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49 Cards in this Set
- Front
- Back
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Monosaccharides are
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glucose, galactose, fructose, etc.
Serve as building blocks |
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Disaccharides are
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lactose
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Oligosaccharides are
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short, non-repetitive complex carbohydrates
Glycoproteins and glycolipids |
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Polysaccharides are
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large, repettive carbohydrates
Glycogen GAG's - usually attached to a protein core |
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In order to link monosaccharides together, they have to be in the...
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nucleotide-activated form, which are specific for a given monosaccharide
UDP-glucose - UDP-N-acetylglucosamine |
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The nucleotide attaches to the _______ of the monosaccharide
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reducing end
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Glycosyltransferases are
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enzymes that catalyze the addition of monosacchardies to proteins, lipids, or growing oligo/polysaccharide chains
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Hydrolysis of the UDP-linkage provides energy for the formation of the
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Glycosidic bond
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Monosaccharides are transferred to...
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mostly hydroxyl groups
serine, threonine, asparagine for proteoglycans and glycoproteins hydroxyl group of ceramide - glycolipids hydroxyl groups of other sugars - lactose, GAG's, and oligosaccharides Drugs, steroids - clearance to the urine Bilirubin - clearance to bile |
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Two main functions of glycosylation
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Increase solubility and integral part of the biomolecule's function
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UDP-glucuronate is essential for the synthesis of _____ and is used for ___
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glycosaminoglycans
production of glucuronides to facilitate the excretion of drugs, toxins, bilirubin, and steroid hormones |
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Glucuronyltransferases add...
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glucouronate to hormones and drugs in the liver.
The formed glucuronides are excreted out of the human body. Mainly in the urine |
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All Gags but hyaluronic acid are synthesized in the...
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Golgi
Hyaluronic Acid is synthesized at the plasma membrane |
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Gags have a ____ charge
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negative charge attracting a lot of water. The behave like sponges and confer resilience to tissues
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Hyaluronic acid is formed from a __ and ___
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glucuronic acid and N-acetyl-glucosamine
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The most abundant gag in the human body is
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Chondroitin sulfates - largest concentration is in the cartilage
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Increased levels of Dermatan sulfate in mitral valves
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is associated with thickening and abnormal displacement of the valve into the left atrium (mitral valve prolapse
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The two types of keratan sulfates are found...
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KS I - cornea, linked to the amide of Asn
KS II - cartilage, linked to the hydroxyl of Ser |
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Carbohydrate sulfotransferase 6 (CHST6) deficiency results in...
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undersulfated keratan sulfate in cornea, which leads to macular corneal dystrophy (cloudy areas, vision impairment)
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Aggrecan
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Cartilage proteoglycan
Mainly chondroitin sulfates with some KSII "Bottle Brush" Provides resiliance under compressive forces |
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Aggrecan is retained in the cartilage ecm through non-covalent interactions with
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hyaluronic acid and link protein
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Excessive degradation of cartilage proteoglycans that leads to defective cartilage function is associated with
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osteoarthritis, rheumatoid arthritis and systemic lupus erythematosus
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Deficient lysosomal degradation of GAGs can cause severe diseases...
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mucopolysaccharidoses
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Hunter Syndrome
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MPS II
Iduronate sulfatase deficiency Degradation of dermatan sulfate and heparin sulfate affects No corneal clouding, but physical deformity and mental retardation is mild to severe |
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Hurler Syndrome
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MPS I H
Alpha-L-iduronidase deficiency Most severe form of MPS I Degradation of dermatan sulfate and heparin sulfate affects corneal clouding, mental retardation, dwarfing, course facial features, upper airway obstruction |
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San Filippo Syndrome Types A-D
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MPS III
Four enzymatic steps necessary for removal of N-sulfated or N-acetylated glucosamine residues from heparin sulfate Type A: Heparan sulfamidase deficiency Type B: N-acetylglucosaminidaase deficiency Type C: Glucosamine-N-Acetyltransferase deficiency Type D: N-Acetylglucosamine 6-sulfatase deficiency Severe nervous system disorders, mental retardation |
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Sly Syndrome (MPS VII)
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B-Glucuronidase deficiency
Hepatosplenomegaly, skeletal deformity, short stature, corneal clouding, mental deficiency Degradation of dermatan sulfate and heparan sulfate are affected |
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5 Functions of glycoproteins
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Cell surface recognition molecules/receptors
Blood group antigens Extracellular matrix molecules (laminins, collagens, fibronectin) Mucins (lubricants, surfactants) Plasma proteins (oligosaccharide chains increase the solubility of the protein) |
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Mucins are
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large glycoproteins found mainly in the digestive tract and airways
Rich in serines and threonines that link to oligosaccharides Highly negatively charged able to aggregate to form large networks able to provide a physical barrier against pathogen invasion in the intestines and airways |
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What are the two types of oligosaccharides
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O-linked - attach to hydroxyl group of serine or threonine, mostly linear
N-linked - attach to the amide group of asparagine, branched structure, can be either mannose-rich or complex |
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General rules of glycoprotein synthesis
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The protein is synthesized in the ER
Monosaccharides have to be in nucleotide activated form to be added Monosaccharides are added by glycosyltransferases |
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O-linked glycoprotein..
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Oligosaccharide chain is built in the golgi
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N-linked glycoproteins
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chain starts to build on a lipid (dolichol) in the membrane of the ER
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What is absolutely crucial for correct lysosomal targeting?
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Mannose-P and Mannose-P receptor
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Defficiency in that Mannose targeting mechanism is...
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I-Cell disease
deficiency of ability to phosphorylate mannose Skeletal abnormalities, restricted joint movement, coarse facial features, and severe pyschomotor impairment Death usually occurs by eight years of age |
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What are the four types of glycolipids?
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Cerebroside, Sulfatide, Globoside, and Ganglioside
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What are the three structural components of a glycolipid
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Sphingosine, fatty acid chain, and a carbohydrate
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What are the functions of glycolipids
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Essential components of outer layer of plasma membrane
Major component of myelin sheets that protect axons Blood group antigens Binding sites for bacterial toxins (cholera and tetanus toxins) |
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First rule of blood grouping
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Every individual has 2 genes that code for glycosyltransferases
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Second rule of blood grouping
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An individual will have antibodies against the blood group antigen that is different from his/her own blood group antigen
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Gaucher Disease
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Accumulation of glucocerebroside
Most common LSD Hepatoslenomegally, osteoporosis of long bones CNS involvement is rare "Crumpled tissue paper" in cytoplasm from enlarged, elongated lysosomes filled with glucocerebroside |
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Glycolipids are degraded in the the
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Lysosomes
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These disease are referred to as..
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Lysosomal storage diseases
Most of them have neurological symptoms Generally diagnosed by measuring the activity of the appropriate enzymes in leukocytes |
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What is the main dietary source of galactose?
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Lactose (milk)
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Cells take up galactose in an...
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insulin dependent manner
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The first step of galactose metabolism
Galactose must be ___ before it can be metabolized |
phosphorylated by galactokinase...or reduced to an alcohol
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The second step of galactose metabolism
galactose must be converted to... |
UDP-galactose
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UDP-Galactose plays a central roll in
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synthesis of complex carbohydrates (glycolipids, glycoproteins, and gags)
synthesis of UDP-glucose (glycolysis, gluconeogenesis) |
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The three Galactose metabolism disorders talked about in the lecture..
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Galactokinase deficiency - causes elevation of galactose in the blood and urine
Aldose reductase Classic Galactosemia - uridyltransferase deficiency. Causes galactosemia and galactosuria, vomiting, diarrhea, and jaundice Accumulation of Galactose 1-P causes liver damage, severe mental retardation, and cataracts Rapid diagnoses and removal of galactose from the diet. (Newborn screening is available) |
