BIO 101- CH 8 MATERIAL

photoautotrophs

organisms capable of producing their own organic compounds from sunlight

heterotrophs

consume organic substances or other organisms for food

chemoautotrophs

organisms that can build organic molecules using energy derived from inorganic chemicals

photosynthesis requires

• specific wavelength of visible light

• carbon dioxide

• water

mesophyll

middle layer of chlorophyll-rich cells in a leaf

stomata

opening that regulates gas exchange and water evaporation

chloroplast

membrane-bound organelle that contains chlorophyll where photosynthesis takes place

• have double membrane

• contain thylakoids

thylakoids

disc-shaped membrane bound structure inside chloroplast where light dependent reactions take place

thylakoid lumen

liquid filled space bound by thylakoid membrane

granum

stack of thylakoid membranes

pigment

molecule that absorbs certain light wavelengths and reflects others

chloroplasts and the endosymbiotic theory

theory that chloroplasts evolved in plant cells, cyanobacteria were engulfed by other cells and performed photosynthesis

2 parts of photosynthesis

light independent and dependent reactions

light-dependent reactions

first stage of photosynthesis where certain wavelengths of visible light are absorbed to form ATP and NADPH

• use energy carriers to temporarily store energy

light-independent reactions

second stage of photosynthesis through which carbon dioxide is used to build carbohydrate molecules using energy from ATP and NADPH (calvin cycle)

electromagnetic spectrum

range of all possible frequencies of radiation

chloropyll A

absorbs violet blue and red light, has bluish green color. gets excited and loses electron to ETC

chlorophyll B

absorbs blue and red orange light

carotenoids

photosynthetic pigments that function to dispose excess energy

photosystem

group of proteins, chlorophyll and other pigments that are used in light-independent reactions to absorb light energy and convert it to chemical energy

2 systems in embedded in thylakoid membranes

photosystem II: integral pigment and protein complex that transports electrons from water to the ETC, oxygen is the product

photosystem I

uses light energy to transport electrons

light harvesting complex

complex that passes energy from sunlight to reaction center

reaction center

complex of chlorophyll molecules and other organic molecules that is assembled around special pair of chlorophyll molecules and a primary electron acceptor

photoact (in light dependent reactions)

ejection of an electron from a reaction center using the energy of an absorbed photon

cytochrome complex

group of reversibly oxidizable and reducible proteins that forms part of ETC between PSII and PSI

primary electron acceptor

pigment or other organic molecule in the reaction center that accepts an energized electron from the reaction center

chemiosmosis

ions go through channel ATP synthase, allows ATP synthase to attach third phosphate group to ATP to form it. called chemiosmosis because ions move from high concentration to low through thylakoid

photosynthesis summary

• pigments absorb sunlight in form of photons

• energy travels to reaction center that has chlorophyl A and goes to ETC, which pumps hydrogen ions into thylakoid

• high hydrogen concentration inside thylakoid flow through ATP synthase during chemiosmosis to form ATP

• ATP used to form sugar molecules in second stage of photosynthesis

• PSI absorbs second photon which forms NADPH

calvin cycle

light independent reactions of photosynthesis that convert carbon dioxide from the atmosphere into carbohydrates using the energy and reducing power of ATP and NADPH.

3 main stages of the calvin cycle

• fixation

• reduction

• regeneration

fixation

CO2,Rubisco, and Rubp initiate light independent reactions

carbon fixation

process of converting inorganic CO2 gas into organic compounds

reduction

6 3-PGAs converts to 6 G3Ps. 3-PGA gain of electrons by an atom or molecule. Each PGA requires 1 phosphate group from an ATP. NADP+ and phosphate as byproducts

regeneration

one G3P leaves to make glucose, Rubp is regenerated

evolution of photosynthesis

earlier process has one photosystem and did not use NADPH or produce oxygen

summary of calvin cycle

• use energy carriers ATP and NADPH to take in CO2 from the atmosphere

• rubisco catalyzes a reaction of CO2 and Rubp

• after 3 cycles one G3P leaves to be part of a carbohydrate molecule

• the remaining G3Ps regenerate to continue the cycle