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bio pages 80-91

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anatomy of a chloroplast
each mesophyll in a typical leaf contains approximately 30-40 chloroplasts. Each chloroplast has two external membranes that contain a fluid interior known as the stroma. Another membrane system extends through the stroma. This membrane system is repeatedly folded into numerous channels and stacked disks known as granum (plural grana). This internal membrane system is many times referred to as teh thylakoid membrane system
thylacoid membrane system/granum
This membrane system is repeatedly folded into numerous channels and stacked disks known as granum (plural grana). This internal membrane system is many times referred to as teh thylakoid membrane system, and it is where the first stage (light dependent reactions) of photosynthesis occur.
the light independent (dark) reactions (Calvin Cycle)
the Calvin Cycle is a cyclic metabolic pathway which is involved in the fixation of carbon from atospheric carbon dioxide and the reduction of the fixed carbon into CARBOHYDRATE (GLUCOSE). the calvin cycle represents the second part of photosynthesis. the calvin cycle can be divided into three phases or steps 1)CARBON FIXATION 2)REDUCTION 3)REGENERATION of CO2 acceptor (RuBP)
where 2 diff types of photosynthesis are done
(both occur in chloroplast) PHOTOSYSTEMS I and II-thylakoid membrane system, CALVIN CYCLE- stroma
phloem (fall away)
tubules that move photosynthetic products/metabolites (sugars, ect.) away from the mesophyll cells
mesophyll
contains teh majority of the photosynthetic tissue. this layer of the leaf consists of a type of leaf parenchyma that contains a large number of cells arranged in a way that provides the internal anatomy of the leaf with numerous air spaces. these air spaces will alow air to circulate throughout the mesophyll layer and connect to the external envoiroment via the stomata. the circulation of air throughtout the leaf brings CO2 to the photosynthetic cells where it will ultimately be used in the carbon fixation process and O2 away from the photo synthetic cells where it can enter the atmosphere. leaves that are orientated perpendicular to the rays of the sun have two layers of mesophyll
Photosystem II occurs before Photosystem I
because it was discovered first
stroma
Each chloroplast has two external membranes that contain a fluid interior known as the stroma
photosystems
groups of chemical reactions
where the light dependent reaction occurs
The space that exists within these channels and disks interconnect and allow for the collection of hydrogen (H+) ions. Ther flow of hydrogen (H+) ions across teh thylakoid membranes will assist the chloroplast in generating adenosine triphospate (ATP) and nicotinamide adenine dinucleotide phospate (NADPH) which will be used in the second part of photosynthesis.(similar to OP)
epidermis
covers every leaf surface that is exposed to the air and is composed fo a single layer of epidermal cells. the surface of teh epidermal cells may be smooth, stickey, or slimy. the epidermis of a leaf may contain hair-like structures, hooks, scale, and even glands.
xylem
tubules that move water and dissolved nutrients towards the mesophyll cells
cuticle
covering the sheet- like array of epidermal cells that make up the epidermis of a leaf is a waxy layer called the cuticle that prevents dehydration of the epidermal cells and leaves
stomata
small openings tha penetrate though the epidermis called stomata exist useually on the lower surface of the leaf. the water lilly is an example of a plant that has the stomata on the upper surface of the leaf. these stomates allow air (CO2) to circulate through the inner portions of the leaf and enter the photosynthetic pathways
guard cells
surround the opening of the stomata and control the flow of air throught the stomata of the leaf. when teh guard cells/leaf are dehydrated, they will close the stomata and reduce the flow of air through the leaf, preventing further dehydration of the leaf cells. when there exists adequate moisture within the guard cells/leaf, the guard cells will open up the stomata and allow air to freely flow through the leaf
spongy layer
composed of columnar epithelium and extends from the middle of the leaf to the bottom of the leaf where it connects to the lower epidermis. the cells of the spongy layer of the epidermis are not as densely packed as those which exist within the palisades layer. these cells have a lower concentration of chloroplasts and consiquently do not have the same photosynthetic activity as the cells that exist in the palisades layer
photosystem I (cyclic electron flow)
STEPS 1,2,3 THE SAME except chlorophyll a is (P700) 4)the electron from photosystem II will fill this electron hole in chlorophyll a(P700) 5)(e-) ->primary electron acceptor, IT CAN TAKE 1 OF 2 PATHS, PATH 1] electrons(e-) are diverted back towards the CYTOCHROME COMPLEX in order to generate more ATP. PATH 2]electrons(e-) -> FERADOXIN(Fd) -> NADP REDUCTASE. the NADP reductase will generate NADPH (final electron acceptor)
"light harvesting antennae complex"
made up of hundreds of moleculse of chlorophyll a, chlorophyll b and various carotenoid pigments. the ligt gathering antennae contain a variety of igments in order to increase the spectrum and quantity of light that it can absorb to perform photosynthesis. at the center of the light harvesting antennae, there exists a single molecule of chlorophyll a and another specialized molecule known as the "primary electron acceptor"
palisades layer
composed of columnar parenchymal cells attached t the upper epidermis. although these cells seem densely packed, most of their cell walls are exposed to the spaces within the leaf through which air is circulating. the cells of the palisades layer contain the highest concentrations of chloroplasts and are responsible for the majority of photosynthetic activity that occurs in the leaf
reason why we use 2 diff types of photosynthesis
PHOTOSYSTEMS I and II- to produce ATP and NADPH for the calvin cycle, CALVIN CYCLE-carbon fixation and production of carbohydrate
photosystem II (non cyclic electron flow)
1] sunlight strikes the chloroplast of a green plant. 2] the light harvesting antennae (photosystem II) absorbs the energy of sunlight which excites an electron in the chlorophyll a molecule. the chlorophyl a (photosystem II) absorbs light with a wavlength of 680nm best (chlorophyll a P680). 3] an electron will be emmitted from chlorophyll a(P680) and travel to the primary electron acceptor. 4] this creates a "electron hole" 5] sunlight is used to split a molecule of water into hydrogen ions, electrons and oxygen (photolysis). 6] the electrons are used to replace the electrons lost in the chlorophyl a (P680) molecule. 7] the electron hole is filled so steps1,2,3 can be done again 8](e-) ->primary electron acceptor ->plastoquinone ->cytochrome complex (generates ATPs) ->plastocyanin 9] the electron reaches the chlorophyl a(P700) of photosystem I
veins
vascular bundles that exist within the leaf are referred o as veins. veins are composed of two types of conducting tubuoles a) xylem and b) phloem
where the light independent reaction occurs
The second part of photosynthesis (light independent) occurs in the stroma and is involved with the carbon fixation and the production of carbohydrate

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