C1.2- Cell respiration Flashcards
(29 cards)
What is ATP
Adenosine triphosphate is a nucleotide that provides activation energy for most chemical reactions in a cell
Composition of ATP
composed of adenine, ribose and 3 phosphates with high energy bonds in between.
The bonds between the last 2 phosphates are unstable and when broken release energy used for activation energy
Properties of ATP that make it ideal for cellular energy
- chemically stable (neutral PH does not break down when releasing energy)
- soluable in water (can diffuse freely in cytoplasm)
- cant diffuse through phospholipid bilayer (cant leak)
- can release a sufficient quantity of energy (sufficient for tasks but little is wasted)
- ATP can be easily regenerated by adding a third phosphate to ADP
Cellular processes requiring ATP
- active transport across membranes
2.systhesis of macromolecules (anabolism) - movement of whole cell by cilia or flagellum
- movement of cell components eg chromosomes in cell division
Conversion of ATP to ADP
:an endlessly inconvertible process.
ATP undergoes hydrolysis which requires a water molecule to form ADP+P1.
Exergonic reaction (energy is released)
Examples include active transport, muscle contractions and anabolic reactions
Conversion of ADP to ATP
-Is converted through a condensation reaction in which a water molecule is produced.
-It is a phosphorylation reaction
-endergonic reaction (energy required)
-examples include respiration
Cell respiration
The part of metabolism in which carbon compounds are oxidised and release energy to form ATP
-glucose and fatty acids are the principle substrates that cells use for respirations but other carbon containing compounds can be used.
Respiration definition
The controlled release of ATP energy to form organic compounds within cells
Similarities or aerobic and anaerobic respiration
-occur in cell
-use glucose as an initial substrate
-use enzymes to calalyse reactions
-produce ATP
Difference of aerobic and anaerobic reactions
aerobic=
-o2 required
-large ATP yield
-CO2+H2O as waste products
-occurs in cytoplasm/mitochondria of human cells
anaerobic=
-no o2
-small ATP yield
-produces lactate in humans as waste product
-occurs in cytoplasm of human cells
Aerobic respiration simple equation
glucose+oxygen= CO2, H2O+ATP
Anaerobic respiration in humans simple equation
glucose= lactate+ATP
How rate of respiration can be determined
- decrease in O2 as it is USED
- increase in CO2 as it is RELEASED
- respirometers
Redox reactions
=reactions when one substance is oxidized and the other is reduced
OXYDATION=
-loss of electrons
-loss of hydrogen
-addition of oxygen
REDUCTION=
-gain of electrons
-addition of hydrogen
-removal of oxygen
Role of NAD as hydrogen carrier
NAD removes 2 electrons and hydrogen from substrates at various stages
-when NAD gains electrons and hydrogen it forms a reduced NAD and substrate is oxydized.
-reduced NAD carries electrons and hydrogens to ETC where reduced NAD becomes oxydised and returns to NAD
Outline of stages of anaerobic respiration (with products and outcomes)
- glycolysis (one glucose-2 pyruvates)
- The link reaction (2xpyruvates-2 actyl coA)
- Kreb cycle (2 acytl coA into 4 c compound oxyloacelate)
- electron transport chain (electrons from Kreb cycle to intermembrance space)
- chemiosmosis (protons-phosphorylation of ADP)
Stages of glycolysis
(happens in cytoplasm)
4 main stages=
1. phosphorylation=
-glucose (6C) is phosphorylated by 2 ATP molecules (unstable) to form hexose biphosphate
-raises energy levels to make more active
2. lysis=
-hexose biphosphate splits to form 2 molecules of triose phosphate ( 2x G3P)
3. oxydation=
-2 Hydrogens are removed from each triose phosphate
-2 NADs are reduced
4. ATP formation=
-triose phosphates are phosphorylated
-4 molecules of ADP converted into ATP from energy release
2 x pyrauvates
Net gain from glycolysis
-2 pyrauvates
-2 NAD+ =2 NADH+2H+
2 ADP+2PIA= 2TP
The link reaction
(occurs in the mitochondria in matrix)
2 x pyruvates move into matrix via active transport
1. oxidative decarboxylation
-2x 3C, carbon dioxide molecule is removed to form 2C molecules
-NAD is reduced, 2C molecules are oxydised (loses hydrogen) to form acetyl compound
-combine with enzyme Co- A to form acetyl Co A
Net gain of link reaction
-Acetyl Co A
-carbon dioxide
-reduced NAD
The Kreb cycle
(takes place in mitrochondria of matrix)
-2 2C acetyl Co A enter circular pathway from link reaction
-4 Carbon compound (oxaloacetate) accepts 2C to form 6C compound (citrate), co A is released back to be used in link reaction
-citrate 6C is converted back to oxaloacetate (4C through a series of Redox reactions
- from citrate to intermediate (5C)=
-releases 1 CO2 molecule
-1 reduced NAD - from intermediate to oxaloacetate=
-releases 1 CO2 molecule
-2 reduced NADs
-1 reduced FAD
-1 ATP formed
The electron transport chain
-reduced NAD and FAD delivers 2 e- to membrane proteins embedded in inner mitochondrial membrane, to become oxidized
NAD at first protein complex of ETC and FAD at second
-electrons power the pumping of protons across membrane from matrix to intermembrane space. Since protons are released when electrons are lost
-electrons are transported along the ETC pumping more H+ as they go
-10 x NADH and 2x FADH will pump enough H+ across the inner membrane and because the space is small and narrow and the H+ ions cant diffuse through the membrane, a high H- conc is established in inter membrane space
-proton gradient= H+ wants to move down conc gradient through specialised protein channels called ATP synthase
Chemiosmosis
Flow of protons down their electro chemical gradient through ATP synthase which catalysis the phosphorylation of ADP to ATP
Oxygen as terminal electron acceptor
Once e- has passed electron transport chain they need to go somewhere so 02 splits and accepts 4 e- and 4 left over H+ ions to form a water molecule (bi product)
