Biochem Final Flashcards
ghrelin
The “Lipid Toxicity” Hypothesis
Insulin resistance in type 2 diabetes may be due to abnormal lipid storage in muscle and liver when adipocytes cannot store additional TAGs
leptin
causes the release of anorexigenic peptides, including α-MSH, to inhibit eating
COX-1
catalyzes synthesis of prostaglandins that regulate gastric mucin secretion
COX-2
catalyzes synthesis of prostaglandins that mediate pain, inflammation, and fever
Atherosclerosis
the obstruction of blood vessels from the pathological accumulation of cholesterol (plaques)
Foam cells
form from macrophages
Aspirin
irreversibly inactivates the cyclooxygenase activity of both COX isozymes
What catalyzes the synthesis of prostaglandins?
Cyclooxygenase (COX)
prostaglandin synthetase
Carnitine shuttle
transports long-chain fatty acids (containing 14+ carbons) through the mitochondrial membrane
phosphodiester linkage
covalent bond that joins successive nucleotides of both DNA and RNA
2′-deoxy-d-ribose =
in DNA
D-ribose
= in RNA
nucleoside
pentose and nitrogen base
nucleotide
pentose, nitrogen base, phosphate
How many bonds between G and C
three more stable
How many bonds between A and T
2 minor groove less stable
What type of bond is found between 2 DNA strands?
hydrogen bonds
Is the DNA backbone stable ?
yes
Is the RNA backbone stable?
no
PPAR gamma
regulates the differentiation of fibroblasts into adipocytes and lipid synthesis and storage in adipocytes
PPAR alpha
regulates the uptake and β oxidation of fatty acids and the formation of ketone bodies during fasting
heart, skeletal muscle, and brown adipose tissue
PPAR delta
regulates β oxidation and energy dissipation through uncoupling of mitochondria
Acts in the liver and muscle
Stage 1 of fatty acid oxidation is ?
Beta oxidation
What does beta oxidation mean?
Fatty acids undergo oxidative removal of successive two-carbon units in the form of acetyl-CoA
Stage 2: Fatty acid ocidation
Oxidation of acetyl-CoA groups to CO2 in the citric acid cycle
Where does stage 2 of fatty acid oxidation occur and what does it generate?
Occurs in the mitochondrial matrix
Generates NADH, FADH2, and one GTP
Acyl-CoA dehydrogenase
flavoprotein with tightly bound FAD that catalyzes the dehydrogenation of fatty acyl-CoA to yield a trans-∆2-enoyl-CoA
Stage 3: Electron transfer chain and oxidative phosphorylation
Generates ATP from NADH and FADH2
Acyl-CoA acetyl-transferase (thiolase
catalyzes the reaction of β-ketoacyl-CoA with free coenzyme A to yield acetyl CoA and a fatty acyl-CoA shortened by two carbons
one pass of beta oxidation removes what
One molecule of acetyl-CoA
Two pairs of electrons
Four protons (H+)
first step of beta oxidation involves what ?
hydration step water is used to produce H+
metabolic water
Each pair of electrons transferred from NADH or FADH2 to O2 yields one H2O (“metabolic water”)
what does monosaturated fat require?
enol COA isomerase
Propionyl-CoA carboxylase
catalyzes the carboxylation of propionyl-CoA to form D-methylmalonyl-CoA
requires biotin
Methylmalonyl-CoA epimerase
catalyzes the epimerization of D-methylmalonyl-CoA to its L stereoisomer
Methylmalonyl-CoA mutase
catalyzes the intramolecular rearrangement of L-methylmalonyl-CoA to form succinyl-CoA (which can enter the citric acid cycle)
Which coenzyme is required for Methyl malonyl COA mutase
Vitamin B12
What does biosynthesis require
malonyl coA
Acetyl-CoA carboxylase
catalyzes the irreversible formation of malonyl-CoA from acetyl-CoA in the cytoplasm. Biotin prosthetic group
fatty acid synthesis step 1
An activated acyl group and two carbons from malonyl-CoA undergo condensation to form a β-keto product
step 2 of fatty acid synthesis is ?
The β-keto product is reduced to an alcohol
Requires NADPH
step 3 of fatty acid synthesis is ?
H2O is eliminated to form a double bond
step 4 of fatty acid synthesis is?
The double bond is reduced to form the corresponding saturated fatty acyl group
requires NADPH
step 5 of fatty acid synthesis?
The butyryl group is transferred from the phosphopantetheine —SH group of ACP to the Cys —SH group of β-ketoacyl-ACP synthase
step 6 fatty acid synthesis
ACP is recharged by the linkage of another malonyl group to the unoccupied phosphopantetheine —SH group
what occurs in the mitochondria
fatty acid elongation
Endoplasmic reticulum
phospholipid sterol synthesis fatty acid desaturation/elongation
cytosol animal
NADPH, pentose phosphate, fatty acid
Fatty acyl-CoA desaturase
catalyzes an oxidative reaction that introduces a double bond into a fatty acid chain
Acyl transferase
catalyzes the acylation of the two free hydroxyl groups of L-glycerol 3-phosphate by two molecules of fatty acyl–CoA to yield diacylglycerol 3-phosphate (phosphatidic acid)
Phosphatidic acid phosphatase
hydrolyzes phosphatidic acid to form a 1,2-diacylglycerol
What facilitates the lands cycle
LPCAT
phospholipids are remodeled through what
LANDS Cycle
What is intermediate of cholesterol?
isoprene
HMG-CoA synthase
catalyzes the condensation of acetyl-CoA with acetoacetyl-CoA to form β-hydroxy-β-methylglutaryl-CoA (HMG-CoA)
Acetyl-CoA acetyl transferase
catalyzes the condensation of two acetyl-CoA molecules
Squalene monooxygenase
adds one oxygen atom from O2 to the end of the squalene chain to form Squalene 2,3-epoxide
Mixed-function oxidase
Requires NADPH
Cyclization of squalene 2,3-epoxide forms
lanosterol
SREBP cleavage-activating protein (SCAP) and Insig (insulin-induced gene protein)
membrane proteins that act as sterol sensors
Leptin
an adipokine produced by adipose tissue that regulates feeding behavior and energy expenditure to maintain adequate reserves of fat
Adiponectin
is a well-known homeostatic factor for regulating glucose levels, lipid metabolism, and insulin sensitivity through its anti-inflammatory, anti-fibrotic, and antioxidant effects.
The first effect of adipoectin is ?
Adiponectin triggers phosphorylation and activation of AMPK
What is AMP responsible for ?
AMPK is allosterically activated by AMP
