Lecture 7 Flashcards
role of white and brown adipose tissue
white = stores E as fat
brown = burns fat to produce heat
in obesity, too much white adipose tissue builds up
in brown tissue, there is a protein called uncoupling protein 1, (UCP1) in the inner mb of mitochondria
disturbs H+ gradient and allows E released during e- transport to be in the form of heat, not ATP
energy extraction from the food molecules stages
- in the mouth and gut
- in the cytosol,
- in mitcondria
most common is glucose, others are converted to glucose of intermediate cmpds
E is found in chemical bonds of molecules
more in depth description of staes
- breakdown of large food molecules into simple subunits.
- breakdown of simple subunits to acetyl CoA
some ATP and NADH produced. - complete oxidation of acetyl grp to water and CO2, a lot fo ATP made in inner mb of mito.
glucose is oxidized in a controlled nad stepwise manner, why?
if direct burning of sugar, like in a non living system,
there is a large activation energy that needs to be overcome + all free energy is released as heat, none stored
in a living system, small consistent oxidation, small Ea overcome by enzymes that work at body temp
majority of free E is stored in E carriers (ATP and NADH), some heat
cells follow thermodynamics… 1.
E is
forms of E
2.
- E is not created or destroyed
E = capacity to cause change/do work
types =
kinetic = motion of objects
chemical = E available in molecules for release in a rxn
thermal = heat = random motion of atoms and molecs
potential E = E that matter has bc of its location/spatial arrangement
- disorder tends to inc
when useful E is dissipated as head
cells generate order, seems like defying the 2nd law, but they do so by inc the disorder of their surr.
Exergonic and endergonic, overview
2 types of chem rxns in cell
exergonic = exothermic = release E into surr
endogenic = endothermic = absorb E from surr
exergonic
energetically favourable rxns
P have less free E than R (so are more stable)
release free E (potential E) from chem bonds
consist of catabolic rxns = breaking down molecules
endergonic
energetically unfavourable
P have higher free E than R (P are less stable)
store energy in molecules made
Anabolic rxns = making small and large org molecs)
cell coupling
endergonic rnxs are unfavourable because need to absorb E to occur so can be coupled with an exergonic rxn that releases E to surr
catabolic RXN = releases 30.5 kJ,
anabolic rxn = needs 23 kJ,
excess 7.5kJ released as heat
only occur if they share one or more intermediates
Activated carrier
stores E released by exergonic rxns
most imp
ATP = adenosine triphosphate = 1 adenosine (nitrogenous base) + 1 ribose (sugar) + 3 phosphate grps
NADH
NADPH (in plants)
enzymes
act as catalysts, lower Ea
lowers E that must be put in for it to occur, make it faster and more possible
even E favourable rxns need Ea to get them started
redox rnx
allow E extraction from org molecs by gradual oxidation
transfer of E = transfer of e-
redox rxn = one substance transfers one or more e-s to another substance
reduction = gaining e
oxidation = losing e
reducing agent = reactant that loses e
oxidizing agent = reactant that gains e
three catabolic processes that harvest E from chem bonds in glucose
- glycolysis, anaerobic always
- cell resp, step after 1. if O2 is present
- fermentation, step after 1. if O2 is lacking
glycolysis, overview
glucose catabolism
glucose => 2 pyruvates + small amount of E
no O2
in cytoplasm
cell resp, overview
O2 from env
1 pyruvate to 3 CO2
includes pyruvate oxidation, citric acid cycle, oxidative phosphorylation (e transport chain, chemisomosis)
in mitochondria
fermentation, overview
no O2
converts pyruvate into lactic acid or ethanol (E rich molecs)
releases less E than cell resp
glycolysis pathway, fr now
10 enzyme catalysed rxns
3 phases,
- energy consuming phase (needs ATP)
- ATP is invested, made up for later - cleavage phase
- 6C molec to 2x 3C sugars - E releasing phase (produces ATP/NADH)
- for each 3C molec, 1 NADH is formed and 2 ATP,
total in this step = 2 NAdH + 4 ATP
- ends w 2x pyruvate
net result = 2 pyruvate + 2 ATP + 2 NADH
pyruvate oxidation
in mito matric
pyruvate is oxidized and undergoes decarboxylation result = 1x acetate molec ( 2C) and 1x CO2
acetate is bound to CoA = forms acetyl CoA
created 1 NADH, when pyruvate gets oxidized, NAD+ gets reduced
CO2 is waste, exhaled out.
total = 2 CO2 + 2 acetyl CoA for each glucose
citric acid cycle
8 reactions
acetyl CoA is the starting point of citric acid cycle
oxidized to 2 x CO2, (waste)
net result of one turn = 2 CO2, 3 NADH, 1 GTP, 1 FADH2
happens for each pyruvate = 4 CO2, 6 NADH, 2 GTP, 2 FADH2,
for each glucose molec
what have we made so far from 1 glucose molec
6 CO2 ( 4 from citric, 2 from pyruvate oxidation)
10 NADH (2 in glyco, 2 in pyruvate ox, 6 in citric)
2 FADH2 ( citric)
4 ATP (2 in glyco, 2 in citric)
oxidative phosphorylation
2 steps = e transport, chemiosmosis
produces ATP from E stored in NADH and FADH
e transport and chemiosmosis
- e from NADH and FADH2 pass through chain and create a proton conc gradient
- protons diffuse back to mito matrix and ATP is made
E transport in inner mb
as e- pass bn carriers
- portions are transferred from metric to inter mb space
- free E is released
- redox potential inc along the chain
ATP is produced during chemiosmosis
uses potential E stored in electrochemical grad of H+ to produce ATP
fermentation
ATP synth w/o Oxygen
NADH => NAD+
NAD+ goes back to glycolysis, plays a part in getting 2 more ATP
