Chapter 9 Flashcards
What is fermentation?
partial degradation of sugars and other organic fuel without oxygen
What is aerobic respiration?
oxygen is consumed as a reactant along with the organic fuel
What is the chemical equation for aerobic respiration?
Organic compound + H2O = CO2 +H2O + Energy
What is oxidation?
Loss of electrons
What is reduction?
gain of electrons
What is a reducing agent? (2)
electron donor
gets oxidized
What is an oxidizing agent? (2)
Electron acceptor
gets reduced
how does electronegativity and energy correlate?
The more electronegative an atom is, the more energy required to take an electron away from it
What is NAD+? (3)
a coenzyme that cycles between an oxidized state and a reduced state (NADH)
Receives 2 e- and 1 proton from glucose
stored energy in NADH is used to make ATP
What is dehydrogenases?
Enzyme that removes e- and protons from glucose and delivers to NAD+
What is the electron transport chain? (2)
number of molecules built into the membrane of mitochondria
e- in NADH is shuttled from the top (high energy) to the bottom (low energy) to form water
What is the electron route in cellular respiration?
Glucose > NADH> Electron transport chain> oxygen
What happens to the pyruvate after glycolysis?
enters the mitochondria and is oxidized to a compound called acetyl CoA, entering the citric acid cycle
What happens to the energy released in the ETC?
it is stored in the mitochondria to make ATP
What is oxidative phosphorylation?
ATP synthesis using electron transport chain
What is substrate-level phosphorylation? (2)
ATP formed directly during glycolysis and the citric acid cycle
occurs when an enzyme transfers a P group from a substrate molecule to ADP
Steps in glycolysis (3)
- glucose is split from a six carbon sugar into 2 three carbon sugars
these sugars are oxidized
Remaining molecules rearrange to form pyruvate
What is the energy investment phase in glycolysis?
where the cell spends ATP
What is the energy payoff phase in ATP?
when ATP produced by substrate level phosphorylation; NAD+ is reduced to NADH
What is the product of glycolysis?
2 ATP, 2NADH, and 2 pyruvate
How is pyruvate oxidized?
In the presence of O2 after glycolysis, pyruvate enters mitochondria through active transport
it is then converted to a compound called acetyl coenzyme
What three reactions does the oxidation of pyruvate catalyze?
- Pyruvated carboxyl group is removed and given off as CO2
- Remaining 2 C fragment is oxidized to form acetate
- extracted e- is transferred to NAD+ to form NADH - CoA, a sulfur-containing compound from vitamin B is attached via its sulfur atom to the acetate from acetyl CoA
What occurs in the citric acid cycle? (5)
oxidizes organic fuel derived from pyruvate
pyruvate is broken down into 3 CO2 molecules
generates 1 ATP per turn
The majority of the energy is transferred to NAD+ and FAD to form NADH and FADH2
takes two cycles to break down one glucose/ 2 Acetyl CoA molecules
Product of citric acid cycle
Two cycles result in 2 ATP, 6 NADH, 2 FADH
What does the ETC do, and what does it consist of? (3)
Make it easier for electrons to fall from food to oxygen
Consists mostly of proteins, named multiprotein comple 1-4
Each complex becomes reduced when accepting e- and oxidized when passing down
What are prosthetic groups? (2)
Tightly bound between proteins in ETC
Act as nonprotein components essential for the catalytic function of certain enzyme
What occurs in Complex 1? (3)
e- from NADH is transferred to the first molecule- flavoprotein
passed to iron-sulfur protein
passed to ubiquinone
What is ubiquinone?
Hydrophobic molecule that is the only nonprotein
what are cytochromes?
protein that make up majority of the ETC between ubiquinone and oxygen
why the prosthetic group is attached to cytochromes
heme group that possess an iron atom that accepts electrons
what is Cyt A3?
the last cytochrome in the chain
passes the e- to oxygen
What does oxygen do at the end of ETC?
takes a pair of H+ from the solution and forms water
Where does the e- come from in the beginning of the ETC? (3)
At complex 1, NADH
at complex 2, FADH2
FADH2 provides less energy for ATP synthesis
what is chemiosmosis?
process which energy in the form of H+ gradient across a membrane is used to drive cellular work
What is ATP synthase? (3)
enzyme that makes ATP from ADP and P group
found in the inner membrane of the mitochondria
uses the energy of an existing ion gradient of H+
What are the steps of chemiosmosis? (5)
- H+ moves down the gradient through a channel in a stator
- H+ enters binding sites within a rotor, changing its shape and spins
- spinning causes the internal rod to spin
- catalytic sites activate, producing ATP
How does the ETC maintain a e- gradient?
Portions of the ETC releases protons along with electrons
proton motive force
continuously deposited H+ from the ETC to maintain an H+ gradient in the cytoplasm
How does energy flow during respiration?
Glucose > NADH > ETC> Proton motive Force> ATP
What is the result of oxidative phosphorylation?
26-28 ATP
Why is the exact result of oxidative phosphorylation unknown? (3)
- the ratio of NADH molecules to ATP is not a whole number
- ATP yields depend on the type of shuttle used to transport electrons from the cytosol into the mitochondria
- The proton motive forced generated by the redox reactions of respiration is also used to drive other kinds of work
How effective is cellular respiration? (2)
34% effective
rest is lost as heat
What are ways cells can oxidize fuel to generate ATP without oxygen?
anaerobic respiration and fermentation
Anaerobic respiration vs fermentation
Anaerobic respiration uses ETC, while fermentation does not
Anaerobic respiration ETC
the final electron acceptor is sulfate, producing hydrogen sulfide
what is fermentation?
extension of glycolysis, continuous generation of ATP through glycolysis
requires a sufficient supply of NAD+ to accept electrons
Electron is transferred from NADH to pyruvate
what is alcohol fermentation? (4)
pyruvate is converted to ethanol
releases CO2 from pyruvate
pyruvate is converted to acetaldehyde
acetaldehyde is reduced by NADH to ethanol, producing NAD+
What is lactic acid fermentation? (4)
pyruvate is reduced directly by NADH to form Lactate
no CO2 is released
used by muscle cells to make ATP when oxygen is scarce
excess lactate causes pain
Fermentation vs cellular respiration
(3)
in fermentation, the final electron acceptor is an organic molecule like pyruvate or acetaldehyde, yielding 2 ATP.
the remaining energy in the molecule is unavailable
in cellular respiration, electrons are transferred to the ETC, and the energy from pyruvate is fully oxidized
what are obligate anaerobes? (2)
carry out only fermentation or anaerobic respiration
cannot survive in oxygen
What are facultative anaerobes?
can make enough ATP to survive using either fermentation or respiration
What is deamination?
removal of amino groups from an amino acid to be used in glycolysis
what is beta oxidation?
breaking fatty acids down to two carbon fragments to enter the citric acid cycle
How does the body make amino acids?
modifying compounds siphoned away from the citric acid cycle
What are essential amino acids?
acids that cannot be made by the boddy
How is glucose made in the body?
from pyruvate
How is fatty acid made in the body?
from Acetyl CoA
