Photosynthesis And Respiration Flashcards
Equation
6CO2 + 6H2O —> C6H12O6+6O2
Autotrophs
Plants and algae are able to carry out photosynthesis and you simple inorganic molecules to synthesise complex organic molecules energy is obtained from light
Heterotrophs
Animals and fungi organisms which obtain organic molecules by digesting and absorbing complex organic molecules
The organic molecules are used for growth and respiration
LDR where
Thylakoid membrane
LIR where
Stroma
Thylakoid
Site if LDR
contain photo systems/ photosynthetic pigments
Granum
Stacks of thylakoid
Stack to maximise likelihood of light striking photosynthetic pigments
Stroma
Site of LIR
Contain enzyme ls
Starch grain
Stores products of photosynthesis as starch
Ribosome
Site of protein synthesis for chloroplast
DNA
Carries genes coding for protein/enzymes found in the chloroplasts
Membrane
Enclose stroma and separate contents from cytoplasm
Control passage of substances in and out of the chloroplast
4 types of photosynthetic pigments
Chlorophyll A
Chlorophyll B
Carotene
Xanthopyll
Action spectrum
Rate of photosynthesis at each wavelength
Photosystems
Where photosynthetic pigment molecules are arranged in clusters in the thylakoids membrane
Accessory pigment
Carotenoids
Around the primary pigment and absorb light energy and pass the energy from one to another and then onto the primary pigment
Primary pigment
Chlorophyll A
Reaction centres were electrons are excited to higher energy levels during LDR
Redox reactions
Involve oxidation and reduction
Occur during photosynthesis
OILRIG
Co enzymes
4
Molecules that aid the function of an enzyme
Usually work by transferring a chemical from one molecule to another
Photosynthesis = NADP
Transfers hydrogens in the form of ions from one molecule to another
Light dependant reaction
5
Excitation and photoionisation
Photolysis of water
Non cyclic phosphorylation
Chemiosmosis
Cyclic phosphorylation
Excitation and photoionisation
LDR
4
Rection requires light energy which is absorbed by the chlorophyll and other photosynthetic pigments present in photo systems
The light energy causes the excitation of electrons in the chlorophyll and results in the electrons having more energy and being released from the chlorophyll molecule
The chlorophyll molecule is oxidised and becomes more positively charged
An electron acceptor gains the electron and becomes reduced
Non cyclic phosphorylation
2
PSII and PSI are linked through a series of protein electron carriers in the thylakoid membranes forming an electron transport chain
Excited electrons lost from PSII are passed through the series of electron carriers to PSI, as they do so the electrons lose energy and this energy is used to add a phosphate to ADP to form ATP and reduce the coenzyme NADP to reduced NADP
Chemiosmosis
4
As the electrons flow down the electron transport chain from PSII to PSI some of the energy is used to transport proteins into the thylakoid space
This produces a proton gradient and the protons move down their concentration gradient into the stroma through the enzyme ATP synthase, which is in the thylakoid membrane
The energy from the movement is coupled to combining ADP and inorganic phosphate
Cyclic photophosphorylation
3
Doesnt involve PSII
Electrons from the chlorophyll molecule are passed through photo system I to
produce ATP but no reduced NADP
Light independent reaction
ATP and reduced NADP produced in the light dependent reaction are used to reduce carbon dioxide into carbohydrate
The reactions were first discovered by a scientist called Melvin Calvin so is called Calvin cycle
Three reactions in LIR
Carbon dioxide fixation
Formation of TP from GP
Regeneration of RuBP
Carbon dioxide fixation
LIR
CO2 molecules enter through the stomata and diffuse into the stroma of the chloroplast it then combines with a five carbon compound called ribulose biphosphate to form two molecules of a three carbon compound called glycerate 3 phosphate
The enzyme catalysing the reaction is Rubisco
Formation of TP from GP
LIR
The GP is the reduced by NADPH to a 3C compound called TP
2 ATP are required as a source of energy
The NADPH and ATP have been produced by all the light dependant reaction
Some GP is used to synthesise amino acids the plant would also require a source of nitrogen and sulphur
Regeneration of RuBP
LIR
5/6th of all TP formed is used to regenerate the RuBP so that the cycle can continue
1/6th of all TP formed is used to produce organic compounds for the plant such as glucose, cellulose lipids
To produce a hexose sugar such as glucose 6x cycles would be required. Therefore a total of 6CO2 , 18ATP and 12 NADPH would be needed
Effect of carbon dioxide concentration on light independent intermediates
When the concentration of carbon dioxide is reduced then less is available to react with RuBP and therefore less GP and TP are formed and the levels of RuBP increase
Effect of light intensity on levels of light independent intermediates
When light is removed the light dependant reactions cannot take place and consequently there is no ATP or NADPH available for the reduction of GP to TP therefore the concentration of GP rises but the concentration of TP and RuBP falls
Effect of temperature on levels of light independent intermediates
As the temperature increases the rate of the reactions increases but the relative levels of the intermediates are i unchanged
However at higher temperatures oxygen competes with carbon dioxide for the rubisco enzyme and so less carbon dioxide is fixed
The level of RuBP rises and the levels of GP and TP fall
Results in photo respiration
At very high temp rubisco enzyme may denature
Increasing plant growth
Agricultural growers can ensure that they provide an environment where plants get the right amount of everything they need to maximise the rates of photosynthesis and therefore increase plant growth and therefore yield
Growers create optimum conditions in glasshouse
Carbon dioxide concentration
Use a propane burner to increase CO2 in the air
Glasshouse
Growers create optimum conditions in glasshouse
Light
Light passes through the glass and fluorescent lighting can be used at night
Growers create optimum conditions in glasshouse
Temperature
Glasshouse can trap heat energy from sunlight which increases the temperature
Heaters can be used to increase the temperature and cooling systems and air vents to decrease the temperature
Compensation point
The light intensity where the rate of photosynthesis exactly equals the rate of respiration and there is no net gas exchange in or out of the plant
Thin layer chromatography
Mobile phase= solvent
Stationary phase= TLC
Rf
Distance travelled by spot/
distance travelled by solvent front
DCPIP
acts as an electron acceptor and gets reduced and there’s a colour change
Respiration is
The process where cells break down glucose go produce ATP from glucose
Aerobic respiration
Requires oxygen and fully breaks down glucose to produce carbon dioxide, water and many ATP. It involves mitochondria
Anaerobic respiration
Does not require oxygen and glucose is not fully broken down
In animals lactate is produced and in plants and yeast ethanol and carbon dioxide
ATP is
3
The immediate source of energy in a cell
A cell is unable to directly get energy from glucose
Therefore the energy released from glucose in respiration is used to produce ATP from ADP and Pi in a condensation reaction
ATP
The energy is stored
5
Short term
As chemical energy in the phosphate bond and ATP synthase is the enzyme that catalysés the reaction
ATP is then used to carry the energy to where it is required where it can be hydrolysed back to ADP and Pi releasing the energy from the phosphate bind which supplies the energy required for the process
The enzyme used from this reaction is called ATP hydrolase
ATP
Uses/ properties
5
Only real ease small manageable amounts of energy
Small, soluble easily transported and broken down inside cells, cannot pass out of cell, can be re made
Used to transfer phosphates to other chemicals, known as phosphorylation
Rapidly hydrolysed to releasable energy
Easily resunthesised using energy from the breakdown of respiratory sub strates eg glucose
Coenzymes
Molecules that some enzymes require in order to function
Play an important role in photosynthesis and respiration
4 co enzyme examples
NAD I’works with dehydrogenase enzymes in glycolysis, link reaction, Krebs cycle and carries hydrogens from one molecule to another
FAD involves in Krebs cycle
Coenzyme A in link reaction and Lrebs
NADP involves in the LDR and LIR of photosynthesis
Structure of mitochondria
4
Inner folded membrane of a mitochondrion forms the Cristae
Embedded in the membrane is a series of electron carriers forming the electron transport chain
The membrane also contains ATP synthase which look like stalked particles
Both of these are involved in oxidative phosphorylation
Metabolically active cells will have
High numbers of mitochondrial to synthesise large amount of ATP by oxidative phosphorylation
Matrix
Role
Interior of the mitochondrion
Where enzymes for the link reaction and Krebs cycle are
Cristae
Role
Highly folded inner membrane provides a large SA
The membrane contains enzymes and proteins involved in oxidative phosphorylation
These include those that make up the electron transport chain and also ATP synthase
ATP synthase
Hydrogen ions can move by facilitated diffusion through the Chanel in the ATP synthase
This movement is coupled to the synthesis
Outer membrane
Quite permeable contains porins that allows small molecules to pass through slowly
Anabolic reactions
Metabolic reactions which build large molecules from small
Catabolic reactions
Metabolic reactions that hydrolyse large molecules into small
Phosphorylation
The addition of a phosphate group to a molecule
Dephosporylation
The loss of a phosphate group from a molecule
Decarboxylation
Loss of a carbon dioxide from a molecule
Reduction
Gain of hydrogen/ electrons
Oxidation
Loss of hydrogen/ electrons
Substrate level phosphorylation
Producing ATP by addition of a phosphate group in the krebs cycle and glycolysis
Oxidative phosphorylation
Producing ATP using a gradient of hydrogen ions
Dehydrogenation
The loss of hydrogen atoms from a molecule
Aerobic respiration 4 stages
Glycolysis
The link reaction
The Krebs cycle
Oxidative phosphorylation
Glycolysis in cytoplasm
5+2
Phosphorylation; glucose is phosphorylated using just the phosphate from the ADP to form glucose phosphate and ADP.
ATP is the used to add another phosphate to form hexose biphosphate.
Hexose biphosphate then splits into two molecules of triose phosphate
Oxidation; triose phosphate is oxidised to form two molecules pyruvate .
NAD is a coenzyme that is used with dehydrogenase enzymes that accepts the hydrogens to become reduced NAD .
Reduced NAD will be used later in oxidative phosphorylation to synthesise more ATP.
Net gain of 2 ATP
Pyruvate are then actively transported into the matrix for the link reaction
The link reaction in matrix
3
Decarboxylation and oxidation; pyruvate 3C is decarboxylated to produce carbon dioxide and oxidised to produce reduced NAD and acetate
The acetate then combines with coenzyme A to form acetyl coenzyme A
For every glucose molecule, 2CO2 2 reduced NAD and 2 acetyl coenzyme As produced. No ATP
Krebs cycle in matrix
5+2
Acetyl coenzyme A enters the Krebs cycle and combine with a 4C compound called oxaloacetate to form a 6C intermediate called citrate and co enzyme A whic can be reused
The 6C intermediate is then decarboxylated and oxidised to form CO2 and reduced NAD and a 5C intermediate
The 5C intermediate is then decarboxylated and oxidised to form reduced NAD and reduced FAD.ATP is also synthesised from ADP ad Pi. This is known as substrate level phosphorylation . The intermediate is oxidised further to form more red NAD and the 4C oxaloacetate is then regenerated so the cycle can continue.
Intermediates can also be used by cells in he manufacture of other substances such as fatty acids and amino acids
For every glucose, cycle occurs twice as two acetyl coA are produced. For every glucose,2CO2,6 reduced NAD 2 reduced FAD
Oxidative phosphorylation
7
- Hydrogen atoms are released from the reduced NAD and FAD. The hydrogen atoms split into protons and electrons.
- The electrons pass through the electron carriers in the electron transfer chain in a series of redox reactions.
- As the electrons move along the chain they lose energy which is used to pump protons(H+) from the mitochondrial matrix into the inter membrane space between the inner and outer membranes of the mitochondria.
- This forms an electrochemical gradient. There are now more protons in the inter membrane space than in the mitochondrial matrix.
- The protons then move down the electrochemical gradient from the inter membrane space back into the mitochondrial matrix through the ATP synthase which is embedded in the membrane.
- The flow of the H+ through the ATP synthase drives the synthesis of ATP from ADP and Pi. The process of ATP production linked to the flow of electrons and production of the H+ gradient is known as chemiosmotic theory
- At the end of the electron transport chain, the protons electrons combine with oxygen, the final electron acceptor to form water.
Anaerobic respiration
Does not require the presence of oxygen
Takes place in the cytoplasm and doesn’t require the presence of mitochondria
Glycolysis takes place in the cytoplasm followed by additional stages
Glucose is not completely broken down which results in less ATP (2) compared to aerobic
Alcoholic fermentation
In plants and yeast
Carbon dioxide is produced to produce ethanol.
Hydrogens from reduced NAD are then used to reduce ethanal and produce ethanol
Consequently NAD is regenerated so it can be used again so glycolysis can continue, as the reduced NAD will not be able to enter oxidative phosphorylation, as there will be no oxygen as the final electron acceptor.
Irreversible
Lactate fermentation
In animals and some bacteria
Hydrogens from reduced NAD are then used to reduce pyruvate to produce lactate.
Consequently NAD is regenerated so it can be used again in glycolysis.
Reversible and after exercise lactate can be converted back to pyruvate and then either respires aerobically to produce ATP or convert back to glucose.
3 respiratory substrate
Carbohydrate
Lipid
Protein
RESPIRATION EXPERIMENTS
LEARN
