C12: Energy & Respiration Flashcards
list 5 reasons why energy is needed in living organisms
- anabolic reactions such as DNA replication and protein synthesis
- active transport through protein pumps
- movement eg muscle contraction
- maintenance of body temp
- formation and secretion of substances
state the structural makeup of ATP
Adenine+Ribose=Adenosine (nucleoside)
Adenosine+3 phosphate groups= Adenosine Triphosphate (nucleotide)
ATP moves via what process
Facilitated diffusion
what features make ATP suitable to be the universal energy currency
- small and water soluble; easy and fast to transport via FD
- unstable and reactive; easily hydrolysed
- high energy release; considerable for its size
- rapid turnover; broken and made equally fast
Reduction _ energy and such a reaction is called _
absorbs
endergonic
Oxidation _ energy and such a reaction is called _
releases
exergonic
which of an oxidised and reduced subtance has more energy
the reduced one
what is dehydrogenation
removal of Hydrogen in the presense of the enzyme dehydrogenase
what is respiration in general terms
taking in O2 and releasing CO2
=>glucose/fats/proteins +O2—>CO2+H2O+Energy in form of ATP
what is cellular respiration
controlled transfer of energy from organic compounds to ATP
why does respiration happen in a series of small steps
- precise control
- allows cell to use small amounts of energy rather than all at once
- glucose cannot be oxidised at once as it is stable and has a high activation energy
summarise the key stages of aerobic respiration
- glycolysis (glucose to pyruvate)
- link reaction (pyruvate to acetyl coenzyme)
- krebs cycle (acetyl coenzyme to CO2)
- electron transport chain + oxidative phorphorylation (H+ removed from above ions are used by ETC to reduce oxygen to water, and produce ATP)
what is glycolysis and where does it happen
breakdown of glucose
cytoplasm
describe the steps of glycolysis
- 6C glucose phosphorylated by ATP to produce (glucose phosphate which is isomerised to) fructose phosphate. Reacts once again with ATP to form 1,6 fructose bisphosphate
- this then splits into 2 molecules of 3C triose phosphate
- these are oxidised by NAD to lose 2H. hence forming 2 pyruvate
- also the phosphate from each is lost to the previous ADP to yield some ATP; this is called Substrate Level Phosphorylation. The 2NAD is reduced to 2NADH
glucose has high activation energy. how can it still be broken down and form ATP
- lower it by using enzymes
- increase energy of glucose by phosphorylation
chemical potenial energy is in form of _
C-H bonds
site of the link reaction
mitochondrial matrix
describe the link reaction
- 2 molecules of pyruvate pass through the outer and inner mitochondrial membranes from the cytoplasm through active transport
- Oxidative Decarboxylation: NAD oxidses pyruvate by dehydogenating it, and pyruvate is also decarboylated to remove CO2 making it 2C acetate from 3C.
- COenzyme A is then added to give acetyl CoA
what is teh composition of CoA
- its a nucleoside composed of adenine+ribose
- and +vitamin called pantothenic acid
function of CoA
carrier of acetyl group to Krebs cycle
how can fat/lipid be used to make acetyl CoA
fatty acids from fat metabolism are broken down in mitochondria in cycles of 2c acetyl, which react with CoA
site of krebs cycle
mitochondrial matrix
define krebs cycle
pathway of enzyme controlled reactions
describe the events of the krebs cycle
- 2 acetyl CoA (from 2 pyruvate from glycolysis) combine with 2 of 4C oxaloacetate to form 6C citrate. called condensation.
- the CoA leaves the cycle
- citrate undergoes oxidative decarboxylation twice with 2NAD to give 4NADH and 4CO2 (oxidation is when NAD is reduced by/oxidised citrate by making it lose H)
- then a 4C compound undergoes substrate level phosphorylation to give 2ATP
- the 2 of 4C compound then undergo oxidative decarboxylation twice, once with 2FAD to give 2DAFH2, and once again with 2NAD to give 2NADH
importance of the krebs cycle
helps in the release of hydrogen in the form of NADH and FADH2 which can be used in oxidative phosphorylation to provide to make ATP
state the importance of electron transport chain/ oxidative phosphorylation
- energy for phosphorylation of ADP to ATP comes from this
- NADH and FADH2 from glyc,krebs,link donate their electrons to the ETC to make ATP
location of oxidative phosphorylation
cistae of inner mitochondrial membrane
state what happens in complex 1 of the ETC
- dehydrogenase enzyme removes H from NADH (from krebs) and splits the H to a H+ proton and an e-
- e- is transferred to a high energy level electron carrier from where it goes to the next one in the series, which is of a lower energy level, releasing energy in the process
- this energy activates a proton pump and H+ moved from matrix to intermembrane space, building up a conc/proton gradient (high in intmem space)
describe what happens in complex 2 of the ETC
-dehydrogenase enzyme removes H from FADH2 (from krebs) and splits the H to a H+ proton and an e-
summarise what happens in complexes 3 and 4 of the ETC
-e- from complexes 1 and 2 undergo a series of jumps/redox reactions from higher to lower energy level electron carriers and release energy, which is used to pump H+ into the intmem space
what happens after complex 4
- due to the proton conc gradient H+ move down it and back into the matrix from the intmem space via protein channels which have an enzymatic part called ATP synthase, which catalyses ATP conversion from ADP+Pi along with the energy from the H+ movement
- H+ + 1/2 O2 + e- —-> H2O
what is the theoretical yield of the ETC in terms of ATP produced and why is the real yield different
1NADH gives 3ATP 1FADH2 gives 2ATP however 25% of total energy is used to transport ADP and Pi into mitochondria and ATP out hence 1NADH gives 2.5ATP and 1FADH2 gives 1.5ATP
what is the relevance of the O2 in aerobic respiration
- acts as the final electron acceptor coming from the ETC
- combines with H+ and e- in ATP synthase
2 ways organic compounds can be used
- building blocks for making other organic molecules
- represent chemical energy which ca be released by breaking the molecules
describe NAD structure
nicotinamide adenine dinucleotide
-has 2 nucleotides: 1 is ribose+adenine+phosphate, other is ribose+nicotinamide ring+phosphate
what does the nicotinamide ring do
accept H+ AND 2e- (accepts and loses electrons therefor acts as coenzyme)
function of NAD
coenzyme by acting as a hydrogen carrier molecule
2 forms of NAD
NAD+ oxidising agent (accepts e-)
NADH reducing agent (donated e-)
state the equation relating the 2 forms of NAD
NAD+ + 2H+ + 2e- —> NADH + H+
what is NADP
nicotinamide adenine dinucleotide phosphate
=has phosphate group instead of hydrogen on c2 hydroxyl of one of the ribose rings and is used as hydrogen carrier in photosynthesis
NADH full form
nicotinamide adenine dinucleotide hydrogenase
what is FAD structure
flavin adenine dinucleotide
-made of 2 nucleotides: one of phosphate+ribose+adenine, other of phosphate+linear ribitol
function of FAD
acts as coenzyme by acting as hydrogen carrier
equation for FAD
FAD + 2H+ + 2e- —> FADH2
FADH2 full form
flavin adenine dinucleotide dehydrogenase
define the term coenzyme
an organic compound required by enzymes for its catalytic activity. it is either vitamin or a derivative of vitamins.
(note: it can act as a catalyst in the absense of enzymes as welll but that would be less efficient)
balance sheet of aerobic respiration (ATP net gain)
-glycolysis=2 (+2NADH)
-link=0 (+2NADH)
-krebs=2 (+6NADH and 2FADH2)
-oxi phor: (10NADH * 2.5) + (2FADH2 * 1.5) = 28
Total=32
structure+function of ATP synthase
3 binding sites:
1) binding ADP and Pi
2) forming tightly bound ATP
3) releasing ATP
- gamma subunit rotates as 3H+ pass through making 1ATP
what is chemiosmosis
ATP generation using electrical potential energy, which comes from the transfer of electrons in the ETC
what is the electron transport chain
transfer of electrons from NADH and FADH2 via a series of higly specific membrane bound protein carrier molecules (embedded in cristae) in order to release energy and set up an electrical/conc gradient
mitochondria have their own 70s ribosomes and dna thus they can
create thier own proteins
what is anaerobic resp
breakdown of glucose in absense of oxygen
the 2 NADH from glycolysis are removed by what 2 methods when there is anaerobic resp
alcoholic and lactic fermentation
why is the amount of energy produced in anerobic resp less
- when there is no oxygen hydorgen cant be disposed of as there is no o2 to combine with
- therefore the proton gradient is lost and so the ETC stops working and no further ATP is formed by oxi phor
- as the ETC stops NADH and FADH2 accumulate in the matrix, this has an effect on the link reaction and krebs cycle- they also stop
- the only continuing pathway is glycolysis hence only 2ATP
- but even after these 2ATP form a cell must pass on the hydrogens from the NADH from glycolysis instead of just dumping them- which will stop even this pathway by not recycling NAD
describe the alcoholic pathway
- pyruvate is decarboxylated to ethanal
- ethanal is reduced to ethanol by enzyme alcohol dehydrogenase by accepting 2H from NADH
which type of fermentation is reversible and which is not
- lactic is
- alcohol is irreversible
describe the lactic pathway
- pyruvate accepts 2H from NADH and is coverted to lactate
- catalysed by the enzyme lactate dehydrogenase
what is the H/e- acceptor in aerobic and anaerobic resp
aero- O2
anaero- ethanal or pyruvate
effect of lactate accumulation?
muscle cramps
oxygen debt
how is the lactate pathway reversed
-when o2 is available lactate may be converted back to pyruvate (which can enter krebs etc)- enzyme lactate dehydrogenase catalyses this reversal- such as when carried to liver by blood plasma which converts some of the lactate inot co2+h2o and the remainder into glycogen.
explain the graph of time against oxygen uptake of a person before during and after excercise
- before its low and flat as theyre absorbing steadily
- more o2 needed as ex starts to support aerobic however this takes a few min for heart and lungs to meet this demand and thus due to lactic fermentation create an o2 deficit
- then enough o2 is supplied
- after wards they breathe deeply and inhale at higher rate to pay the o2 debt
high volume of oxygen after excercise is needed to
- convert lactate to glycogen in liver
- reoxygenate haemoglobin
- high metabolic rate as organs are operating above rest levels
RQ value of carbohydrates eg glucose
1.0
RQ value of fats/lipids
0.7
RQ value of proteins
0.9
order of energy values per 100g of basic foods
fats
carbs
proteins
why do lipids transfer more energy than carbs or like why do they have the highest energy value
- most energy liberated in aerobic respiration comes from oxidation of hydrogen to water when NADH and FADH2 are passed in the ETC
- hence more the no of hydrogens in substrate structure more energy released cos more NADHs and FADH2s
- hence greater energy value per unit mass aka energy density
proteins can act as supplementary energy store when in excess but first must be _ before safe respiration
deaminated
define the respiratory quotient
-ratio of volume of co2 produced to volume of o2 used in given time
what does rq even mean
indicates which substrate is prioritised eg more H means more energy needed to respire
rq > 1 means
when above 1 it means some anaerobic respiration is taking place
rq values for the 2 anaerobic resp types
- alcoholic: infinity as o2 (which we divide the co2 produced by) is 0
- lactic: 0 as no co2 made
where do lactic and alcoholic resp happen
alcoholic- yeast and plants
lactic- mammalian muscles
how can rq be less than infinity for yeast
some aerobic resp is happening
from where are NAD and FAD derived
nad- niacin aka vitamin-B
fad- riboflavin
define a cofactor
a non protein, either inorganic metallic ion, or a complex organic molecule ie coenzyme, chemical compound required for enzyme activity
define energy density
energy value for a respiratory per unit mass
order of energy densities
lipid>protein>carb
state swamp conditions (where most plants cannot grow)
- roots submerged in water
- soil has saptotropic bacteria aka decomposers therefore all o2 used up in the waterlogged soil
state the requirements of rice
-o2 for aerobic resp as ATP is needed for high metabolic activity of roots which manufacture essential amino acids
-ions from soil (get via roots active transport)
-
3 adaptations of rice
aerenchyma tissue
anaerobic resp
extra growth
explain how aerenchyma make rice better adapted to their environment
- roots, stems, leaves have large interconnecting air spaces
- allow oxygen diffusion to the root `which is deep in, because gas diffuses faster in air than in water
explain how anaerobic resp makes rice better adapted to their environment
- via alcoholic fermentation
- rice cells can tolerate much higher alcohol levels due to the presense of a greater no of alcohol dehydrogenase enzymes
explain how extra growth makes rice better adapted to their environment
-tall so leaves are above and gas exchange can happen through stomata
what controls rice extra growth
ethylene a plant growth substance controls and stimulates pruduction of gibberllin, which stimulates cell division and elongation
describe how the effect of temp on rate of respiration can be investigated
use different yeast solutions mixed with DCPIP or methylene blue- these are the redox indicators and turn from blue to colorless when oxidised- and heat over range of temp using a water bath and record time taken for color change
in the experiment of effect of temp on respiration why is the mixture topped with oil
prevents entry and dissolving of oxygen in air which can reoxidise the DCPIP
in the experiment of effect of temp on respiration what are the controlled independant and dependant variables
controlled- vol+conc of yeast, vol of oil
indep- temp
dep- time for decolisation
describe how the effect of temp on rate of respiration of germinating seeds/small invertebrate can be investigated USING a simple respirator
organism in chamber alters gas vol. soda lime absorbs CO2 therefore only oxygen intake changed the vol. colored drop in capillary tube moves which can be used to calculate the change in vol
limitations of simple respirometer
atmospheric pressure may affect
temp may be altered cos of touching
how is differential respirometer used to get more reliable results
-manometer connected to chamber and it cancels out equal external pressure on both sides
-temp kept constant using thermostatically controlled water bath
-
why does temp affect rate of resp
respiration enzymes are proteins and denature
how does differential respirometer work
- soda lime absorbs co2 but changes in oxygen affect manometer level making it either rise or fall on one arm
- then syringe is adjusted so manometers bpth arms are at an equal level and vol of o2 used is read off graduated syringe
how to measure RQ value using a respirometer
exp 1: o2 vol taken in found for some temp as x
exp2: co2 vol released found for same temp by not using soda lime
- when o2=co2 RQ=1
- when co2 > o2 then vol of air increases by y. hence x+y/x
- when co2 < o2 then vol of air decreases by z. hence x-z/x
controlled, dep and indep variables in experiment of effect of temp on rate of respiration of germinating seeds/small invertebrate USING a simple respirator
controlled- mass of invertrebrate, amount of soda lime, pressure
indep- temp
dep- rate of resp
rate of resp of organism =
distance travlled by drop or mercury in manometer / time
