respiration Flashcards
energy required for life processes is derived from
oxidation of macromolecules
organisms which can produce their own food
green plants and cyanobacteria
chemical energy derived from light energy by photosynthesis is stored in
bonds of carbohydrate, glucose, starch
only containing __ photosynthesize
chloroplast
chloroplasts are located in
superficial layers
why does food have to be translocated to different parts of plants
all non green parts of plants also require food for oxidation
saprophytes are dependent on
dead and decaying matter
ultimately all food that is respired for l life processes comes from
photosynthesis
what is cellular respiration
mechanism of breakdown of food materials for release of energy and storage of this energy for synthesis of atp
breakdown of complex molecules for release of energy occurs in
cytoplasm and mitochondria only in eukaryotes
what is respiration
breaking of carbon carbon bond of complex compounds through oxidation within the cells for the release of energy
compounds oxidised during respiration are called
respiratory substrate
preferred respiratory substrate
carbohydrate
floating respiration
fats or carbohydrate
protoplasmiic respiration
protein
when are compounds other than carbohydrates used as respiratory substrate
in some plants under certain conditions
how is the energy released in the cell after oxidation
in a series of slow step wise reactions controlled by enzymes and stored as chemical energy as atp
can energy released by oxidation by used directly
no only indirectly by synthesising atp which is broken down when it needs to be utilised
maximum energy is released by
fats
instant source of energy
carbohydrate
what is the energy currency of cell
atp
carbon skeleton produced during respiration is used as
precursor for biosynthesis or other molecules in cell
plants have a system which ensures
availablity of o2
plants have no
special organs for gaseous exchange
what do plants have as structures for respiration
stomata, lenticels
1st reason why plants get along without respiratory organs
each plant part takes care of its own gaseous exchange, there is very little transport of gases from one part of plant to another
2nd reason
plants do not have great need for gas exchange, roots, stems and leaves respire at rates far slower than animals, only during photosynthesis large volumes of gas is required, availablity of o2 is not a problem as o2 is released inside the cell
3rd reason
distances that plants must diffuse in large bulky plants is not much each living cell in a plant is located quite close to the surface of plant
arrangement of living cells in stems
organised in thin layers inside and beneath bark with openings called lenticels
cells in the interior of stem
are dead and provide mechanical support
most cells of a plant have
atleast a part of their surface in contact with air
which tissue provides an interconnected network of air spaces
loose parenchyma cells in leaves, stems and roots
the complete combustion of glucose gives out
co2, h20, and energy which i is given out as heat
how does plant make sure that all energy liberated does not turn into heart after catabolizing a glucose molecule
oxidise glucose in multiple steps, enabling some steps to be large enough such that the energy l liberated can be coupled to atp synthesis
all living organisms retain the enzymatic machinery to
partially oxidise glucose without help of oxygen
the scheme of glycolysis was given by
embden, meyerhof, parnas emp pathway
in anaerobic organism the only process of respiration
emp pathway
where does glycolysis occur
cytoplasm present in all living organisms
in glycolysis glucose undergoes
partial oxidation into 2 molecules of pyruvic acid
in plants glucose is derived from
sucrose, end product is photosynthesis or from storage carbohydrates
all enzymes of glycolysis are found in
cytoplasm
sucrose is converted into glucose and fructose by enzymes
invertase
which monosaccharides enters the glycolic pathway
fructose and glucose
glucose and fructose are phosphorylated to form
glucose6 phosphate by use of 1 atp in the presence of enzyme hexokinase
glucose 6 phosphate is converted into
fructose1,6 phosphate in the presence of enzyme isomerase
fructose1,6 phosphate is converted into
fructose 1,6 biphosphate by use of 1 atp in the presence of enzyme phosphofructokinase
how many steps are there in glycolysis
10 enzyme controlled steps
fructose 1,6 biphosphate is split into
phosphoglyceraldehyde , dihydroxy acetone phosphate in the presence of enzymes aldolase
phosphoglyceraldehyde is covered into
1,3 biphosphoglyceric by reduction of nad to nadh2, in presence of enzymes pga dehydrogenase
1,3 biphosphoglyceric acid is converted into
3 phosphoglyceric acid by formation of atp in presence of enzymes bga kinase
3 phosphoglyceric acid is converted into
2 phosphoglyceric acid in p presence of enzymes mutase
2 phosphoglyceric acid is converted into
phosphoenolpyruvate in o presence of enzymes enolase
pep is converted into
pyruvic Acid by formation of 1 atp in presence of enzyme pepkinase
what is the product of glycolysis
pyruvic Acid
what are the ways pyruvic acid is used
alcoholic fermentation, lactic acid fermentation, aerobic respiration
fermentation takes place under
anaerobic conditions in many prokaryotes and unicellular eukaryotes
for the complete oxidation of glucose, organisms adopt
krebs cycle which is carried as aerobic respiration which requires o2 supply
in fermentation, by yeast oxidation of glucose is achieved under anaerobic conditions where pa is converted into
co2 and ethanol
which enzymes catalyse fermentation
pa decarboxylase, alcohol dehydrogenase
organisms like bacteria produce
lactic acid from pa
in muscles when o2 is insufficient pa is
reduced to lactic acid by lactate dehydrogenase, reducing agent nadh2
in both lactic acid and alcohol fermentation
not much energy is released, less than 7 percent of energy in glucose is released
lactic acid and alcohol fermentation are ___
hazardous in nature
yeast poison themselves to death when concentration of alcohol reaches
13 percent
aerobic respiration is most common in
higher plants
for aerobic respiration, pa is transported to
mitochondria
what is link reaction
link between glycolysis and krebs cycle
site of link reaction
Matrix of mitochondria
in link reaction pa undergoes
oxidative decarboxylation
reactions catalysed by pa dehydrogenase require participation of
coA and NAD
the acetyl coA produced by link reaction enters
krebs cycle or tca cycle
tca cycle starts with the
condensation of acetyl group with oaa and water
first product of tca
Citric acid
condensation of acetyl group is facilitated by enzymes
citrate synthase
citrate is isomerized to form; enzym3
isocitrate ; aconitase
isocitrate decarboxylases to form
alpha keto glutaric acid, nad reduces to nadh2, enzyme is isocitrate dehydrogenase, co2 is removed
alpha keto glutaric acid changes to
succinyl coA, nad is reduced to nadh2, co2 is removed, enzyme is Substrate dehydrogenase
succinyl coA change to
succinic acid, gtp is formed, enzyme is thiokinase
succinuc acid changes to
funeric acid, fad changes to fadh2, enzyme is succinic acid dehydrogenase
succinic acid changes to
fumeric acid, enzyme is
fumeric acid changes to
malic acid enzyme is fumerase
malate changes to
oaa , fad changes to fadh2, enzyme is malate dehydrogenase
all enzymes of krebs cycles are found in ; except
Matrix of mitochondria except succinic dehydrogenase which is found in imm
steps in which energy stored in nadh2 and fadh2 is utilised and released
electron transport system
when is electron transport system accomplished
when nadh2 and fadh2 are oxidised through ets and electron are passed to oxygen resulting in formation of h20
the metabolic pathway through which the electrons pass from one electron carrier to another is called
electron transport system/oxidative phosphorylation
ets occurrs in
inner mitochondrial membrane
electron from nadh are produced where in tca
Matrix of mitochondria
in ets electron from nadh are
oxidised by nadh dehydrogenase age electrons are transferred to ubiquinone
in ets ubiquinone also receives
reducing equivalents from fadh2 that is generated during oxidation of succinic acid in tca
the reduced ubiquinone is
then oxidised with further transfer of electrons to cytochrome c by complex cytochrome bc complex
what is cytochrome c
small protein attached to outer side of the immm , acts as a mobile electron carrier by between 3 and 4 complex
complex 4 is
cytochrome a,a3 cytochrome c oxidase complex with 2 copper centres
when electrons pass from one carrier to another via complex 1 to 4 in the ets they are
coupled to atp synthase(complex 5) for production of atp from adp and inorganic phosphate
although the aerobic process of respiration takes places only in presence of oxygen in ets the role of oxygen
its limited to the terminal stage o of the process
the presence of oxygen is vital in ets because
it drives the process by removing hydrogen from the system
what is the final hydrogen acceptor in ets
oxygen
how is a proton gradient made in ets
by energy of oxidation reduction
energy released in during electron transfer in ets is utilised in
the synthesis of atp
f1 headpiece of atp synthase
peripheral membrane protein complex, contains site for synthesis of atp from adp and ip
f0 of atp synthase
integral membrane protein complex, forms the channel through which protons enter the inner membrane
the passage of proton through the channel is coupled to
catalytic site of f1 component
for each atp produced
4H pass from f0 from ims to matrix down there electrochemical gradient
under what assumptions can calculations of atp be made
there is a sequential orderly pathway , with one substrate forming after another and with glycolysis, tca and ets following ones after another
nadh synthesized in glycolysis is transferred to mitochondria for oxidative phosphorylation
none of the intermediates are utilised to synthesize another compound
only glucose is being required no other substrates enter the pathway
in fermentation, nadh is oxidised rather
slowly
what is the favoured substrate for respiration
glucose
all carbohydrates are usually first converted into
glucose
do substrate other than glucose enter the pathway at c the first step
no
fats need to be broken down into
fatty acids and glycerol
proteins are converted into
amino acids
glycerol would enter the pathway after being converted to
pgal
proteins would be degraded by
proteases and individual amino acids after deamination would enter the pathway at some stage within the krebs cycle as pyruvate or acetly coa
when organisms need to synthesize fatty acid
amino acids would be withdrawn from the pathway
respiratory pathway can be considered a
amphibolic pathway
ratio of volume of co2 evolved to the volume of o2 consumed is called
respiratory quotient
respiratory quotient depends on
type of substrate used
for carbohydrate rq is
1
when fats are used rq is
less than 1
when proteins are used rq is
0.9
in living organisms respiratory substrate are often
more than one
are pure proteins and fats used as respiratory substrates
no
one atp yields
34kJ/mol
total energy obtained from 38 atp is
1292kJ/mol
how much energy does glucose store
2870kj/mol
efficiency of respiration
45%:- 1292/2870×100
rq for organic acids
more than one
rq for oxalic acid
4
rq for malic acid
1.33
for anaerobic respiration
infinity
can acetly coa be considered a high energy molecule
yes
