3.3 Respiration/Glycolysis Flashcards
Stages of aerobic respiration
Glycolysis
Link Reaction
Krebs cycle
Respiration definition
Catabolic process that involves a series of enzyme catalysed reactions in cells
Aerobic respiration
Complete breakdown of glucose ad requires oxygen as the final electron a vote or
Large amounts of energy are released
Large number of ATP molecules
Oxidative phosphorylation
Anaerobic respiration
Incomplete breakdown of glucose
No oxygen
Little energy is released
Small number of ATP molecules
Substrate level phosphorylation
NAD and FAD allow
Enzymes to work
What do NAD and FAD do
Transfer hydrogen atoms from stages of respiration to the ETC
NAD
Nicotinamide adenine dinucleotide
FAD
Flavin adenine dinucleotide
Where does glycolysis take place
In cytosol
Glycolysis is anaerobic as it requires no
Oxygen
The amount of ATP molecules needed for the phosphorylation of glucose
2
Glucose is phosphorylised and forms
Hexose bisphosphate
Hexose bisphosphate is
Unstable
More reactive
Hexose bisphosphate splits into
2 molecules of triose phosphate
Each TP molecule loses 2 hydrogen atoms by
Dehydrogenation
TP is oxidised to form
Pyruvate
Enzyme thar dehydrogenates
Dehydrogenase
What picks up hydrogen atoms
NAD +
NAD + and hydrogen atoms forms
NADH
The amount of ATP molecules synthesised
2
Type of phosphorylation that forms pyruvate
Substrate level
Products of glycolysis
Pyruvate
NADH
2 x ATP
Some energy lost as
Heat
If oxygen is available some energy is released in
Krebs Cycle
Glucose + 2NAD + 2ADP + pi =
2 Pyruvate + 2NADH + 2ATP + HEAT
Where link reaction takes place
Matrix of mitochondria
If oxygen is available
Pyruvate is actively transported into matrix of mitochondria
In link reaction the Pyruvate…down a concentration gradient
Diffuses
Pyruvate is…by decaroxylase
Decarboxylated
Enzyme that decarboxylates
Decarboxylase
What is released during decarboxylation
Carbon dioxide
Pyruvate is also
Dehydrogenated
Enzyme that dehydrogenates
Dehydrogenase
What is released during dehydrogenation
2 Hydrogen atoms
Pyruvate is converted into
2C acetate
NAD is…by hydrogen
Reduced
NAD + Hydrogen =
NADH2
Acetate is activated by combining with
Co-enzyme A
Acetate + Co-Enzyme A =
Acetyl Co-enzyme A
Each molecule of glucose produces 2 molecules of pyruvate so link reaction takes place…per glucose
2 times
Pyruvate is…
Oxidised
What happens to the Acetyl CoA
Enters the Krebs cycle
How many carbons does Acetyl CoA have
2
What happens to the hydrogen that is released
Goes into the NADH
What is the Krebs cycle
A series of enzyme controlled reactions
Where the Krebs cycle takes place
Matrix of mitochondria
The Krebs cycle is a series of…and…reactions
Decarboxylation
Dehydrogenation
The energy in the bonds is carried by
Electrons in the hydrogen atoms in the NADH and FADH
Krebs cycle takes place…times per glucose molecule
2
Acetate from the Acetyl CoA combines with…and forms a…
4C compound
6C compound
The co-enzyme is….and returns to…
Regenerated
Link reaction
The 4C Compound is regenerated via series of…and…intermediates
6C and 5C
Amount of atoms of carbon lost in 2 molecules of CO2
2
Carbon lost in CO2 and oxygen comes from water molecules. So as process uses water it is
Oxidative decarboxylation
How many hydrogens are lost in Krebs
8
What do the 8 lost hydrogen atoms/four pairs do
Reduce NAD AND FAD
How many molecules of NADH2 are produced per acetyl co-a molecule
3
How many molecules of FADH2 are produced for each acetyl-CoA molecule
1
How many molecules of ATP are produced in Krebs
1
What is the ATP in Krebs produced by
Substrate level phosphorylation
Decarboxylation
Decarboxylase removes a carbon from a carboxyl group
Dehydrogenation
Dehydrogenase removes one or more hydrogen atoms
How many H2Os used per cycle
3
How many ATP produced per glucose molecule
2
Decarboxylation happens…per cycle
Twice
Where is the electron transport chain located
Cristae of the inner mitochondrial membrane
What carries hydrogen atoms to the ETC
NADH and FADH
In the ETC NADH and FADH are
Oxidised
As NADH and FADH release hydrogens, the protons and electrons drive…
Chemiosmosis
At the end of the ETC the electrons ad protons combine with
Oxygen
Oxygen in the ETC is the
Final electron acceptor
In the ETC oxygen removes..
Electrons ad protons from the matrix
By removing electrons and protons there is an
Electrochemical gradient
If there was no gradient…would not function
ATP synthetase
NAD feeds electrons into the chain…than FAD
Earlier
Reduced NAD is associated with..pumps
3
NADH produces…ATPs via oxidative phosphorylation
3
FADH is associated with..pumps
2
FADH produces…ATPs via oxidative phosphorylation
2
Cyanide
Non competitive respiratory inhibitor of the final electron carrier
Prevents electrons and protons passing to oxygen to form water
Prevents gradient forming between inter membrane space and matrix
Chemiosmosis would stop
No oxygen means
No final electron acceptor
Krebs and Link stop
NAD cannot be re-oxidised so cannot pick up more hydrogen
No oxidative phosphorylation takes place
No ATP formed
For glycolysis to take place with no oxygen…and…must be constantly removed
Pyruvate
Hydrogen
If there is no oxygen then…is used to oxide NAD
Alternative pathway
How many different anaerobic pathways
2
Where do the anaerobic pathways take place
Cytoplasm
Anaerobic in animals
Cytoplasm
NADH must pass its hydrogen atoms to pyruvate
Pyruvate is the final electron acceptor
Lactate or lactic acid is formed
Anaerobic in yeast and plants
Pyruvate is decarboxylated
Forms ethanal
Carbon dioxide is released
NADH passes hydrogen atoms to ethanal
Ethanol formed
Called alcoholic fermentation
Non reversible and ethanol is toxic and will eventually kill cells
Anaerobic respiration ATP production
Produced via substrate level phosphorylation
2 ATPSs per glucose molecule
2% efficient
Less efficient than oxidative phosphorylation
Aerobic respiration produces…ATP molecules per glucose molecule respired
38
Why 38 ATP may not be produced
ATP is required to move Pyruvate across membrane
Proton gradient can be compromised due to proton leakage across membrane rather than going through ATP synthetase
Molecules may leak through
When glucose molecules have been depleted….can be used as alternative respiratory substances
Lipids
Amino acids
Lipids are hydrolysed into…
Fatty acids
Glycerol
What enzyme hydrolyses lipids
Lipase
Glycerol is converted into
3C compound triose phosphate
Enters via glycolysis
Fatty acids are split into
2C acetate molecules
Enter Krebs cycle as acetyl coA
Proteins are hydrolysed into
Amino acids
Deaminated/amino group removed
In liver
Forms keto acid and ammonia
Keto acids join at
Glycolysis via pyruvate
Krebs cycle via Acetyl CoA
Amino acids are used
Only as an energy source in severe circumstances
Starvation
Glycogen and starch are polymers of
Alpha glucose
Glycogen and starch are hydrolysed to release
Glyocse
Enters glycolysis
Sucrose
Disaccharide of glucose and fructose
The electron transport chain
A series of props pumps and electron carriers
RQ
Number of CO2 molecules produced / number of O2 consumed
