Chapter 10 Photosynthesis I. Photosynthesis – when sunlight is used to manufacture carbohydrate a. Autotrophs – organisms that make all of their own food from ions and simple molecules. i.e. plants b. Heterotrophs – non-photosynthetic organisms such as humans and fungi and the bacterium E. coli who obtain the sugars and other macromolecules they need from other organisms c. CO 2 + 2H 2 0 + light energy = (CH 2 O) n + H 2 0 + O 2, energy from light is transformed to chemical energy in the C-H bonds of carbohydrates. d. Van Neil’s purple sulfur bacteria experiment proves that CO 2 and H 2 0 do not combine directly and that O 2 is not released from photosynthesis. i. O 2 comes from H 20 e. Calvin cycle – the light-independent component of photosynthesis] i. Reduce carbon dioxide and result in the production of sugar ii. Takes place in the stroma of chloroplasts f. Electrons released during the formation of O 2 are transferred to NADP+ and form NADPH and ATP. g. The reactions during the Calvin Cycle use the electrons from NADPH and potential energy from ATP to reduce CO 2 to carbohydrate. II. Chloroplast a. Thylakoids – vesicle-like structures which often contain interconnected stacks called grana, found on the interior of the chloroplast b. Lumen – the space inside of thylakoid c. Stroma – fluid filled space between the thyladkoids and the inner membrane. d. Thylakoid membranes are abundant in pigments i. Pigments are molecules that absorb only certain wavelengths of light – other wavelengths are transmitted or reflected. ii. Chlorophyll is the most abundant pigment found in the thylakoid membrane, it absorbs blue and red light and reflects green light. e. Proplastids – the colorless organelles from which chloroplasts are derived i. Plastids are a family of double membrane-bound organelles found in plants. 1. 3 major types of plastids a. Chloroplasts i. Responsible for photosynthesis b. Leucoplasts i. Often function are energy storehouses c. Chromoplasts i. Are brightly colored because they synthesize and hoard large amounts of orange, yellow or red pigments in their vacuoles. f. Electromagnetic energy in the form of sunlight is converted into chemical energy in the C-H bonds of sugar
i. Wavelength – the distance between two successive wave crests, determines the type of electromagnetic radiation. Shorter wave lengths contain more energy ii. Electromagnetic spectrum – the range of wavelengths 1. visible light – electromagnetic radiation that humans can see 400 to 710 nm
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