Quiz 8 Flashcards
1
Q
The smallest sugars are
A
aldoses and ketoses
formula (C x H2O)n
2
Q
monomers cyclize to form
A
a or B anomers
3
Q
monosaccharides can be linked to other or to other molecules by
A
glycosidic bonds
4
Q
monosaccharides, or simple sugars are synthesized from smaller precursors that are derived from
A
CO2 AND H2O by photosynthesis
5
Q
monosaccharides
A
not broken into simpler sugars under mild conditions
6
Q
oligosaccharides
A
oligo “a few” usually 2 to 10 simple sugar residues
7
Q
polysaccharides
A
polymers of simple sugars
8
Q
aldoses and ketoses contain
A
aldehyde and ketone functions
9
Q
chiral monosaccharides
A
- aldoses with 3 or more carbon atoms
- ketoses with 4 or more carbon atoms
10
Q
D,L designation refers to
A
the configurations of the highest numbered chiral center
11
Q
D sugars
A
predominate in nature
12
Q
steroisomers that are mirror images of each other are
A
enantiomers
13
Q
diasteromers
A
pairs of isomers that have opposite configurations at one or more chiral centers but are NOT mirror images of each other
14
Q
epimers
A
two sugars that differ in configuration at only one chiral centers
15
Q
cyclic form of glucose is a
A
pyranose (6-membered ring)
16
Q
cyclic form of fructose is a
A
furganose (5-membered ring)
17
Q
glucose (an aldose) can cyclize to form
A
a cyclic hemiacetal
18
Q
fructose (a ketose) can cyclize to form
A
a cyclic hemiketal
19
Q
when hemiacetals and hemiketals are formed,
A
the carbonyl carbon atom becomes a new asymmetric center
20
Q
isomers of monosaccharides that differ only in their configuration about that new asymmetric carbon are called
A
anomers
21
Q
equilibrium between linear and cyclic forms means
A
anomers interconvert
22
Q
“reducing sugars” have
A
free anomeric carbons which fluctuate between circular and linear forms
23
Q
silica acid on a mucosal cell membrane glycoproteins is the
A
binding site for the flu virus
24
Q
sugar alcohols
A
are formed by mild reduction of sugars
25
deoxy sugars
are constituents of DNA
26
sugar esters
phosphate esters like ATP are important for energy
27
amino sugars
contain an amino group in place of a hydroxyl group
28
acetals, metals and glycosides
basis for oligo- and polysaccharides
29
disaccharides
are the simples oligosaccharides : two monosaccharides linked by a glycosidic bond
30
each unit in an oligosaccharide is termed a
residue
31
each of the disaccharide structures is a
mixed acetal
with one hydroxyl provided from one monosaccharide and one hydroxyl from the other monosaccharide
32
each of these except for sucrose possesses one
free anomeric carbon and is thus a reducing sugar
33
sucrose is not
a reducing sugar, because it does not have a free anomeric carbon
34
homopolysaccharide
a polysaccharide that contains only one kind of monosaccharide
35
heteropolysaccharide
a polysaccharide made up of different monosaccharides
36
starch and glycogen are
storage molecules
37
chitin and cellulose
are structural molecules
38
starch is a
plant storage polysaccharide
39
amylose has
a(1->4) links, no branches, one reducing end
40
the branches in amylopectin are
a(1->6), every 12-20 residues, one reducing end
41
iodine fits into the helices to produce a
blue color, diagnostic of amylose
42
suspensions of amylose in water adopt a
helical conformation
43
iodine can into the
hydrophobic middle of the amylose helix to give a blue color that is characteristic and diagnostic for starch
44
glycogen is the
glucose storage device in animals
45
glycogen constitutes
up to 10% of liver mass and 1-2% of muscle mass
45
glycogen constitutes
up to 10% of liver mass and 1-2% of muscle mass
46
a(1->4) backbone, a(1->6)
branches every 8-12 residues
47
the composition of structural polysaccharides
is similar to storage polysaccharides: glucose units
structural: cellulose consists of B(1->4) linkages
48
amylose(storage) prefers
a helical conformation due to its bent a(1->4) linkages
49
cellulose,(structural) with
b(1->4) linkages can adopt a fully extended conformation
50
cellulose is a
structural polysaccharide
- found in cell walls of nearly all plants
51
giraffes, cattle, deer and camels are ruminant animals that are able to metabolize
cellulose, thanks to bacterial cellulase in the rumen, a large first compartment in the stomach of a ruminant
52
chitin is found in the
exoskeletons of crustaceans, insects and spiders, and cell walls of fungi
- it is a similar to cellulose but C-2s are N-acetyl
53
cellulose strands are
parallel
54
chitin strands can be
parallel or antiparallel
55
glycosaminoglycans
repeating disaccharides with amino sugars and negative charges
56
glycosaminoglycans are
linear chains of repeating disaccharides in which one unit is an amino sugar and one or both is negatively charged
57
heparin, with very high negative charge is a natural
anticoagulant
58
hyaluronates are components of the vitreous humor of the eye and of synovial fluid,
the lubricant fluid of the body's joints
59
chondroitin and keratan sulfate are found in
tendons, cartilage, and other connective tissue
60
glycosaminoglycans
are constituents of proteoglycans
61
proteoglycans
large glycosaminoglycan-containing proteins
62
peptidoglycan
bacterial cell walls consist of glycan chains cross-linked by peptides
63
glycoproteins
the oligosaccharide chains covalently attached to eukaryotic proteins play a role in protein structure and recognition
64
carbohydrates
may be N-linked or O-linked
65
O-linked carbohydrates are attracted to
side chain hydroxyl groups of usually serine residues on glycoproteins and proteoglycans
66
the difference between proteoglycans and glycoproteins in the type of sugars
- proteoglycans have O-linked glycosaminoglycans
- glycoproteins have N-linked and O-linked oligosaccharides
67
proteoglycans are a subset of glycoproteins whose carbohydrates are mostly, but not always solely
glycosaminoglycans
68
they are components of
animal cells, membranes, and the glycocalyx
69
they typically consist of
proteins with one or two types of glycosaminoglycan
70
cell surface and extracellular matrix [ECM] proteins
with covalently attached sulfated glycosaminoglycan chains
71
proteoglycan production and shedding is
part of cell-cell recognition and adhesion, cell proliferations
72
the carbohydrate groups of proteoglycans are predominantly glycosaminoglycans
O-linked residues on protein
73
structure of rat cartilage matrix proteoglycan
- highly hydrated
- compression of cartilage squeezes water out of the cartilage tissue
0 water is reabsorbed when the stress and compression diminishes
74
soluble protein component of the
extracellular matrix outside the cell membrane
75
structure of rat cartilage matrix proteoglycan
- chondroitin sulfate[green]
- keratan sulfate [blue]
- O-linked oligosaccharides [also blue]
- N-linked oligosaccharides [black]
76
modulation of cell growth processes
binding of growth factor proteins by proteoglycans in the glycocalyc
77
cushioning in joints
cartilage matrix proteoglycans absorb large amount s of water
78
bacteria cell walls are composed of
1 or 2 membranes a peptidoglycan shell
79
gram positive
one membrane a thick peptidoglycan outer shell made of a pentaglycine bridge connected by tetrapeptides
80
gram negative
two membranes with a thin peptidoglycan shell in between, with direct amide bonds between tetrapeptides
81
bacteria
peptidoglycan wall, lipopolysaccharides
82
animals
proteoglycans, glycoproteins and glycolipids
83
the peptidoglycan layer is a
fence or mesh of glycosaminoglycan heterosaccharide "rails" connected by tetrapeptides
84
gram negative cells are
"hairy"
85
lipopolysaccharide consiste of
a lipid group joined to a polysaccharide made up of long chains with various repeating monosaccharides.
86
animal cell surfaces contain an incredible diversity of
glycoproteins and proteoglycans
87
the polysaccharide structures regulate cell-cell
recognition and interaction with cell-surface receptors
88
the uniqueness of the "information"
in these structures is determined by the enzymes that synthesize these polysaccharides
89
N-linked glycoproteins are of three types
- high mannose, complex, and hybrid
90
the carbohydrate groups of glycoproteins may be linked to the protein by
serine or threonine residues [in the O-linked oligosaccharides]
91
function in many cases is to adopt an
extended conformation
92
bristle brush structure
extends functional protein domains up out of glycocalyx
93
the O-linked saccharides
often adopt extended conformations to life the functional domains of these proteins above the membrane surface
94
oligosaccharides can
- alter the chemical and physical properties of proteins
- can stabilize protein conformations and/or protect against proteolysis
- cleavage of monosaccharide units from N-linked glycoproteins in blood targets them for degradation in the liver
95
progressive cleavage of silica acid residues
- exposes gal residues. binding to liver receptors increases as more Gal is exposed
96
lectins are
the translators of the sugar code
97
selectin-carbohydrate interactions
modulate the rolling of leukocytes along the vascular wall, so that leukocytes can migrate efficiently to the sites of inflammation
