Cellular Respiration Flashcards
goal of Cellular Respiration
goal is to make ATP by breaking down glucose
Redox reactions-
oxidation-reduction reactions in which there is a transfer of 1+ electrons from one reactant to another
Oxidation
loss of electron (greater positive charge)
Reduction
addition of electron (greater negative charge)
Oxidation and reduction always…
goes together
4 stages: Cellular Respiration
Glycolysis Formation of acetyl coA Citric Acid cycle (Krebs cycle) Electron transport chain and oxidative phosphorylation
lyse
break apart
Respiration
exchanges energy found in glucose for ATP
How many molecules of ATP are formed for each molecule of glucose?
between 36 and 38 molecules of ATP are formed
Glycolysis
splitting of glucose, in cytoplasm; 10 steps (each with own enzyme), two phases (Energy investment phase + Energy payoff phase)
Energy investment phase
cell uses 2 ATP
Energy payoff phase-
substrate level phosphorylation (onto ADP to produce ATP
phosphorylation–
adding a phosphate group
substrate level phosphorylation ( Energy payoff phase)
enzyme transfers P group to ADP forming ATP by using energy from the breakdown of a compound/substrate (here glucose)
i
inorganic
Pi
inorganic phosphate
Glycolysis–Net Glucose
2 pyruvate
Glycolysis–Net 2 ADP + 2 Pi
2 ATP from SLP
Glycolysis–Net 2 NAD+
picks up H+ + e- = 2NADH
coenzyme
type of cofactor, nec for enzyme to do their job
NAD+ (nicotinamide adenine dinucleotide)
is a coenzyme that can accept H+ ions and electrons becoming NADH
electron transport chain
NADH can later transfer electrons to oxygen in a series of steps called the electron transport chain, helping an enzyme form ATP
Glycolysis occurs whether or not O2 is present- but if it is present….
energy stored in NADH can becan be further released from glucose
Prestep–krebs cycle
formation of acetyl coA
Krebs cycle
releases the energy (GET FINISH); Takes place within mitochondrial matrix; For each pyruvate (of the two produced)- enters the mitochondrial matrix, where it’s converted to molecules called acetyl CoA.
mitochondrial matrix
inner fluid part of the mitochondria
What 3 things happen during formation of acetyl coA?
Carboxyl group on pyruvate is removed and given off as CO2; Electrons are extracted from remaining 2 carbon molecules, forming acetate (electrons and H+ ions join NAD+ to form NADH) Coenzyme A attaches to acetyl, forming acetyl CoA
acetate
acetyl
What happens to the 2-Carbon acetate in acetyl CoA?
joins the 4-C oxaloacetate (last product of the cycle) to form the 6-C citrate which goes through many steps eventually reforming oxaloacetate
Products of KC (assuming 2 pyruvate molecules enter):
4 CO2 (waste), 2 ATP, 6 NADH, 2FADH2
How are ATP formed during KC?
substrate level phosphorylation
How are NADH formed during KC?
cycle passes electrons to 6 NAD+
How are FADH2 formed during KC?
cycle passes electrons to 2 FAD
FADH2
also coenzyme that carries electrons and H+ ions also gonna help form ATP, but fewer than NADH
cristae
mitochondria’s inner membrane
Where does e-t chain take place?
collection of molecules embedded in the cristae
Where do the electrons in the e-t chain come from originally?
came from the original glucose, made it this far
Where do the electrons in the e-t chain enter from?
NADH and FADH2 FADH2 adds electrons at a lower energy level–generate fewer ATP molecules
What happens to the electrons in the e-t chain?
Electrons are then passed from one molecule to the next, slowly losing energy along the way. electrons will join H+ ions and O2 and form water O2 is the final electron acceptor. This makes no ATP directly- depends on chemiosmosis
Chemiosmosis
energy coupling mechanism that uses energy stored in the form of an H+ gradient (from the redox reactions) to drive the formation of ATP
ATP synthase-
enzyme that makes ATP. Works by using a proton gradient (ion gradient) as power source for generating ATP.
Where is ATP synthase?
In the inner membrane of mitochondria (after the electron transportchain) are many copies
mechanics of e-t chain/chemiosmosis
Electron transport chain uses the energy from falling electrons to pump H+ ions from the matrix to the intermembrane space, building up the proton gradient in that space (forms proton-motive force.) The protons then flow down their gradient through a special H+ channel in ATP synthase. Then OP happens.
Formation of acetyl coA net product
2NADH (which becomes 6ATP) OP
Krebs cycle net product
2ATP (SLP), 2FADH2(becomes 4ATP (OP)), 6NADH (becomes 18ATP(OP))
Electron transport chain, which drives oxidativephosphorylation net product
USES so negative (10NADH + 2FADH2)
total net product CR
32-34 ATP from OP + 4 from SLP total=36-38 ATP
oxidative phosphorylation
The ATP synthase harnesses the force to phosphorylate ADP, turning it into ATP
proton
H+ ion
Glycolysis total net products (SLP and OP)
2 NADH, which results in 4-6 ATP through OP (range bc may use some for transport of NADH) and 2 ATP from SLP
Complete oxidation of glucose
686 kcal/ mol
ATP stores…(#)
7.3 kcal/ mol
efficiency of respiration
40% (rest is lost as heat).
Fermentation
Extension of glycolysis that can generate 2 NADH and 2 ATP only by substrate level phosphorylation; Does not break down glucose fully; Only yields enough energy to sustain single celled organism
anaerobicrespiration
respiration w/o O2
aerobicrespiration
respiration with O2
- Glycolysis generates 2 ATP whether or not…
O2 is present
Why does NAD+ need to be regenerated?
there must be a sufficient supply of NAD+ to accept electrons from KC
Aerobic- how is NAD+ regenerated?
NAD+ is regenerated from NADH during electron transport chain
Anaerobic- how is NAD+ regenerated?
transfer electrons from NADH to pyruvate
Alcoholic fermentation
pyruvate is converted to ethanol. carried out by yeast and certain bacteria (this is how wine is made)
alcoholic fermentation process
pyruvate–>CO2 + acetaldehyde (intermediate compound here). Acetaldehyde + NADH–>ethanol=ethyl alcohol + NAD.
Lactic acid fermentation
pyruvate + NADH –> lactate + NAD+. Carried out by fungi and certain bacteria (this is how cheese/yogurt is made and food spoils). Also performed by muscle cells during strenuous exercise
Facultative anaerobes
organisms, such as yeast and bacteria (and our muscle cells), that can make ATP by both fermentation and respiration
Fate of electrons from NADH–aerobic respiration v fermentation
ar–electron transport chain; f–pyruvate
Final e- acceptor in e- transport chain–aerobic respiration v fermentation
ar–O2; f–N/A
Reduced product(s) formed–aerobic respiration v fermentation
ar–water; f–lactic acid or ethyl alcohol
Mechanism of ATP synthesis–aerobic respiration v fermentation
ar–oxidative + SL phosphorylation; f–just SLP
ATP formation–aerobic respiration v fermentation
ar–36-38; f–2
Phosphofructokinase
enzyme in glycolysis; pacemaker of respiration when active, more respiration, when inactive, respiration will stophigh levels of ATP inhibits
Carbohydrates taken in can be broken down into…
glucose to be used directly for respiration
Proteins can be broken down into…
amino acids and converted into intermediates of glycolysis and the krebs cycle
Fats can be broken down so that glycerol is converted to…
G3P (a glycolysis intermediate)fatty acids break down into acetate, entering there
substrate level =
get the energy by breaking down substrate or some compound
e-
electron
