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32 Cards in this Set
- Front
- Back
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What are the 2 main GENERAL roles of carbohydrates in tissues?
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-storage - fuel for metabolism
-structural constituents |
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What are the 3 elements of carbohydrates?
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-carbon
-hydrogen -oxygen |
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What are the 3 main general types of carbohydrates?
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-monosaccharides - simple sugars - 1
-polysaccharides - large amounts of sugar - 10+ -oligosaccharides - a few sugars - 2-10 |
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Carbohydrates form rings 99% in solution. What are the 2 most common?
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-Pyran - six member ring, C-1 forms oxygen bridge w/ C-5
-Furan - 5 member ring, C-2 forms oxygen w/ C-5 |
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What are the two ways monosaccharides are classified?
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# of carbons in ring - Triose-3, Tetrose-4, Pentose-5, Hexose-6, Heptose-7, Octose-8, Nonose-9, Decose-10
Aldehyde or ketone derivative -aldose - reducing group at C-1 -ketose - reducing group not at terminal C |
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What is used to link monosaccharides together?
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Oxygen bridges - glycosidic bond
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How many monosaccharides need to be linked to get a polysaccharide?
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more than 10
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In what form do animal store polysaccharides?
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GLYCOGEN - most prevalent in skeletal muscle and liver
---extensive branching makes molecule compact and also many ends to take molecules off - you can get |
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Glycogen is highly branched. Why is this advantageous?
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-makes molecule compact
-many ends to take off so you get energy quickly |
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What enzyme degrades glycogen for metabolic use?
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glycogen phosphorylase
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How does the functional role of glycogen differ between skeletal muscle and liver?
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-muscle - serves as an energy reserve mostly for contraction
-liver - glycogen supplies glucose to other tissues via the blood circulatory system |
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What 2 cells maintain glycogen in the eye?
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-corneal epithelial cells
-retinal muller cells - glial cells that support neurons |
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What ocular cells do not have glycogen?
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-corneal endothelial cells
-retinal photoreceptors - uses glucose at such a high rate can't store it |
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Oligosaccharides have structural effects and are usually attached to proteins. How do they affect these proteins?
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-protect protein from proteolysis
-limit protein freedom -stabilize conformations -glycosylation - process of adding sugars onto proteins (happens in Golgie apparatus) |
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What are glycosaminoglycans (GAGs) made of?
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-gel-like matrix made of repeating units of dissacharides (sugar bound to an aminosugar)
e.g. dissachride - Uronic acid bound to Hexosamine -non branching |
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Where are glycosaminoglycans (GAGs) found?
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-found in extracellular spaces of cartilage, tendon, skin, blood vessel walls
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What is hyaluronic acid and where is it found?
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-a glycosaminoglycan (GAG)
-found in connective tissue, synovial fluid, vitreous fluid |
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Hyaluronic acid is found in the vitreous? What does the vitreous do?
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-support the retina in its concave configuration
-prevent detachment of retinal neurons from the photoreceptors -absorb mechanical blows to the eye -cushion the eye during eye movements |
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What are the 2 types of GAGs found in the corneal stroma?
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-keratin sulfate
-dermatin sulfate ---they're linked to core proteins to form proteoglycans |
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What are proteoglycans?
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a core protein with GAGs attached covalently
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What purpose do the proteoglycans serve in the corneal stroma?
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-spacer molecules between the collagen fibers of the stromal lamellae.
---this maintains corneal clarity |
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What is the difference between glycoproteins and proteoglycans?
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Glycoproteins: contain more protein than carbohydrate
---carbohydrate usually consists of short chains (oligosaccharides), often branched Proteoglycans: long linear polysaccharide chains attached to a core protein ---carbohydrate portion consists of glycosaminoglycans |
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What are some common GAGs?
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Hyaluronic acid, Chondroitin sulfate, Dermatan sulfate, Heparan sulfate, Heparin, Keratan sulfate
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What are the functions of Glycoproteins?
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fxns span the entire spectrum of protein activiteis
---enzymes, transport proteins, receptors, hormones, structural proteins |
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How and where are glycoproteins synthesized?
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-polypeptide components is synthesized first on the membrane bound ribosomes of RER
-carbhydrate side chains are added during passage thru ER and Golgi apparatus (glycosylation) |
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What is glycosylation and the main enzyme involved?
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-attaching carbohydrate chains to a protein through N- or O-glycosidic linkages
-glycosyl transferase |
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How does non-enzymatic glycation work and where is it found?
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-condensation of a monosaccharide w/ certain reactive amino groups on the protein.
-Hemoglobin A1c ---continuous process occuring during 120 day lifespan of RBC ---Elevated levels in diabetes patients - HA1c measured at 3-6 month intervals |
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What do oligosaccharides do on the cell surface?
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Mediate Recognition Events
---Glycoconjugates, Antigenic Determinants |
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What do glycoconjugates (type of oligosaccharide) do?
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-sugars that coat all cells
-intercellular communication |
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What do Lectins do?
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-proteins that bind carbohydrates (like glycoconjugates)
-Appear on surfaces of cells |
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What do Selectins do?
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-proteins expressed continually by leukocytes
-mediate attachment to endothelial cells -recoginize and bind specific oligosaccharides -endothelial cells only transiently express selectins (usually in response to tissue damage) |
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What are Antigenic Derminants
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-ABO blood group antigens
A blood type: A antigens and anti B antibodies B blood type: B antigens and anti A antibodies AB blood type: A+B antigen (universal acceptor) O blood type A+B: H antigen and antibodies (universal donor) |
