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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