Cellular Respiration Flashcards
what are the 2 electron carriers, what do they do? what do they turn into? where do they go?
NAD+ and FAD
- pick up electrons from the organic molecules that are being oxidized
- Become reduced (addition of electrons and hydrogen atoms) –> NADH and FADH2
- Drop off electrons at electron transport chain
which is the oxidized vs reduced forms of the electron carriers? which is high/low energy?
NAD+ and FAD: -lower energy molecules -oxidized forms NADH and FADH2 -higher energy molecules -reduced forms
what do NADH and FADH2 store?
store energy that will eventually be used to synthesize ATP
what are the components of the mitochondria?
- smooth outer membrane
- highly folded inner membrane
- Space between membranes
- Matrix in center
what are the 3 main stages of cellular respiration?
- Glycolysis
- Citric Acid Cycle
- Oxidative Phosphorylation
what are the original molecules and product molecules of cellular respiration?
C6H12O6 + 6O2 → 6H2O + 6CO2
Glycolysis: 1. what step is it? 2. where does it occur? 3. input(s): 4. output(s): summary:
- 1st step in cellular respiration
- happens outside of mitochondria in cytoplasm
- glucose C6H12O6 (6-carbon sugar)
- 2X pyruvate (3-carbon molecules)
2X ATP (energy released from reaction
2X NADH (reduced NAH+ ie. carrying high energy electrons)
summary: breaks glucose into 2 3-carbon
molecules, some ATP produced, NAD+ reduced
where is most of the energy contained after glycolysis?
Pyruvate still contains most of the energy from the
original glucose molecule
what are the 2 phases of glycolysis?
- Energy Investment phase
2. energy payoff phase
what happens during the first phase of glycolysis?
- energy from 2 ATP are added to activate glucose (For each molecule of glucose, two molecules of ATP are hydrolyzed (water added to in order to make ADP + P(i) which transfers energy) to provide energy to drive the early steps)
- glucose splits into 2X 3-carbon pyruvate
what happens during the 2nd phase of glycolysis?
2 NADH and 4 ATP produced
-but because of initial investment during the 1st phase, net ATP = 2 (4-2)
what “mini” stage happens between the 1st and 2nd main stages of cellular respiration? what occurs?
Oxidation of Pyruvate -first the pyruvate enters the mitochondria via active transport -input: 2X 3-carbon pyruvate -Output: 2X 2-carbon acetate 2X CO2 molecule 2X NADH
The Citric Acid Cycle 1. what step is it, what is it also known as? 2. where does it occur? 3. input(s): 4. output(s): summary:
- 2nd. Krebs cycle
- mitochondrial matrix
- Input: 2X 2-carbon acetate
- Output: 2X (2x CO2) = 4X CO2
2X ATP
2X (3x NADH) = 6X NADH (carrying pair of high energy electrons)
2X FADH2
summary: breaks down organic molecule to CO2, some ATP produced, NAD+ and FAD reduced
per glucose molecule, how many citric acid cycles need to take place to get to the next main stage?
- 2 citric acid cycle turns
- Each turn of the citric acid cycle:
1. oxidizes one 2-carbon acetate to form 2 CO2
2. makes 1 ATP, 3 NADH, 1 FADH2
Where does the energy go that was released from the oxidation of glucose?
Energy is stored in NADH and FADH2 will be used to generate ATP during oxidative phosphorylation (stage 3) from Glycolysis: -2X ATP -2X NADH from Oxidation of Pyruvate: -2X NADH from the Citric Acid Cycle: -2X ATP -6X NADH -2X FADH2
Oxidative Phosphorylation
1. what step is it, what is it also known as?
2. where does it occur?
summary:
- 3rd and final stage
- Occurs inside the mitochondria
Summary: Energy released during exergonic reactions of ETC produces H+ gradient that is used to drive the
endergonic synthesis of ATP
what are the 2 phases of Oxidative phosphorylation?
- The Electron Transport Chain
2. Chemiosmosis
what is the Electron Transport Chain? how are electrons transported to this chain?
Series of protein complexes embedded in the inner mitochondrial membrane
-transported to chain (“dropped off”) by NADH and FADH2
As electrons ‘fall down’ electron transport chain, they … energy. Electrons are in what kind of energy state when they reach the O2 at the end of the chain?
release
-very low energy state
how do electrons move along the electron transport chain?
-Electron transport involves a sequence of oxidation-reduction reactions –> eg a transfer of electrons between two species (proteins)
1. High energy electrons dropped off by NADH/FADH2
2. Reduces first molecule in electron transport chain
3. First molecule is oxidized when it transfers pair of
high energy electrons to next molecule in chain
4. This transfer of electrons from one molecule to next
continues until electrons are transferred to O2
what happens at the end of the electron transport chain when electrons are transferred to O2?
When the electrons are transferred to oxygen, two
hydrogen ions join to form water molecule
where does NADH drop off it’s electrons? FADH2? how much ATP can be synthesized from each donation from NADH? FADH2?
NADH –> at the beginning of electron transport chain
-3 ATP
FADH2 –> farther along chain
-2 ATP
what happens to the energy that is released as electrons are transferred from one protein acceptor to the next in the ETC?
-energy is used to move H+ across the inner membrane against their concentration gradient (electrochemical gradient –> positive charge on outside, negative charge on inside)
what is involved in chemiosmosis?
- H+ gradient across the inner mitochondrial membrane is used to drive the synthesis of ATP
- Energy is released as H+ diffuse down their concentration gradient
- Released energy is captured by ATP synthase (pump from video) and is used to synthesize ATP
