ch. 9 cellular respiration
DESCRIPTION
Ch. 9 Cellular Respiration. Harvesting chemical energy. Living is lots of work Polymerization, Growth, highly organized, and movement all require energy Energy enters Earth’s ecosystems as sunlight Harvesting of energy requires a series of metabolic steps AEROBIC CELLULAR RESPIRATION - PowerPoint PPT PresentationTRANSCRIPT
Ch. 9 Cellular Respiration
Harvesting chemical energy
Living is lots of work Polymerization, Growth, highly organized,
and movement all require energy Energy enters Earth’s ecosystems as sunlight Harvesting of energy requires a series of
metabolic steps AEROBIC CELLULAR RESPIRATION
Glycolysis Kreb’s cycle Electron transport chain
Organic compounds
Energy stored in chemical bonds (position) Enzymes help regulate this metabolism Organic macromolecules are rich in potential
energy and are broken down to simpler compounds with less energy.
Breaking of bonds allows work to be done.
Organic + oxygen carbon + water + energy compounds dioxide
Exergonic reaction
Organic + oxygen carbon + water + energy compounds dioxide
C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy
(ATP + heat)
G = - 686 kcal
Possible pathways
Complete, aerobic cellular respiration Complete oxidation of carbohydrates using
Glycolysis Kreb’s cycle and Electron transport chain REQUIRES OXYGEN
Incomplete/ partial oxidation Gylcolysis only Glycolysis + Lactic acid fermentation Glycolysis + Alcoholic fermentation
Redox reactions
Movement of e- is what is used to store and release energy in bonds of organic cpds.
Redox reactions – “oxidation-reduction reactions” transfer an e- from one reactant to another
Reduction Addition/receipt of e-, more negative
Oxidation Loss of e- (often to O), more positive
Falling electrons
The step wise fall of electrons from organic compounds rich in bonds, to simpler compounds increases the entropy of the system.
Electrons are shuttled through a series of carriers (membrane proteins) that allows for release of energy to be in small (usable) increments.
Electron transport chains
Aerobic cellular respiration
Requires oxygen ( for e- acceptor at end of ETC) 3 parts
Glycolysis ( splitting of sugar molecules ) Some substrate level phosphorylation of ATP
Kreb’s cycle ( transfer of e- to NADH, FADH) Some substrate level phosphorylation of ATP
ETC ( generates ATP using ETC) Much oxidative phosphorylation of ATP
Occurs in eukaryotic cells – need mitochondrion (for Krebs and ETC) and oxygen supply for (ETC)
Glycolysis
Glyco = sugar, glucose Lysis = to split or break “sugar splitting” Cytoplasm ALL CELLS ! Doesn’t require mitochondrion or O2
1 glucose = 2 ATP and 2 NADH 2 ATP are net ( 4 generated – 2 invested ) Know steps on pgs. 168-169….green boxes Note color coding used in chapter – green =
glycolysis, salmon = Kreb’s and purple = ETC
Summary of Steps
1. Spend 1 ATP
Add P to glucose
2. Glucose converted to isomer (fructose) by an enzyme
3. Spend 2nd ATP
add 2nd P to fructose
now in debt ( 2ATP)
Molecule very unstable (primed)
Summary of Steps
4. 6 C sugar “cleaved” into 2 – 3C sugars
They are isomers
5. An enzyme called ‘isomerase’ converts both isomers into glyceraldehyde (PGAL)
From now on all steps are X2
PGAL
Summary of Steps
6. Enzyme adds an inorganic phosphate, sugar give e- and H+ to NAD making NADH…remember x2
7. MAKE ATP (X2) now out of debt, organic acid
8. Relocate P ( on both molecules)
Summary of Steps9. Generates water and creates double bond…. P bond now unstable10. P leaves – adds to ADP generates more ATP (2more) now have 2 net ATP. Glucose is now split into 2 – 3 C molecules PYRUVATE2 NADH can go to ETC and make ATP using oxidative phosphorylation
Krebs Cycle – aka Tricarboxylic Acid Cycle (TCA) and Citric Acid Cycle Sir Hans Krebs: 1900-1981, 1953 Nobel Prize, 1958 knighted 3 C pyruvate at end of glycolysis Not soluble in mitochondrial membrane Loses C (CO2) becomes acetyl Creates a NADH ( stores some energy ) Bonds to coenzyme for transport – now Acetyl CoA Crosses mitochondrial membrane Bonds to 4C oxaloacetate to make 6C citrate or citric acid Series of steps to lose C ( makes CO2 ) and Store energy as NADH and FADH and ATP Regenerates the oxaloacetic acid…. “cycle”
Electron Transport Chain
Collection of molecules embedded in the inner mitochondrial membrane
Folding increases surface area ( # of reactions) Most compounds are proteins (some pigments) cytochrome c
used to trace DNA lineage Function as enzymes directing the flow of reactions that move
e- (alternate between oxidized and reduced state) NADH and FADH2 are from Krebs and glycolysis NADH and FADH2 release H to these reactions H is split into H+ and e- The e- move through the carriers to the biggest e- acceptor
(moving down hill – releasing potential energy and increasing entropy)
The H+ accumulate in space btwn membranes
ETC continued
As the e- get to the last acceptor they have released all the energy they were carrying from C-C bonds in glycolysis and Krebs
The H+ can not accumulate indefinitely btwn membranes (high acidity)
H+ flows through protein pump called ATP synthase toward e- and their acceptor (OXYGEN)
This creates water and also Is used to generated energy to add P to ADP ATP is generated using oxidative phosphorylation