Photosynthesis Part 2 Flashcards
molecular complexes in the thylakoid membrane
PS II
PS I
ETC
ATP synthase complex
consist of pigment complex and electron acceptor molecules, receives electrons from water as water splits, releasing oxygen
Photosystem II
carries electrons from PS II to PS I
ETC
pumps H+ from the stroma into the thylakoid
plastoquinone
ETC consists of what
plastoquinone (Pq)
cytochrome complexes
proteins that contain heme as their prosthetic group and whose principal biological function, in the cells of animals, plants, and microorganisms, is electron transport
cytochrome
consist of pigment complex and electron acceptor molecules which is adjacent to NADP reductase
PS I
reduces NADP to NADPH
NADP reductase
has a channel and protruding ATP synthase
ATP synthase complex
joins ADP + P
ATP synthase
acts as a reservoir for hydrogen ions
thylakoid space
when water is oxidized, these remain in the thylakoid space
hydrogen ions
gives up energy and is used to pump H+ from the stroma into the thylakoid space
electrons
which space has more H (stroma or thylakoid)
thylakoid
provides kinetic energy that allows an ATP synthase complex enzyme to produce ATP from ADP + P
flow of H from high to low concenrtation
method of producing ATP that is tied to the establishment of H+ gradient
chemiosmosis
produces NADPH and ATP
thylakoid membrane
move through sequential molecular complexes within the thylakoid membrane and the last one passes electrons to NADP+ after which it becomes NADPH
electrons
pumps hydrogen ions from the stroma into the thylakoid space through an ATP synthase complex
Carrier
produced from ADP + P
ATP
won the 2007 Nobel Prize for raising awareness concerning global warming
Al Gore
according to the Nobel Committee, could induce large-scale migrations and lead to greater competition for the Earth’s resources
global warming
refers to a rise in the average global temperature during the twenty-first century due to the introduction of certain gases into the atmosphere
global warming
for at least a thousand years prior to 1850, atmospheric carbon dioxide (CO2) levels remained fairly constant at
0.028%
since industrialization began, the amount of CO2 in the atmosphere increased to what
0.038%
examples include CO2 and other gases which trap radiant heat from the sun
greenhouse grases
increasing concentration of this is predicted to cause global warming
greenhouse gases
without green house gasses, the temperature would be this
33 degrees cooler
adds CO2 to the atmosphere
burning of fossil fuel
tropical forest deforestation
amount of rainforest lost every year
10 to 30 million hectares
reason why rainforest is lost
ranching
logging
mining
developed for human needs
accounts for 20-30% of all CO2 in the atmosphere
deforestation
adds CO2 to the atmosphere and removes trees that absorb CO2
burning a forest
acts as a sink for CO2
process of photosynthesis and oceans
make a substantial contribution to global CO2
tropical rainforest
percent of reduction of tropical rain forest size
14% to 6%
taking account all ecosystems, marine and terrestrial, this produces organic matter that is 300 to 600 times the mass of people
photosynthesis
contribute greatly to the uptake of CO2 and the productivity of photosynthesis since they are most efficient of all terrestrial ecosystems
tropical rain forests
where tropical rain forests occur
equator
characteristics of tropical rainforests
exist in temperatures above 26 degrees and rainfall is heavy (100-200cm)
huge trees and buttressed trunks and broad, undivided dark-green leaves
nearly all plant plants are woody and woody vines are also abundant
increase amount of CO2 in the atmosphere will cause photosynthesis to
increase in the remaining portion of the forest
how did researchers test the possibility that an increased amount of CO2 in the atmosphere increases the rate of photosynthesis
measured CO2 levels, daily temperature levels, and tree girth in La Selva, Costa Rica for 16 years
were found at higher temperatures
lower forest productivity
what did the findings of researchers in La Selva Costa Rica suggest
as temperatures rise, tropical rain forest may add to ongoing atmospheric CO2 accumulation and accelerated global warming
in the mid 1970s, established a system of national parks and reserves to protect 12% of the country’s land area from degradation
Costa Rica
what percent does the country wants to expand in the near future
12% to 25%
occur after the light reactions, a series of reactions that produce carbohydrate before returning to the starting point once more
Calvin cycle reactions
Calvin cycle was named for him, who with colleagues used radioactive isotope 14C as a tracer to discover the reactions making up the cycle
Melvin Calvin
Calvin cycle includes the following
Carbon dioxide fixation
Carbon dioxide reduction
Regeneration of RuBP
RuBP
ribulose-1
5-biphosphate
first step of the calvin cycle
Carbon dioxide fixation
Carbon dioxide from the atmosphere is attached to what
RuBP
5-carbon molecule that CO2 attaches to
RuBP
product of CO2 and RuBP
6-carbon molecule
the 6-carbon molecule splits into this
Two 3-carbon molecule
enzyme that speeds up the carbon dioxide fixation
RuBP carboxylase
protein that makes up 20-50% of the protein content in chloroplasts
RuBP carboxylase
reason why RuBP carboxylase is abundant
unusually slow process (processes only few molecules compared to thousands per second for a typical enzyme)
there has to be a lot to keep the cycle going
first 3-carbon molecule in the Calvin cycle
3PG (3-phospoglycerate)
3PG
3-phosphoglycerate
3PG -> G3P undergoes what
reduction
this sequence signifies the reduction of carbon dioxide to carbohydrate
R-CO2 -> R-CH2O
supplies the energy needed for carbon dioxide reduction reaction
ATP and NADPH
times of Calvin reaction cycles multiplied by because it takes this much to allow one G3P to exit
3 times
for every three turns of the Calvin cycle, this much G3P are used to re-form three molecules of RuBP and the cycle continues
5 molecules of G3P
how many carbons in G3P
3
how many carbons in RuBP
5
product of the Calvin cycle that can be converted to other molecules a plant needs
G3P (glyceraldehyde-3-phosphate)
G3P
glyceraldehyde-3-phosphate
among the organic molecules that result from G3P metabolism
glucose phosphate
glucose phosphate can be combined with this (and remove the phosphate) to produce sucrose
fructose
plants use these to transport carbohydrates from one part of the plant to the other
sucrose
glucose phosphate is also the starting point of the production of these
cellulose
starch
form of glucose where some of it is stored in chloroplasts
starch
where most of the starch is stored in roots
amyloplasts
structural component of plant cell walls and becomes fiber in our diet because we are unable to digest it
cellulose
component of G3P to that plant uses to form fatty acids and glycerol
hydrocarbon skeleton
fatty acids and glycerol combined to this, examples include sunflower, corn, and olive
plant oils
when added to the hydrocarbon skeleton derived from G3P, amino acids are formed
nitrogen
examples of land plants that carry on photosynthesis as described earlier
Azaleas
maples
tulips
use the enzyme RuBP carboxylase to fix CO2 to RuBP in mesophyll cells
C3 plants
C3 plants include
wheat
rice
oats
first detected molecule following fixation
3PG
describe the CO2 fixation in C3 plants
RuBP + CO2 -> 2 3PG
openings n leaves where water can escape and CO2 can enter
stomata
when this happens, stomata closes to conserve water
Hot weather
might cause plant to wilt and die
water loss
Due to stomata closing, what happens to the concentration of gas
CO2 decreases and O2 increases
when O2 increases in these plants, what does RuBP carboxylase do to O2?
combines it with RuBP instead
product of O2 fixing with RuBP
one molecule of 3PG and CO2 is released
in the presence of light (photo), oxygen is taken up and CO2 is released (respiration)
photorespiration
difference between C3 and C4 plants in the location of mesophyll cells
C3 - parallel layers, well-formed chloroplasts
C4 - chloroplasts in bundle sheath cells and mesophyll cells
in C4 plants, are arranged cocentrically around the bundle sheath cell
mesophyll cells
use the enzyme PEP carboxylase (PEPcase)
C4 plants
PEPcase
Phosphoenolpyruvate carboxylase
used to fix CO2 to PEP
PEPcase
C3 molecule that becomes C4 when fixed with CO2
PEP
result of fixing CO2 to PEPcase
oxaloacetate
reduced form of oxaloacetate that is pumped into the bundle sheath cell
malate
only in C4 plants, where does CO2 enter
calvin cycle
because of CO2 entering the calvin cycle in C4 plants, what are the differences with C3 plants
faster photosynthetic rater
example of C4 plants
sugarcane
corn
bermuda grass
what does C4 avoid
photorespiration
wasteful cycle because it is not part of the calvin cycle
photorespiration
how do C4 plants avoid photorespiration
PEPcase does not combine with O2
Even if the stomata are closed, CO2 is delivered into the calvin cycle in the bundle sheath cells
when weather is moderate which is more advantaged C3 plants or C4 plants?
C3 plants
when weather becomes hot, which plants become more advantaged
C4 plants
CAM
crassulacean-acid metabolism
family of flowering succulent (water-containing) plants that live in warm, dry regions of the world
crassulaceae
was first discovered on the family of Crassulaceae, but was already known on other groups of plants
CAM
difference of C4 and CAM plants in partitioning
C4 - partitions in space (CO2 fixation in bundle sheath cells)
CAM - partition by the use of time
During the night, CAM plants use PEPcase to do what
fix CO2, forming C4 molecules, which is stored in large vacuoles in mesophyll cells
During the day, C4 molecules do what
release CO2 to the Calvin cycle when ATP and NADPH are available from the light reactions
primary advantage for CAM partition
conservation of water
only opened at night, and at that time does atmospheric CO2 enter the plant
stomata
during the day, the stomata are claused because??
to conserve water (CO2 cannot enter though sad)
minimal because limited CO2 is fixed but it does allow CAM plants to live under stressful conditions
photosynthesis
why are there different types of photosynthesis
organisms are metabolically adapted to their environment
most likely evolved and adapted to areas of high light intensities, high temperatures, and limited rainfall
C4 plants
plants that are more sensitive to cold
C4 plants
can do better than C4 plants below 25 degrees
C3 plants
compete well with either type of plant when the environment is quite arid
CAM plants
example of CAM plants
orchids
lillies
ferns
cone-bearing trees
