Final Exam Review: Weeks 8 Flashcards
lectins
proteins that bind to sugars
aldose numbering
carbonyl: numbered relative to aldehyde at C1 (C1 is always carbonyl C)
ketose numbering
carbonyl: numbered relative to ketone end which is always at C2
anomer
isomers that only differ at a newly formed chiral carbon in ring structure
epimer
differ at only 1 chiral/asymmetric carbon
reducing sugar test
free aldehyde reduces cupric to cuprous ion forming copper oxide (visually detected), aldehyde oxidized to acid
disaccharide formation
lone pair of electrons on hydroxyl O attacks anomeric C1 carbon
intermolecular glycosidic bond is between ____ and ____
Always between hydroxyl or amine and an anomeric carbon on another molecule
what hormone is at play in the anabolic state and what does it do
insulin signaling recruits glucose transporters to import glucose from the blood for glucose uptake and glycogen synthesis
how and where is excess glucose stored
excess glucose is stored as glycogen in muscle or liver by glycogen synthase
what organ secretes insulin
pancreas
under what conditions do ____ and ____ signal for glycogen breakdown? is this catabolic or anabolic?
epinephrin = exercise, glucagon = blood glucose drops signaling for catabolic state for glycogen breakdown
is glycolytic pathway exergonic or endergonic? how about under standard vs cellular conditions?
exergonic in both standard and cellular
how does feed forward regulation work in step 3 of glycolysis
if too much substrate (fructose 6-phosphate) builds up, side reaction with PFK-2 makes fructose-2,6-bisphosphate which activates/stimulates PFK-1
____ activates the PDC and ____ inhibits PDC
PD phosphatase activates, PD kinase inhibits
what 2 molecules inhibit the PDC and activate PD kinase
NADH and acetyl CoA
what subunit of the PDC does acetyl CoA inhibit
E2
what 2 monosaccharides make up sucrose
glucose and fructose
should the hydroxyl be on the right or left of carbonyl when looking at sugar in linear form? why?
right - enzymes look for D hydroxyl isomer when binding, D is physiologically relavent
hemiacetal is ____ derivative and hemiketal is ____ derivative
aldehyde, ketone
furan vs pyran
furan is five member ring, O came from hydroxyl that attacked carbonyl.
pyran = 6 member ring, hydroxyl from further down in sugar
what functional group and where makes a sugar a reducing sugar
free hydroxyl adjacent of O in a ring to allow opening to linear form
N-linked vs O-linked glycosylation
N-linked = Asn, O-linked = Ser/Thr
where does glycolsylation occur
ER and Golgi
How to name disaccharides
- O or N linked
- 1st sugar configuration anomer + name-yl
- # s of carbons linked together
- 2nd sugar configuration anomer + name -ose or -oside
example: O-a-D-glucopyranosyl(1-4)-a-D-glucopyranose
what are the 3 main ways polysaccharides can differ?
- composition (Glc vs Gal)
- connectivity (1->4, 1->6)
- configuration (alpha vs beta)
what does the enzyme glycosyl transferase do
specificity for certain sugars and can link them in proper orientation and connectivity
what molecule is first needed for a glycosyl transferase reaction? why? does this make the process catabolic or anabolic?
UTP to make high-energy sugar-nucleotide intermediate allowing sugar transfer onto another sugar or molecule. needs energy so anabolic
what are the 2 subunits of maltose? what is their connectivity? what is their configuration?
glucose and glucose
a-1,4
what are the 2 subunits of lactose? what is their connectivity? what is their configuration?
glucose and galactose
b-1,4
after how many units of glucose does glycogen branch? what stops them from falling apart? where are glucose units added/removed?
branches every 8-12 units
glycogenin is dimer at center that primes reducing ends
glucose added/removed from non-reducing ends
unbranched glucose units with a-1,4 linkages is ____ and linear gllucose units with a-1,4 linkages and an a-1,6 at branch points every 30 units is ______
amylose, amylopectin
what is the structure of cellulose? what enzyme digests cellulose? is it expressed in humans?
unbranched chains of glucose units (homopolymer) joined by b-(1→4) and many H bonds (linear, no spiral, negative iodine test). Cellulase not expressed in humans
