Photosynthesis Flashcards
Two orders
- More orderly
- Less orderly
- highly ordered, highly structured system
- accomplished by putting energy into a living system
more orderly
- increase of entropy
- accomplished through energy transfers
less orderly
measure of randomness or disorder in a system
entropy
Two (2) methods sunlight maintains the state of low entropy
- Directly
- Indirectly
Method sunlight maintains the state of low entropy:
Directly
photosynthesis
Methods sunlight maintains the state of low entropy:
Indirectly
respiration
basis for a major, fundamental distinction in the types of organisms
- photosynthesis
- respiration
organisms that gather energy directly from light and use it to assimilate small inorganic molecules into their own tissues
Photoautotrophs
Ex. of photoautotrophs
- all green plants
- cyanobacteria
- few bacteria capable of photosynthesis
organisms take in organic molecules and respire them, obtaining energy available in them
Heterotrophs
Ex. of heterotrophs
- all animals
- completely parasitic plants
- fungi
- non-photosynthetic prokaryotes
plants that are not capable of photosynthesis and obtain all nutrients and water from a host plant
Holoparasitic plants
specialized, modified root of parasitic plants that penetrates into a host plant and functions to acquire necessary nutrients from the host plant they attached themselves to
haustorial root
Ex. of holoparasites
Cuscuta
Difference between Photoautotrophs and Heterotrophs:
Source of energy
Photoautotrophs:
sunlight
Heterotrophs:
food: carbohydrates, proteins, fats
Difference between Photoautotrophs and Heterotrophs:
Source of building material
Photoautotrophs:
carbon dioxide
Heterotrophs:
food
Difference between Photoautotrophs and Heterotrophs:
Organisms
Photoautotrophs:
1. photosynthetic plants and bacteria
2. algae
3. cyanobacteria
Heterotrophs:
1. animals
2. protozoa
3. non-photosynthetic parts of ordinary plants
4. completely parasitic plants
5. most bacteria
6. fungi
process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar
Photosynthesis
what drives endergonic reactions in photosynthesis
Adenosine Triphosphate (ATP)
carries new bonding orbitals filled by electrons to the reaction
NADPH
Energy enters the biological world through _____
photosynthesis
two major pigments involved in photosynthesis
- Chlorophyll A
- Chlorophyll B
absorbs violet and orange light the most.
chlorophyll a
absorbs mostly blue and yellow light.
chlorophyll b
Chlorophyll a and b also absorb light of other wavelengths with ___ intensity.
less
Cons of energy carriers
- large molecules
- not very mobile
- too energetic
Three (3) methods of synthesizing ATP
- Photophosphorylation
- Substrate-level phosphorylation
- Oxidative phosphorylation
Energy source:
Photophosphorylation
sunlight
Energy source:
Substrate-level photophosphorylation
reactions not involving oxygen
Energy source:
Oxidative photophosphorylation
oxidations with oxygens
Site:
Photophosphorylation
chloroplast
Site:
Substrate-level photophosphorylation
cytosol
Site:
Oxidative photophosphorylation
mitochondria
potential or power of any substance to reduce another substance that can be either by addition or removal of hydrogen or by loss or gain of electrons
reducing power
- chemical reaction in which electrons are transferred between two reactants participating in it
- transfer of electrons can be identified by observing the changes in the oxidation states of the reacting species
oxidation-reduction reactions
an atom loses electrons (e-), increasing positive charge
oxidation
an atom gains an electron (e-), reducing its positive charge
reduction
When the oxidation state increases, means electrons are removed, thus, the substance is ____
oxidized
substance that is being oxidized is called ____
reducing agent
When the oxidation state decreases, means electrons are added, thus the substance is ____
reduced
substance that is being reduced is called the ____
oxidizing agent
The oxidation state of an atom in any pure element is ____
0 (zero)
The oxidation state of hydrogen is ____ when in a regular compound
+1
The oxidation state of hydrogen is ____ when bonded to a metal
-1
Oxygen usually has an oxidation number of ____
-2
most highly oxidized forms of carbon and hydrogen
- carbon dioxide
- water
Compounds in the environment are predominantly in the ____ _____ because of our oxygen-rich atmosphere
oxidized state
Most compounds in organisms are in the ____ ____
reduced state
oxidize the material they interact with
oxidizing agents
Ex. of oxidizing agents
- NAD+
- NADP+
Two strong reducing agents
- NADH
- NADPH
have a powerful tendency to place electron onto other molecules, reducing those molecules and becoming oxidized themselves
reducing agents
tendency to accept or donate electrons varies greatly
redox potential
involved in an oxidation reaction of cellular respiration
Nicotinamide Adenine Dinucleotide (NAD+)
involved in an oxidation reaction of photosynthesis
Nicotinamide Adenine Dinucleotide Phosphate (NADP+)
What is formed after NAD+ and NADP+ take electrons away from other molecules (gaining of electrons)
- NADH
- NADPH
proteins that contain heme as their prosthetic group
Cytochromes
Biological function of cytochromes
electron transport
Cytochromes carries electrons and cycles between the ___ and ___ oxidation states
- +2
- +3
Where are cytochromes localized
compartment between the inner and outer mitochondrial membrane
Other electron carriers
- Cytochromes
- Plastoquinone
- Plastocyanin
- associated with Photosystem II
- mobile electron carrier through the membrane of the thylakoid
- hydrophobic; allows them to dissolve easily into the lipid component of chloroplast membrane
Plastoquinone
Plastoquinone is reduced; accepts two protons (H+) from the stromal matrix of the chloroplast, coupled to two electrons (e-) from photosystem II, forming ____
plastoquinol
Plastoquinone being hydrophobic allows them to ___ ___ into the lipid component of ___ ___
- dissolve easily
- chloroplast membrane
- a copper-containing protein that mediates electron-transfer
- acts as a redox protein in oxygenic photosynthesis,
- carry electrons from cytochrome f to a protein in photosystem I
Plastocyanin
Loosely associated with chloroplast membranes Plastocyanin transport route involves two steps:
- import into the chloroplasts
- subsequent routing over the thylakoid membrane into the lumen
Why are carbon dioxide and water used?
- abundant and cheap
- diffuse into plants automatically
- stable and contain little chemical energy
- nontoxic
Carbon atom in carbon dioxide is at the ____ oxidation state during photosynthesis
+4
Carbon atoms in carbohydrate are at ___
+0
Electron source
water
energy source
light
Light-dependent reactions
thylakoid reactions
process that creates the intermediates ATP and NADPH
photosynthesis
stroma reactions
dark reactions
ATP and NADPH interact with carbon dioxide and actually produce ____
carbohydrate
one small segment of the electromagnetic radiation spectrum (gamma rays, X-rays, ultraviolet light, infrared light, microwaves, and radio waves, in addition to visible light.)
Light
What are included in the electromagnetic radiation spectrum
- gamma rays
- x-rays
- ultraviolet light
- visible light
- infrared light
- microwaves
- radio waves
- energy that comes from a source and travels through space at the speed of light
- has an electric field and a magnetic field associated with it, and has wave-like properties
- also called “electromagnetic waves”
Radiation
Radiation can be thought of and treated physically either:
- set of particles- Quanta also called Photon
- set of waves
have relatively large amounts of energy in each quantum
short wavelengths
short wavelengths
- cosmic rays
- gamma rays
- ultraviolet rays
- low energy
- lower frequency
long wavelengths
long wavelengths
- infrared
- microwaves
- radar
- radio waves
Most of us see all wavelengths from ___ to ___
760nm to 390nm
760 nm color
red
390 nm color
violet
All animals see in the range from ___ to ___, which is also the radiation that plants use for photosynthesis
350 to 760 nm
- Any material that absorbs certain wavelengths specifically and therefore has distinctive color
- Substances that absorb light as part of their biological function
pigment
pigment of our skin
melanin
- Transfer absorbed light energy to electrons that then enter chemical reactions
- The pigment should at least absorb high- energy radiation (ultraviolet light and gamma rays) instead of the fairly weak visible light
Photosynthetic pigments
In general, plants only capture about ____ of the energy available in the electromagnetic radiation that strikes them.
5%
an integral membrane protein complex that uses light energy to catalyze the transfer of electrons across the thylakoid membrane from plastocyanin to ferredoxin
phtosystem 1
Location of Photosystem 1:
Plants and Algae
thylakoid membrane
Location of Photosystem 1:
Photosynthetic bacteria
cell membrane
An energy diagram for electron transfer in the “light reactions” of plant photosynthesis.
z-scheme
A small protein with an active site consisting of two iron atoms bound to two sulfur atoms
ferredoxin
The pair of chlorophylls of the photosystem I reaction center is given the special name ___ because they absorb red light of 700 nm most efficiently.
P700
an electron acceptor and is going to be reduced to NADP or NADPH
NADP+
- donates electron to Photosystem 1
- extracts electron from water molecules
Photosystem II
Process of Photosystem II:
- light absorption
- high electron energy
- electron transport chain
- water molecule electron extraction
Location of Photosystem II
inside the chloroplast in the thylakoid membrane
Photosystem II:
1. Light energy is absorbed by pigment molecules and chlorophylls that then transfer that energy into the ___.
P680
Photosystem II:
2. The photons from the light energy excite an electron putting it into a _____.
high-energy state
Photosystem II:
3. What does the electron in the high-energy state undergo to go back to a low-energy state?
Electron Transport Chain
Photosystem II:
4. The electron will then be donated to _____
Photosystem I
Photosystem II:
5. Once the P680 loses the electron in grabs unto the nearest ____ ____ and takes away its electron.
water molecule
Photosystem II:
6. The water molecule falls apart into ___ and ___ ___
oxygen and hydrogen ions
gets new electrons from water molecules
phaeophytin
donates electron to plastoquinone
Q
donates electron to cytochrome b6/f complex
plastoquinone
donates electron to plastocyanin
cytochrome b6/f complex
donates electron to the chlorophyll a of the Photosystem I reaction center
plastocyanin
- energy currency of cells or living organisms
- required for various cellular activities such as active transport of ions, muscle contraction, cell signaling, synthesis of biomolecules
- primarily synthesized in the cellular respiration process
Adenosine Triphosphate (ATP)
- product of the first stage of photosynthesis
- used to help fuel the reactions that take place in the second stage of photosynthesis
Nicotinamide Adenine Dinucleotide Phosphate Hydrogen (NADPH)
third, and final, biological pathway responsible for the production of ATP from an inorganic phosphate and an ADP molecule via oxidative phosphorylation
Chemiosmotic phosphorylation
any of the membranous disks of lamellae within plant chloroplasts that are composed of protein and lipid and are the sites of the photochemical reactions of photosynthesis
thylakoid
stack of thylakoid
grana (singular: granum)
thylakoids that lie between grana
frets
liquid surrounding the thylakoid system
stroma
continuous aqueous phase enclosed by the thylakoid membrane.
thylakoid lumen
enzyme complex that catalyzes the formation of ATP from ADP and inorganic phosphate
ATP Synthetase
The ATP synthetase of chloroplasts is known specifically as the _____ ____
CF0 - CF1 complex
Two (2) types of electron transport
- noncyclic electron transport
- cyclic electron transport
electrons flow through the Z scheme from water to nicotinamide adenine dinucleotide phosphate hydrogen (NADPH)
noncyclic electron transport
Electrons flow from P700 to plastoquinone, which carries a proton to the lumen and returns the electron to P700
cyclic electron transport
where conversion of carbon dioxide to carbohydrate occurs
stroma reactions
other names of stroma reactions
- Calvin/Benson cycle
- c3 cycle
overall purpose of the Calvin/Benson cycle
convert carbon dioxide from the atmosphere into carbohydrates
what does the Calvin/Benson cycle reactions use to convert CO2 to carbohydrates
ATP and NADPH produced by light reactions
The Stages of Calvin/Benson Cycle
- Fixation
- Reduction
- Regeneration
The enzyme RuBisCO incorporates carbon dioxide into an organic molecule, 3-PGA
fixation
The organic molecule is reduced using electrons supplied by NADPH
reduction
RuBP, the molecule that starts the cycle, is regenerated so that the cycle can continue
regeneration
one of the largest and most complex enzymes known—a giant complex of two kinds of protein subunits
RuBP carboxylase (RUBISCO)
set of life-sustaining chemical transformations within the plant cell
metabolism
breakdown of larger molecules
catabolism
synthesis of larger molecules
anabolism
- composed of 3-phosphoglyceraldehyde, water, nitrates, sulfates, and minerals
- basis of all animal metabolism
anabolic metabolism
Types of Storage Compounds
- short-term storage
- intermediate-term storage
- long-term storage
- ATP and NADPH
- last only briefly
short-term storage
- simple sugar glucose and disaccharide sucrose
- last for week or months
intermediate-term storage
- starch and lipids
- lasts for years
long-term storage
anabolic synthesis of glucose
gluconeogenesis
Starch (storage)
- amylose
- amylopectin
structural
cellulose
- Unbranched Polymer of Glucose
- Has one end and synthesized slowly
- Digested more slowly
amylose
- Branched Polymer of Glucose
- Has thousands of enzymes simultaneously adding glucose
- Can be digested back to glucose monomers much more faster than amylose
amylopectin
- Digests the amylopectin portion of starch rapidly
- Makes glucose available to our bloodstream quickly
salivary amylase
polysaccharides are stored as ___ in animals
glycogen
polysaccharides are stored as ___ in plants
starch
where are starch located in plants
- chloroplasts
- amyloplasts
Most of the 3-phosphoglyceraldehyde is retained, converts it to glucose, and polymerized to starch
daylight
Chloroplasts are swollen because of large starch grains they contain
afternoon
Starch is depolymerized back to glucose
night
Three (3) important properties of light
- Quality
- Quantity
- Duration
- refers to the wavelength and the colors composing the light which affects the growth of the plant
- factors are being manipulated by the planet refracting and reflecting certain types of waves and color varies by it’s rotation and atmosphere.
Quality of sunlight
- refers to light intensity, brightness and availability of light, and is affected by several factors
- light is more available for photosynthesis during a clear day compared to a cloudy one as an example
Quantity of light
number of hours of light a plant needs per 24-hour period and allows the plant to make sufficient food to survive and grow which can be embedded to the plant making some varieties that need a specific time-span to be exposed to light
Duration of Light
major factor for a plant to absorb carbon dioxide
light
Photosynthesis is __ and __ on overcast days, but __ on brighter days
- slow and dull
- faster
The __ of photosynthesis is directly affected by the amount of light available
rate
reduce the water lost from the leaf
Cuticle
- contains no chloroplasts
- prevents water from getting out and stopping unwanted substances/organisms from getting in
Epidermis
most of the photosynthesis occurs in the leaf
Palisade Mesophyll Layer
contain a lot of chloroplasts to help them perform photosynthesis and are closely packed together to maximize light absorption
Palisade Cells
The cells are not as closely packed as the cells in the palisade mesophyll layer
Spongy Mesophyll Layer and air spaces
creates air spaces inside the leaf to enable gases to move in and out
Air Spaces
There are not as many chloroplasts in the spongy mesophyll cells as there are in the palisade mesophyll cell
Spongy mesophyll layer
holes found in leaves where it allows gases to diffuse in and out of the leaves
stoma
two highly specialized epidermis cells that forms stoma
guard cells
movement of gases in opposite directions
gas exchange
excellent for absorbing carbon dioxide but inefficient for conserving water
- Palisade parenchyma
- spongy mesophyll
Method of Minimizing Water
- Keep their stomata closed so much of the time that they would starve
- Reduce external surface by means of cylindrical leaves
evaporation of water from plants occurring at the leaves while their stomata are open for the passage of CO2 and O2 during photosynthesis
Transpiration
- wasteful pathway that competes with the Calvin cycle
- begins when rubisco acts on oxygen instead of carbon dioxide.
Photorespiration
occasionally binds to oxygen instead of carbon dioxide, acting as an oxygenase
RuBP carboxylase
molecules produced when RuBP carboxylase binds to oxygen instead of carbon dioxide
- one molecule of 3-phosphoglycerate
- one of phosphoglycolate
Where is phosphoglycolate transported
from the chloroplast to peroxisomes and mitochondria
Some of the phosphoglycolate is converted to useful amino acids
- glycine
- serine
much of the phosphoglycolate is broken down to
two molecules of carbon dioxide
Three main types of photosynthesis are C3, C4, and CAM (crassulacean acid metabolism)
- C3 metabolism
- C4 metabolism
- Crassulacean acid metabolism (CAM)
- mechanism by which carbon dioxide is absorbed, transported through, and concentrated in a leaf, whereas oxygen is kept away from RuBP carboxylase
- occurs in leaves with Kranz anatomy
C4 metabolism
meaning wreath or ring in Germany
Kranz
C4 plants have little ____
photorespiration
Mesophyll contains an enzyme called ___ ___; has a high affinity for carbon dioxide.
PEP carboxylase
PEP carboxylase adds CO2 to PEP, producing a 4-carbon organic acid which is called ____, hence the name C4 metabolism.
Oxaloacetate
Oxaloacetate is reduced to ___ by a molecule of ____
- malate
- NADPH
Malate from throughout the mesophyll moves into the bundle sheath and breaks down into ____ by releasing carbon dioxide
pyruvate
This reaction is powerful enough to drive the formation of a new molecule of ____, so, the process results in the transport by malate of both carbon dioxide and reducing power
NADPH
Because NADPH is synthesized by this unusual method in bundle sheath cells, the bundle sheath chloroplasts primarily carry out ___ ___ ___, pumping protons and making ATP
cyclic electron transport
- Like any other carrier, malate must be shuttled back to its recharge site, the mesophyll.
- In the bundle sheath it is converted to (1)___ by the release of (2)___ ___;
- pyruvate moves back to the mesophyll and receives a phosphate group from ATP, which converts it to (3)___.
(1) pyruvate
(2) carbon dioxide
(3) PEP
Types of Carbon dioxide processing of C3, C4, and CAM Plants:
Ultimate carboxylase
C3 plants, C4 plants, CAM plants
- RuBP carboxylase
Types of Carbon dioxide processing of C3, C4, and CAM Plants:
Adjunct metabolism
C3 plants
- None
C4 plants, CAM plants
- CO2 transfer
Types of Carbon dioxide processing of C3, C4, and CAM Plants:
Adjunct carboxylase
C3 plants
- none
C4 plants, CAM plants
- PEP carboxylase
Types of Carbon dioxide processing of C3, C4, and CAM Plants:
Photorespiration
C3 plants
- high
C4 plants
- low
CAM plants
- moderate
Types of Carbon dioxide processing of C3, C4, and CAM Plants:
Stomata open
C3 plants, C4 plants
- day
CAM plants
- night
Under warm, dry conditions, ___ ___ has a strong selective advantage over ___ ___: Much less water is lost during carbon dioxide absorption
- C4 metabolism
- C3 metabolism
- second metabolic adaptation that improves the conservation of water while permitting photosynthesis
- allows a plant to photosynthesize during the day, but only exchange gases at night.
Crassulacean Acid Metabolism(CAM) is a
It is so named because it was first discovered in those members of the family ___
Crassulaceae
A CAM plant leaves its stomata open at ___, allowing CO2 to enter and be converted as organic acids through a ___ ___ resembling the C4 pathway.
- night
- PEP reaction
As the Calvin cycle requires ATP and NADPH, products of light-dependent reactions that does not occur at night, to function, the generated organic acids are ___ ___ ___ for later use
stored in vacuoles
The mesophyll cells’ vacuoles release the organic acids that store CO2 during the ___ as the stomata ___ to preserve water.
- day
- close
The CO2 is released by an ___ ___ ___ ___ of chloroplasts, where it enters the Calvin cycle to enable photosynthesis
- enzyme in the stroma
almost identical to those in chloroplasts, having chlorophyll a but lacking chlorophyll b
Cyanobacterial light reactions
Accessory pigments of cyanobacteria
- phycobilins
- open-chain tetrapyrrole rings
the ___ ___ forms accumulation spaces for protons and the generation of a ___ ___
- folded membrane
- chemiosmosis gradient
Purple and green bacteria do not contain chlorophyll, either a or b, but have ____
bacteriochlorophylls
