Aerobic respiration

what store chemical energy

carbohydrates and fats

what are the stages of aerobic respiration

glycolysis

link reaction

krebs cycle

electron transfer chain

which stages need oxygen

link reaction

krebs cycle

electron transfer chain

where does glycolysis occur

cytoplasm of cell

what is glycolysis

carbohydrate splitting

occurs in aerobic and anaerobic respiration

what are the 2 stages of glycolysis

1. phosphorylation

2. oxidation

stage 1 of glycolysis- phosphorylation

1. glucose phosphorylated by adding 2 phosphates from 2 molecules of ATP

2. hydrolysed to 2x triose phosphate

stage 2 of glycolysis- oxidation

1. 4ATP produced yet 2 used in phosphorylation so net gain of 2 ATP

2. coenzyme NAD+ collects H+ and electrons forming 2 reduced NAD

3. triose phosphate oxidased forming 2 pyruvate molecules

what is oxidation

loss of electrons, H+ ions and energy

what is reduction

gain of electrons, H+ ions and energy

overall equation for glycolysis

glucose + 2ATP + 2NAD + H2O —> 2 pyruvate + 4ATP + 2NADH

what happens to pyruvate if oxygen present

link reaction

what happens to pyruvate if no oxygen present

anaerobic respiration

what does the link reaction do

link glycolysis to Krebs cycle

where does link reaction occur

matrix

what happens in link reaction

1. one carbon atom removed from pyruvate in form of CO2

2. remaining 2 carbon atom molecule combines with coenzyme A to form acetyl CoA

3. NAD+ collects more hydrogen ions forming reduced NAD (oxidised)

products of link reaction

2 CO2

2 reduced NAD

where does the krebs cycle occur

matrix of mitochondria

what is the krebs cycle also known as

citric cycle

what happens in krebs

1. acetyl CoA and 4C intermediate (oxoaloacetate) react to form citrate (6C), releases CoA

2. 6C molecule decarboxylated, releases CO2 produces 5C intermediate, again releases another CO2 to form 4C molecule. 6C and 5C also dehydrogenated and oxidised

3. electrons accepted by NAD and FAD

4. substrate level phosphorylation generates ATP

5. oxoaloacetate regenerated, cycle starts again

carbon chain numbers in krebs and the weird rhyme and the diagram

665 44444

DENA
DENA
A
FA
NA

products for one turn of krebs cycle

3 reduced NAD

1 ATP

1 reduced FAD

2 CO2

products for 1 glucose (2 turns of krebs cycle)

6 reduced NAD

2 ATP

2 reduced FAD

4 CO2

differences between NAD and FAD

• NAD accepts electrons in glycolysis, link reaction and krebs, FAD only accepts electrons in krebs

• NAD accepts 1 hydrogen, FAD accepts 2

where does oxidative phosphorylation (electron transfer chain) occur

cristae of inner mitochondrial membrane, utilises embedded proteins

how does ETC make ATP

from reduced NAD and FAD

process of ETC and Chemiosmosis

• reduced coenzyme (NADH/FADH2) carry H+ and electrons to electron transport chain

• electrons pass from one electron carrier to next in series of oxidation reactions

• protons (H+) move across inner mitochondrial matrix, creates high conc.

• H+ diffuse back into inner mitochondrial matric down electrochemical gradient

• H+ diffusion allows ATPase to catalyse ATP synthesis

• electrons pass to oxygen (final electron acceptor), combines with protons and electrons to form water

what happens if the supply of oxygen stops

ETC and ATP synthesis stops

why is oxygen important

• so H+ ions produced in glycolysis and krebs can be used to drive production of ATP, and then be converted to water

• divert pyruvate into aerobic respiration in mitochondria