Chapter 10 Lecture Outline

Chapter 10 Lecture Outline - Biology 100 Vandan Desai...

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Biology 100 Vandan Desai 1 Chapter 10: Photosynthesis (Lecture Outline) -------------------------------------------------------------------------------------------------------------------------- When sunlight is used to manufacture carbohydrate , photosynthesis is said to occur Autotrophs (self-feeders) – photosynthetic organisms such as trees and mosses and ferns o Make their own food from ions and simple molecules Heterotrophs (different-feeders) – non-photosynthetic organisms such as humans, fungi, and the bacterium Escherichia coli o Obtain the sugars and many of the other macromolecules needed from other organisms Ecologically , photosynthesis is most important b/c no heterotrophs w/o autotrophs I. An Overview of Photosynthesis A. 6 CO 2 + 12 H 2 O + light energy → C 6 H 12 O 6 + 6 O 2 + 6 H 2 O B. Energy from light is transformed to chemical energy in C-H bonds of carbohydrates C. Photosynthesis: Two Distinct Sets of Reactions i. Van Neil’s research program a. Showed that CO 2 and H 2 O do not combine directly during photosynthesis; instead of acting as a reactant in photosynthesis, H 2 O is a product of the process b. Showed that oxygen atoms in CO 2 are not released as oxygen gas (O 2 ) ii. Oxygen atoms released during photosynthesis must come from water in the presence of sunlight iii. Melvin Calvin began feeding labeled carbon dioxide ( 14 CO 2 ) to algae and identifying the molecules that subsequently became labeled with radioisotope a. Labeled carbon dioxide became incorporated into complex organic compounds in algae in the dark b. So, photosynthesis depended on light but reduction of CO 2 did not c. Light-independent component of photosynthesis – Calvin Cycle iv. Light-dependent reactions – result in production of oxygen from water v. Light-independent reactions – result in production of sugar from CO 2 D. The Structure of Chloroplasts i. Photosynthesis only takes place in green portions of plants ii. Chloroplasts – site of photosynthesis a. Organelle is enclosed by an outer and an inner membrane b. Interior dominated by vesicle-like structures called thylakoids c. Interconnected stacks of thylakoids are called grana d. Space inside the thylakoids is lumen e. Fluid-filled space b/w thylakoids and inner membrane is stroma iii. Thylakoids membranes contain huge quantities of pigments a. Molecules that absorb only certain wavelength of light and either transmit or reflect other wavelengths b. Color we see is the wavelength that is being transmitted or reflected c. Chlorophyll – most abundant pigment found in thylakoids membranes Absorbs blue light and red light and reflects/transmits green Responsible for green color of plants, algae, & many bacteria
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Biology 100 Vandan Desai 2 II. How Does Chlorophyll Capture Light Energy? A. Photosynthesis begins with light-dependent reactions , and these reactions begin with the simple act of sunlight striking chlorophyll B. Light is a type of electromagnetic radiation, which is a form of energy i. Photosynthesis converts electromagnetic energy in form of sunlight into chemical energy in the C-H bonds of sugar ii. Light behaves like a wave and a particle a.
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This note was uploaded on 03/08/2010 for the course BIOL 100 taught by Professor Staff during the Fall '07 term at UMBC.

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Chapter 10 Lecture Outline - Biology 100 Vandan Desai...

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