Carbs Flashcards
what is carb RDA?
130g/day
what is carb?
1C: H2O
which isomer of simple sugars (MS) nutritionally important?
D isomer
disaccharides are MS condensed by __ bond
glycosidic
homopolysacc of glucose?
starch, glycogen
examples of heteropolysaccs?
glycosaminoglycans, hemicellulose, pectin, gum
soluble fibre
fermented by bacteria in colon (SCFA). delay absorp of glu
insoluble fibre
prevent constipation
disacc digestion in:
mucosal cells of microvilli/brush border
most abundant complex compound in world, insoluble fibre
cellulose
fructose crosses by ___
facilitated diffusion
fructose is absorbed faster than ____
xylitol and sorbitol
in liver, glucose enters cells by ____ and is insulin _____
facilitated diffusion; insulin independent (GLUT2)
in muscle and adipose, glu enters cells by fac. diffusion and is insulin ____
dependent (GLUT4)
what is hyperglycemia?
blood glu lvl above normal –>doesn’t enter cells, not reabsorbed by kidney
diff between IDDM and NIDDM?
first is insulin dependent, other is not (cells resistant, control by diet and hypogly drugs)
what is renal threshold for gluc?
10mmol/L or 180mg/dL –>idneys no longer reabsorb glu as fast as being filtered
what is hypoglycemia?
blood glu below normal (hypersecretion of insulin)
in fasted states, what are increased?
glucagon, glu release by liver/musc/adipose, glucocorticoids from adrenal, gluconeogenesis
priority of utilization of absorbed MS?
energy–>glycogen–>FA–>PPP
what is the embden meyerhof path?
fermentation
PDH needs:
thiamine pyrophosphate (TPP)
why pyruvate needed to keep TCA cycle running?
supply oxaloacetate (in presence of CO2)
how many coenzymes and prosthetic groups in PDH?
5; 3 (TPP, lipoamide, FAD)
what is function of TPP?
decarboxylation of a-ketoacids
decarboxylation of pyruvate and oxidation of acetate takes place in:
mito matrix
ATP synth takes place in:
mito inner mem
what is UDP?
step in glycogenesis (uridine 5’ diphosphate)
which form of glycogen synthase is more active?
dephosphorylated (target of insulin)
three fates of G6P?
glycolysis, liver G6phosphatase (to blood/other tissues), PPP
why is PPP necessary?
ribose for synth of DNA/RNA/ATP/GTP, provide NADPH for fa synth and for glutathione reductase rxn
tissues with active PPP
adrenal, liver, mammary, testes, RBC, ovary, adipose
glutathione composed of :
glutamate, cysteine, glycine