MCAT BIOCHEM Part 3 Flashcards
The enzymes of the Krebs cycle and the pyruvate dehydrogenase complex are located in the ___
matrix
The enzymes of the electron transport chain and ATP synthase are bound to the __
inner mitochondrial membrane
The two goals of the electron transport or oxidative phosphorylation are to:
- reoxidize all the electron carriers reduced in glycolysis, PDC, and the Krebs cycle
- Store energy in the form of ATP i nthe process
The ___ is a group of five electron carriers. Each reduces the next member down the line.
Electron transport chain
The first electron carrier in the electron transport chain is ___
NADH dehydrogenase it oxidizes NADH to NAD+
The reason cyanid is a poison is that it inactivates cytochrome C oxidase by binding to its active site with high affinity. When a person is exposed to cyanide what happens?
The electron transport chain ceases to transport electrons and therefore ceases to pump protons
Each molecule of NADH provides the energy to produce approximately ___
2.5 ATP molecules
The ETC must pump ___ protons to produce 1 molecule of ATP
4 protons
FADH2 gives its electrons to ___
ubiquinone
FADH2 pumps ___ protons across the inner membrane
6 protons
FADH2 oxidation to FAD only produces___ ATP
1.5
The electrons of NADH produced in glyoclysis must be transported into the mitochondria before they enter the ETC by a pathway termed the __
glycerol phosphate shuttle
The glycerol phosphate gives electrons from NADH directly to ___
ubiquinone
Cytosolic NADH from glycolysis only produces
1.5 molecules of ATP
Krebs cycle produces ___,___,and ___
6 NADH
2 FADH2
2 GTP
The Pyruvate Dehydrogenase Complex produces ___
2 NADH
The total number of ATP for cellular respiration is
30 ATP
In energy-starved states ___ levels activate PFK while inhibiting F-1,6-BPase, resulting in enhanced glycolsysi activity and a suppression of gluconeogenesis
AMP
Skeletal muscle lacks glucose-6-phosphatase the absence of this enzyme__
keeps glucose phosphorylated and unable to leave the muscle cell
The enzyme ____ is required to transport glucose in the bloodstream
Glucose-6-phosphatase
___ are composed of long unsubstituted alkanes that end in a carboxylic acid
Fatty acids
____ are typically 14-18 carbons long and synthesized two carbons at a time from acetate, thus in humans ___ are even numbered predominantly
Fatty acids
___ have one or more double bond in the tail and they are almost always (cis) or (Z)
Unsaturated fatty acids
Triglyceride is composed of ____
three fatty acids esterified to a glycerol molecule
Glycerol is a three-carbon triol
Soaps are formed by base-catalyzed hydrolysis of triglycerides from animal fat into fatty acid salts, reaction called__
saponification
What are the two reasons fats are more efficient energy storage molecules than carbohydrates?
- Packing
2. Energy content
Describe the packing that makes fats more efficient than carbohydrates.
Hydrophobicity of fats allow them to pack together closer than carbohydrates.
Carbohydrates carry a great amount of water-of-solvation (water molecules hydrogen bonded to their hydroxyl groups)
Amount of carbon per unit area or unit weight is much greater in a fat droplet than in dissolved sugar
Describe why a fat has more energy content than a carbohydrate
A fat is much more reduced than a carbohydrate. Energy metabolism begins with the oxidation of foodstuffs to release energy. Since carbohydrates are more oxidized to begin with, oxidizing them reelases LESS energy
__ and ___ are the most common phospholipids in the eukaryotic cell
Phosphatidylcholine and phosphatidylethanolamine
___ is a major lipid component of lung surfactant (important in reducing surface tension inside lung alveoli)
Phosphatidylcholine
