Flashcards in Part 2 - lecture 1 - Quiz Deck (57):
Which sugar can act non-enzymattically to make modifications?
Why must glucose always be at a certain concentration in our blood?
Anaerobic and brain cells require glucose for energy and without them they would be damaged
What do sugars interact with and how?
proteins, lipids, glycoproteins, glycolipids, proteoglycans, themselves - enzymatic reactions - they are chemically reactive
What are the dietary polysaccharides?
Glycogen (amylose and amylopectine) and starch (glycoproteins and proteoglycans)
What are the dietary dissacharides?
Sucrose and lactose
What makes up lactose?
Glucose and galactose
What makes up sucrose?
Glucose and fructose
What are indigestable carbs?
Carbs with unusual linkages, cellulose and fiber
What is glucose stored as?
Where is alpha amylase found and what does it do?
Mouth and pancreas to small intestine to digest larger polyglucoses like starch and glycogen
What cannot be digested by alpha amylase?
Lactose and sucrose
What happens in the small intestine?
Uses enzymes on mucsal cells to break down starch and glycogen into maltose and isomaltose - receives the disaccharides
What happens to monosaccharides?
They are absorbed by mucosal cells on epithelium
What happens if you are lactose or sucrose intolerance?
No enzyme on mucosal cells to break down so go to large intestine where bacteria have the enzyme to digest but produces a lot of gas and large intestine reacts to foreign substance by bloating, diarrhea, dehydration
How can lactose intolerance be tested?
Hydrogen breath test because gases like H2 are produced along with CO2 and carbon metabolites
What does SGLT-1 do?
Sodium glucose transport system - Active symporter of enterocytes that uses 2 sodium ions to move glucose and galactose from luminal side into cytosol
What is needed to counteract effects of SGLT-1
Sodium potassium ATPase on capillary side to push sodium out to protect membrane potential
What is GLUT-5?
Facilitated transporter of enterocytes specific to fructose to move inside cytosol
What is GLUT-2?
Facilitate transporter to move all monosaccharides (Glc, Gal, Fru) out of cytosol and into blood stream (on capillary side)
What is the function of glycolysis?
Sets stage for aerobic oxidation of carbs, supplies intermediates for carbohydrate storage and pentose phosphate pathway, can take up glycerol for triglyceride storage and degredation and can take up other monosaccharides
Where does glycolysis occur?
Cytosol - aerobic goes to mitochondria
What are some cell types that use anaerobic pathways because they lack mitochondria or have limited blood supply?
RBCs, cell of the eye like cornea, lens, retina, testis, leukocytes, white muscle fibers, kidney medulla
What are some aerobic cell types with lots of oxygen and mitochondria?
Brain, skeletal and heart muscle
What are the 3 stages of glycolysis?
Priming (energy investment), splitting stage, and oxidoreduction-phosphorylation stage (energy gaining)
What is the process of glycogen becoming glucose?
What is the process of glucose becoming glycogen?
What is the process of glucose becoming lactate?
What is the process of lactate becoming glucose?
What sugar comes from mushrooms?
Disaccharide - Trehalose - glucose + glucose
What linkages do amylose and amylopectin contain?
Amylose = alpha 1,4 glycosidic (linear)
Amylopectin = alpha 1,6 glycosidic (branched)
What enzymes degrade amylose and amylopectin?
amylose degraded by alpha-amylase and amylopectin degraded by isomaltase - further digestion occurs by maltase
What is the first regulation step in glycolysis?
Glucose --> G6P by hexokinase activated by AMP, Fructose, 2-6-bis phophate, and inhibited by ATP and citrate
Where does ATP investment occur in glycolysis?
In the Priming phase = Glucose to G6P and F6P to Fructose 1,6-bis-phosphate
What is hexokinase called in the liver?
Why is the converstion of Glucose to G6P a junction point in metabolism?
Can either go on to become glycogen for storage, continue in glycolysis, or become glucuronate for carb synthesis
What happens after G6P is made in glycolysis?
Fructose 6 phophate is made by phosphoglucose isomerase
What happens after F6P is made in glycolysis?
Fructose 1,6-bis-phosphate is made by PFK1 (6-phosphofructo-1-kinase) using ATP
What is the second regulation step in glycolysis?
F6P to frustose-1,6-bisphosphate conversion -- extensively regulated!! - it is a commitment step and rate limiting
What is the commitment/rate limiting step of glycolysis?
F6P to fructose-1,6-bisphosphate conversion
What happens in the splitting phase of glycolysis?
Fructose,1-6-bis-phosphate gives 2 3C sugars by aldolase forming DHAP (dihydroxyacetone phosphate) and GAP (glyceraldehye 3 P)
How is DHAP converted to GAP?
Triose - P - isomerase
What is the general starting and ending phases of the oxidoreduction-phosphorylation stages of glycolysis?
2 GAPs becomes 2 lactate by production of 4 ATPs
What happens after 2GAPs are made in glycolysis?
Become 2 1,3-bisphosphoglycerate by GAPDH and 2 NAD+ are reduced
What happens after 2 1,3 bisphophoglycerate molecules are made in glycolysis?
2 3-phosphoglycerate molecules are made by phopho-glycerate kinase which produces 2 ATPS - 1st substrate level phosphorylation
What happens after 2 3-phosphoglycerate molecules are made?
Phosphoglycerate mutase makes 2 2-phosphoglycerate molecules
What happens after 2 2-phosphoglycerate molecules are made?
Enolase produces 2-phosphenolpyruvates
What happens after 2 phosphoenolpyruvates are made?
Pyruvate kinase makes 2 pyruvates by utilizing 2 ADPs to give off 2 ATPs - second substrate level phosphorylation
What is the 3rd regulation step of glycolysis?
The formation of pyruvate from phosphoenol pyruvate - can be activated by fructose 1,6 - bisphosphate
Which steps in glycolysis are irreversible?
The regulation steps
How does pyruvate become lactate?
lactate dehydrogenase uses NADH oxidation
What is the special RBC shunt in glycolysis?
Bypasses the phospglycerate kinase step by converting 1,3BPG into 2,3 BPG by using 2,3BPG mutase - no net ATP formed
How is NADH generated from GAPDH in glycolysis used in aerobic and anaerobic pathways?
Aerobic - uses to make ATP from TCA oxidation and is shuttled into mitochondria
Anaerobic - used by LDH to get lactate
What is the shuttle used in liver and muscle cells?
Muscle uses glycerol phosphate while liver uses malate aspartate
What is the energy production of anerobic glycolysis?
What is the energy of glycolysis under aerobic conditions?
How does the glycerol phosphate shuttle work?
Glycerol 3 phosphate is produced when NADH is oxidized by glycerol-3-phosphate dehydrogenase