Carbohydrates Flashcards
carbohydrates stored as ……….. in human
glycogen
monosaccharide’s
glucose galactose fructose
disaccharides
monomers linked with glycosidic bonds
hydroxyl + carbon group
important disaccharides
maltose
lactose
sucrose
Maltose is a breakdown product of
starch
maltose can be ………. (so is a reducing sugar)
oxidised
Lactose is formed from a glycosidic bond between
reducing sugar
galactose and glucose
Sucrose is NOT a
reducing sugar
two types of glucose polymer in starch
amylose
amylopectin
Starch has lots of ………….. and very few ………….
non-reducing ends
reducing ends
90% of glycogen is kept in the
liver and skeletal muscle
Glycoproteins
proteins that have carbohydrates covalently attaches
Glycosaminoglycans (GAGS)
polymers made from repeated units of hexuronic acid and an amino sigar
Proteoglycan
made from GAGs covalently attaching to proteins
Mucopolysaccharidoses
disorders caused by the absence or malfunction of enzymes that are required to breakdown GAGs
Mucopolysaccharidoses example
hurler syndrome
Glucose is absorbed through an
ATP powered process
ATP driven Na+ pump maintain a low cellular Na+
so glucose can be continually moved in to the epithelial cells
cellulose and hemicellulose cannot be
digested by the gut
lack of oligosaccharides leads to
poor health
Most common disaccharide deficiency
lactose intolerance
Glucose diffuses through the intestinal epithelium into the
portal blood and on to the liver
Glucose is immediately phosphorylated into
glucose 6 phosphate by the hepatocytes
Synthesis of glycogen
glycogenin begins the process by covalently binding glucose from
UDP-glucose
forms 8 glucose residues
Synthesis of glycogen
glycogen synthase takes over to…
extend the glucose chains
Synthesis of glycogen
the chains formed by glycogen synthase are broken by…
glycogen-branching enzymes
then reattached by alpha 1 to 6 bonds to give BRANCH POINTS
von gierke’s disease
liver glucose-6-phosphatase deficiency
high liver glycogen
low blood glucose
high blood lacatate
McArdle’s disease
skeletal muscle phosphorylase deficiency
high MUSCLE glycogen
Glycolysis
saves some potential energy from glucose/glucose-6-phosphate by forming ATP through substrate level phosphorylation
Glycolysis gives a net gain of ….ATP (and NADH) per glucose molecule
2
only G3p can participate in glycolysis so….
the other 3 C sugar produced must convert into G3P
so theres 2 G3Ps per glucose molecules
Glycolysis first step
glucose to G6P
glycolysis G6P –>
F6P
Glycolysis F6P –>
F 1,6 p bisp
F16 bisp then gets cleaved to give
splitting of glycolysis
2 different 3C triose sugars
after 2 G3P’s are formed…
oxidation of G3P to 1,3 bisPG
1,2 bis pG to
ADP
2 ATP are produced
3-PG to
2 - PG
2 PG to
PEP
PEP to
ADP
2 ATPs produced
final step that produces pyruvate
No NAD+ mean no
glycolysis
What happens to pyruvate? can turn into……
ethanol
lactate
co2
pyruvate goes to lactate in cells lacking
oxygen
via fermentation
Cori Cycle
ATP is make via substrate level phosphorylation - producing lactate
in the cori cycle - lactate is converted to glucose in the liver by…
gluconeogenesis
bypass reactions
4 reactions that sidestep the 3 irreversible reactions of glycolysis
….. and ……… can enter glycolysis at various points
fructose and galactose
pentose pathway produces
NADPH for all organisms
pentose pathway has 2 phases
irreversible oxidative part
reversible, non-oxidative part
NAD+ is used in
metabolism of dietary sugars in the redox reactions of glycolysis
NADP+ is used in
anabolism to convert simple precursors into FAs
alcohol inhibits
gluconeogenesis
black water fever
G6P dehydrogenase deficiency
TCA cycle occurs in the
mitochondrial matrix
TCA cycle removes e-‘s and passes them on to form
NADH and FADH2
TCA
pyruvate from glycolysis and FAs are oxidised to
acetyl CoA in the mitochondrial matrix
via the help of pyruvate dehydrogenase
