Respiration + Photosynthesis Flashcards
why is respiration needed?
- growth - building larger molecules from smaller ones
eg. make new organelles or biomass - movement - muscle contraction
- keeping warm - birds + mammals use a lot of e for keeping warm and lose it to environment
- active transport - plants use it to absorb nitrates from soil
equation for respiration
C6,H12,O6 + 6O2 —> 6Co2 + 6H2O + ATP
4 stages in aerobic respiration + where they take place
- glycolysis - cytoplasm
- link reaction - matrix in mitochondria
- krebs cycle - matrix in mitochondria
- oxidative phosphorylation - cristae in mitochondria
what happens if mitochondria is isolated
respiration cant occur as 1st step is glycolysis and occurs in cytoplasm
what is a coenzyme + give examples
molecule aiding functioning of an enzyme by transferring a chemical group from one molecule to another
NAD + FAD transfer H
coenzyme A transfers acetate
NADP transfer H
explain glycolysis
anaerobic process
makes pyruvate from glucose
1. phosphorylation of glucose to glucose phosphate, then again to hexose biphosphate
- Pi comes from ATP molecules (2)
- bond unstable so splits into 2 triose phosphate
2. oxidation
- NAD molecules come and oxidise triose phosphates by taking a H, becomes reduced itself - NADH.
- forms 2 pyruvates
products of glycolysis + where they go
- 4x ATP , but 2 used in phosphorylation so net gain of 2
- 2x NADH - go to stage 4
- 2x pyruvate, go to matrix by active transport for link
explain link reaction
converts pyruvate to acetyl coenzyme A
- pyruvate is decarboxylated
- pyruvate is oxidised to acetate by NAD
- NAD reduced to NADH
- acetate + Coenzyme A –> acetyl CoA
products of link reaction + where they go
2x acetyl CoA
2x CO2 as waste
2x NADH to stage 4
explain krebs cycle
produces reduced CoA + ATP
series of redox reactions
- acetyl CoA combines with oxaloacetate to make citrate
- CoA goes back to stage 2
- decarboxylation + dehydrogenation occurs to make 5C. H is used to make NADH
- decarboxylation + dehydrogenation occur again to make 4C, release 1x FADH and 2x NADH
-ATP is produced by substrate - level phosphorylation.
products of 1 krebs cycle + where they go
- 1x CoA, reused in link
- oxloacetate, regenerated for next cycle
- 2x CO2, waste
- 1x ATP for energy
- 3x NADH, go to stage 4
- 1x FADH, go to stage 4
explain oxidative phosphorylation
1) H released from NADH + FADH and split into H+ and e-
2) e-s travel down electron transport chain, losing energy at each level
3) energy lost used to pump H+ to intermembrane space(ims) from mmatrix
4) electrochemical gradient is formed cuz ↑er conc of H+ in ims than mmatrix
5) H+ go ↓ ecg across inner mitochondrial membrane + back in membrane via ATP synthase (in IMmembrane). this movement drives synthesis of ATP from ADP+Pi (chemiosmosis)
6) at end of transport chain in mmatrix,
H+ + e- + O2 (from blood) –> H2O
O2 =final electron acceptor
work out total ATP produced in aerobic respiration
glycolysis - 2xATP , 2xNADH - 2 + (2.5 x 2) = 7 link reaction - 2xNADH - 2 x 2.5 = 5 krebs cycle - 2xATP , 6xNADH , 2xFADH - 2 + (6x2.5) + (2x1.5) = 20
7 + 5 + 20 = 32 total ATP
anaerobic respiration
alcoholic fermentation + lactate fermentation
alcoholic fermentation - plants + yeast
1) glycolysis
2) pyruvate –> ethanal + CO2
3) ethanal –> ethanol + NAD (from NADH)
lactate fermentation - animal cells + some bacteria
1) glycolysis
2) pyruvate –> lactate + NAD (from NADH)
how many ATP are made from 1 FADH?
1.5
what is a electrochemical gradient
conc gradient of ions
what is a electrochemical gradient
conc gradient of ions
name 2 types of anaerobic respiration
lactate fermentation
alcoholic fermentation
how does glycolysis continue in lack of O2?
regeneration of oxidised NAD, so at least a small amount of ATP can be produced to keep biological processes continuing
equation for photosynthesis
6CO2 + 6H2O + energy —> C6,H12,O6 + 6O2
what are metabolic pathways
processes occurring in series of small enzyme controlled reactions
eg photosynthesis + respiration
properties of ATP making it good energy source
6 things
- stores or releases small manageable amounts of E at a time so no E wasted as heat
- easily broken down - immediate E release
- quickly remade
- small + soluble so easily transported around cell
- can phosphorylate other molecules
- cant pass out of cell, so always there as E supply
ATPs role
- carries E around cell released from glucose since it cant get it directly from it
- condensation reaction of ADP + Pi (+ATP synthase) using E from E releasing reaction - breakdown of glucose
- E stored as chemical E in P-P bond
- diffuses to area of cell needing E
- broken by hydrolysis using H2O and ATP hydrolase to release E from bond
compensation point
- plants carry out photosynthesis and respiration
- Cp is point where ROPhotosynthesis = RORespiration
- Cp for light intensity is the point where ROP = ROR at certain light intensity
where in cell does photosynthesis take place?
- describe structure of organelle
chloroplasts - small flattened organelles surrounded by double membrane
- thylakoids = fluid filled sacs , contain pps
- grana = structures of stacked thylakoids
- lamellae = bits of thylakoid linking grana
- stroma = gel like substance in inner membrane containing enzymes, sugars + organic acids
how are carbohydrates produced by photosynthesis stored
stored as starch grains in stroma
photosynthetic pigments (pp) + photosystems (ps)
- pp in thylakoid membranes, eg carotene and chlorophyll a + b
- coloured substances absorbing light E for photosynthesis
- pp attached to proteins
- pp + protein = ps
wavelength photosystem 1 absorbs light best at
700nm
- primary pigment is chlorophyll a
wavelength photosystem 2 absorbs light best at
680nm
- primary pigment is chlorophyll b
light dependent reaction (LDR)
- Chlorophyll in ps absorbs light energy
- Excites e-s which eventually get removed from chlorophyll molecule due to high E (photoionisation)
- e-s move along carriers in etc releasing E
- E used to join ADP and Pi to form ATP
- Photolysis of water produces protons, electrons and oxygen
- NADP reduced and carries H to LIR
what E from photoionisation is used for
- photophosphorylation (phosphorylation using molecule of light)
- making reduced NADP from NADP
- photolysis of water
non-cyclic photophosphorylation
- light E absorbed by psII, exciting e-s in chlorophyll which are removed from chlorophyll + move down etc to psI
- photoloysis of water (producing 2e- , 2H+ , 1/2O2) to replace e- lost from psII
- excited e-s lose E moving down etc, which is used to transport H+ into thylakoid from stroma so proton gradient along thylakoid membrane
- H+ move along gradient, driving synthesis of ATP from ADP + Pi + ATP synthase which is embedded in membrane
- light E absorbed by psI, exciting e-s to even higher E level + e- and H+ (from stroma) reduce NADP
- this process produces ATP, NADPH and O2
cyclic photophosphorylation
- no O2 or NADPH produced
- only produces small amount ATP
- e- from chlorophyll aren’t passed to NADP but back to psI via electron carriers
- electrons recycled + repeatedly flow through psI
light independent reaction
- in stroma
- doesn’t use light E directly, but uses products of LDR
- NADPH + ATP supply E and H to make glucose from CO2
1. CO2 enters leaf via stomata and diffuses to stroma
2. CO2 + ribulose biphosphate (rubp) –rubisco catalyst–> unstable 6c compound –> 2 x glycerate phosphate (gp)
3. hydrolysis of ATP from LDR provides E to reduce gp –> triose phosphate (tp)
using H+ from NADPH + oxidising to NADP
4. 5/6 tp used to regenerate rubp in cycle, using up rest of ATP from LDR
1/6 is converted to useful organic compounds like hexose sugars
hexose sugars
= 6c sugars eg glucose
- made from 2x tp
- can be used to make larger carbohydrates
- calvin cycle turns x6 to make 1 hexose since 3 turns makes 6 tp - only 1 will go towards being a hexose
what can gp and tp be used to make
- carbohydrates - made from joining 6cs together
eg cellulose, starch and sucrose - lipids - glycerol is made from tp + Fas (made from gp)
- amino acids - some made from gp
