Sugars Flashcards
Anomeric Carbon
has 4 diff ligands
Epimer
isomer that differs in only 1C
non-reducing sugar
sucrose - O is not avail for redox rxn
pyranose
5C ring w O
furanose
4C ring w O
sucrose is made of what sugars and linkage?
glucose + fructose
alpha 1 - beta 2
lactose is made of what sugars and linkage?
glucose + galactose
beta 1-4
- the only Beta linkage we can break down
- via Lacatase
maltose is made of what sugars and linkage?
glucose + glucose
alpha 1-4
cellulose
beta 1-4
the type we can’t break down
plant starch
unbranched starch
amylose
branched starch
amylopectin
human “starch”
linkages?
glycogen
more branched than amylopectin
chain: alpha 1-4
branch pts: alpha 1-6
Polysaccharides are broken down to mono by?
brush border enzymes of the SI
- they are then absorbed into the cell by Na+ cotransporter and released into the blood stream
ATP
Adenosine Triphosphate
- adenine, ribose, phosphate
Kreb’s/TCA/Citric Acid cycle is where?
mitochondria
- mainly LR!!!
beginning and end constituents of the Kreb’s cycle?
AcetylCoA + OAA –>
- C6 (citrate)
- C4 (oxaloacetate)
how many ATP per glucose molecule?
36-38 ATP
B1
active form?
Thiamin
- thiamin diphosphate (in dehydrogenase rxns)
B2
active form?
Riboflavin
- FAD
B3
active form?
Niacin
- NAD
B5
active form?
Pantothenic Acid
Coenzyme A
ETC action located where?
Inner Membrane of Mitochondria
problems of ETC
- Uncoupling - dt poison - ADP + P
- Inhibition - upstream of “coupling” usu dt antibiotics like oligomycins and piericidin
Rate Limiting Enzymes of Glycolysis
- inhibited by
Phosphofructokinase
- takes 1 ATP
- inhibited by ATP and Citrate
- glycolysis
Phosphofructokinase
at what step?
F6P –> F-1,6 P
- glycolysis
Hexokinase and Glucokinase
at what step?
Glucose –> G6P
takes 1 ATP
- glycolysis
Glucokinase is specific to what tissue?
LR and Pancreas
at PEP step of Glycolysis net ATP is?
0
Pyruvate Kinase
at what step?
PEP —> Pyruvate
- glycolysis
Pyruvate Dehydrogenase
at what step?
Pyruvate —> Acetyl CoA
- in mitochondria
- glycolysis
increase LDD means?
increase in anaerobic glycolysis
- could be a dz
G6P —> Glucose
in gluconeogenesis
what enzyme?
Glucose-6 Phosphatase
Hexokinase located in what tissue?
Muscle
pyruvate —> OAA
C3->C4
what enzyme
Pyruvate Carboxylase
- in mitochondria
- gluconeogenesis
- OAA -> malate - malate shuttle -> out of mitochondria -> OAA
OAA —> PEP
what enzyme
Pyruvate Carboxykinase
- gluconeogenesis
F-1,6P —> F-6P
what enzyme
F-1,6 Diphosphatase
Gluconeogensis stimulated and inhibited by
- stimulated by stress hormones
- inhibited by insulin
Rate Limiting Step of Gluconeogenesis
Fructiose 1,6 Diphosphatase
Blood glucose maintenance done by which organ?
It takes how long before glycogen stores are depleted?
LR
12-18 hrs
G6P —> G-1,6 Bisphosphate
enzyme
Phosphoglucomutase
- glycogenesis
an increase in cAMP stimulates?
Glycogenolysis
- and inactivated glycogen synthesis
Rate Limiting Step of Glycogenolysis?
Phosphorylase-a
when you see “UDP” think…
glycogen
products of the HMPS or Hexose Monophosphate Shunt
ribose residues + NADPH
- NO ATP!!
- in cytosol
- not part of glycolysis
Oxidative phase of HMPS
G6P —> Ribulose 5P
- nonreversible
- — vs the reversible nonoxidative phase (ribulose 5P —> G6P)
if deficiency in G6P Dehydrogenase, then…
Hemolytic Anemia
- this enzyme is part of HMPS
antioxidant that breaks down peroxide and protects RBCs
Glutathione
HMPS is used in the Glutathione Redox Cycle
- produces NADPH to reduce glutathione
- so if there is a deficiency in G6P dehydrogenase, no NADPH, no reduction of glutathione and RBCs are sensitized
just read it
Fructose –>
enzyme
F6P or sorbitol
- to F6P uses Hexokinase
- in muscle
if you can’t use fructose for energy, think
increase in sorbitol
think Diabetes
toxic to neuro tissue - diabetic neuropathy
How does Galactose become Glucose
becomes Glycogen first
“galactose laundering”
How to make Lactose in mammary glands
UDP Galactose + Glucose
Hexokinase - Km value?
LOW = HIGH AFFINITY FOR GLUCOSE
Glucokinase located where and Km is what?
Km is high = LOW AFFINITY FOR GLUCOSE
- LR and Pancreas
