Cellular Respiration Flashcards
What is cellular respiration?
the set of rxns (about 20) that use electrons harvested from high-energy molecules to produce ATP
What are the 4 processes involved in CR?
- glycolysis
- pyruvate processing
- citric acid cycle
- electron transport and oxidative phosphorylation
Where does glycolysis occur?
cytosol of eukaryotes and prokaryoted
Where does pyruvate processing and citric acid cycle occur?
matrix of mitochondria or cytosol of prokaryotes
Where does electron transport/oxidative phosphorylation occur?
inner membrane of mitochondria or plasma membrane of prokaryotes
Cell respiration plays a central role in _______.
metabolism
What is the rxn that occurs for glycolysis?
glucose (6 cabon) —-> 2 pyruvate (3 carbon) + 2 NADH + 2 ATP
In glycolysis, what is the energy investment phase?
- the first 5 rxns
- further increases potential energy of glucose to split in half
- 2 ATP used
In glycolysis, what is the energy-payoff phase?
- second 5 rxns
- phosphates removed as pyyruvate is formed
- 4 ATP used, 2 NADH gained
In glycolysis, there are ______ rxns and ______ enzymes.
10; 10
Describe the 5 steps in the energy investment phase of glycolysis.
1,3: phosphorylation (kinase adds ATP)
2,5: isomerization (rearrange atoms)
3*: commitment step (once that 2nd phosphate is added, no going back)
Describe the steps in the energy-payoff phase of glycolysis.
7,10*: substrate-level phosphorylation
8: isomerization
How is glycolysis regulated?
feedback inhibition of phosphfructokinase
What is substrate level-phosphorylation?
enzyme-catalyzed reactions that result in ATP production; it is one of the two ways to make ATP
What is the reaction for pyruvate oxidation?
pyruvate + NAD^+ —-> acetyl CoA + CO2 + NADH (twice per glucose molecule)
Where does pyruvate oxidation occur?
mitochondrial matrix
Where is most energy stored before the citric acid cycle begins?
acetyl CoA
What is the reaction that occurs for the citric acid cycle?
acetyl CoA + 3NAD^+ + FAD +ADP —-> 2CO2 +3NADH + FADH2 + ATP (twice per glucose molecule)
What is another name for the citric acid cycle?
TCA (tricarboxylic acid) and the Krebbs Cycle
Describe reaction 1 of the CAC?
acetyl CoA combined with 4C molecule to form a 6C molecule (2 acetyl CoA + 4C molecule —> 6C molecule)
What is reaction 2 of the the CAC?
isomerization (movement of the OH group)
What is reaction 3 of the CAC?
redox rxn ( isocitrate is oxidized, NADH is product)
What is reaction 5 of the CAC?
substrate level phosphorylation (bc ATP is produced)
What is reaction 6 of the CAC?
redox rxn (succinate oxidized, fumarate reduced, FADH2 produced)
What is reaction 8 of the CAC?
redox rxn (oxaloacetate reduced, malate oxidized, NADH produced)
Provide a brief summary of glucose oxidation.
- glucose fully oxidized into CO2
- however we only gained 4 ATP
What reaction happens with the ETC and oxidative phosphorylation?
NADH + FADH2 + O2 —> NAD^+ + FAD + H2O
Describe the ETC.
- coordinates a series of redox rxns
- establishes a proton gradient
- O2 is final electron acceptor
Describe oxidative phosphorylation.
- proton gradient (made from ETC) drives motor protein to produce ATP
- primary method of ATP production in cells
In the ETC, proteins differ in _____________.
redox potential
What is redox potential?
- the ability to accept electrons
- small amts of energy released each time
What is Ubiquinone/Coenzyme Q?
- occurs in almost all organisms
- lipid-soluble carrier protein, moves through membrane to transfer electrons
What is the final electron acceptor in the ETC?
O2
Describe the parts of oxidative phosphorylation.
- occurs at motor protein (ATP synthase)
- proton gradient results in proton motive force
- chemiosmosis
What is chemiosmosis?
use of a proton gradient to drive energy-requiring process
How many ATP total does cell respiration produce?
25-30
Oxidative phosphorylation is very efficient, but requires O2 making it _________.
aerobic respiration
In anaerobic respiration, the final electron receptor is something other than __________.
O2
Why is anaerobic respiration less efficient than aerobic?
because O2 is the strongest oxidizing agent
What are obligate anaerobes?
organisms that rely entirely on anaerobic (O2 is “poisonous”)
What are facultative anaerobes?
technically aerobic; organisms that can use O2 when its available, but can also survive using fermentation when O2 is absent
What are obligate aerobes?
organisms that require O2 to grow (some can use fermentation for short time periods)
Why do some organisms have to use fermentation?
because there is no ATP to go through the citric acid cycle, other processes, etc
- without O2 there would be a buildup of NADH
Glycolysis provides some energy, but it can’t take place w/o __________.
NAD+
What is fermentation?
metabolic pathway that regenerates NAD+ by oxidizing stockpiles of NADH
