Chapter 7 Flashcards
(32 cards)
What is cellular respiration?
A process by which living cells obtain energy from organic molecules and release waste products.
How is metabolism different than other chemical reactions?
Metabolism that occurs in living cells is extremely controlled.
What is aerobic respiration?
A type of cellular respiration in which O2 is consumed and CO2 is released.
What are the three energy intermediates that are released in addition to heat when certain chemical bonds in glucose are broken?
ATP, NADH, FADH2
What are the four metabolic pathways of anaerobic cellular respiration that lead to the release of ATP, NADH, and FADH2?
- Glycolysis
- the breakdown of pyruvate
- citric acid cycle
- oxidative phosphorylation
Describe Glycolysis:
A metabolic pathway that breaks down glucose into 2 pyruvate molecules (3 carbons each), producing a net energy yield of 2 ATP and 2 NADH molecules. ATP is synthesized through substrate-level phosphorylation.
Where does Glycolysis take place?
In the cytosol
Describe the breakdown of pyruvate:
The two pyruvate molecules are further broken down into an acetyl group (2 carbons each) and one CO2 molecule. One NADH is made for every pyruvate molecule that is oxidized.
Describe the citric acid cycle (formally know as the Krebs cycle):
Each acetyl group is incorporated into an organic molecule and is later oxidized to release 2 CO2. This process results in the creation of 1 ATP, 3 NADH, and 1 FADH2. So, a total of 2 ATP, 6 NADH, 2 FADH2, and 4 CO2.
Where does the breakdown of pyruvate and the citric acid cycle occur?
In the mitochondrial matrix.
Describe oxidative phosphorylation:
High-energy electrons taken from NADH and FADH2 are transported via the H+ electrochemical gradient to make more ATP via the phosphorylation of ADP and Pi.
What does chemiosmosis refer to?
A process for making ATP in which energy stored in an ion electrochemical gradient is used to make ATP from ADP and Pi.
How many ATPs are made via oxidative phosphorylation?
Approximately 30-34 ATP molecules.
Where does oxidative phosphorylation occur?
In eukaryotes, it occurs along the cristae. In bacteria and archaea it occurs along the plasma membrane.
What are the three phases of Glycolysis?
- (steps 1-3) Energy investment phase
- (steps 4-5) Cleavage phase
- (steps 6-10) Energy liberation phase
Why don’t we make too much ATP?
When a cell has a sufficient amount of ATP, feedback inhibition occurs. At high concentrations, ATP binds to an allosteric site on the phosphofructokinase enzyme and causes a confrontational change that render the enzyme useless.
What is Coenzyme A?
An organic molecule that attaches to acetyl via a covalent bond. The hydrolysis of this bond releases a large amount of free energy, making it possible for the acetyl group to attach to be transferred to other organic molecules.
Define metabolic cycle:
A biochemical cycle in which particular molecules enter while others leave; the process is cyclical because it involves a series of organic molecules that are regenerated with each turn of the cycle.
How is the citric acid cycle controlled?
The rate of the cycle is largely regulated by the availability of substrates acetyl-CoA and NAD+ and by feedback inhibition.
What is the electron transport chain (ETC) (also called the respiratory chain)?
A group of protein complexes and small organic molecules within the inner membranes of mitochondria and chloroplasts and the plasma membrane of prokaryotes. The components accept and donate electrons to each other in a linear manner and produce a H+ electrochemical gradient.
What molecule is at the end of the respiratory chain?
Oxygen, which is the most electronegative.
How is oxidative phosphorylation controlled?
This process is regulated by a variety of factors, including the availability of ETC substrates, such as NADH and O2, and by the ATP/ADP ratio.
What are the two main reasons we don’t make the maximum amount of ATP during oxidative phosphorylation?
- NADH and FADH2 are also used for anabolic pathways.
2. Some of the energy in the H+ gradient is used for other purposes.
What does anaerobic mean?
Refers to an environment that lacks oxygen or a process that occurs in the absence of oxygen; a form of metabolism that does not require oxygen.
