Respiration and photosynthesis Flashcards
What is respiration used for
Active transport
Movement such as transporting a protein from ribosome to Golgi apparatus
Synthesising large molecules
ATP stands for
Adenine triphosphate
ATP is made from
Adénine, ribose sugar, the phosphate groups.
It a is a phosphorylated nucleotide
ATP is a good energy currency because
1 water soluble-easily transported around cell
2 releases energy quickly in small packets, 30.5kj/mol of energy, little wasted energy
3 relatively stable only hydrolysis with ATPase not at any time. loses phosphate group
4 can be regenerated
In general how is ATP made
Phosphate group combines with ADP
2 ways atp is maxe
Substrate linked reaction
Chemiosmosis
Chemosmosis
As electrons move down carriers they lose energy which is used to pump hydrogen ions into thylakoid interior. When hydrogens move back into stra via atp synthase and converts adp and inorganic phosphate to atp
Substrate linked reaction
Transfer of phosphate from a substrate molecule directly to ADP to produce ATP using energy provided directly form another chemical reaction
Glycosis
The splitting of glucose. First stage of aerobic respiration molecule with six c into 2 with 3 c
where does the light dependent reaction take place
thylakoid membrane
where does the light independent reaction take place
stroma
how is reduced NADP produced
in light dependent reaction when NADP combines with electrons from photolysis of water
what is nadph from ldr used for
light independent reaction
whats passed form ldr to lir
Energy from ATP and hydrogen from reduced NADP
Cyclic Photophosphorylation
Light is absorbed by photosystem I and passed to the photosystem I primary pigment (P700)
An electron in the primary pigment molecule (ie. the chlorophyll molecule) is excited to a higher energy level and is emitted from the chlorophyll molecule in a process known as photoactivation
This excited electron is captured by an electron acceptor, transported via a chain of electron carriers known as an electron transport chain before being passed back to the chlorophyll molecule in photosystem I (hence: cyclic)
As electrons pass through the electron transport chain they provide energy to transport protons (H+) from the stroma to the thylakoid lumen via a proton pump
A build-up of protons in the thylakoid lumen can then be used to drive the synthesis of ATP from ADP and an inorganic phosphate group (Pi) by the process of chemiosmosis
Chemiosmosis is the movement of chemicals (protons) down their concentration gradient, the energy released from this can be used by ATP synthase to synthesise ATP
The ATP then passes to the light-independent reactions
Non-Cyclic Photophosphorylation
Light is absorbed by photosystem II (located in the thylakoid membrane) and passed to the photosystem II primary pigment (P680)
An electron in the primary pigment molecule (ie. the chlorophyll molecule) is excited to a higher energy level and is emitted from the chlorophyll molecule in a process known as photoactivation
This excited electron is passed down a chain of electron carriers known as an electron transport chain, before being passed on to photosystem I
During this process to ATP is synthesised from ADP and an inorganic phosphate group (Pi) by the process of chemiosmosis
The ATP then passes to the light-independent reactions
Photosystem II contains a water-splitting enzyme called the oxygen-evolving complex which catalyses the breakdown (photolysis) of water by light:
H2O → 2H+ + 2e- + ½O2
As the excited electrons leave the primary pigment of photosystem II and are passed on to photosystem I, they are replaced by electrons from the photolysis of water
Photosystem I
At the same time as photoactivation of electrons in photosystem II, electrons in photosystem I also undergo photoactivation
The excited electrons from photosystem I also pass along an electron transport chain
These electrons combine with hydrogen ions (produced by the photolysis of water) and the carrier molecule NADP to give reduced NADP:
2H+ + 2e- + NADP → reduced NADP
The reduced NADP (NADPH) then passes to the light-independent reactions to be used in the synthesis of carbohydrate
calvin cycle produces
complex organic molecules including carbohydrates like starch cellulose and sucrose
3 steps of calvin cycle
Rubisco catalyses the fixation of carbon dioxide by combination with a molecule of ribulose bisphosphate (RuBP), a 5C compound, to yield two molecules of glycerate 3-phosphate (GP), a 3C compound
GP is reduced to triose phosphate (TP) in a reaction involving reduced NADP and ATP
RuBP is regenerated from TP in reactions that use ATP
Carbon fixation
Carbon dioxide combines with a five-carbon (5C) sugar known as ribulose bisphosphate (RuBP)
An enzyme called rubisco (ribulose bisphosphate carboxylase) catalyses this reaction
The resulting six-carbon (6C) compound is unstable and splits in two
This gives two molecules of a three-carbon (3C) compound known as glycerate 3-phosphate (GP)
The carbon dioxide has been ‘fixed’ (it has been removed from the external environment and has become part of the plant cell)
Glycerate 3-phosphate (GP) is not a carbohydrate but the next step in the Calvin cycle converts it into one
Reduction of glycerate 3-phosphate
Energy from ATP and hydrogen from reduced NADP – both produced during the light-dependent stage of photosynthesis – are used to reduce glycerate 3-phosphate (GP) to a phosphorylated three-carbon (3C) sugar known as triose phosphate (TP)
One-sixth of the triose phosphate (TP) molecules are used to produce useful organic molecules needed by the plant:
Triose phosphates can condense to become hexose phosphates (6C), which can be used to produce starch, sucrose or cellulose
Triose phosphates can be converted to glycerol and glycerate 3-phosphates to fatty acids, which join to form lipids for cell membranes
Triose phosphates can be used in the production of amino acids for protein synthesis
Regeneration of ribulose bisphosphate
Five-sixths of the triose phosphate (TP) molecules are used to regenerate ribulose bisphosphate (RuBP)
This process requires ATP
chlorpohyl a colour
yellow-green
chlorophyl b color
blue-green
carotenoids and color
beta carotene is orange
xanthophyll is yellow
absorption spectrum
shows absorbance of different wavelength
action spectrum
rate of photosynthesis of different waveelngths
membrane of chloroplast contains
pigments enzyems electron carriers
plasmids and photosynthsis
the dna codes for chlorplast proteins
use of atp in protein synthesis
unwinding dna
activating rna nucleoptides
making peptide bonds
moving ribosomes along mana
