week9 Flashcards
Cells need energy to perform….(4)
- synthesis of macromolecules
- active transport
- movement
- reproduction
Catabolic pathways:
energy production (ΑΤΡ) by breaking down organic compounds (e.g. cellular respiration)
Αnabolic pathways:
energy consumption for the synthesis
of organic compounds (biosynthesis; e.g. photosynthesis)
Energy production and conversion organelles :
mitochondria and chloroplasts
Photosynthesis location in what organelle
in chloroplasts
Cellular respiration location in what organelle
in mitochondria
how do Catabolic pathways produce energy/feul
by oxidizing organic fuels
breakdown of organic molecules is what?
what does it release?
fact?
• The breakdown of organic molecules is exergonic (ΔG < 0)
– releases energy (as ATP
– the reactants are more energy-rich than the products
Ginitial > Gfinal)
2 major cellular catabolic processes:
• Cellular respiration (aerobic respiration):
– the most prevalent and efficient catabolic pathway
– complete degradation of carbohydrates in the
presence of oxygen (aerobic)
– Yields high amount of ATP
• Anaerobic respiration (Fermentation):
- partial degradation of carbohydrates in the absence of
oxygen
– Yields low amount of ATP
Photosynthesis: formula
CO2 + H2O——sunlight—-»»C6H12O6 + O2
Cellular respiration (aerobic): formula
C6H12O6 + Ο2———–»>CO2 + H2O + ΑΤP
Glycolysis:
Krebs cycle (citric acid cycle):
Οxidative phosphorylation:
- Glycolysis: in the cytosol
- Krebs cycle (citric acid cycle): in mitochondrial matrix
- Οxidative phosphorylation: in the inner mitochondrial
membrane
Mitochondria: amount of stages of reperations
2 out of 3 stages of cellular respiration
Mitchondria structure:
• Diameter: 1-10 μm
• Structure:
- Outer membrane:
- Inner membrane: cristae formation (contains ETC complexes,
ATP synthase) - Intermembrane space
- Matrix: contains mtDNA and free ribosomes
Cellular resperation:formula
During cellular respiration, the fuel (glucose) is oxidized,
and O2
is reduced:
C6H12O6 + 6O2————»»6CO2 + 6H2O + ATP
three metabolic
stages of resperation and which ones ar Aerobic?
- Glycolysis: anaerobic stage - in the cytosol
- The citric acid cycle(Aerobic stage)
- Oxidative phosphorylation (Aerobic stage)
Glycolysis:
The citric acid cycle:
Oxidative phosphorylation:
• Glycolysis: glucose breaks down into 2 molecules of
pyruvate
- The citric acid cycle: pyruvate is broken down into CO2
- Oxidative phosphorylation:
– Driven by the electron transport chain (ETC)
– ETC causes chemiosmosis which generates ATP
(by ATP synthase)
Production of ATP during cellular respiration *****
• Glycolysis and the citric acid cycle:
– generate some ATP (10% of total) by substrate-level
phosphorylation
• Most ATP (90%) is generated by oxidative
phosphorylation (by ATP synthase)
Electron (energy) transport by redox coenzymes NAD+
and FAD
• The electrons released from the oxidation of organic
compounds (during glycolysis and Krebs cycle):
- First transferred to the coenzymes NAD+ and FAD
=> become reduced to NADH and FADH2 - Then transferred to the electron transport chain (ETC)
- Finally transferred to O2 => production of H20
- NAD
* FAD
NAD= Nicotinamide adenine dinucleotide
FAD= flavin adenine dinucleotide
Dehydrogenases:
enzymes that remove efrom organic
compounds (become oxidized) and transfer them to NAD+ or FAD
- NAD+ becomes reduced to NADH
FAD becomes reduced to FADH2
————– for both: Electrons transferred to the ETC
structers NAD and FAD in redox
FAD: 2 protons. 2 electrons
NADH: 1 proton, 2 electrons. 1 proton is released
Cellular respiration
stages?
Locations?
- Glycolysis: cystol
- Citric acid cycle:
- Oxidative
phosphorylation: Inner membrane of mitchondria
Glycolysis:
Meaning? Breaks down what? Occurs where? Anerobic or aerobic? Products? ATP production how?
– Means “splitting of sugar”
– Breaks down glucose (6 C) into 2 molecules of
pyruvate (3 C)
– Occurs in the cytosol of the cell
– Anaerobic stage (does not require oxygen)
– Products: 2 ATP, 2 NADH, 2 pyruvate molecules
– ATP production: by substrate-level
phosphorylation
Phases of Glycolysis
Glycolysis consists of
two major phases:
- Energy investment
phase: ATP spent - Energy payoff
phase: ATP
produced
2 ATP spent
Net products of glycolysis:
2 ATP, 2 NADH, 2 pyruvates
Location?
Citric acid cycle:
Oxidative phosphorylation:
- Citric acid cycle: in mitochondrial matrix
* Oxidative phosphorylation: inner mitochondrial membrane
- Electron transport chain (ETC):
2. Chemiosmosis:
- Electron transport chain (ETC): located on the inner
mitochondrial membrane - Chemiosmosis: H+ gradient drives ATP synthesis by ATP synthase (enzyme located on inner mitochondrial membrane)- ATP synthesis takes place in matrix
- Citric acid cycle (Krebs cycle/ TCA cycle)
• Takes place in the mitochondrial matrix
• The citric acid cycle completes the oxidation of organic
molecules => CO2 and energy production
• Conversion of pyruvate (glycolysis product) into acetylCoΑ before the beginning of the citric acid cycle
• Acetyl-coenzyme A (acetyl-CoA) is produced either by
glycolysis or β-οxidation of fatty acids
Acetyl -CoA enters Krebs cycle
Krebs cycle products:
Krebs cycle energy gain:
Net energy profit :
• Krebs cycle products: Each acetyl-CoA that enters the cycle is converted to: - 2 CO2 - 3 NADH - 1 FADH2 - 1 ATP
• Krebs cycle energy gain:
1 ATP, 3 NADH and 1 FADH2
1 NADH 3 ATP
1 FADH2 2 ATP
=> Net energy profit : 12 molecules of ATP from 1 Krebs
cycle
(sooo for some reason x2 the products)
Oxidative phosphorylation:
Electron transport chain
and chemiosmosis
- Oxidative phosphorylation
Oxidative:
Phosphorylation
-Phosphorylation:
Chemiosmosis:
- Oxidative: NADH and FADH2 donate electrons to the electron transport chain (ETC)
- Phosphorylation: ETC powers ATP synthesis
- Phosphorylation: production of ATP from ADP + Pi (ATP
synthase)
• Chemiosmosis: an energy-coupling mechanism
-couples electron transport chain (ETC) to ATP synthesis
during oxidative phosphorylation
- uses energy from a H+ gradient across a membrane (H+
flow) to drive cellular work (ATP production)
Cellular respiration oxidizes glucose in a series of steps
thats it lol
(Stepwise Energy Transfer in the Electron Transport Chain)
• The electron transport chain:
The electron transport chain:
– Passes electrons in a
series of steps instead
of in one explosive
reaction
– Uses the energy from
the electron transfer to
form ATP
– Each e- carrier is more
electronegative than the
previous one
(Stepwise Energy Transfer in the Electron Transport Chain)
• The electron transport chain:
The electron transport chain:
– Passes electrons in a
series of steps instead
of in one explosive
reaction
– Uses the energy from
the electron transfer to
form ATP
– Each e- carrier is more
electronegative than the
previous one
The electron transport chain
• Electrons from the oxidation of
NADH and FADH2 are
transferred to the electron
transport chain (ETC)
- These electrons from NADH
and FADH2 are initially
transferred to ubiquinone - Electrons passed from higher
energy carrier to lower energy
carrier (more electronegative) - Electrons are eventually
transferred to O2
(most
electronegative) forming H2O
Electron transport chain complexes:
1)-Complex Ι: ΝADH dehydrogenase -Complex ΙI: Succinate dehydrogenase
2) Coenzyme Q (CoQ): ubiquinone
3) Complex ΙΙΙ: cytochrome oxidoreductase
4) . Cytochrome c
5) Complex ΙV: cytochrome oxidase
