Chapter 4 Flashcards
How come wood releases a lot of energy
The major component of the wood that burns= cellulose.
- Cellulose molecules, main component of plant cell walls, are complex carbs made of glucose.
- When cellulose burns, it combines with O2
in atmosphere & releases a tremendous amount of potentially life-threatening energy
Most of the energy that enters the biosphere is ___________________
solar radiation
- photosynthesis transforms this light energy into
chemical potential energy, which is then available to plants & other organisms in food webs.
What type of cells need ATP?
all cells
Aerobic cellular respiration is
AKA aerobic respiration
- the process that extracts energy from food (organic compounds) in the presence of oxygen
- The energy is used to synthesize ATP from ADP & Pi
- The ATP molecules are then used to supply energy
directly to the cells for their energy-demanding activities.
- Equation: C6H12O6 + 6O2 –> 6CO2 + 6H2O
∆G= –2870 kJ/mol
An Obligate Aerobe is
an organism that cannot live without oxygen, and they use aerobic cellular respiration exclusively or most of the time.
Aerobic cellular respiration can be divided into four stages: List them
1) Glycolysis
2) Pyruvate Oxidation
3) Citric acid cycle
4) Electron transport & oxidative phosphorylation
Each stage involves the transfer of free energy, producing ATP in 1 of 2 ways: substrate-level phosphorylation & oxidative phosphorylation.
https://www.youtube.com/watch?v=eJ9Zjc-jdys
Substrate-level phosphorylation forms ATP…
directly in an enzyme-catalyzed reaction through the transfer of a phosphate group from one molecule to an adenosine diphosphate (ADP) molecule.
Oxidative phosphorylation forms ATP…
indirectly through a series of redox reactions involving a final electron acceptor.
- In aerobic respiration, oxygen is the final electron acceptor
Glycolysis Overview
- (occurs in cytosol) –> doesn’t take place in mitochondria, & doesn’t require O2, thus all cells can do it.
- Enzymes break down one molecule of glucose into two molecules of pyruvate. Some high-energy ATP (via substrate-level phosphorylation) & NADH is synthesized.
Pyruvate Oxidation Overview
- in mitochondria
- Each of the 2 molecules of pyruvate produced in glycolysis is transported to mitochondria and is oxidized, resulting in the production of CO2 (a waste molecule), NADH, & an acetyl group that is initially
attached to coenzyme A (acetyl-CoA)
Citric acid cycle Overview
- AKA kreb’s cycle
- (in mitochondria)
- Acetyl-CoA molecules from pyruvate oxidation enter a metabolic cycle, where the acetyl group is completely oxidized to CO2. In the process, ATP (via substrate-level phosphorylation) & the e- carriers NADH & FADH2 are synthesized.
Electron transport & oxidative phosphorylation Overview
- (in mitochondria)
- The NADH & FADH2 (synthesized during glycolysis, pyruvate oxidation, and the citric acid cycle) are oxidized. Their high-energy e- & hydrogens are passed from one oxidizing agent to the next until they are transferred to O2, producing water. The free energy released during electron transport is indirectly used to synthesize a large amount of ATP by oxidative phosphorylation
The mitochondrion is referred to as the powerhouse of the cell because
as the location of the citric acid cycle and electron transport, it generates most of the ATP that is used by the cell
The mitochondrion is composed of two membranes
- the outer membrane and the inner membrane, which together define two compartments
- The intermembrane space is between the outer and inner membranes, and the matrix is the interior aqueous environment of the organelle
Some prokaryotes undergo aerobic cellular respiration without ______________. ELABORATE
mitochondria
- In prokaryotes, the process of glycolysis, pyruvate oxidation, &the citric acid cycle occur in the cytosol of the cell, whereas e- transport occurs on internal membranes derived from the plasma membrane
- These prokaryotes possess the full complement of reactions that make up aerobic cellular respiration—from glycolysis through electron transport & oxidative phosphorylation.
There are 2 general processes by which certain cells can oxidize fuel molecules & generate ATP in the absence of oxygen:
anaerobic respiration & fermentation
- Both anaerobic respiration & fermentation r catabolic (energy-yielding) processes.
Anaerobic respiration is
similar to aerobic cellular respiration in using a series of electron-transferring steps, but it uses an inorganic molecule other than oxygen as the final oxidizing agent.
Fermentation is
does not use an electron transport system. Thus, fermentation is not considered to be a form of respiration. It relies on an organic compound to act as the final oxidizing agent.
https://www.youtube.com/watch?v=YbdkbCU20_M
- This equation shows the overall reaction for 1 common fermentation pathway. The released free energy is used to make ATP. Note the products of this fermentation pathway are ethanol (CH3CH2OH) & CO2:
C6H12O6 –> 2 CH3CH2OH + 2CO2 ∆G= –218 kJ/mol - Note how fermentation releases much less free energy than aerobic respiration & thus makes less ATP
An obligate anaerobe is
an organism that cannot survive in the presence of oxygen
- use inorganic substances such as NO2, S, and Fe 3+ as final electron acceptors to obtain energy
aerobic respiration made the evolution of large animals possible because
it allowed them to meet their very high energy demands.
- RMR from amoeba sisters –> anaerobic respiration produces much less ATP
every 1 of ur billions of active cells requires access to more than ____________ ATPs per second
1 million
Glycolysis is considered to be the most fundamental & probably most ancient of all metabolic pathways. This is supported by the following facts.
1) glycolysis is nearly universal, being found in almost all organisms, both prokaryotes & eukaryotes
2) it does not require O2. Oxygen became abundant
in Earth’s atmosphere only about 2.5 billion years ago—about 1.5 billion years after scientists think that life began.
3) Third, glycolysis occurs in the cytosol of all cells and
involves soluble enzymes. Therefore, it does not require more sophisticated cellular organelles in order to operate –> indicating that it might have began before complex organelles were formed (i think)
The first experiments investigating glycolysis took place over ____ years ago.
100
- Using extracts from yeast cells, researchers showed that they could study biological reactions in an
isolated system.
- These experiments became the foundation of modern biochemistry
Glycolysis consists of ___ sequential enzyme-catalyzed reactions that lead to….
10
the oxidation of the 6-carbon sugar glucose, producing two molecules of the 3-carbon
compound pyruvate.
- The PE & e- released in the oxidation leads to the overall synthesis of both ATP & NADH.
Glycolysis has two phases: 1) an initial energy investment phase 2) an energy payoff phase
- both phases have 5 steps