How can a bear sleep for 6 months? Part 1 Flashcards
What happens when glucose is burnt to CO2?
Energy is released as heat and light
What is the formula for aerobic cellular respiration?
C6H12O2 + 602 -> 6CO2 + 6H2O + light and heat
What is a redox reaction?
Reactions that may include the loss of electrons (oxidizing) or gaining electrons (reducing)
What is Aerobic Respiration?
A chemical process in which oxygen is used to make energy from glucose
What are the 4 processes of Aerobic Respiration
Glycolysis
Pyruvate Processing
The Citric Acid Cycle (Krebs Cycle)
Electron Transport Chain & Oxidative Phosphorylation
What is Glycolysis?
A 6 carbon glucose is broken down into two 3 carbon pyruvate molecules
What goes into Glycolysis?
Glucose (6C)
2 ATP
2 NAD
2 ADP
What comes out of Glycolysis?
2 Pyruvate (3C each)
2 ATP
2 NADH + H
4 ATP
Where does Glycolysis occur?
Occurs in the cytosol
What happens during Glycolysis?
- Glycolysis starts by using 2 ATP in energy investment phase
- During the energy payoff phase, NADH is made and ATP is produced
- The net yield is 2 pyruvate, 2 ATP and 2 NADH
How much energy is released as ATP is broken down?
The phosphates release 30.5 kg/mol
The last phosphate releases 46.5 kg/mol
How is Glycolysis regulated?
Regulated by feedback inhibition by Phosphofructokinase which has 2 binding sites for ATP
When ATP is high: ATP binds to a regulatory site and inhibits PFK from catalyzing rate if ATP production
When ATP is low: ATP binds to the active site and decreases the inhibition of PFK and catalyzes rate of ATP production
What is Processing Pyruvate?
Each pyruvate from glycolysis is oxidized to form Acetyl CoA
What goes into Pyruvate Processing?
2 Pyruvate
2 NAD+
2 CoA
What comes out of Pyruvate Processing?
2 CO2 (1C)
2 NADH + H
2 Acetyl CoA
Where does Pyruvate Processing occur?
In the mitochondrial matrix
What happens during Pyruvate Processing?
- One of its carbons is oxidized to CO2 and NADH is produced
- The remaining 2 carbon unit is attached to Coenzyme A, producing acetyl CoA.
How is Pyruvate Processing regulated?
Regulated by feedback inhibition by pyruvate dehydrogenase
Pyruvate dehydrogenase is shut down when it is phosphorylated
The rate of phosphorylation increases when levels of NADH, acetyl CoA and ATP are high
What is the Citric Acid Cycle (Krebs Cycle)
Each acetyl CoA from Pyruvate Processing is oxidized to CO2
What goes into the Krebs Cycle?
2 Acetyl CoA
6 NAD+
2 FAD
2 ADP + Pi
What comes out of the Krebs Cycle?
4 CO2
6 NADH + H
2 FADH2
2 ATP
Where does the Krebs Cycle occur?
Eukaryotes: In the mitochondrial matrix
Prokaryotes: In the cytosol
What happens during the Krebs Cycle?
Reduces 3 NAD to NADH
Reduces 1 FAD to FADH
Phosphorylates ADP (or GDP) to form ATP (or GTP)
How is the Krebs Cycle regulated?
Regulated by feedback inhibition at multiple points
Reaction rates are high when ATP and NADH are scarce
Rates are low when ATP and NADH are abundant
What is produced for each glucose molecule at this point?
6 CO2
10 NADH
2 FADH
4 ATP
Where do the electron carriers go?
Transformed to the Electron Transport Chain?
What is the Electron Transport Chain?
Electrons move through a transport chain and their energy is used to set up a proton gradient, which is used to make ATP
What goes into the Electron Transport Chain?
6 NADH + H
2 FADH2
What comes out of the Electron Transport Chain?
2 H2O
NAD
FAD
Where does the Electron Transport Chain occur?
Eukaryotes: In the inner membrane of mitochondria
Prokaryotes: The plasma membrane
What happens during Electron Transport Chain?
The ETC is organized into 4 protein complexes (i-iv), with different ability to accept electrons, called their redox potential
As electrons move from one molecule to another, they are held more tightly, a small amount of energy is released in each reaction and each successive bond holds less potential energy
At the end, low energy electrons are passed to oxygen with H protons and form water.
What is Chemiosmosis / Oxidative Phsphorylation?
Chemiosmosis: The energy from the redox reactions is sued to pump protons from the matrix into the inter-membrane space establishing a proton gradient
Oxidative Phosphorylation: The proton gradient allows the chain to make ATP with ATP Synthesis
What is the ATP yield from Cellular Respiration?
About 29 ATP is produced from each glucose molecule
Most of it is made from Oxidative Phosphorylation
What happens when there is no Electron acceptor?
The electrons have no place to go so the ETC stops
NADH will build up if there is no NAD available thus stopping glycolysis, pyruvate processing and Krebs cycle causing a life threatening situation
What is Anaerobic Respiration?
The respiration through which cells can break down sugars to generate energy in the absence of oxygen
What is fermentation?
A metabolic pathway that regenerates NAD from NADH and serves as an emergency backup
True or False: Glycolysis still occurs during anaerobic respiration
True
How does Glycolysis happen during fermentation?
By substrate level phosphorylation
What is the Lactic Acid Pathway?
When our muscle cells cannot get enough oxygen. Is temporary until we get oxygen again
Pyruvate produced by glycolysis accepts electrons from NADH producing Lactate and NAD
What is the Alcohol Fermentation Pathway?
What yeast cells perform
Pyruvate is converted to acetaldehyde and CO2. The acetaldehyde accepts electrons from NADH and ethanol (a by-product) and NAD are produced
How much ATP does fermentation produce compared to aerobic respiration?
It is less efficient and yields about 2 ATP whilst aerobic yields 29
What is the name of organisms that can switch between fermentation and aerobic respiration?
Facultative anaerobes (bacteria)
What other pathways does cellular respiration interact with?
Catabolic and Anabolic Pathways
What are catabolic pathways?
Involve the breakdown of molecules
Often harvest stored chemical energy to produce ATP (Digestion)
What are anabolic pathways?
Result in the synthesis of larger molecules from smaller components
Often use energy in the form of ATP (DNA synthesis)
What can substitute for substrates in cellular respiration?
First carbs are used
then fats
then proteins
