CH 9: Oxidative Phosphorylation, ATP yield, Fermentation

CH 9: Oxidative Phosphorylation, ATP yield, Fermentation

Describe the structure of the mitochondria

has an inner membrane (originally plasma membrane of protobacteria before endosymbiosis)

outer membrane result of phagocytosis

has cristae (inner membrane folds)

importance:

Intermembrane space (between inner and out membrane), (gaps in cristae) is where phosphorylation and chemiosmosis occurs

Mitochondrial Matrix: fluid in the mitochondria

directly in cristae is where the ECT is

Where is electron transport chain, what is its structure?

The ECT is located directly in the cristae (mitrochondria inner memrbane folds)

and is made up of several transmembrane proteins

each its own complex (ex. I, II, III, IV)

and proteins that move in-between complexes

How does the Electron Transport Chain work?

Complexes I, III, and IV takes in electron energy and uses it to move H+ protons from the mitochondrial matrix into the intermembrane space

Complex 1 takes electrons from NADH and that travels to III, and IV (by proteins)

proteins exist in multiprotein complexes

Complex II takes electrons from FADH2 and

then it travels to III, and IV (makes less ATP than NADH cos 2 vs 10)

After electrons are passed to Complex IV via a number of proteins they are given to O2,

one O will take electrons and join to form H2O

reducing the O

What happens to the electrons and Electron carriers in ECT

NADH and FADH2 alternate between an oxidized and reduced state as they accept and donate electrons to complexes in ECT

NADH - complex 1

FADH2 - complex 2

as electrons move down the ECT (thru each complex) they lose free (workable) energy

the energy lost powers the complexes proton pumps, bring H+ from matrix into inner membrane

the ECT does not directly produce ATP but releases energy in small manageable amounts which power a proton gradient

and this gradient powers atp synthesis

at the end electrons are give to O2 making H2O

What is the ECT’s function and why is it important

it breaks down the free (workable) energy (high energy electrons) from food (glucose) to O2, so it can be released in small manageable amounts

this

1. keeps the cell from getting damaged (if released all at once)

2. Gradual release of electrons also powers the proton pumps in ETC complexes which creates electrochemical gradient (H+ ions brought in) which powers chemiosmosis (makes ATP)

Recap what is Chemiomosis

the movement of protons across electrochemical gradient (membrane) to produce ATP

What is meant by Proton Motive force

the potential energy held in electrochemical gradient. (Stored energy that can do work if released)

this potential energy is caused by ETC because its electrons/redox reactions power proton pumps

and when energy is released from gradient it build ATP (ADP +Pi)

can create ATP without ATP synthase techincially

Define ATP Synthase and function

the enzyme complex of multiple protein subunits attached to inner membrane.

they help

protons go down their concentration gradient/diffuse (from higher to lower concentration) /

from intermembrane space to mitochondrial matrix through enzyme complex

and

these enzymes also help catalyze the conversion of ADP and Pi to ATP using energy from gradient

Is the inner membrane space (mitochondria) and mitrochondrial matrix acidic or basic?

the area that is more acidic has more H+ protons (will be the mitochondrial matrix since free floating)

innermembrane space will thus be more basic

Describe how ATP synthase structure helps it make ATP

a transmembrane enzyme protein

uses the release of H+ ions (exergonic)

to power Phosphorylation of ATP (adding Phosphate to ADP)

the release of protons will spin F0 unit (ridged cap)

which then spins the F1 unit (cashew looking)

which turns ADP + Pi into ATP

Why is ATP yield per glucose lower than what’s calculated

ATP yield per one glucose shows up as 38 but is 29 in realty because the proton gradient is used for processes aside from helping ATP production

Describe the sequence of energy flow in ETC/oxidative phosphorylation

Glucose

NADH

FADH

ETC: Proton Motive Force

(NADH: Complex 1 - III - IV
FADH2: Complex 2 - III - IV

Proton Pumps)

ATP

Last Electron to O2 - H2O

note: most energy moves to high energy electrons (electron transporters) not directly to ATP

What is Maximum ATP production

29 ATP

4 from substrate phosphorylation (2 for citric acid cycle, 2 from glycolysis)

25 from oxidative phosphorylation

Define Fermentation

a process which REGENERATES NAD from NADH to continue Glycolysis so it can continue producing 2 ATP per Glucose

uses substrate phosphorylation to produce ATP (anabolic pathway)

How is Glycolyisis related to fermentation

fermentation is a process which helps power Glycolysis and thus produces ATP from food without presence of O2

fermentation and Glycolysis are both anarobic and function without presence of O2

helps anerobic organisms get energy

in the absence of O2 Glycolysis couples with anerobic respiration / fermentation

Reactants of Fermentation/Glycolysis

Reactants:

Glucose, 2 ADP, 2 Pi, 2 NAD+

Differentiate between Fermentation and Anerobic Respiration

Anerobic respiraiton produces ATP using an Electron transport chain that substitutes O2 with a different electron acceptor (make water at end) ex. sulphate

While fermentation uses substrate phosphorylation to make ATP

What are the 2 types of Fermentation

Alcohol fermentation

Lactic Acid fermentation

depends on where electrons from NADH+ return

Lactic Acid fermentation

After glucose is spilt into pyruvate (glycolysis), the pyruvate takes electrons from NADH which reduces it to NAD+ and produces Lactic Acid

without releasing CO2

pyruvate is final electron acceptor

Use of Lactic acid

Dairy: makes yogurt, cheese

Muscles: when they undergo lack of oxygen (exercise causes lactic acid production to supply ATP to handle muscle contractions)

organisms: low oxygen intake or distribution

What is alcohol fermentation

when pyruvates are converted into ethanol in 2 steps

this helps make some ATP and also releases CO2

alcetyldehyde is the final electron acceptor

Use of alcohol fermentation

makes yeast

the Co2 can be used to make dough rise

ethanol used to produce beer + other liquors