Exam 2 Flashcards
Three pentose sugars
ribose
deoxyribose
ribitol
What is special about sugar alcohols (structure)
two alcohol groups
what is special about sugar alcohols (metabolism)
low calorie
three dietary monosaccarides
glucose
galactose
fructose
beta anomers have this
OH on the same side of the ring
alpha anomers have OH group in this position
down (axial)
beta anomers have OH group in this position
up (equitorial)
OH group of this mono is on the right side of the stick drawing
glucose
OH group of this mono is on the left side of the stick drawing
galactose
The aldehyde group of this mono is on the second carbon
fructose
This is formed between the hemiacetal group of a saccharide and the hydroxyl group of the same compount
glycosidic linkage
a substance containing a glycosidic bon is this
glycoside
This Di has an alpha 1-4 glycosidic bon
maltose
this di has a beta 1-4 glycosidic bond
lactose
this di has an alpha 1-2 glycosidic bond
sucrose
this di is found in fungi and plants
trehalose
glucose bound to galactose
lactose
glucose bound to fructose
sucrose
glucose bound to glucose
maltose and trehalose
when a sugar has an open chain form with an aldehyde group it is classified as this
reducing sugar
this can be oxidized via a redox reation in which another compound is reduced
aldehyde of a reducing sugar
only non reducing sugar covered in class
sucrose
examples of oligo saccharides (3)
raffinose
stachyose
verbascose
foods containing alot of oligo saccharides
beans
peas
bran
whole grains
starch is composed of these polys
amylose
amylopectin
glycogen is found here
liver
skeletal muscle
poly which is a dietary fiber and not an energy source
cellulose
percent of amylose and amylopectin in startch
15-20
80-85
glycosidic bonding in amylose
alpha 1-4 (all glucose)
this poly is the energy storage in plants
amylopectin
consists of glucose moleculeds bonded togther in a highly branched arrangement (plant source)
amylopectin
amylopectin has these two types of bonds
alpha 1-4
alpha 1-6 (branches)
energy storage in animals
glycogen
this poly has multiple non-reducing ends
glycogen
this is the most branched poly
glycogen
glycogen has these two types of bonds
alpha 1-4
alpha 1-6 (branches)
why cant cellulose be digested by humans
beta 1-4 bonds
what enzyme begins the digestion of amylose and amylopectin
salivary amylase
what bond is broken by salivary amylase, and what is formed
a 1-4 bonds
dextrins
t/f: the stomach is the main center of CHO digestion
f
the pancreas releases this to continue CHO digestion
pancreatic a-amylase
pancreatic a-amylase activity for amylose
breaks a 1-4 bonds
dextrins are broken down into maltose
pancreatic a-amylase activity for amylopectin
breaks a 1-4 bonds
produces limit dextrins, maltotriose, isomaltose, and maltose
pancreatic a-amylase activity stops here on amylopectin
4 residues away from a 1-6 glycosidic bonds
maltose is hydrolyzed by this enzyme, a brush border enzyme froming free glucose
maltase
maltotriose, isomaltose, and maltose are broken down by these enzymes to glucose
maltase and isomaltase
this enzyme is the sole carbohydrase capable of hydrolyzing a 1-6 bonds
a-dextrinase
disaccharide digestion occurs here
brush border
maltose is digested by
maltase
lactose is digested by
lactase
sucrose is diegested by
sucrase
this enzyme is messing in lactose intolerant people
sucrase
type of bond in sucrose
a 1-2
this type of starch does not release glucose within the small intestine, but rather reaches the large intesting where it is consumed or fermented by colonic bacteria
resistant starch
beano contains this to digest aligosaccharides
a-galactosidase (enzymes)
these are poorly absorbed and can cause stomach aches, and diarrhea
sugar alcohols
glucose and galactose are absorbed by these two transporders
SGLT1
Glut2
Fructose is absorbed by this transporter
glut5
This transporter of glucose and galactose uses sodium and is a form of active transport
SGLT1
These two transporters of monos are facilitative transporders
Glut2
Glut5
This mono is more slowly absorbed than glucose
fructose
This transporter of monos is the onlyone present on the basal surface of the intestinal cell
Glut2
this transporter is transferred to the apical side of the cell when sugar-rih meals are ingested
glut2
this hormone causes the translocation of the glut2 transporter from the apical surface of the cell to the inside of the cell
insulin
an increase in this substance causes glut2 to join the lumen of the membrane
glucose
digestion and absorption of CHO occurs here
brush boarder
this transporter is insulin dependent
glut4
These are the two transporters with high Km
glut2
glut4
kidney, liver, and brain can work independent of this hormone
insulin
storage hormone
insulin
how does insulin affect glucose uptake
increases uptake by causing glut4 to bind to apical surface of cell
6 steps of translocation of Glut4 to the cell membrane
biosynthesis transported tethering docking fusion endocytosis
increase in glood glucose during 2-hour period after consumption of a certain amount of CHO compared with equal CHO from reference food
Glycemic index GI
This considers quantity and quality of CHO in a food
glycemic load
formula for calculating glycemic load
GI x g of CHO in 1 serving of food
examples of things that affect glycemic index
temp
nutrient composition
health of individual
fitness level
these monos are used as energy for the liver or made into fatty acids
fructose
galactose
anabolic or catabolic: glycogenesis
anabolic
anabolic or catabolic: glycogenolysis
catabolic
anabolic or catabolic: glycolysis
catabolic
anabolic or catabolic: gluconeogenesis
anabolic
anabolic or catabolic: pentose phosphate pathway
anabolic
anabolic or catabolic: tricarboxylic acid cycle
catabolic
synthesis of glycogen
glycogenesis
breakdown of glycogen
glycogenolysis
oxidation of glucose
glycolysis
synthesis of glucose from non CHO intermediates
gluconeogenesis
production of 5-carbon monos and NADPH
pentose phosphate pathway
oxidation of acetyl-CoA to CO2 and H2O
TCA cycle
what role in CHO metabolism do kinases play
substrate level phosphorylation (ADP to ATP) or phosphorylation of intermediates (hexokinase, pfk))
what role in CHO metabolism do dehydrogenases play
Oxidize intermediates utilizing NADH and FADH2
number of ATP produced by the breakdown of 1 glucose
32 (max 38 if system is perfect)
this is the main source of energy for GI and brain
glycolysis
gross atp from glycolysis
2
gross nadh from glycolysis
2
these enzymes are major regulation sites in glycolysis
PFK (main)
hexokinase
pyruvate kinase
galactose enters glycolysis at this step
glucose-6P
fructose from adipose tissue enters glycolysis at this step
fructose-6P
fructose from the liver (ingested frucose) enters glycolysis at this step
DHAP
GAP
fructose is only metabolized here
liver
aerobic fate of pyruvate
TCA cycle
anaerobic fate of pyruvate
cori cycle
pyruvate can be converted to this AA
alanine
the cori cycle happens in these two places
blood cells
active muscles
t/f: more energy is used during gluconeogensis than is gained during glycolysis
t
this enzyme converts pyruvate into acetyl CoA while releasing NADH and CO2, and utilizing CoA
pyruvate dehydrogenase
TCA cycle accounts for this % of energy production from food
90
number of ATP, NADH, and FADH2 produced from one glucose model passing through the TCA cycle
2
6
2
this byproduct of CHO metabolism can be used to determine energy production in the body
carbon dioxide
two major regulatory enzymes in the TCA cycle
isocitrate dehydrogenase
a-ketogluterate dehydrogenase
t/f: AA can enter the TCA cycle
T
T/F: with the utilization of an ATP and CO2 pyruvate can be converted into oxaloacetate
T
This much NADH is made during the conversion of pyruvate into acetyl CoA
2
What is the purpose of the Cori cycle
turn lactate back into glucose for utilization by skeletal muscle when glucose availability is scarce
This system shuttles NADH into the mitochondria from the cytosol by converting NADH to FADH2 through the utilization of G3P and DHAP
G3P shuttle system
This system shuttles NADH into the mitochondria from the cytosol by utilizing redox reactions involving malate, and two inner mitochondrial membrane transport proteins
malate-aspartate shuttle system
the more efficient method of shuttling NADH into the mitochodria
malate-aspartate shuttle system
What is the purpose of the G3P, and malate-aspartate shuttle systems
move energy from NADH from the cytosol into the mitochondria
this tissue has disfunctional mitochondria and is found in hibernating animals, infants, and some adults
brown adipose tissue
How is energy harvested from NADH and FADH2 in the ETC
NADH gives electrons to complex 1
FADH2 gives electrons to complex 2
oxygen acts as the final electron acceptor of the ETC at this complex
complex 4
these are pumped across the inner mitochondrial membrane during the ETC to great an energy gradiant which is used to drive the synthesis of ATP from ADP
H+
glycogen makes up this percent of the livers weight
7
glycogen makes up this percent of skeletal muscle weight, and this percent of glycogen stores in the body
1%
70%
T/F: glycogen is formed principally from gluconogenic precursor substances rather than from glucose directly
T
glycogen is mostly fromed from this gluconeogenic precursor
lactate produced from red blood cells
how does glycogenesis differ in the liver and skeletal muslces
liver uses glucokinase
muslce uses hexokinase to get glucose into the cell
during glycogenesis this reacts with G1P to from an activated compound (UDP-Glucose)
uridine triphosphate
T/F: the dephosphorylated form of glycogen synthase is more active than the phosphorylated form
T
this hormone facilitates the dephosphorylation of glycogen synthase
insulin
this is the primary target of insulins stimulatory effect on glycogenesis
glycogen synthase
protein glucose is attached to, to from glycogen
glycogenin (tyrosine residues)
Enzyme used form glycogen
Glucosyl transferase (glycogenin)
T/F: the less branching on glycogen increases its solubility
F
This produces more non-reducing ends on glycogen
branching
This occurs during glycogenolysis
non-reducing ends of glycogen are systematically cleaved from the larger molecule to form free glucose
what is the significance of branching in glycogen
more free non-reducing ends to allow for quicker release of energy
difference in location of hexokinase and glucokinase
hexokinase is only in muscle
glucokinase is in the liver and pancreas
how is the inhibition by G6P different between hexokinase and glucokinase
hexokinase is allosterically inhibited by G6P
glucokinase is not inhibited by G6P
Km differences between hexokinase and glucokinase
hexokinase has a low Km so it functions maximally at fasting blood glucose concentrations
glucokinase has a high Km so it functions maximally when glucose levels are high
Induced or not induced by insulin in normal individuals: hexokinase
not
Induced or not induced by insulin in normal individuals: glucokinase
induced
Induced or not induced by insulin in insulin resistant individuals: hexokinase
not
Induced or not induced by insulin in insulin resistant individuals: glucokinase
not
Anabolic pathway used to generate NADPH and ribose-5-phosphate to synthesize fatty acid and nucleotide production
hexose monophosphate shunt (HMS)
Key enzyme of the hexose monophosphate shunt
G6P dehydrogenase
number of NADPH and R5P made during hexose monophosphate shunt
2
1
NADPH helps to do these things
detoxify
fatty acid synth
reduce oxidative stress
the hexose monophosphate shunt is used most in these tissues
mammary glands, adipose, and liver
these are a major source of free radicals
mitochondria
glucose-6-phosphatase and fructose 1,6 bisphosphatase make it possible to do this
reverse the reactions of glycolysis during gluconeogenesis
glucose 6 phosphatase is only found in this organ
liver
ATP, NADH, and NADPH are used in this mannor to have a negative or positive modulation of allowsteric enzymes
sense of how much energy is in the body
5 substances that are gluconeogenic
pyruvate lactate glycerol alanine glutamine
this hormone uses covalent modification to regulate the synthesis (decreases) and degredation (increases) of glycogen
glucagon
this condition stimulates the release of glucagon
low blood glucose
this hormone acts similarly to glucagon in CHO metabolism
epinephrine
where does gluconeogenesis occr
liver
3 enzymes which act as major regulation factors for glycolysis
hexokinase
PFK
pyruvate kinase
4 enzymes which act as a major regulation factors for gluconeogensis
glucose 6 phosphatase
fructose 1,6 bisphosphatase
phosphoenolpyruvate carboxykinase
pyruvate carboxylase
nondigestable CHO and lignin that are intact and intrinsic in plants
dietary fiber
nondigestable CHO that are isolated, extracted, or manufactured and know to ahve physiological benefits
functional fiber
Cellulose is this type of fiber
dietary and functional
heterogeneous group of polysaccharide substances, dietary fiber
hemicellulose
water-soluble, gel-froming, dietary and functional fiber that is stable at low pH
pectin
dietary and functional fiber, insoluble in water, hydrophobic binding capacity, generally poorle fermented by colonic bacteria
structural component of plant
lignin
dietary and functional fiber, tree and shrub exudate, composed of sugars and derivatives
gums (hydrocolloids)
dietary and functional fiber, water-soluble, inproves glycemic control and lowers cholesterol
B-glucans
inulin, oligofructose, fructooligosaccharides
fructans
dietary fibers, prebiotics (found in fiber one products)
fructans
this fructan can be used to replace fat in recipes
inulin
recommended consumption of resistant starch to obtain health benificts
20g/day
amylose tightly packed together and cannot be digested or absorbed by humans
resistant starch
similar to cellulose in cell walls, found in exoskeletons, and interacts with cholestrol
chitin
chitosan
used as bulking agen or sugar substitue
polydextrose
polyglycitol and malitol, found in syrups
polyols
functional fiber, mucilage from husk of psyllium seeds, high water binding capacity and provides viscosity
psyllium
4 important properties of fiber
solubility in water
water-holding capacity and viscosity
absorption or binding ability
degradability/fermentability
this type of fiber dissolves in hot water
soluble
this type of fiber doesnt dissolve in hot water
insoluble
only three insoluble fibers given in class
lignin
cellulose
hemicellulose
soluble fiber can cause gel formation leading two the 4 following
decrease nutrient absorption
increase transit time
decreased digestive function (binding)
decrease in rate of gastric emptying
T/F: insoluble fiber can do everything soluble fiber can
F, true in reverse
how does fiber aid in disease management
cardiovascular disease
diabetes
obesity and weight control
3 characterisitcs of soluble fiber not shared by insoluble fiber
delay gastric emptying
increase transit time
decrease nutrient absorption
2 characteristics of insoluble fiber notshared by soluble fiber
decrease transit time
increase fecal bulk
T/F: inadequate intake of fiber is related to diverticular disease, colon cancer, and constibation
T
