Define cellular Define cellular respirationrespiration
Cell respiration is the controlled release of energy from organic compounds in cells to form ATP
Covalent bonds are slowly oxidized by enzymes releasing ATP molecules
Takes place in the presence or in absence of oxygen
Know These Numbers
GlycolysisGlycolysisglucose + 2 ATP 2 pyruvate + 4 ATP + 2
NADPH
The breakdown of one molecule of glucose into two molecules of pyruvate with the release of some energy
Takes place in the cytoplasm
Does not require oxygen
Glycolysis Video
Alcoholic Alcoholic FermentationFermentation
Done when no oxygen is present
Starts with glycolysis
The pyruvate is then broken down further
Yeast turn the pyruvate into ethanol and carbon dioxide
Used to make bread and alcohol
Lactic Acid Fermentation
Cell that normally do aerobic respiration can perform fermentation
Done when you sprint and the body can not supply the muscles with enough oxygen to perform aerobic respiration
Can cause muscle cramps
Aerobic cellular respirationAerobic cellular respiration In the presence of oxygen
pyruvate is broken down in the mitochondria into carbon dioxide and water This is the most efficient
use of this molecule to harvest energy
Reaction takes place in the mitochondria
Yields approximately 28-34 more ATP
Oxidation and Oxidation and ReductionReduction
Redox (reduction – oxidation) reaction: the enzyme controlled transfer of electrons
Oxidation Is the Loss of electrons Involves gaining an oxygen or losing a hydrogen Energy is lost (exergonic reaction) In respiration glucose is oxidised to carbon
dioxide All hydrogens are gradually removed from the
glucose molecule
Reduction Is the Gain of electrons Involves losing oxygen or gaining hydrogen Energy is absorbed (endergonic reaction) This substance now has the power to reduce
other substances and become oxidised in the process
In respiration oxygen is reduced to water
Remember it by the saying OIL RIG
Oxidation Reduction
Loss of electrons Gain of electrons
Gain of oxygen Loss of oxygen
Loss of hydrogen Gain of hydrogen
Results in many C-O bonds Results in many C-H bonds
Result is a compound with low potential (stored) energy
Result is compound with high potential (stored) energy
GlycolysisGlycolysis Linear series of reactions in which glucose is broken down into 2
molecules of pyruvate
Glycolysis takes place in the cytoplasm Glucose + 2ADP + 2Pi + 2NAD+ 2Pyruvate + 2ATP +
2NADH + 2H+ + 2H20
Anaerobic process that does not require oxygen
Glycolysis takes a 6-carbon hexose sugar and created 2 3-carbon monosaccharides
The first step is phosphorylation ATP is used to add a phosphate group to the glucose A second phosphorylation using another ATP follows adding a
second phosphate This creates fructose biphosphate 2 molecules of ATP are consumed for every molecule of
glucose at this point
Glycolysis Cont.Glycolysis Cont.• The second step is lysis
o Fructose biphosphate is split producing 2 triose phosphate molecules each with 3 carbons
• The third step is oxidationo The above chemicals are then involved in a combined
oxidation phosphorylation reactiono Hydrogen is removed from the triose phosphateso NAD acts as the hydrogen receptor
• The last step is ATP formationo Lastly the triose biphosphate gives up one of the
phosphates to ADP to make it ATP and producing pyruvate
• Total ATP production for each glucose molecule is 4 but the NET gain is only 2o Remember we spent 2 ATP at the beginning to start the
process
Electron Micrograph of a Electron Micrograph of a MitochondriaMitochondria
Micrograph ExplainedMicrograph Explained Found in the cytoplasm of all Eukaryotic
cells, usually in large numbers Large organelle surrounded by an outer
membrane and an inner membrane Inner membrane is folded – cristae Between the inner membrane and the outer
membrane is the matrix Inside is a watery fluid containing enzymes and
molecules There are also ribosomes and DNA The DNA is maternal DNA and can be used to
trace heredity
Structure and FunctionStructure and FunctionStructure Function / Role
External Double Membrane Permeable to pyruvate, CO2, O2 and NAD/NADH
Matrix Site of enzymes of link reaction and Krebs cycle
Inner Membrane Surface area greatly increased by in tucking to form cristae (increases surface area for electron chain), impermeable to hydrogen ions (allows for a concentration gradient to be created
Inter-membrane Space Relatively tiny space, allows the accumulation of hydrogen atoms , facilitates phosphorylation
Aerobic Respiration Aerobic Respiration Link Reaction Link Reaction
Forms the link between glycolysis and the Krebs cycle
Pyruvate is transferred from the cytoplasm to the mitochondrial matrix Pyruvate + CoA + NAD+ Acetyl CoA + CO2 +
NADH + H+
This reaction is known as decaboxylation of pyruvate A carbon dioxide is removed The molecule is also oxidised by the removal of a
hydrogen NAD is formed at this time
Aerobic RespirationAerobic RespirationKrebs CycleKrebs Cycle
Also known as tricarboxylic citric acid cycle or TCA cycle
Occurs in the matrix of the mitochondria
1 molecule of acetyl CoA yields 2 CO2
3 NADH + 3H+
1 FADH2
1 ATP
Krebs Cycle DetailsKrebs Cycle Details Acetyl CoA combines with a 4-carbon compound to create
a 6-carbon compound
This compound is then decarboxylated A CO2 is removed 5-carbon compound is created
The 5-carbon compound is decarboxylated A CO2 is removed 4-carbon compound is created
This takes us back the original 4-carbon compound that starts the cycle
The main outputs are energy freed from the compounds
Krebs Cycle Important Krebs Cycle Important NotesNotes
per molecule that enters Two molecules of
carbon dioxide are given off in separate decaboxylation reactions
One molecule of ATP is formed
Three molecules of NADH (aka reduced NAD) are formed
One molecule of FADH (aka reduced FAD) is formed
Summary to this PointSummary to this PointStep CO2 ATP NADH FADH
Glycolysis 0 2 2 0
Link Reaction
2 0 2 0
Krebs Cycle
4 2 6 2
Totals 6 CO2 4 ATP 10 NADH
2 FADH
Terminal Oxidation and oxidative phosphorylationTerminal Oxidation and oxidative phosphorylation
A.K.A. – the electron transport chain
The removal of H+ from NADH and FADH Releases energy that is transferred to ADP to form ATP End receiver of the H+ is O2 and this forms water For every molecule of NADH that is reduced – 3 ATP are
formed
Total yield from aerobic respiration is 38 ATPs
Phosphorylation by Phosphorylation by ChemiosmosisChemiosmosis
The synthesis of ATP is coupled to electron transport via the movement of protons
Electron –carrier proteins are arranged in the inner mitochondrial membrane Oxidize the reduced coenzymes Energy from the oxidation is used to pump hydrogen
ions from the matrix into the space between the inner and outer membranes of the mitochondria
A gradient forms generating a potential difference across the membrane – a store of potential energy
Hydrogens flow back across the membrane through ATP synthesis enzymes (ATPase) Follow the concentration gradient from high hydrogen to
low hydrogen Energy is transferred to ATP
Role in Fat MetabolismRole in Fat Metabolism Your body can plug other things into the Krebs cycle
to generate energy including Starch Glycerol Fatty acids Amino acids
Plants can also add cellulose to this list
Explains why fats are considered to be energy sources to the body
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