Monosaccharides 1 Glucose 2 3 4 5 Glucose is prepared by 1 hydrolysis of sucrose 2 hydrolysis of starch Glucose is found in blood stream Found in tissue fluids If found in urine it is an indicator of diabetes ID: 933391
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Slide1
Monosaccharides
1
Slide2Cyclic Form of Monosaccharides1. Glucose2
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Slide6Glucose is prepared by: 1. hydrolysis of sucrose 2. hydrolysis of starchGlucose is found in blood streamFound in tissue fluidsIf found in urine, it is an indicator of diabetes (glucosuria
)
Glucose may show up in urine during extreme excitement (
emotional
glucosuria
) or after ingestion of a large amount of sugar (
alimentary
glucosuria
)
6
Slide72. Galactose7
Slide8Glucose & Galactose are epimers.Epimers: are 2 sugars that differ only in about a single carbon atom. D-galactose epimerase D-glucose
Galactosuria
Is a severe inherited disease results in the inability of infants to metabolize
galactose
because of a deficiency in either:
1. Galactose-1-phosphate-uridyl
transferase
(GALT)
2. Galactokinase (GALK) As a result the galactose concentration will increase in blood and urine (galactosuria)8
Slide93. Fructose9
Slide10Fructose is often called fruit sugar or levuloseCan be prepared by hydrolysis of sucroseIt also can be prepared by hydrolysis of Inulin
Fructose is 1.7 times sweeter than sucrose
Fructosemia
:
An inherited disease (prevents the conversion of fructose to glucose) due to a deficiency of the enzyme fructose-1-phosphate
aldolase
.
As a result fructose will increase in blood.
symptoms may include vomiting, hypoglycemia, severe malnutrition
10
Slide1111
Slide12Reactions of hexosesHexoses which are either aldoses or ketoses have reducing properties.This reducing property of hexoses is the basis of the test for sugar in urine or blood.
Gluconic
acid
12
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Slide1414
Slide15Reduction of MonosaccharidesNote:Accumulation of sorbitol in the eye is a major factor in the formation of cataracts due to diabetes.
15
Slide16FermentationIn the presence of yeast (or enzymes of yeast) glucose forms ethanol and carbon dioxideFructose can ferment but galactose can not.Pentoses do not ferment in the presence of yeast.16
Slide17Formation of Phosphate EstersGlucose forms phosphate esters at carbons 1, 617
Slide18Amino SugarsAmino sugars (hexosamines) contain an amino group on place of an –OH group.Examples of natural amino sugars:D- GlucosamineD-galactosamineD-mannosamineAmino sugars are components of some antibiotics such as
Erythromycin
and
Carbomycin
18
Slide19Protein-Sugar InteractionsWhen the glucose level in the blood is elevated over a period of time, normal hemoglobin binds to glucose covalently.The amount of glucosylated hemoglobin HbA1c in blood is used as a measure of the effectiveness of blood glucose control in a diabetic patient. The concentration of HbA1c directly reflects the elevation of blood glucose over the preceding several days.
19
Slide20In diabetic patient HbA1c is about 7 – 11% of the total hemoglobin (HbA)In nondiabetic person this value ranges 4 – 6%.20