Lactose Galactose Glycoconjugate Sugars

Front 1

What UDP-glucunorate derived from?

Back 1

UDP-glucose

Front 2

What UDP-glucuronate a precursor to (6 types of molecules)?

Back 2

~proteoglycans & glucoprotein
UDP-xylose
~GLUCURONides
~iduRONATE
~bilirubin diGLUCURONide

Front 3

Where do glucuronidation reactions take place?

Back 3

Mostly in liver and intestine

Front 4

What is mutarotation?

Back 4

spontaneously change at anomeric sugar between the α and β configurations, possible by opening of the ring structure

Front 5

What 2 molecules does sucrose starts has?

Back 5

O-α-D-Glucopyranosyl
(1—> 2)-β-D-Fructofuranoside

Front 6

Which enzyme cleaves sucrose?

Back 6

Invertase

Front 7

Why does muturotation need to occur after sucrose cleavage?

Back 7

D-fructose is in the β-form, needs to change to α-conformation

Front 8

Which enz initiates fruc metab in muscles if this enz is in LARGE qty?
What is 1st step?

Back 8

hexokinase
fructose --> F6P (direct glycolytic intermediate)

Front 9

Diff between liver vs. muscle fruct metabl?

Back 9

predominance of glucokinase in liver which is gluc specific so diff enz needed vs. hexokinase in muscle which can phosph. fruct.

Front 10

Fruct metabolized by which enz in liver? 1st reaction? 2nd reaction & enz?

Back 10

fructokinase
1st: fru --> F1P (commited step)
F1P aldolase
2nd: F1P ------->glycealdehyde

Front 11

Faith of gyceraldehyde in fructose metabolism?

Back 11

->glycealdehyde-3-P (glyceyde Kase) --> glycolysis
--->glycerol(alcohol dehyoase) ->glycer3P(kinase)-->dihydroxyacertone--> glycolysis

Front 12

2 faith of glycehyldehyde in fruct metabolism?

Back 12

1. phopho by glyceralhdehyde
2. Hydrolysed by alcohol dehydrogenase

Front 13

percent of lactose in cow's milk?

Back 13

4-5%

Front 14

What type of bond in lactose?

Back 14

β-1,4 glycosidic bond

Front 15

Since lactose is a heiacetal, what reaction can it undergo? What does this make it?

Back 15

Mutorotation
Reducing sugar

Front 16

Which enz and product phosphorylase galactose?

Back 16

Galactokinase
G1P

Front 17

Type of enzyme epimerizes UDP-glalactose to UDP-glucose?
What other products after that?

Back 17

isomerase
Gal1P --> G1P --> G6P --> glycolysis(tissues) or glucose in liver

Front 18

Which enzymes involved in Classic galactosemia and
non-classic galactosemia?

Back 18

Classic galactosemia: galactose-1-phosphate uridyl transferase.non-classic: galactokinase.

Front 19

Whic 2 types of molecule require UDP-Galactose?

Back 19

Glycoproteins
Glycolipids

Front 20

Where does lactose synthesis take place? Which enzyme, made of what?

Back 20

only in mammary glands
ER enz: called lactase synthetase made of glalactosyltransferease + α-lactalbumin

Front 21

Which hormonal signal stimulates lactose synthesis?
Describe what happens:

Back 21

Prolactin following partution
lowers Km of α-lactalbumin from 1200 to 1 mM.

Front 22

What other role will galactotransferase take in the absebce of α-lactalbumin?

Back 22

Function in the glycoprotein pathway

Front 23

What 2 substate are needed for lactose synthesis?

Back 23

UDP-glalactose
GLucose

Front 24

Which enz. and type of glycosydic bond link can be hydrolysed in month?

Back 24

α-amylase
INTERNAL α-1,4 glycosidic bonds randomly hydrolyzed

Front 25

Where does complex CHO hydrolysis continue? what does it produce?

Back 25

Small intestine: mix of disaccharide, trisaccharide, and sl oligosaccharides called limit dextrins, containing (1,6) branches

Front 26

Final hydrolysis of alpha(1,6)bond are done by which type of enzyme?

Back 26

glycosidases

Front 27

2 ways to classify glycosidases?

Back 27

1. By what part of polysacch. they cut:
endoglycosidase (middle)
exo... (end)
2. if change alpha to beta (inverting) vs. not (returning)

Front 28

Where do you primarely find (1)glycolipids, (2)glycoprotein, (3)proteoglycans?

Back 28

1.exoplasmic cell membrane
2. blood and cell membrane 3.ECM

Front 29

Where do 1.synthesis and 2.degradation of glycoconjugates occur?

Back 29

1. endoplasmic reticulum and golgi.
2.lysosome

Front 30

Generalized Glycosyltransferase Reaction?

Back 30

Nucleotide-Sugar + HO-Acceptor --> Sugar-O-Acceptor
enz. glycotransferase

Front 31

Define proteoglycans, decriscribing main componants:

Back 31

GAG-GalGalXyl-O-CH2-protein
GAG:glycoaminoglycan (repeating dissach units GalNAc or GlcNAc + uronic acid (glucuronic or iduronic))
trissacharide (gal/gla/xyl)
O-glycosidic bond to S residue of core protein

Front 32

Why are proteoglycans possess lg neg charge?
Advantage?

Back 32

1. residues are frequently sulfated
2. highly hydrated --> take large space in ECM (good as lubricant and molecule stucture

Front 33

Proteoglycans are componant of what? Name 4

Back 33

ECM
joint fluid,
humor of the eye,
arterial walls
bone and cartilage

Front 34

What are glycosaminoglycans (GAGs)?

Back 34

long unbranched polysacc of repeating disacc(contain either of 2 modif. sugars (N-GalNAc or N-GlcNAc, and uronic acid (glucuronate or iduronate)

Front 35

2 class of glycoprotein?

Back 35

carbohydrate chains that are N-linked (via an Asn), O-linked (via Ser or Thr)

Front 36

Name 3 GAGs

Back 36

1. Heparin (lining the arteries of the lungs, liver and skin)
2. Hyaluronates (synovial fluid, vitreous humor, ECM)
3. Keratan sulfates (cornea, bone, cartilage)

Front 37

Name a common O-linked glycoprotein:

Back 37

Mucins

Front 38

Some mucins propreties:

Back 38

-Found in gastro, resp. and resp. tract secretion
-Form protective physical barrier on skin, involv. cell-cell interactions, may mask or contain antigens
-Extended stucture = high vicoelasticity
-high in O-glycan chains

Front 39

Main features of O-glycolysation:

Back 39

-enzymes are called: glycolyltransferase
-enz located in gogli apparatus
-occurs pOst-translationally at Ser or Threonine residues

Front 40

N-linked transferred ____ translationally to protein

Back 40

co-

Front 41

In glycolipids what is CHO attached to?

Back 41

Carbohydrates are attached to ceramide(a sphingolipid: sphingosineplus fatty acid).

Front 42

A main funtion of glycolipids?

Back 42

Involved in cell-cell contact/interactions

Front 43

2 main classes of glycolipids and composition? And each are found where?

Back 43

-CEREBROsides: single sugar group linked to ceramide, (gal or glu) high [ ] in brain
-Gangliosides–contain sialic acid residues, longer and branched vs. cerebrosides, in cell membrane

Front 44

What are sulfatides:

Back 44

sulfated cerebosides

Front 45

galactocerebroside has which 2 main:components

Back 45

Galactose + ceramide

Front 46

Back 46

Galactose metabolism

Front 47

Back 47

Fructose metabolism

Front 48

Back 48

glucuronic metab