Chapter 7-8 Flashcards
Photosynthetic process:
is the process by which light energy is captured and then stored as chemical energy in the bonds of organic molecules such as sugar
Chloroplasts
Chloroplasts are organelles that consist of a double outer membrane enclosing a semifluid substance, the stroma.
Thyllakoids and grana
interconnected membrane-enclosed compartments, embedded in the stroma, often forming disc shaped structures called grana.
6 CO2 + 6 H2O + light energy = C6H12O6 (sugar) + 6 O2
photosynthetic chemical reaction formula
light reactions of photosynthesis
chlorophyll capture sunlight energy and convert it into chemical energy, stored as ATP and NADPH. Water is split and oxygen is released.
.
Calvin cycle
enzymes in the stroma surrounding the thylakoids combine CO2 and ATP, NADH. creating a three-carbon sugar that is used to make glucose.
Chlorophyll a, appearance and absorbance
the key light-capturing pigment molecule in chloroplasts, strongly absorbs violet, blue, and red light, but reflects green, thus giving green leaves their color
accessory pigments
other molecules inside chloroplasts.
chlorophyll b, appearance and absorbance
an accessory pigment. reflects yellow-green light and absorbs the blue and red-orange wavelengths missed by chlorophyll a.
Carotenoids appearance and absorbance
accessory pigments, they absorb blue and green light and therefore appear mostly yellow or orange
electron transport chain (ETC)
a series of electron-carrier mol- ecules embedded in the thylakoid membrane.
photosystem II (and ETC)
Capture Light Energy, Create a hydrogen Ion Gradient, and Split Water.
Photosynthetic steps:
Step 2.
The energy hops from one pigment molecule to the next until it is funneled into the photosystem II reac- tion center
Photosynthetic steps:
Step 3.
When the energy from light reaches the reaction center, it boosts an electron from one of the reaction center
chlorophylls to the primary electron acceptor.
Photosynthetic steps:
Step 4.
water replaces electrons that were excited and left the reaction centre. water is split producing O2 molecule.
Photosynthetic steps:
Step 5.
the electron travels from one electron carrier to the next, Some of this energy is harnessed to pump H+ across the thylakoid mem- brane and into the thylakoid space, contributing to the H+ gradient.
Photosynthetic steps:
Step 6.
the energy-depleted electron leaves the ETC and enters the reaction center of photosystem I, where it replaces the electron ejected when light strikes photosystem I energy is passed to a chlorophyll a in the reaction centre.
Photosynthetic steps:
Step 7.
chlorophyll a energizes an electron that is absorbed by the primary electron acceptor of photosystem I
Photosynthetic steps:
Step 8.
the energized electron is passed to a second ETC adjacent to photosystem I in the thylakoid membrane.
Photosynthetic steps:
Step 9.
Here, the final electron carrier is an enzyme that cata- lyzes the synthesis of NADPH. To form NADPH, the enzyme combines NADP+ and H+ (both dissolved in the stroma) with two energetic electrons from the ETC
Photosynthetic steps:
Step 1.
photons of light are absorbed by pigment molecules clustered in pho- tosystem II
Hydrogen ion gradient generates:
ATP
Chemiosmosis
is the process by which some of the energy stored in the concentration gradient of H+ is captured in ATP as H+ flows down its gradient.
Calvin Cycle
step 1.
Rubisco combines 3 CO2 molecules with 3 RuBP molecules to produce 3 six-carbon molecules that immediately split in half, forming six PGA
What is PGA
phosphoglyceric acid
Rubisco
An enzyme of which initiates Calvin cycle. it fixes carbon although is not completely selective, and will allow O2 instead of CO2 to combine with RuBP
Calvin Cycle
step 2.
Energy from ATP and NADPH is used
to convert the six molecules of PGA to six molecules of G3P
Calvin Cycle
step 3.
with energy from ATP, the five remaining molecules of G3P are converted to three molecules of RuBP
Calvin Cycle
step 4.
One molecule of G3P leaves the cycle
Calvin Cycle
step 5.
Two molecules of G3P combine to form glucose.
C3 pathway is referred as;
the Calvin cycle
When O2 replaces CO2 reducing the rate of carbon fixation by roughly 33%, is a wasteful process called…
photorespiration
C4 plants chloroplast location and carbon fixing.
in both mesophyll and bundle sheath cells. The mesophyll chloroplasts lack Calvin cycle enzymes and use the enzyme PEP carboxylase to fix CO2. as malate.
PEP carboxylase is selective?
highly selective for CO2 over O2.
malate
carbon energy storage, produced in mesophyl of C4 plant, which travels through bundle sheath cell to undergo breakdown and calvin cycle in a CO2 rich environment.
CAM plants
use the C4 pathway. in contrast, CAM plants do not use different cell types but utilize different timings for calvin cycle.
CAM plants open their stomata;
at night, when less water will evaporate.
What occurs at night and in the day through the CAM pathway?
carbon fixation occurs at night. sugar synthesis occurs during the day (production of malate eg C4 process).
C4 and CAM plants greatly reduce;
competitive inhibition of rubisco by O2
glucose breakdown energy efficiency %
when oxygen is present, 40% efficiency.
C6H12O6 + 6O2 = 6CO2 + 6H2O + ATP energy
Glucose breakdown reaction
Glycolysis
the splitting of a six-carbon glucose molecule into two molecules of pyruvate with help from 2 ATP.
Glycolysis net gain of energy=
4ATP + 2NADH - 2ATP = 2ATP + 2NADH
Cellular respiration (Krebs cycle)
Cellular respiration breaks down the 2 pyruvate molecules produced by glycolysis into 6CO2 molecules and 6H2O molecules.
Where does cellular respiration occur?
Mitochondia of eukaryote cells.
each glucose molecule produces how many of each electron carriers; 10 ______ and 2 ______ over the first stage of cellular respiration.
10 NADH and 2 FADH2 molecules
NADH and FADH2 excited electrons are passed over to the _____ in the mitochondria.
ETC (electron transport chain.
excited electron transport chains in the mitochondria power ___ pumps creating a _____ gradient.
H+ pump, chemical concentration gradient inside the mitochondrial intramembranous space.
intermembrane space or the matrix of the mitochondria has a higher H+ concenttration?
intermembrane space.
Oxygen O2 accepts ____ at the end of the ETC.
the spent electrons forming H2O
What would occur in cellular respiration without oxygen?
Without oxygen to accept electrons, the ETC would become saturated with electrons and could not acquire more from NADH and FADH2.
fermentation
the process by which pyruvate (after glycolysis) is converted either into lactate or into ethanol and CO2. (micro organisms) yeasts etc.
total yield of ATP from 1 glucose molecule through cellular respiration:
36 ATP
What is the role of PEP in a C4 plant?
An enzyme which catalyzes the reaction for CO2 to be converted into malate through use of energy in the form of ATP and NADH produced from light reactions of photosynthesis.
