New types evolved a more powerful photosynthesis i. Splitting H 2 O take more energy the H 2 S c. Important was the byproduct O 2 2. Dated sediments show ocean was rich in dissolved Fe +2 more than 2.7 billion years old
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a. ~2.7 billion years ago most Fe +2 began precipitating as iron oxides (rust) i. O 2 liberated by new cyanobacteria oxidized Fe +2 to Fe +3 which is insoluble in water 3. Over time oceans, then the atmosphere became O 2 enriched Prokaryotes 1. Two types of prokaryotes evolved: a. b. Comprise 2 of 3 domains of life i. 3 rd is Eukaryotes c. Includes animal, plant, fungi, protista Kingdoms 1. Bacteria spilt from common ancestor of all life about 3.5 billion years ago a. i. Many believe that archs are more closely related to euks than bac. One problem is establishing relationships is horizontal gene transfer so much gene transfer
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This note was uploaded on 04/27/2010 for the course BIO 1500 taught by Professor Maurinak during the Spring '10 term at University of Minnesota Crookston.

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Bio notes - Bio Lecture 1 What is Life 1 All life a Composed of 1 or more cells b Has growth and development c ATP based metabolism d Has

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