Chapter 9- Imi Biochem Flashcards
(64 cards)
1
Q
function of collagen
A
structure
2
Q
function of epithelial mucins
A
lubrication and protection
3
Q
function of synovial fluid glycoproteins
A
lubrication and protection
4
Q
function of ceruloplasmin
A
transport, a copper carrier
5
Q
function of transferrin
A
transport, an iron carrier
6
Q
function of thyrotropin
A
endocrine regulation
7
Q
function of chorionic gonadotropin
A
endocrine regulation
8
Q
function of erythropoietin
A
endocrine regulation
9
Q
function of proteases
A
catalysis
10
Q
function of nucleases
A
catalysis
11
Q
function of glycosidases
A
catalysis
12
Q
function of hydrolases
A
catalysis
13
Q
function of immunoglobulins
A
defense against infection
14
Q
function of complement proteins
A
defense against infection
15
Q
function of interferons
A
defense against infection
16
Q
function of selectins and integrins
A
defense against infection
17
Q
function of acetylcholine
A
membrane receptor
18
Q
function of cholera toxin
A
membrane receptor
19
Q
function of electromagnetic radiation (e.g rhodopsin)
A
membrane receptor
20
Q
function of blood group substances
A
antigens
21
Q
function of fibronectin
A
cell-cell recognition and adhesion
22
Q
function of laminin
A
cell-cell recognition and adhesion
23
Q
function of chondronectin
A
cell-cell recognition and adhesion
24
Q
function of glycophorin
A
miscellaneous, an intrinsic red blood cell membrane constituent
25
function of intrinsic factor
miscellaneous, essential for absorption of dietary vitamin B12
26
function of clotting factors
miscellaneous, e.g. fibrinogen
27
what are glycoproteins
proteins that possess covalently attached polysaccharide chain with o-glycosidic or n-glycosidic linkages
28
physiologic functions of glycoproteins
structural molecules, lubricants, cell attachment and recognition sites, certain hormones, immunologic components
29
o-glycosidic linkage occur via
serine, threonine, hydroxylysin, hydroxyproline
30
n-glycosidic linkage occur via
asparagine
31
microheterogeneity
when glycoproteins with an identical polypeptide sequence varies in the structure of their oligosaccharide chains. arises from incomplete synthesis or partial degradation and poses problems in purification and characterization of glycoproteins
32
α1 acid glycoprotein
human serum α1 -acid glycoprotein has five linkage sites for carbohydrates and occurs in at least 19 different forms as a result of differences in oligosaccharide structures
33
collagen glycoproteins
contains an amount of carbohydrate that varies with the source: skin tissue collagen, about 0.5%; cartilage collagen, about 4%; and basement membrane collagen, more than 10%
34
where are glycoproteins synthesized
ER and golgi where sugars can be added or removed
35
how are glycoproteins added
CHO chain produced by sequential addition of monosaccharide units to the non-reducing end
36
glycoprotein carbohydrate additions involve
specific glyosyltransferases and their substrates (UDP-sugars, GDP-mannose, GDP-L-fructose, and CMP-NANA:cytidine monophosphate N-acetylneuraminic acid, and in some glycoproteins an oligosaccharide carrier dolichol
37
what is dolichol phosphate
a lipid involved in the synthesis of glycoproteins (N of Asn): sugars are added sequentially to dolichol phosphate, which is associated with ER membrane -> branched polysaccharide chain is transferred to an amide N of an Asn
38
what ways can glycoproteins leave the cell
glycoproteins are segregated into lysosomes, attached to the cell membrane, or secreted by cell
39
what is glycation
Addition of CHO residues without any of the complex enzymatic pathways of CHO addition (AKA non-enzymatic glycation)
40
glycation of hemoglobin
Hemoglobin A1c via N-glycosidic linkage into the N-terminal amino group of Val of each β-chain throughout the lifespan of RBC's 120 days
41
glycation of human serum albumin
producing a stable condensation product known as fructosamine
42
what is fructosamine
a generic term applied to the stable condensation product of glucose with serum proteins
43
estimation of short-term (1-3 weeks) plasma glucose levels
measurement of fructosamine
44
integrated plasma glucose levels over a longer period (2-3 months)
measurement of HbA1c concentration
45
glycation of α-, β-, γ-crystallins occurs where
human lens proteins, age dependent non-enzymatic glycation at the ε-amino groups of Lys, in diabetics, this process occurs twice as often as in normal individuals
46
what are cell membrane constituents
Lipids (phospholipids, glycosphingolipids, cholesterol), Carbohydrates and proteins
47
glycoproteins or glycolipids linked to
CHO residues are covalently linked to proteins or lipids to form glycoproteins or glycolipids
48
The ratio of protein:lipid:carbohydrate in cell membranes
on a weight basis varies considerably from membrane to membrane: human erythrocytes (49:43:8), myelin (18:79:3)
49
Membrane glycoproteins properties
amphipathic molecules, CHO moieties of glycoproteins are distributed asymmetrically in cell membranes
50
role of glycoproteins in cell-cell interaction
coordination & regulation of adhesion, growth, differentiation of cells, and cell size
51
fibronectin properties
a large, external, transformation-sensitive protein, promotes attachment and subsequent spreading of many cell types, contain 5% of CHOs by weight
52
Cell surface fibronectin
adhesion of cell with its extracellular matrix
53
Plasma fibronectin
role in wound repair, formation of fibrin clot, the enhancement of opsonic activity of macrophages, attracting fibroblasts
54
Fetal fibronectin
unique form found at the uteroplacental junction, presence in cervicovaginal secretions used as marker in assessing the risk for preterm delivery, measured by enzyme immunoassay
55
antigenic variation of blood group substances is due to
specific glycosyltransferases responsible for synthesis of the oligosaccharide determinants
56
what are blood group antigens
specific classes of oligosaccharides present on surface of human RBCs, inherited according to Mendel's law
57
what adds sugar to RBC
gene encodes an enzyme that adds sugar to RBC to make blood type
58
All serum proteins except Serum Albumin
glycoproteins
59
The sugar residues found most commonly in the outer domain of the oligosaccharides of serum glycoproteins are
galactose, N-acetylhexosamine, and sialic acid
60
Role of liver in the synthesis and catabolism of glycoproteins
Lose their terminal sialic acid residues through the action of neuraminidase (sialidase) during circulation in the blood, which exposes the galactose residues. The resulting galactose-terminated glycoproteins, known as asialoglycoproteins are taken up after binding to receptors on hepatocytes. Internalized receptor-mediated endocytosis and subjected to lysosomal degradation
61
elevated plasma asialoglycoproteins detected in
liver disease
62
molecular mimicry of oligosaccharides and host susceptibility
Infectious agent contain antigenic epitope, elicit antibodies that cause a disease
63
Guillain-Barre syndrome (GBS)
self-limited autoimmune disease, resulted from an antecedent, acute infection of bacterial or viral origin, in children, following vaccination causing common antigenic epitope with host that elicits antibodies that cause disease resulting in molecular mimicry
64
C. jejuni
lipopolysaccharides contain terminal tetrasaccharides identical to ganglioside GM1, antibodies cause immune-mediated destruction of nerve fibers resulting in molecular mimicry
