Final Exam Review: Weeks 8

Question 1

lectins

Answer 1

proteins that bind to sugars

Question 2

aldose numbering

Answer 2

carbonyl: numbered relative to aldehyde at C1 (C1 is always carbonyl C)

Question 3

ketose numbering

Answer 3

carbonyl: numbered relative to ketone end which is always at C2

Question 4

anomer

Answer 4

isomers that only differ at a newly formed chiral carbon in ring structure

Question 5

epimer

Answer 5

differ at only 1 chiral/asymmetric carbon

Question 6

reducing sugar test

Answer 6

free aldehyde reduces cupric to cuprous ion forming copper oxide (visually detected), aldehyde oxidized to acid

Question 7

disaccharide formation

Answer 7

lone pair of electrons on hydroxyl O attacks anomeric C1 carbon

Question 8

intermolecular glycosidic bond is between ____ and ____

Answer 8

Always between hydroxyl or amine and an anomeric carbon on another molecule

Question 9

what hormone is at play in the anabolic state and what does it do

Answer 9

insulin signaling recruits glucose transporters to import glucose from the blood for glucose uptake and glycogen synthesis

Question 10

how and where is excess glucose stored

Answer 10

excess glucose is stored as glycogen in muscle or liver by glycogen synthase

Question 11

what organ secretes insulin

Answer 11

pancreas

Question 12

under what conditions do ____ and ____ signal for glycogen breakdown? is this catabolic or anabolic?

Answer 12

epinephrin = exercise, glucagon = blood glucose drops signaling for catabolic state for glycogen breakdown

Question 13

is glycolytic pathway exergonic or endergonic? how about under standard vs cellular conditions?

Answer 13

exergonic in both standard and cellular

Question 14

how does feed forward regulation work in step 3 of glycolysis

Answer 14

if too much substrate (fructose 6-phosphate) builds up, side reaction with PFK-2 makes fructose-2,6-bisphosphate which activates/stimulates PFK-1

Question 15

____ activates the PDC and ____ inhibits PDC

Answer 15

PD phosphatase activates, PD kinase inhibits

Question 16

what 2 molecules inhibit the PDC and activate PD kinase

Answer 16

NADH and acetyl CoA

Question 17

what subunit of the PDC does acetyl CoA inhibit

Answer 17

E2

Question 18

what 2 monosaccharides make up sucrose

Answer 18

glucose and fructose

Question 19

should the hydroxyl be on the right or left of carbonyl when looking at sugar in linear form? why?

Answer 19

right - enzymes look for D hydroxyl isomer when binding, D is physiologically relavent

Question 20

hemiacetal is ____ derivative and hemiketal is ____ derivative

Answer 20

aldehyde, ketone

Question 21

furan vs pyran

Answer 21

furan is five member ring, O came from hydroxyl that attacked carbonyl.
pyran = 6 member ring, hydroxyl from further down in sugar

Question 22

what functional group and where makes a sugar a reducing sugar

Answer 22

free hydroxyl adjacent of O in a ring to allow opening to linear form

Question 23

N-linked vs O-linked glycosylation

Answer 23

N-linked = Asn, O-linked = Ser/Thr

Question 24

where does glycolsylation occur

Answer 24

ER and Golgi

Question 25

How to name disaccharides

Answer 25

1. O or N linked
2. 1st sugar configuration anomer + name-yl
3. # s of carbons linked together
4. 2nd sugar configuration anomer + name -ose or -oside

example: O-a-D-glucopyranosyl(1-4)-a-D-glucopyranose

Question 26

what are the 3 main ways polysaccharides can differ?

Answer 26

1. composition (Glc vs Gal)
2. connectivity (1->4, 1->6)
3. configuration (alpha vs beta)

Question 27

what does the enzyme glycosyl transferase do

Answer 27

specificity for certain sugars and can link them in proper orientation and connectivity

Question 28

what molecule is first needed for a glycosyl transferase reaction? why? does this make the process catabolic or anabolic?

Answer 28

UTP to make high-energy sugar-nucleotide intermediate allowing sugar transfer onto another sugar or molecule. needs energy so anabolic

Question 29

what are the 2 subunits of maltose? what is their connectivity? what is their configuration?

Answer 29

glucose and glucose
a-1,4

Question 30

what are the 2 subunits of lactose? what is their connectivity? what is their configuration?

Answer 30

glucose and galactose
b-1,4

Question 31

after how many units of glucose does glycogen branch? what stops them from falling apart? where are glucose units added/removed?

Answer 31

branches every 8-12 units
glycogenin is dimer at center that primes reducing ends
glucose added/removed from non-reducing ends

Question 32

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 ______

Answer 32

amylose, amylopectin

Question 33

what is the structure of cellulose? what enzyme digests cellulose? is it expressed in humans?

Answer 33

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