aerobic respiration Flashcards
what are the four stages of aerobic respiration ?
1) glycolysis
2) link reaction
3) kreb cycle
4) oxidative phosphorlation
where does glycolysis , kreb cycle , link reaction , oxidatve phosphorlation take place ?
Glycolysis - cytoplasm
kreb cycle - Mitochondrial matrix
link reaction - Mitochondrial matrix
Oxidative phosphorlation -inner mitochondrial membrane
stage 1 - Glycolysis - what does it do?
makes pyruvate from glucose and its the first stage of both aerobic and anerobic respiration.
stage 1 - Glycolysis how does it do it ?
- Glucose(6c) is phosphorlated into hexose bisphosphate by adding two molecules of ATP ,this process also makes two molecules of ADP.
- Then hexose bisphosphate(6c) is split into 2 molecules of triose phosphate (2*3c)
- Triose phosphate is then oxidised(loses hydrogen) forming 2 reduced NAD, in this process 4 molecules of ADP are phosphorylated TO 4 ATP , however 2 of those atp are used again in the phospholation of glucose in the start. in this processs two molecules of pyruvate(3c) are also made.
stage 2 - Link reactiion- what does it do ?
coverts pyruvate into acetyl coenzyme A
stage 2 - how does it do it ?
- pyruvate is decarboxylated (one carbon atom is removed from pyruvate)forming co2.
- Nad is reduced to nadh -(it collects hydrogen from pyruvate) changing pyruvate to acetate.
- Acetate is then combined with coenzyme A to form acetyl coenzyme A (acetyl coA).
- No ATP is reduced in this reaction.
*2Pyruvate + 2Nad –>2 Acetate + 2co2 + 2nadh
*
2Acetate +2 co2 + 2nadh+ 2coenzyme A —>
2Acetylcoenzyme A + 2co2 + 2nadh
how many times does a link reaction occur for every glucose molecule ?
two times for every glucose molecule so there are two of each product formed so, 2 acetylcoenzyme a , 2 co2, 2nadh
Stage 3- kreb cycle - what does it do ?
produces coenzyme A and ATP
Stage 3 - kreb cycle - how does it do it ?
- the acetyl group(2c) from acetyl coenzyme (produced in the link reaction) combines with oxaloacetate (4c) to form Citrate (6c) this process is synthesised by enzyme Citrate synthase. - coenzyme A goes back to link reaction to be used again.
- The 6 C citrate molecule is converted to a 5 C molecule , decarboxylation occurs and co2 is removed. – denhydration also occurs where hydrogen is removed and Nad is produced from Nadh (reduced Nad ).
- the 5 carbon molecule is then converted into a 4 C molecule - decarboxylation and dehydration happens that produces one molecule of fad , 2 molecules of reduced nad and 1 molecule of co2.
- Atp is produced by the direct transfer pf phosphate group from an intermediate compound to ADP. when a phosphate group is directly transferred from one molecule of anothert its substrate level phosphorlation. Citate has now been converted again to oxaloacetate .
what are the products of kreb cycle ?
1 coenzyme A - reused in the link reaction
- 2 co2 - released as a waste product
- oxaloacetate- reused in the next kreb cycle
- 1 Atp - used for energy
- 3 reduced NAD - to oxidative phosphorylation
- 1 reduced FAD- to oxidative phosphorylation
whats substrate level phosphorylation?
when a phosphate group is directly transferred from one molecule to another .
stage 4 : oxidative phosphorylation - what does it do ?
produces lots of ATP . its a process where energy is carried by electrons, from reduced enzymes (reduced Nad and reduced FAD) is used to make ATP.
- protons are pumped across the inner mitochondrial membrane.
Stage 4 : oxidative phosphorylation , how does it do it ?
- -Hydrogen atoms are released from reducede Nad and reduced Fad as they are being oxidised to NAD and FAD .
- the hydrogen atom then splits into protons (H+) and electrons.
- the electrons move along the electronb transport chain (made up of electron carriers ) and loose energy at each carrier. (the electron transport chain is located into inner mitochondrial membrane , the membrane is folded into cristae , which increases surfcae area tio maximise respiration
- the energy lost from electrons is used by the electron carriers to pump protons from tyhe mitochondrial matrix into the intermembrane space ( the space between the inner and outer mitochondrial membrane)
- the concentration of proton is now higher in the innerspace membrane than in the mitochonfdrial matrix - this forms a electrochemical gradient ( a concentration gradient of ions )
- Protons move down the electrochemical gradient, back into the mitochondrial matrix, via atp synthase. this movement drives the synthesis of atp from asp and phosphate.
- this process of atp production is driven by the movement of h+ ions across a membrane due to electron transport chain- this is called chemiosmosis
- in the mitochondrial matrix, at the end of the transport chain, the protons , electrons and o2 combine to form water. oxygen is said to be the final electron acceptor.
- in this process a total of 32 atp are made from one glucose molecule.
whats a respiratory quotient??
volume of co2 released/ volume of o2 consumed
what are the different energy levels of and the different substrates
carbohydrate- 15.8
lipids-39.4
proteins- 17.0
different respiratory substrates release different amount of energy when respired. lipids have the highest energy level value because most atp is made in oxidative phosphorylation and requires hurdogen atoms from reduced nad and reduced fad . this means that the respiratory subrate (lipids) contain more hydrogen atoms per unit of mass cause more atp to be produced as respired.
