intro to carbohydrates Flashcards
types of carbohydrates
monosaccharides, the simplest carbohydrates.
disaccharides, which consist of two monosaccharides.
polysaccharides, which contain many monosaccharides
monosaccharides composition
3-6 carbon atoms typically.
a carbonyl group (aldehyde or ketone).
several hydroxyl groups to make correct basic structure
aldoses
monosaccharides
with an aldehyde group O=C-H => carbon double bond oxygen at end of group
with many hydroxyl (-OH) groups.
ketoses
monosaccharides
with a ketone group = C=O => carbon double bond oxygen in middle of chain
with many hydroxyl (-OH) groups.
Fischer projection
is used to represent carbohydrates.
places the most oxidized group at the top.
shows chiral carbons as the intersection of vertical and horizontal lines.
L and D notation
In a Fischer projection, the -OH group on the
chiral carbon farthest from the carbonyl group determines an L or D isomer.
left is assigned the letter L for the L-form.
right is assigned the letter D for the D-form.
D glucose
found in fruits and honey.
an aldohexose with the formula C6H12O6.
known as blood sugar in the body.
the monosaccharide in polymers of starch, cellulose, and glycogen.
Galactosemia
lack of enzyme(s) required for galactose metabolism
can result in accumulation of galactose intermediates
toxic effects in liver, brain, kidneys and eyes
tests for sugars
use feature that they’re reducing =>
reduce Cu2+ to Cu+ but donating electron, gaining proton and sugar becomes oxydised => Fehling’s reagent has alot of copper and allows us to mesure => have to boil tho = unreliable
=> goes from blue to orange if there is sugar as copper is reduced
benedicts solution
not just knowing that its there but how much is what’s important
test for how much sugar
spectrophotometer => mesure
shine light through sample => see how much light absorbed => amount of colour directly proportional to concentration of sugar
make known sample=> create graph/ generate standard curve then can read unknown
reliable sugar test
glucose oxidase test => physically emprisoned => chemical redox reaction => converts incolor into color => get a degradation of coulour
why control glucose
diabetes
high concentration in blood => detrimental to health
hemoglobin is in red blood cells => as a chemical reaction, glycation => glucose can bind to hemoglobin
can mesure amount of glycated blood cells and can tell how a person’s control of diabetes has been over last few months
Glucose enters red blood cells in a non-insulin dependent manner.
Uncontrolled hyperglycemia results in a covalent linkage between
glucose and the NH2 terminal amino acid of the hemoglobin β chain.
The resulting adduct is designated as HbA1c.
lactose intolerance
Lactase splits lactose into glucose and galactose.
no lactase
-> Can be born lactose intolerant- autosomal recessive .
Or fail to express lactase into adulthood (most animals turn off expression at weaning) OR acquire following injury to small intestine
polysaccharides - glycogen
The most common homopolymer in animal cells is glycogen.
Glycogen is the storage form of glucose.
Predominantly found in liver and muscle.
Glycogen is a highly branched polysaccharide made of multiple glucose units linked by α-1,4 and α-1,6-glycosidic bonds.
starch
Starch is the plant form of carbohydrate ingested by humans.
Amylose is an unbranched starch comprised of glucose units (α-1,4 linkage).
Amylopectin is the branched form with α-1,4 linkage (30X) to the α-1,6 linkage.
α-amylase secreted by salivary glands and the pancreas hydrolyzes amylose and amylopectin.
