Things To Know Flashcards
Centrosome vs centromere
Centrosome - product spindle fibers
Made up of centrioles/microtubules
Centromere - region of DNA that’s highly constricted to form tiny area holding the 2 sister chromatids together during cell division
GLUT 2 vs GLUT 4
GLUT 2: low affinity transporter; in hepatocytes and pancreatic cells; moves excess Glucose brought in via hepatic portal vein into storage; HIGH Km; if [glucose] < Km then rest of glucose enters peripheral circulation; serves at glucose sensor on beta islet cells - 1st order kinetics
GLUT4: in Adipose and muscle; insulin increases # of GLUT4 on membrane via exocytosis; moves gluc out of peripheral circulation so its Km is close to [gluc] in blood - so transporter easily saturated when gluc is high - 0 order kinetics
Galactose metabolism and how it enters glycolysis
Enters via hepatic portal vein and phosphorylated by galactokinase; galactose 1-P converted to gluc-1P by galactose -1 phosphate uridyltransferase and a UDP-Galactose epimerase
Fructose metabolism and how it enters glycolysis
Enters via hepatic portal vein; trapped by fructokinase into fructose-1-phosphate. Which is then cleaved into glyceraldehyde and DHAP by aldolase
Pyruvate dehydrogenase complex
Converts pyruvate into acetyl CoA - irreversible
Contains thiamine pyrophosphate, lipoic acid, CoA, FAD, NAD+
Enzyme inhibited by acetyl-CoA
In liver, PDH is activated by insulin
Glycogenesis
Talk about the 2 enzymes
Core protein glycogenin
Gluc-6P converted to Gluc-1P, which interacts with UTP to form UDP-glucose. Now glycogen synthase can move glucose into glycogen chain and release UDP
Glycogen synthase- forms alpha-1,4 glycosidic bond; stimulated by insulin and gluc-6-P; inhibited by epinephrine and norepinephrine
Branching enzymes - glycosides alpha-1,4;alpha-1,6 transferase
- hydrolysis an alpha-1,4 bond and moves that to form alpha-1,6 linked branches
- glycogen synthase extends both branches
Glycogenolysis
Enzymes used
Glycogen phosphorylase - CANNOT break alpha-1,6 bonds so nears branch points but only breaks alpha-1,4 bonds to form Glucose 1P (!!!!!!!) which is then converted by mutate into glucose
Debranching enzymes- breaks alpha -1,4 bond near branch point of branch and moves branch to linear molecule forming new alpha-1,4 bond; then hydrolysis the alpha-1,6 to release the single residue as GLUCOSE (!!!!!!)
Gluconeogenesis
Occurs in liver and kidneys after 24 hours of fast; stimulated by glucagon, epinephrine, cortisol, and growth hormone
Enzymes: glucose-6- phosphatase, fructose-1,6 bisphosphatase, PEP carboxykinase, pyruvate carboxylase
Glucogenic vs ketogenic AMino acids
Glucogenic amino acids: all except leucine and lysine; concerted to intermediated that go into gluconeogenesis
Ketogenic amino acids: converted into ketone bodies
Fatty acids with odd number tails make propionyl-CoA which is GLUCOgenic
Acetyl-CoA inhibits and activates?
Acetyl CoA also made by
Acetyl-CoA inhibits pyruvate dehydrogenase and activates pyruvate carboxylase
Acetyl CoA also made from fatty acids
Where is glucose 6 phosphatase found?
Only found in lumen of endoplasmic reticulum of liver cells
Purpose of PPP
Pentose phosphate pathway produces NADPH and ribose-5-phosphate, which is used for nucleotide synthesis
-Requires glucose-6-P dehydrogenase
NADPH: electron donor; reducing agent; important for biosynthesis (of FAs and cholesterol); bactericidal activity in white blood cells; antioxidant (maintains glutathione supply)
Rate limiting step of citric acid cycle
Isomerase dehydrogenase
Also first time NADH is made
