Exam 2 Review Flashcards
two types of functional groups found on the anomeric carbon of straight chain sugars
aldehydes and ketones
glycation
-clinical significance
the process of a protein reaction and combining with a sugar without the presence of a cofactor such as an activated sugar
-Hb can be glycated when diabetics dont take their insulin and take too much sugar and can be used in a test to see if people have been compliant
polysaccharide, glycolipis, and glycoprotein bond formation requirements
- this process is called glycosylation and it differs from glycation in that cofactors are needed to carry out the reaction
- these are in the form of activated sugar nucleotides
glycogen structure
- series of alpha 1,4 linked glucose molecules with alpha 1,6 branches
- the end at which sugars get added is called the nonreducing end
glycosaminoglycans GAGs
- what are they
- most common
long, linear sugars with disaccharide repeats that are negatively charged (sulfates)
- can be free or attached to protein
- chondroitin sulfate is the most common
chondroitin sulfate
bone, cartilage, cornea formation
keratan sulfate
cornea, connective tissue
dermatan sulfate
binds LDL to plasma walls
heparan sulfate
aortic wall, basement membrane
heparin
anticoagulant
hyaluronic acid
cell migration, lubricant, (not covalently attached to protein)
proteoglycans
-provide part of the ground substance for tissue epithelia, bind growth factors/cytokines and provide cushioning in joints
enzymatic glycosylation
-where does it occur
- outside of the cell or oriented outside of the cell except in O-GlcNac
- can be O linked or N linked with a specificity determined by the nucleotide sugar and the substrate
- sugar processing occurs as proteins traffic from the ER through the golgi
what enzymes are involved in I cell disease
- there are multiple!!
- results in the accumulation of many biosynthetic materials
glycoproteins are critical for…
- biological recognition
- mannose-6-P as a lysosomal targeting signal, influenza or helicobacter, leucocyte adhesion deficiency 2
what does lactase insufficiency cause when lactose is consumed
-fluid to rush into the colon causing watery diarrhea and the formation of H2 gas
the different mechanisms in which monosaccharides can enter the cell
simple diffusion, facilitated diffusion, active transport
Glut 4
- type of transport
- found where
- regulation
- difference between glut 2
- facilitated transporter
- important in fat and muscle
- not found in the liver **
- regulated by insulin
- glut 2 is not regulated by insulin
affect of insulin on blood glucose in type 1 diabetics
-blood glucose does not go down nearly as much
insulins action on glucose metabolism
- decreases blood glucose by increasing uptake in muscle and adipose tissue (not in the liver)
- increases glycolysis in the liver, increasing acetyl-CoA formation
- decreases gluconeogenic reactions
- decreases glycogen breakdown and increases synthesis
purpose of forming G6P from Glu
- locks it into the cell so the exterior glucose concentration doesnt pull it back out of the cell
- this is done by hexokinase everywhere and by glucokinase in hepatocytes
- glucokinase in pancreatic beta cells regulates glycolysis and hence insulin secretion (MODY)
glucokinase vs hexokinsae concentrations
- glucokinase is 100 times more concentrated in liver cells than hexokinase is anywhere else in the body
- this makes sure that the liver does not miss any glucose molecules passing through it
4 different things you can do with glucose in a general sense
- glycogen synthesis
- glycolysis
- PPS
- glucuronides
niacin deficiency
- vitamin B3
- dermatitis
- diarrhea
- dementia (pellagra)
thiamine deficiency
- VitB1
- opthalmoplegia
- gait difficulties
- confusion
- beri beri
- wernicke korsakoff
riboflavin
- VB12
- cheilosis and glossitis
lipopoate
-targeted by arsenic (pyruvate and a ketoglutarate dehydrogenase)
ratios of NAD vs NADH and NADPH vs NADP
- NAD+»_space; NADH
- NADPH»_space; NADP
- basically, what the cell wants are NADPH and NAD, these are what are the cell uses as substrates in important reaction
- however, there are reaction within the cell that can convert NADH and NADP back to their original states
- it is an oxidation reduction cycle
regulated enzymes of glycolysis
- hexokinase/glucokinase
- phosphofructokinase 1 (PFK1)
- pyruvate kinase
ATP producing enzymes of glycolysis
- phosphoglycerate kinase (1,3BPG to 3PG)
- pyruvate kinase (PEP to pyruvate)
glycolysis
- where
- yield
- limited by and requires
- deficiencies affect
- regulatory enzymes, reversible?
- what is the most important site of regulation?
- cytoplasm
- 2 ATP per glucose even under anaerobic conditions
- limited by Pi and requires NAD+ (used by G3PDH)
- deficiencies affect mainly RBC’s (anemia, pyruvate kinase) and skeletal muscle (exercise intolerance, PFK1)
- glucokinase, phosphofructokinase, pyruvate kinase (liver vs muscle)
- PFK1 is the most important step in glycolysis
regulation of PFK1
activators: ATP and F2,6BP
- F2,6BP is particularly important because in its absence, F1,6BP could be used for gluconeogenesis (the opposite of glycolysis)
- inhibitors: ATP and citrate
intermediates of glycolysis are used for
- amino acid synthesis
- fats
- nucleic acid
posions that affect glycolysis
- 2 deoxyglucose inhibits hexokinase
- arsenate inhibits G3PDH
- fluoride inhibits enolase
fructose entering the pathway
gets phosphorylated to F1P then aldolase B splits it into DHAP and glyceraldehyde which are both intermediates in glycolysis
fructokinase deficiency vs an aldolase B deficiency
fructokinase: less serious, causes essential fructoseria
- aldolase B: more serious as it causes a build up of F1P which blocks glycogen breakdown and glucose synthesis via sequestering Pi, this is called hereditary fructose intolerance
matabolic diseases of galactose
- galactokinase deficiency causes minor problems
- Gal-1-P-uridyl transferase causes major problems and is called classic galactosemia
what is UDP-Glucoronic acid used for?
- what enzymes does this
- what happens if there is a problem
- conjugated with other molecules such as bilirubin and drugs in order to make them more polar so that they are excreted from the body
- this is done via UGT = UDP-alpha-glucuronyltransferase
- problems cause Gilberts syndrome
alcohol is converted into what and then what?
-what cofactors does this process use? What does that lead to
- acetaldehyde by alcohol dehydrogenase and then acetate by aldehyde dehydrogenase
- acetate can then lead to acidosis or be converted to acetyl CoA
- This process uses 2 NAD and produces 2 NADH
- The increased NADH leads to inhibition of gluconeogenesis and increased triglyceride synthesis by blocking the conversion of FA’s to Acetyl CoA
alternative alcohol pathway, when does this occur
- MEOS (CYTP450) pathway
- uses NADP, creating NADPH
- this is an adaptive pathway and found to be used by alcoholics
- one reason why they can handle more booze
production of NADH from ethanol does what
- inhibits gluconeogenesis
- stimulates fat production
alcoholics are often deficient in what?
- vitamins, particularly thiamine (VB1)
- this causes W-K and beri-beri
PDH is inactivated by
-being phosphorylated by PDH kinase
-what activates PDH kinase and what does this cause
- Acetyl CoA, CO2, NADH (products)
- this causes the inhibitions of the TCA cycle, basically this happens when your body is in an energy surplus
what inactivates PDH kinase and what does this cause
- via inhibiting the kinase:ADP (low energy), Pyruvate, CoASH, NAD+
- By activating the phosphotase: Insulin, Ca++
- This is when your body has low energy or you have just eaten a high carb meal or you have a build up of the substrate for PDH
what macromolecules feed into the TCA cycle
- carbohydrates
- fatty acids
- amino acids
where does the great majority of energy derived from glucose come from?
-TCA cycle
