the mitochondrion and energy Flashcards
main parts of the mitochondrion
matrix: internal space
inner membrane highly folded into cristae, outer membrane, enclosing inter membrane space
what is chemiosmotic coupling?
the process which links the electron transport chain to ATP synthesis
(2nd part of oxidative phosphorylation)
how does the e- transport chain work?
e- from the oxidation of food transferred down carriers in inner membrane (e-transp chain), releasing energy which pumps protons across the membrane, generating an electrochemical gradient
name the e- donor and e- acceptor in the e-transport chain
e- donor = NADH (as hydride ion => H+ and 2e-)
e- acceptor = oxygen (form water)
how does the electrochemical gradient generate ATP?
via catalyst ATP synthase, a mechanical rotary pump, driven by the proton motive force (memb potential + proton grad) across the inner membrane
define oxidative phosphorylation
e- transport chain + chemiosmosis
ratio of ATP:ADP in cells
10:!
high ratio maintained by mitochondria as ATP is moved out, ADP flows into the matrix
define catabolic / anabolic pathways
catabolic = break down foodstuffs into smaller molecules, generating energy and building blocks for the cell
anabolic = uses energy harnessed by catabolism to drive synthesis of molecules
How is NADH generated?
a product of the citric acid cycle
where does the citric acid cycle occur
in the matrix of the mitochondria
what does the mitochondria use for fuel ?
pyruvate (from glucose)
fatty acids (from fats)
both transported from the cytosol into the matrix for use in the CitA cycle
what type of reactions are central to metabolism?
redox
Gibbs energy equation
G = H - TS
H is enthalpy
T is temperature
S is entropy
how to interpret a Gibbs energy value
∆G < 0, energetically favourable, spontaneous
∆G>0, can only occur when coupled to a second energetically favourable reaction
at equilibrium, ∆G = 0
name some activated carrier molecules and their features
ATP, NADH, NADPH
energy rich covalent bonds
store energy in an easily exchangeable form
hydrolysed to release
(links energy from catabolism to energy provided for anabolism)
In ATP, which bond is broken in hydrolysis?
the high energy phosphate bond to produce ATP and Pi
define glycolysis and where it occurs
the process by which glucose is broken down to produce energy (pyruvate, ATP, NADH, H2O)
ANAEROBIC - no O2 involved
occurs in the cytosol of the cell
how is pyruvate from glycolysis converted to acetyl CoA?
pyruvate produced in cytosol transported to mitochondria
decarboxylated by pyruvate dehydrogenase complex
produces CO2, NADH, acetyl CoA
in aerobic organisms / conditions, how is ATP mostly generated?
by glycolysis (not O2 requiring)
pyruvate and NADH e- stay in cytosol.
also true in skeletal muscle when O2 is limited
fermentation energy definition
the extraction of energy from carbohydrates in the absence of O2
two ways energy storage in animals
store fatty acids as fat droplets of triacylglycerols
short term: sugar as glucose subunits stored in large branched polysaccharide glycogen
how is acetyl CoA produced
by the breakdown of glucose (glycolysis, converted from pyruvate) and the oxidation of fatty acids
oxidation of fatty acids in the mitochondria produces
acetyl CoA
NADH
FADH2
major products of the citric acid cycle
CO2 and high energy e- in the form of NADH
in starvation conditions, what happens to metabolism
amino acids are used to fuel ATP production
in excess conditions, what happens to metabolism
mitochondrion supply cytosol w excess citrate used for fatty acid synthesis and storage
