Chapter 10 Flashcards
Photosynthesis
- the process that converts solar energy into chemical energy
- helps nourish the biosphere
Chloroplasts
found in plants
- use photosynthesis to capture light energy from the sun and convert it into stored sugars and organic molecules
Autotrophs
- are major producers of the biosphere that produce organic molecules from CO2
i. e. plants
2 types of Autotrophs
1) Photoautotrophs
2) Chemoautotrophs
Photoautotrophs
use the energy of sunlight to make organic molecules from water and CO2
i.e. plants
Chemoautotrophs
.
Heterotrophs
- live on organic compounds produced by other organism
- are the consumers of the biosphere
- i.e. animals, fungi, and many prokaryotes
Where photosynthesis occurs?
- plants
- algae
- certain other protists
- some prokaryotes
Chloroplasts
- the sites of photosynthesis in plants
- found in the mesophyll cells forming the tissues in the interior of the leaf
- the organelles in which photosynthesis occurs
Leaves of plants
major sites of photosynthesis
Chlorophyll
leaf color comes from this
Stomata
the pores in the leaf through which O2 and CO2 leave and enter
The composition of Chloroplasts
- 2 membranes around an aqueous space
- the stroma
- contain thylakoids and grana
Thylakoids
stacked into grana
contain the chlorophyll
Photosynthesis overview
6 CO2 + 12 H2O + Light source => Glucose + 6 O2 + 6 H2O
overall chemical reaction change during photosynthesis is the …
- reverse of cellular respiration
- anabolic
Anabolic
energy (sugar synthesizing) reaction
Chloroplasts split …
H2O => H2 + O2
- incorporating the electrons of H2 into sugar molecules
Photosynthesis is a redox reaction
H2O is oxidized
CO2 is reduced
2 stages of photosynthesis
1) The light (photo) reactions
2) The Calvin Cycle (synthesis)
1) The light (photo) reactions
- occurs in the grana,
- split H2O, release O2,
- produce ATP, and form NADPH
2) The Calvin Cycle (synthesis)
- occurs in the stroma
- Input: ATP, NADPH, CO2
- Output: Sugar, ADP + P + NADP+
(forms sugar from CO2, using ATP for energy and NADPH for reducing power)
Light Reaction convert…
solar energy to the chemical energy of ATP and NADPH
Light
- is a form of electromagnetic energy: which travels in waves
Wavelength
the distance between the crests of waves and determines the TYPE of electromagnetic energy
Visible Light Spectrum
includes colors of light we can see and the wavelengths that drives photosynthesis
Pigments
i. e. Chlorophyll a
- substances that absorb visible light and reflect the light that we see
Action-Spectrum
of a pigment profiles
the relative effectiveness of different wavelengths of radiation in driving photosynthesis
- 1st determined by Theodor W. Engelmann 1833
Chlorophyll a
the main photosynthetic pigment
Chlorophyll b
an accessory pigment
Accessory pigments
absorb different wavelengths of light and pass the energy to chlorophyll a
when a pigment absorbs light
its electrons become unstable and goes from a ground state to an excited state, that releases heat energy and sometimes fluorescence
in the Thylakoid Membrane
chlorophyll is organized with other proteins into a photosystem
-ATP is produced in here
Photosystem
composed of a reaction center (chlorophyll a) surrounded by a number of light-harvesting complexes or pigment molecules
Light-harvesting complexes
funnel the energy of photons of light to the reaction center
Reaction-Center chlorophyll molecules
absorbs energy and as the electrons “fall” to a lower energy level, their energy is harnessed to produce ATP
Chemiosmosis in Chloroplasts vs. Mitochondria
Both organelles:
- redox reactions of electron transport chains generate a H+ gradient across a membrane
- use ATP synthase and proton-motive force to make ATP
Calvin Cycle
uses ATP and NADPH to convert CO2 => sugar
occurs in the stroma
has three phases
(carbon fixation, reduction, regeneration of CO2 acceptor)
similar to the Citric Acid Cycle
3 phases of the Calvin Cycle
1) Carbon fixation
2) Reduction
3) Regeneration of the CO2 acceptor
