Unit 2: metabolic processes Flashcards
single sugars
saccharide
double sugars
disaccharide
glucose has an explosive amount of what
potential energy
What is ATP
a usable form of energy for the cell
mitochondria are:
- small, bean shaped
- have their own DNA and Ribosomes- tought to have originated from bacteria (endosymbiotic theroy)
- 2 membranes- inner and outer
- inner has many folds called cristae
- space between the 2 membrane is called intermembranous space
- its function is to convert food energy into usable energy
what enzyme is requird for cellular resp
ATP synthase
the conversion of glucose to ATP requires
a series of chemical reactions
cellular resp equation
C6H12O6 + 6O2 -> 6CO2 + 6H2 + ATP
glycolysis where does it occur
cytoplasm
where does the krebs cycle occur
matrix of the mitochondrion
where does the electron transport chain occur
inner membrane of the mitochondrion (cristae)
NADH & FADH2
important energy carrier molecules involved in cellular resp
2 ways of ATP is made
1) substrate level phosphorylation - simple
2) oxidative phosphorylation - complex
describe substrate level phosphorylation
- involves the generation of ATP directly in an enzyme catalyzed reaction whereby a phosphate contaning compound transfers a’ phosphate group to ADP.
- the formation of ATP is endergonic and it is coupled with an exergonic reaction
- the release of energy from the exergonic reaction is greater than the energy needed for the generation of ATP
describe oxidative phosphorylation
- ATP is generated by a diffusion force similar to osmosis
- it is performed by transmembrane channels that pump protons from one side of a membrane to another
- proton pumping proteins use excited eelctrons to induce shape changes in the transmembrane proteins
-these shape changes “spit” out the protons on the other side of the membrane - proton concentration on one side of the membrane becomes high (compared to the other side)
protons are driven down the concentration gradient by diffusion - protons pass through special membrane channels that use their passage and energy to change ADP and one inorganic phosphate into ATP
why is oxidative phosphorylation reffered to as oxidative phosphorylation
oxygen is the final acceptor of the excited electrons that help establish the concentration gradient of H+
most basic way of generating ATP
substrate level phosphorylation
majority of ATP is produced by
oxidative phosphorylation
wher do the electrons that drive the protein pumping channels come from
chemical bonds
light energy
chemical bonds
- this occurs in all organisms
- high energy electrons are extracted from chemical bonds and carried to the proton pumps
light
-occurs in photosynthetic organisms
- light energy excites electrons and they move to higher energy levels, which are used to drivee the proton pumps
ATP is a type of
nucleic acid
photosynthesis makes
glucose
cellular resp breaks/uses
glucose
hydrolysis
addition of H20 to split a large molecule into smaller components .
ex. sucrose + water -> glucose + water
condensation (dehydration)
produces H20 as smaller components are joned to form larger ones .
Ex. glucose + glucose -> maltose + water
decarboxylation
a carboxyl group is lost , giving off CO2 and H+
Ex. COOH -> CO2 + H+
oxidation
a molecule loses electrons and hydrogen ions
reduction
a molecule gains electrons and hydrogen ions
glycolysis occurs in
cytoplasm
in glycolysis how many oxidations occur
one
overall chemical equation of glycolysis
C6H1206 + 2ADP + 2Pi -> 2 Pyruvate + 2 ATP + 2 NADH + 2H+
9 steps of glycolysis
step 1: glucose is phosphorylated by transferring a phosphate from ATP to produce glucose-6-phosphate
step 2: isomerase rearranges glucose-6-phosphate to fructose-6-phosphate
step 3: another phosphate group is added (taken from an ATP) to make fructiose 1, 6- diphosphate
step 4: enzyme aldolase cleaves glucose into 2 molecules of glyceraldehyde-3-phosphate (known as G3P or PGAL)
everything below occurs twice
step 5: G3P is oxidized, forming NADH
- an inorganic phosphate is added to G3P to produce 1, 3-diphosphoglycerate
step 6: substrate level phosphorylation of 1, 3-diphosphoglycerate to produce ATP from ADP. left with 3-phosphoglycerate
step 7: relocation of the phosphate group to form 2-phosphoglycerate
(mutase reaction)
step 8: removal of water to form phosphoenopyruvate
step 9: substrate level phosphorylation. the remaining phosphate group is removed and transferred to ADP to make ATP.
Final product of glycolysis
PYRUVATE
Whats produced at the end of glycolysis
4 ATP produced and 2 ATP used = 2 ATP net
2 NADH produced
2 pyruvate
whats pyruvate oxidation
the little side step before Krebs cycle
pyruvate oxidation chemical equation
2 pyruvate + 2NAD+ + 2COA -> acetylCOA + 2NADH + 2H+ + 2CO2
what happens in pyruvate oxidation
- pyruvate from glycolysis enters the matrix
- one carbon atom is removed through decarboxylation
hydrogen is removed using NAD+ - COA attached to remaining carbon atoms,creating Acetyl-COA
9 steps of the Krebs cycle
(x2 per molecule of glucose)
step 1: oxaloacetic acid (4C) combines with the acetyl (2C) group of Acetyl COA to form citric acid (6C)
step 2a: condensation following by hydrolysis to facillitate an..
step 2b: isomerization(6C)
step 3: redox reaction - isocitric acid (6C) is oxidized
- NAD is reduced to NADH
step 4: decarboxylation (6C) molecules loses a CO2 to form a (5C) molecule
step 5:redox reaction - NAD reduced to NADH
decarboxylation - 5e to 4e
step 6: substrate level phoshorylation ADP + Pi-> ATP
Step 7: redox reaction - FAD is reduced to FADH2
step 8: hydrolysis
step 9: redox reaction -4C malic acid is oxidized to reform oxaloacetic acid, NAD reduced to NADH
Summary of Krebs cycle
Per 1 glucose molecule
- 6NADH
- 2 FADH2
- 2 ATP
Overall chemical equation for Krebs Cycle
Oxaloacetic acid + acetylCOA + ADP + Pi+3NAD +FAD ->COA + ATP +3NADH + FADH2 + 4CO2 +oxaloacetic acid
Where does electron transport chain take place
- Along the Cristae of the inner mitochondrial membrane
What does ETC consist of
3 protein complexes and 2 mobile electron carriers (ubiquinone (Q) and cytochrome c (c)) arranged in order of increasing electronrgativity
Greater electronegativity=
Greater attraction for electrons
Explain what happens in ETC
- The complexes are alternately reduced (as the electrons are accepted) and then oxidized(as the electrons are lost or passed along go the next component of the chain)
- this electron transport is highly endothermic and the free energy released is used to pump protons (H+) into the inter membranous space from the matrix
- NADH passes it’s 3 electrons to the first protein complex and this can move 6 H+ in total
- FADH2 passes it’s 2 electrons to the second component in the chain( ubiquinone) and thus only move 4H+
- NADH molecules produced in glycolysis must be moved into the mitochondrial matrix from the cytoplasm via a shuttle and the shuttle transfers the electrons to a molecule of FAD. Which is reduced to FADH2 and thus only moves 4H+
- oxygen is the final acceptor of the electrons that have passed through the ETC
- oxygen strips the 2 electrons from the last protein complex along with 2 H+ floating in the matrix to form water
- this stage of cellular respiration is aerobic since it’s dependant in the presence of oxygen
fermentation
a process in which hydrogen atoms of NADH are transerred to organic compounds other than an ETC.
2 types of fermentation
ethanol and lactic acid
explain ethanol fermentation
- after glycolysis occurs, the pyruvate moleules lose a carbon molecule creating ACETALDEHYDE
- the carbon atoms combine with oxygen to create CO2
- acetaldehyde receives a hydrogen from NADH, resulting in the production of ethanol
explain Lactic acid fermentation
- Afe glycolysis occurs, the 2 pyruvate molecules receive hydrogen atoms from
- lactate can be converted back into pyruvate in the liver
- the pyruvate can then enter the Krebs cycle and cellular respiration can proceed
photosynthesis general equation
6CO2 + 6H2O + light energy -> C6H12O6 + 6O2
all of the worlds oxygen is produced by what
photosynthesis
what can photosynthesize
plants, some bacteria, and some protist(algae)
light energy is converted to what
the energy of chemcial bonds within chloroplasts
where does photosyntheiss occur
chloroplast which contains a pigment called chlorophyll
2 steps for photosyntheiss
1) light reactions: part 1 and 2 (AKA ELECTRON TRANSPORT SYSTEM)
2) Dark reaction/ light independent reaction(AKA CALVIN CYCLE)
light reaction part 1 main goal
capturing light energy
light reaction part 2 main goal
make ATP and NADPH
calvin cycle main goal
carbon fixation
most photosytnheiss occurs in
leaves of plants
the clear ___ layer on leaves allow __ to pass througth the __cells where ___photosytnhesis takes place and where __ chlorophyll are found
1- epidermis
2- light
3- mesophyll
4- most
5- most
photosyntheis occurs partly in the
stroma and wthin the thylakoid membrane of chlorophast
guard cells do what
create tiny openings called stomata that regulate exchange of CO2 and O2 and allow H2O vapour to transpire.
what happens to guard cells when K+ moves across the membrane
guard cells swell and stoma opens
what also opens stoma
decrease in CO2
what happens to guard cells when K+ diffuses out
guard cells becomes flaccid and stoma closes
what also closes stoma
decrease of sucrose
what evens out the change of K+
H+ proton pump actively pumping out H+
what stimulates an influx of k+
light and this causes stoma to mostly open in day and closes at night
light is a form of what and how does it travel
energy that travels in wave packets called photon
whats embedded in thylakoid membrane and what do they absorb and do
photosynthetic pigments and absorb photons of certain wavelengths and through the light reactions these transfer their energy to ADP, Pi, and NADP+(which from ATP and NADPH…the H+ comes from from water molecules)
different pigments of what absorb what
chlorophyll- a and b
chlorophyll a does what
transfers the energy of light to the 3rd stage- the calvin cycle
chlorophyll b and the carotenoids do what
transfer their energy to chlorophyll a
where does light reaction occur
across the thylakoid membrane and in the thylakoid space of a chloroplast
what do electrons do when it interacts wtith a photon
molecules gain energy and is called excitation
what happens to electrons after they are xcited
they are released from the double bonds in the porphin ring
plants use what to produce NADPH and ATP
Photosystems I and II and this is called noncyclic electron flow and photophosphorylation
what happens first when a photon strikes pigment molecules in photosysrem II(P680)
it excites an electron that, thorugh a series of redox reactions, is transfered to PQ(Plastoquinone)
z proteins do what
splits water into oxyygen, hydrogen ions and electrons
what happens to oxygen at end of photoexcitation
oxygen leaves the cell and the H+ remains in the thylakoid space
what is noncyclic electron flow
the process in which photon-energized electrons form from water to NADP+ this process produces NADPH by reduction
why is it called noncyclic
once an electron is lost by a reaction centre, it does nt reutrn to the same reaction centre, but ends up as NADPH
what happens in photophosphorylation
ATP is prduced by chemiosmosis(uses electrochemical gradient and ATP synthase like in ETC in cell resp.)
what is required for proton gradient to be made
light
what happens in cyclic electron flow
where an electron is ejected from photosystem I and is passed back to help generate the proton gradient in phosphorylation (but never used to make NADPH)
what happens to the NADPH and ATP produced
goes on to calvin cycle
where does the calvin cycle occur
stroma of chloroplasts
phase 1 of calvin cycle cycle
carbon fixation
what happens in phase 1: carbon fixation
- 3 molecules of CO2 combine with ribulose biphosphate (RuBP) with the help of the enzyme rubisco
- this forms into an unstable compound that plits to form 6 molcules of 3-phosphoglycerate(PGA)
- these PGA combine witg phosphate groups from ATP to form six 1,3-biphosphoglycerate (1, 3BPG)
one of the most important enzymes to exist
rubisco
phase 2 of calvin cycle
reduction reaction
what happens in the secod phase of calvin ccle
- 1,3,BPG is reduced using NADPH to form glyceraldehyde 3-phosphate(B3P)
- one G3P leaves the cycle and is later used to form glucose (or stored as starch), while the other 5 continue through
phase 3 of calvin cycle
regeration of RuBP
what happens in phase 3 of calvin cycle
- the 5 G3P go through a series of reactions to become RuBP which is then used to fix more CO2.
- 3 ATP are used in one turn of the cycle to fix one CO2(so 9 ATP needed for 3CO2)
- as tge cycle continues the G3P that leaves is used to make larger sugars
overall chem equation per one tunr of the calvin cycle
3RuBP+ 3CO2 + 9ATP + 6NADPH + 5H2O -> 9ADP + 8Pi+ 6NADP + G3P + 3 RuBP
photorespiration
the alternative method of photosynthesis
what causes photorespiration
the active site of rubisco accepting O2 which acts as a competitor inhibitor instead of CO2, and if O2 binds to rubisco it decreases the amount of carbohydrates that can be produced.
what conditions facilitate photorespiration
hot,dry, bright days
what happens to the plant during hot dry and bright days
stomata closes to conserve water thus decreases the amount of CO2 inside the leaf
the light reaction of photosynthesis continues so O2 levels begin to build inside the leaf.
where doe C3 fixation occur
soybeans, rice,wheat, oats and sunflowers
what temperature region does C3 fixation occur
mainly in temperate region
C4 plants what type of plants
sugar cane, corn and many grasses
wha do C4 plants seperate
the location where carbon fixation and the calvin cycle occur
SPARTIAL SEPERATION
C4 plants contain 2 types of photosythetic cells
bundle sheath cells surrounded by mesophyll cells
mesophyll cells contain an enzyme called
PEP carboxylase that incorporates CO2 into molecules of Cu organic acids
how do organic acids travel
via plasmadesmats from the mesophyll cells to the bundle sheath cells where they are decarboxylation and the CO2 is free to enter the Calvin cycle
what do C4 plants strategy ensure
that the concentration of CO2 in the bunle sheath cells where the cxalvin cycvlr is always kept high
what type of plants ar CAM plants
water storing plantssuch as cacti anf pineapple
wat do cam plants do
seperate the time of day carbon fixation and calvin cycle occur
TEMPORAL SEPERATION
cam plants are the reverse of what
other plants as stomata open during the night and close during the day
cam plants take in what at night
CO2 and incorporates them into C4 organic acids using PEP carboxylase which are stored in vacuoles until morning.
what happens when stomata plants closes during the day
these organic acids release CO2 to allow calvin ctcle to occur
the main idea of cam plants
they store CO2 at night and uses them during the day
