Review Flashcards
What functions as an accessory storage depot for energy and as an “ATP Buffer”?
phosphocreatine
High energy phosphate bond
3x more abundant than ATP
Cannot participate directly in energy transfer
Essential amino acids
PVT TIM HALL Phe. Val Thr Trp Ile Met His Arg Leu Lys
How is a peptide bond formed?
aa + ATP -> aa-amp +2Pi
aa-amp + tRNA -> aa-tRNA + AMP
Attachment of tRNA to mRNA codon-anticodon
aa linked to another aa with peptidyl transferase + GTP
How many high energy phosphate bonds are needed to form one peptide linkage?
4
Where is urea formed?
in the liver
What is the first step of degradation of amino acids?
deamination
- generally involves transamination
- one end product is ammonia
Diagram the Ornithine (Urea) cycle
In the mitocondria:
Ammonia +CO2 -> carbamoyl phosphate
Carbamoyl phosphate + ornithine -> Citrulline
In cytoplasm -> Citrulline + aspartate -> argininosuccinate
Argininosuccinate _> arginine + fumerate
Arginine -> urea + ornithine
Ornithine mnemonic
Word Molecule Orange Ornithine Colored Carbamoyl Phosphate Cats Citrulline Always Aspartate (enters the cycle) Ask Argininosuccinate For Fumarate (leaves the cycle) Awesome Arginine Umbrellas Urea (leaves the cycle)
Rate of overall chemical reaction is determined by what?
concentration of the enzyme
concentration of the substrate
Michaelis-menten equation
What is the overall rate of a series of chemical reactions determined by?
The rate of reaction of the slowest step in the series
Rate-limiting step
What is the major rate-limiting factor for almost all energy metabolism in the body?
ADP
*oxidative metabolic pathways or other pathways for the release of energy
ADP concentration increases during cellular activity
Energy equivalent of oxygen =
- 825 Cal: energy liberated per liter of oxygen with average diet
* avg of metabolizing 1 liter of oxygen with glucose, fat, protein
Thyroxine increases or decreases rate of chemical reactions in cells and metabolic rate?
Increases:
max secretion may increase metabolic 50 to 100% above normal
Loss of thyroid secretion decreases metabolic rate to 40 to 60 % of normal
Testosterone increases or decreases metabolic rate?
increases rate 10 to 15%, mainly related to anabolic effect of increase in skeletal muscle mass
What is much of the decline in BMR with increasing age probably related to?
loss of muscle mass and replacement with adipose tissue with a lower rate of metabolism
Skeletal muscle accounts for 20 to 30 % of BMR even at rest
Glycogenolysis:
is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1).
Gluconeogenesis:
is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol, and glucogenic amino acids.
How does the blood flow through the lobule?
Portal vein-> sinusoids-> central vein -> hepatic veins
Hepatic artery -> sinusoids -> central vein -> hepatic veins
Describe liver cell plates
Two layers of hepatocytes and bile canaliculi lie between the two layers of hepatocytes in each cell plate
What are sinusoids lined with?
Endothelial cell
Kupffer cells
What is found between endothelial cells and hepatocytes?
Space of Disse
Describe liver blood flow and vascular resistance
Liver has high blood flow and low vascular resistance
In the urea cycle, what reaction occurs in the mitochondria?
Ammonia + CO2 -> carbamoyl phosphate
+ ornithine
What is the effect of cirrhosis on the liver?
Increases liver resistance to blood flow