Light and Photosynthesis Flashcards
theory for the evolution of photosynthesis
theory of endosymbiosis
endosymbiosis theory explained
- photosynthetic cyanobacterium enters simple non photosynthetic eukaryote
- turns into chloroplast
- evolves into green algae
4.evolves into plants
properties of light with plants
-Plants sense light with photosynthetic pigments, phytochrome, and blue light receptors
* Light affects many aspects of plant life, including stomatal movements, timing of leaf loss,
germination (in some plants), and growth.
Electromagnetic radiation
Shorter wavelength = higher energy and
vice versa.
what type of radiation does the sun create? what does it include
-The sun creates electromagnetic radiation, which includes visible light, UV, infrared, X-rays etc.
UV properties
what does it do to DNA and what blocks it
-UV damages DNA and proteins; partly blocked by atmosphere
who said light is made of particles of energy, what are these particles called?
Einstein, photons,
what did newton discover about light
-When visible light travels through a prism, the wavelengths separate into the colors of the rainbow ().
-Each color is a different wavelength.
Which color has the greatest havelength and lowest energy
red because big wave = low energy and low frequency
chlorophyll vs carotenoids
chlorophyll absorb blue-red region of the light spectrum while carotenoids absorb maximum light in the blue-green region and violet region
carotenoids
-accessory pigments in photosynthesis, just like chlorophyll b, absorbing wavelengths that chlorophyll a does not
-prevent damage to chlorophyll molecules by light.
-The human body converts beta-carotene into vitamin A, which we need for eye health etc.
what is special about the light absorbing parts of pigments
The light-absorbing parts of the chlorophyll and carotenoid molecules have conjugated double bonds, which is common
among pigments.
Chlorophyll a
Chlorophyll a is the essential pigment of photosynthesis, in cyanobacteria, algae, and plants. It’s been around for >3 billion years
where is chlorophyll and carotenoids embedded?
Chlorophyll and carotenoids are embedded in the thylakoids, in units called photosystems
Anthocyanins
Anthocyanins may provide photoprotection during the breakdown of chlorophyll, but this is just a hypothesis.
Antenna complex and reaction center
-energy transferred molecule to molecule as long as they are close enough to each other.
-then hits the reaction center, then the ETC
how is light energy converted to chemical energy
When photosynthetic pigments absorb light, their electrons become excited and move to a higher energy level. When the electron return to their original energy levels (orbits), 3 things may happen
what are the three things that may happen after the electron returns to original energy levels
a) Fluorescence
b) Heat
c) Resonance energy transfer
Resonance energy transfer
occurs in the antenna complex and energy is transferred to two molecules of Chl a in the reaction center.
how do electrons go from reaction centre to ETC
(1)
1) The amount of energy that the two Chl a’s in the reaction centre of PS II is so great that one electron is ejected from each Chl a.
2) These electrons are accepted by the primary electron acceptor and transported through the electron
transport chain to PS 1
how do Chl a’s in reaction center get their electrons back from water? (2)
oxygen is split producing oxygen and protons. Oxygen is released and protons accumulate inside the thylakoid space.
while photosystem 2 is taking place
-Chl a’s in PSI also lose electrons due to light energy transferred to them by PSI antenna pigments that they receive from the antenna pigments.
-They get back the electrons that come to them from PSII through the electron transporters and the ejected electrons are transported to be finally accepted by NADP+ to form NADPH
when is a proton gradient established?
-A proton gradient is established when protons accumulate from water splitting and during electron transport.
-This gradient is dissipated when protons flow into the stroma.
-The energy of this proton gradient dissipation
is used to produce ATP.
calvin cycle shit
Products of the light-dependent reactions (NADPH and ATP) drive carbon-fixation
-In the first step of carbon fixation, a 5-C acceptor molecule (RuBP) reacts with a molecule of CO2
-The new 6-C molecule produced breaks into two 3-C molecules (PGA)
-The enzyme that carries out this reaction is RUBISCO. This is the key enzyme of the Calvin cycle.
-The cycle must run 6 times to make a 6-C sugar like glucose, i.e., RUBISCO must fix 6 CO2
molecules for that.
