(part I) concept 10.3: the light reactions convert solar energy to the chemical energy of ATP and NADPH

wavelength

a measure of the distance between crests of electromagnetic waves

what determines the type of electromagnetic energy

the wavelength

what is light

electromagnetic readiation

around what wavelength is visible light

380- 740

what is light made of

photons

what is unique about photons

has a fixed quantity of energy related to the wavelength, short wavelength= more energy

pigments

substances that absorb visible light

what differentiates pigments

different pigments absorb different wavelengths and the wavelengths that are not absorbed are relfected or transmitted

what are the three different types of pigments in chloroplasts

Chlorophyll A

Chlorophyll B

carotenoids

what is a spectrometer

measures a pigments ability to absorb various wavelengths by sending light through pigments and measuring the amount of light transmitted at each wavelength

chlorophyll A

the key light capturing pigment, the main photosynthetic pigment

chlorophyll B

an accessory pigment

carotenoids

other accessory pigments

an absorption spectrum

a graph plotting a pigments light absorption versus wavelength

what light works best for photosynthesis for chlorophyll A

violet blue and red light

what light works best for photosynthesis for chlorophyll B

blue and orange light

what does an action spectrum provide

the relative effectiveness of different wavelengths of radiation in driving a process

Theodor W Engelmann

first demonstrated the action spectrum of photosynthesis

describe the experiment carried out by Theodor W Engelmann

he exposed different segments of a filamentous algae to different wavelengths of light and the areas that received wavelengths favorable to photosynthesis produced O2. he used the growth of aerobic bacteria clustered along the algae as a measure of O2 production

what is the difference between chlorophyll A and B

they have different absorption spectrums due to a slight difference between pigment molecules and different in their functional groups

what is the chemical equation for chlorophyll A

CH3

what is the chemical equation for chlorophyll B

CHO

what do accessory pigments do

broaden the spectrum used for photosynthesis

what do carotenoids do

absorb excessive light that would damage the chlorophyll by oxidizing the oxygen

what are the two new forms of chlorophyll that have been discovered recently

chlorophyll d and chlorophyll f

what does chlorophyll d and f do

absorb higher wavelengths of light and some organisms need to use them in place of chlorophyll a in shaded conditions

what happens when chlorophyll gets excited

when a pigment absorbs light one electrons goes from a ground state to an excited state, which is unstable

what is a photosystem

consists of a reaction-center complex, a type of protein complex surrounded by light harvesting complexes

what is consisting of the reaction center complex

an association of proteins holding a special pair of chlorophyll A molecules and a primary electron acceptor

what is consisting of the light- harvesting complexes

pigment molecules bound to proteins

what do the light- harvesting complexes do

transfer the energy of photons to the chlorophyll A molecules in the reaction center complex

what is unique about the chlorophyll A molecules that are in the reaction center complex

they are able to transfer an excited electron to a different molecule

what happens after a primary electron acceptor in the reaction center accepts excited electrons

the eletron is reduced

what are the two different types of photosystems in the thylakoid membrane

photosystem II and photosystem I

how are photosystem I and II numbered

in order of discovery

Photosystem II

its reaction center chlorophyll A is best at absorbing light with a wavelength of 680 nm

another name for photosystem II

P 680

photosystem I

reaction center chlorophyll A is best at absorbing light with a wavelength of 700 nm

another name for photosystem I

P 700

why do photosystem I and II accept different wavelengths better

because of their association with different proteins