Topic 9: cellular respiration Flashcards
Define catabolic pathways
- Energy production = ATP
- Breaking down organic compounds
- E.g. respiration
Define anabolic pathways
- Energy consumption
- Synthesis of organic compounds
- E.g. photosynthesis
What is the energy flow in an ecosystem?
Sunlight > photosynthesis in chloroplast + respiration in mitochondria > heat energy
Explain the catabolic pathways
- Cells must regenerate ATP = in order to keep working
- Produce energy by oxidizing organic molecules = exergonic = releases energy
- Reactants > energy rich than products
PROCESSES
1) Cellular respiration
2) Anaerobic respiration
Describe cellular respiration
- Most efficient catabolic pathway
- Complete degradation of carbohydrates in presence of O2
- Chemical energy in glucose bonds transferred to phosphate bonds in ATP
- Yields highest ATP
- Energy from ATP hydrolysis used to perform endergonic reactions
What is the equation for cellular respiration?
C6H12O6 + Ο2 —-> CO2+ H2O+ ΑΤP
What are the 2 energy production/conversion organelles?
1) Chloroplasts = photosynthesis
2) Mitochondria = 2/3 stages of respiration
3 stages of respiration
1) Glycolysis = anaerobic = cytosol
2) Krebs cycle = aerobic =mitochondria matrix
3) Oxidative phosphorylation =aerobic = inner membrane
Describe the structure of a mitochondria
- Diameter = 1-10 μm
- Outer membrane
- Inner membrane = cristae = ETC complexes + ATP synthase
- Intermembrane space
- Matrix = mitochondrial DNA + free ribosomes
Define redox reactions
- Transfer e- from 1 reactant to another via oxidation/reduction
- Oxidation = lose e-
- Reduction = gain e-
Describe redox in respiration
- Glucose oxidized
- O2 reduced
Describe the ATP production at each stage
- Glycolysis + Krebs = 10% of total = substrate level phosphorylation
- Oxidative phosphorylation = 90% ATP = ATP synthase
Describe how e- energy is transferred and transported
- e- released from oxidation of organic compounds
- Co-transferred with H+
- Transferred to coenzymes FAD + NAD+ = reduced NADH + FADH2
- They transport to ETC
- Transferred to O2 = H2O
What do NAD + FAD stand for?
- NAD = nicotinamide adenine dinucleotide
- FAD - flavin adenine dinucleotide
Define dehydrogenase
- Enzymes that remove e- from organic compounds = transfer them to NAD + FAD
Describe glycolysis
- Breaks down glucose
- Location = cytosol
- Anaerobic
- Products = 2ATP + 2NADH + 2 Pyruvate
PHASES
1) Energy investment
2) Energy payoff
Explain energy investment
- 2 ATP spent
- Substrates phosphorylated = energy-rich = unstable
- Splits glucose
Explain energy payoff
- 4 ADP + 4 Pi = 4 ATP
- 2 NAD + 4e- + 4 H+ = 2NADH
- 2 Pyruvates
Give the net products of glycolysis
- 2 ATP
- 2 NADH
- 2 Pyruvate
Describe the Krebs cycle
- Completes the oxidation of organic molecules
- Location = mitochondrial matrix
- Products = CO2 + energy
Describe the conversion of pyruvate
- Pyruvate is converted into acetyl-CoA before starting Krebs cycle
- Undergoes pyruvate dehydrogenase reaction
- 3 carbon > 2 carbon acetyl-CoA = 1 carbon released = CO2
- NAD+ reduced = NADH
Describe Krebs cycle
- Acetyl-CoA combines with oxaloacetate = citric acid
- NADH + FADH2 produced = transferred to ETC
- Each acetyl-CoA =
> 2 CO2
> 3 NADH
> 1 FADH2
> 1 ATP
How many ATP are produced by 1 NADH + FADH2 in Krebs cycle?
- 1 NADH = 3 ATP
- 1 FADH2 = 2 ATP
Give the net products for Krebs cycle
- 12 molecules ATP