Cellular Respiration Flashcards
(52 cards)
how do cells release energy energy
Catabolic pathways release energy by breaking down complex molecules
Aerobic respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP/heat, ∆G = -2870
Fermentation:
Anaerobically produced ATP
what are Redox reactions
Redox reaction: Reduction-oxidation reactions
Reduction: addition of electron to another substance
Reduced the amount of positive Charge
Oxidation: loss of electron from one substance
Increases amount of positive charge
Xe^- + Y –> X + Ye-
X becomes oxidized, Y becomes reduced
how would a C6H12O6 + 6O2 –> 6CO2 + 6H2O reaction be a redox reaction
In respiration
C6H12O6 becomes oxidized when turned into 6CO2
6O2 becomes reduced to form 6H2O
how do cells process glucose as a redox reaction
Redox Reactions: reduction-oxidation reactions
Oxidation of glucose takes many small steps
Electrons travel with H+ → H, passed on to electron carrier:
what is NAD+ and NADH
NAD+ = Nicotinamide (oxidized form)
NADH = Nicotinamide (reduced form)
$NAD^+ +2H<–>NADH +H^+$
Uses Dehydrogenase as enzyme
how do electrons from NADH reach O2
How do the electrons from NADH finally reach O2?
- Electron transport chain: series of redox reactions
- Controlled release of energy for synthesis of ATP
- Turns 2H + 0.5O2 → H2O
what are the two phases of Glycolysis
Energy Investment Phase:
- 1 Glucose in
- 2 ATP → 2 ADP + 2P
Energy payoff phase:
- 4ADP + 4P → 4ATP
- 2 NAD+ + 4e- + 4H+ → 2 NADH + 2H+
- 2 Pyruvate + 2 H2O out
What are steps 1-3 of Glycolysis
Glucose: C6
- Hexokinase
Add Phosphate
Glucose 6-phosphate: C6-P
- Phosphoglucoisomerase
Convert
Fructose 6-phosphate: C6-P
- Phosphofructokinase
Add phosphate
Fructose 1,6-bisphosphate: C6-PP
what are steps 4-6 of Glycolysis
Fructose 1,6-bisphosphate: C6-PP
- Aldolase
Cleave in two
Glyceraldehyde 3-phosphate ← → Dihydroxyacetone phosphate (DHAP): 2 C3-P
- Isomerase
Convert to only
Glyceraldehyde 3-phosphate (G3P): 2 C3-P
- Triose Phosphate dehydrogenase
transfer e-, add P: 2NAD+ → 2 NADH + 2H+
1,3-Bisphosphoglycerate: 2 C3-PP
what are steps 7-10 of Glycolysis
1,3-Bisphosphoglycerate: 2 C3-PP
- Phosphoglycerokinase
transfer P to ADP, forms ATP
3-phosphoglycerate: 2 C3-P
- Phosphoglyceromutase
Relocate P
2-Phosphoglycerate: 2 C3-P
- Enolase
Forming double bond
Phosphoenol pyruvate (PEP): 2 C3-P
- Pyruvate Kinase
Transfer P to ADP, forms ATP
Pyruvate: 2 C3
describe the Krebs cycle
- Oxaloacetate + Acetyl CoA → Citrate
- Citrate → Isocitrate
- Isocitrate + NAD+ → a-Ketoglutarate + NADH + H+ + CO2
- a-Ketoglutarate + NAD+ + CoA-SH → CO2 + NADH + H+ + Succinyl Coa
- Succinyl Coa + P + GDP* → Succinate + CoA-SH + GTP
- GTP + ADP → GDP + ATP
- Succinate + FAD → Fumarate + FADH2
- Femarate + H2O → Malate
- Malate + NAD+ → Oxaloacetate + NADH + H+
Redox reactions in steps 3, 4, 6, 8
CO2 relased in steps 3, 4
ATP regenerated at step 5
what does the Krebs cycle do
From one Pyruvate molecules you get:
- 3 CO2
- 1 ATP
- 4 NADH
- 1 FADH2
These go into the electron transport chain
what happens in the Krebs Cycle
→ C2 → 2 CO2
→ recycling of C2 acceptor
how does the electron transport chain work
Electron transport chain:
- Proteins organized in multiprotein complexes I-IV
- Organized on inner mitochondrial membrane
- Series of Redox reactions passing down the electrons and H+
- Transport of e- and H+
→ H+ gradient (proton-motive force)
what does chemiosmosis do
Chemiosmosis: after e- transport chain
- ATP synthase uses H+ gradient to produce ATP
how efficient is respiration
Glucose oxidation ∆G = - 2870 KJ/mol
ADP + P → ATP = 30.5 KJ/mol
This results in 34% efficiency when 32 ATP are produced per glucose
what happens to starch, proteins, and fats
Are we only consuming glucose?
- Starch, Glycogen:
- broken down to glucose
- Proteins: amino acids to build new proteins
- Fats: glycerol + fatty acids
how is glycolysis regulated
Glycolysis is regulated by feedback mechanism.
ATP and citrate inhibit Phosphofructokinase , Stimulated by AMP
how does Anaerobic respiration and fermentation work
Anaerobic respiration: final electron acceptor e.g. SO4 2-
Fermentation: no electron transport chain
- Needed sufficient supply of NAD+
what is alcohol fermentation
Alcohol Fermentation
2 Pyruvate from Glycolysis lose CO2 and turn into 2 Acetaldehyde. Which then turns NADH + H+ back into 2 NAD+, and becomes 2 Ethanol. The new NAD+ allows more glycolysis to form 2 ATP
what is lactic acid fermentation
Lactic acid fermentation
2 Pyruvate from Glycolysis regenerate NAD+ and turn into 2 Lactate. The new NAD+ allows more glycolysis to form 2 ATP
who was Rosalind Franklin
DNA structure was uncovered using X-ray diffraction with the aid of Rosalind Franklin, however Franklin is often left out of the history of our understanding of DNA.
describe the structure of DNA
DNA has the structure of a Sugar-phosphate backbone attached to a number of Nitrogenous bases. There are two chains which run antiparallel to each other, and the nitrogenous bases connected via hydrogen bonds.
The bases Cytosine, Thymine, and Uracil and Pyrimidines with one ring.
Adenine and Guanine are Purines with two rings.
A and T have two hydrogen bonds between them, G and C have three.
what affects DNA helix stability
DNA double helix stability is affected by:
- Temperature
- denaturation or melting of the helix
- Cations
- stabilize the helix; reduce charge repulsion of the two strands
- Base mismatched
- destabilize the helix
- Length of the helix
- longer helices are more stable
- Proteins
- histones - positively charge proteins
More H bonds can also make a chain more stable, so more GC pairs
how is DNA organized in eukaryotes
- complex of DNA double helix and proteins called histones
- Loosely packed form of DNA
- DNA replication and gene expression
- the DNA helix is 2nm wide, Nucleosomes are 10 nm wide.
Nucleosomes coil into a 30 nm wide fibre, then looped into a 300 nm wide fibre, which forms a chromosome 1,400 nm wide.
