structure and function of carbohydrates

Question 1

define the following terms, what are all of these?

1. monosaccaharides
2. disaccharides
3. oligosaccharides
4. polysaccharides

Answer 1

main groups of carbohydrates in the human body

1. monosaccharides
   
   1. glucose, galactose, fructose….others
   2. provide energy for the human body
   3. serve as building blocks for complex carbohydrates
2. dissacharides
   
   1. lactose (milk sugar)
3. oligosaccharides
   
   1. short, non-repetative complex carbohydrates
   2. glycoproteins-extracellular and cell membrane malecules
   3. glycolipids-cell mombrane molecules
4. polysaccharides
   
   1. large, repetative carbohydrates
   2. glycogen-energy stores
   3. glycosaminioglycans-usualy attached to a protein core andfound in extracelular and cell membrane molecules

Question 2

define the folllowing terms

1. starch
2. glycogen
3. cellulose
4. lactose
5. sucrose
6. various other relavent monosaccharides (think processed foods)

Answer 2

1. starch- plant origin, glucose polymer
   
   1. amylose [alpha(1-4)]
   2. amylopectin[alpha(1-4) and alpha(1-6)]
2. glycogen-animal origin, glucose polymer
   
   1. [alph(1-4)] and [alpha(1-6)]
3. cellulose-glucose ploymer
   
   1. beta(1-4) plymer
   2. cannot be digested by human
4. lactose-milk sugar,
   
   1. galactosyl-beta(1-4)-fructose
5. sucrose-table sugar
   
   1. glucosyl-beta(1-4)-fructose
6. honorable mentions
   
   1. fructose, honey and fructose corn-syrup

Question 3

diagram the ingestion, digestion, absorption and secretion. start with.

1. starch, lactose, sucrose
2. include three main organs
   
   1. what digestive secretions are invovled with these organs?
3. where does digestion/absorption occur.

Answer 3

1. starts in the mouth by salivary a-amylase
2. pncreatic a-amylase further degrade complex carbohydrates to small oligiosaccharides
3. specific epithelial brush border enzymes degrade oligosaccharides to monosaccharides

Question 4

Jerry experiences severe diarreah after three bowels of ice cream. Explain a possible disease and mechanism.

what is the same thing for sucrose intolerance?

Answer 4

lactose intolerance

1. unable to digest lactose b/c of lactase deficiency
2. lactose passes to large intestine
3. attracts water (osmotic diarrhea)
4. intestinal bacteria degrade lactose to CO2 and H2
5. flatulence, abdominal cramps, diarrhea

isomaltse-sucrase dificiency

1. inability to digest sucrose
2. same symptoms as in lactose intolerance

digestive enzyme deficiency can also be cause by intestinal damage

Question 5

describe mechanisms of absorption: include location, two transporters and mechanism. release into blood stream: transporter and mechanism.

Answer 5

monosaccharide

1. absorption-small intestine
   
   1. transporters
      
      1. glucose and galactose
         
         1. SGLT1
            
            1. Na+ dependent glucose transporter 1
      2. fructose
         
         1. GLUT-5
            
            1. Na+ independent monosaccharide transporter
2. release into the bloodstream
   
   1. transporter
      
      1. GLUT-2
         
         1. ​Na+ independent monosaccharide transporter

Question 6

list the type of transporter, location and/or cell type these are found

1. GLUT1
2. GLUT2
3. GLUT3
4. GLUT4

Answer 6

these are Na+ independent glucose transporters. all GLUT’s are independent.

1. GLUT-1
   
   1. insulin dependent
   2. location
      
      1. RBC
      2. BBB-endothelial cells of the brain
2. GLUT-2
   
   1. bidirectional
   2. location
      
      1. liver
      2. kidney
      3. pancrease
3. GLUT3
   
   1. location
      
      1. neurons
4. GLUT-4
   
   1. the only INSULIN-REGULATED TRANSPORTER
   2. location
      
      1. muscles
      2. adipose

Question 7

what are GAG’s?

1. composition
2. attachment
3. synthesis
4. charge
5. purpose

Answer 7

glycosaminoglycans

1. composed of repeating disaccharide units of an acidic sugar (glucuronic or iduronic) and N-acetylated amino sugar
2. all, accept hyaluronic acid, are attach to a protein core
3. synthesized in golgi
   
   1. accept hyaluronic acid-synthesized at plasma membrane
4. all are negatively charged and sulfated
   
   1. hyaluronic acid is NOT sulfated
5. excreted from cell, due to negative charges attracting water
   
   1. ​these anions attract cations (K,Na) which also water.
   2. responsible for the compresive forces holding tissues in place
      
      1. confer resilience

Question 8

fill in the summary of glycosaminoglycans

Answer 8

Question 9

what is being described in this photo

what are they? puropose? and attachment?

Answer 9

1. proteoglycans
   
   1. proteins to which at least one GAG chain is attached
2. purpose
   
   1. cell surface receptors or extracellular matrix molecules
3. GAGs are attached to the protein core through a specific linkage
   
   1. linkage region attached to hydroxyl of
      
      1. Ser
      2. Asn

Question 10

what is an aggrecan? location, composition, and role?

Answer 10

cartilage proteoglycans (aggrecan)

1. highest [GAG]
2. main aggrecan = 100GAG
   
   1. chondrotin sulfate
   2. some keratin sulfate
3. role of aggrecan
   
   1. retained in extracellular matrix through non-covalent interactions w/ hyaluraonic acid and link protein(small glycoprotein)
   2. the large GAG content of cartilage provides the tissue with ressilience under compressive forces

Question 11

synthesis of proteoglycans

start with core protein add the following structures and locations

location: ER, GOLGI and ER, GOLGI
structures: UDP-sugars( Xyl, GAL), PAPS and core protein
actions: glycosyl transferase, sulfotransferases, growing the GSG chain, addition of linkage region, epimerization of glucuronic acid residues, sulfation

Answer 11

every sugar has its own glycosyl transferase.

energy for bonds between sugars comes from the UDP on the sugar.

sugars are added as monosaccharides.

we only add glucoronic acid to the chain and then convert it to iduronic acid in epimerization.

PAPS is the sulfer donor. sulfer gives the molecule its highly negative charge

Question 12

what diseases may cause excessive degradation of aggrecans?

Answer 12

1. osteoarthritis
2. rheumatoid arthritis
3. systemic lupus

are accompoanied by excessive degradation of aggrecans, which leads to defectiv cartilage function

Question 13

What diseases manifest from deficient degradation of GAG.

General group name, define the normal vs disease state mechanism of both diseases, describe what builds up in the body.

Answer 13

1. GAGs are taken up by the cell through endocytosis
2. GAGs are transported to lysosomes where they are degraded by specific enzymes
3. disease manifestation - occurs when the the enzymes are not present to catalyze reaction in degradation process involving the lysosome. the lysosome will swell leading to cellular inhibition and cell death.
   
   1. deficient lysosomal degradation of GAGs can cause sever disease
      
      1. mucopolysaccharidoses-a group of lysosomal storage diseases
         
         1. hunter syndrome
            
            1. ​symptoms
               
               1. mild physical deformity and mental retardation
               2. GAGs in urine
                  
                  1. heparin sulfate and dermatin sulfate
            2. mechanism
               
               1. iduronate sulfatase is deficient
                  
                  1. removes the 3rd sulfer group from the iduronic acid.
            3. cause
               
               1. x-linked
            4. treatment
               
               1. enzyme replacement
            5. 2. hurler syndrome
            6. ​symptoms
               
               1. severe physical deformaty and mental retardation
               2. GAGs in the urine
                  
                  1. heparin sulfate and dermatin sulfate
            7. mechanism
               
               1. alpha-Liduronidase deficiency
                  
                  1. removes the iduronic acid and/or the removal of the iduronic acids sulfate.
               2. ​this affects the break down of the glycoaminoglycans sulfate containing groups
                  
                  1. heparin sulfate
                  2. dermatan sulfate
            8. treatment
               
               1. bone marrow or cord transplant, before 18months old
               2. enzyme replacement therapy
      2. look at leukocytes/fibroblast for enzyme observation.

Question 14

define glycoproteins.

1. repating units?
2. size compared to GAGs
3. functions
   1.

Answer 14

glycoproteins- proteins with oligosaccharides attached them covalently

1. do not have repeating dissacharade units
2. much smaller than GAGs
3. function-widespread
   
   1. cells surface recognition molecules/receptors
      
      1. recognized by pathogens
   2. blood group antigens
   3. extracellular matric molecules
      
      1. laminin
      2. collagens
      3. fivronectin
   4. mucins
      
      1. lubricant
      2. surfactants
   5. plasma proteins
      
      1. oligosaccharide chains increase the solubility of the protein

Question 15

define the types of oligosaccharaides

Answer 15

1. o-linked
   
   1. attached to the hydroxyl group of Ser or Thr
   2. mostly linear
2. N-linked
   
   1. attached to amide group of asparagine
   2. branched structure
   3. two subtypes
      
      1. mannose rich
      2. complex

Question 16

discuss the start to the general oligosaccharide generation steps, what must happen? where does the pathway split? how?

Answer 16

general rules

1. protein is synthesized in the ER
2. monosaccharide have to be in nucleotide activated form to be added
   
   1. UDP linked
3. monosaccharides are added by glycosyltransferases
4. location
   
   1. Olinked glycoproteins
      
      1. ollisosaccharides chain is buil in the golgi
   2. N-linked glycoproteins
      
      1. the oligosaccharide chain synthesis starts in the ER and completes in the Golgi

Question 17

how does influenza virus cause infection? what structures are involved how?

Answer 17

1. influenza
   
   1. binds to tspecific sugars (sialic acids) present on cell surface glycoproteins on target cells
   2. designations of influenze viruses
      
      1. Hemagglutinin
         
         1. binds to sialic acid on target cells
         2. facilitates viral entry into target cell
      2. neuraminidase (enzyme)
         
         1. cleaves sialic acid from target cell surface
         2. facilitates release of new viruses from infected cells
         3. pharmacological target
            
            1. tamiflu=competative enzyme inhibitor

Question 18

a mutation in the N-acetylglucosamine phosphotransferase was found in a 6 year child child aftergene screening.

what is the normal mechanism of this enzyme, reprecussions of enzyme modification, name of disease

oligosaccharides target enzymes into the lysosomes. some are secreted outside and others to be delivered to organelles.. How can a disease manifest with oligosaccharide deformities?

Answer 18

1. N-linked oligiosaccharides involved with specific lysosomal enzymes.
2. lysosomal enzyme delivery must have a mannose phosphorylated on the N-links oligosaccharide.
   
   1. lysosomes are essential for the intracellular degradation of macromolecules.
3. defective oligosaccharides may lead to the enzymes deposited out side the cell.
   
   1. all macromolecules that are brought into the cell will not be digested correctly, b/c there is no lysosome to merge and digest the contents.
      
      1. leading to mucopolidosis 2 (I-cell disease)

Question 19

discuss the disease manifestation of tagging the lysosomal enzymes to go to the wrong place.

Answer 19

mucolipidosis 2 (I-cell disease)

1. deficient mannose phosphorylation, leads to endocytosed content aggregation intracellularly
   
   1. cells enlarged with- apear as inclusion bodies
      
      1. GAGs are not degraded
      2. all other macromolecules are not degraded
2. no treatment
   
   1. large number of different enzymes are ending up in the blood stream, which is the diagnostic marker.
      
      1. nothing is wrong with the enzymes the are being tagged to go to the wrong place.
      2. 3. symptoms
   2. skeletal sbnormalities
   3. developmental delays
   4. joint problems
   5. psychomotor impairment

Question 20

discuss the components of glycolipids. list the carbohydrate component of the following.

1. cerebroside
2. sulfatide
3. globoside
4. ganglioside

what are their involvment in the body?

Answer 20

glyco(sphingo)lipds have 3 structural components

1. sphingosine
2. fatty acid chain
3. carbohydrate

Function as

1. components are essential to outer layer of the plasma membrane
   
   1. brain and peripheral nervous system are very rich in glycolipids
2. major component of myelin sheets
3. are the blood group antigens
   
   1. antigens on the surface of red blood cells

Question 21

what region is affected by glycolipid deformation?

Answer 21

since the glycolipds mostly represent neurological structures, disease manifestation will mostly be involved in these regions.

Question 22

summarize the lysosomale storage diseases

Answer 22

Question 23

list the blood types and corresponding relationships with respected enzymes. why is this important?

Answer 23

blood groups are determined by addition/lack of glycoproteins/glycolipids(R group).

blood group antigens are generated by modifying the H substance.

1. blood types
   
   1. O
      
      1. defetive glycosyltransferase
   2. A
      
      1. only N-acetylgalactosamine transferase
   3. B
      
      1. only galactosyl transferase
   4. AB
      
      1. both glycosyltransferases
2. importance
   
   1. must have respected markers for blood transfusion

Question 24

Answer 24

1. genes
   
   1. every person has 2 genes that can code for three different alleles to produce the blood group antigens
2. an individual will have antibodies against the blood group antigen that is different from their own blood group antigen
3. RBCs can only be transferred if the recipient does not have antibodies against the donor’s blood group antigens
4. transfer of non-matched RBCs will cause antibody mediated hemolysis of the those RBCs

Question 25

Answer 25

Question 26

describe the following terms give examples

1. proteoglycans
   
   1. GAGs
   2. protein core
2. glycoproteins
3. glycolipids
4. saccharides
   
   1. monosaccharides
   2. disaccharides
   3. oligosaccharides
   4. polysaccharides

Answer 26

1. proteoglycans
   
   1. glycosaminoglycans
      
      1. CS
      2. DS
      3. KS
      4. HS
      5. H
      6. hyaluronic acid
   2. protein core- attachment for GAGs
2. glycoproteins-smaller than GAG
   
   1. cell surface markers
      
      1. blood groups
         
         1. o linked- membrane bound
            
            1. sugar attached to oxygen
         2. n-linked- non membrane bound
            
            1. sugar attached to nitrogen
   2. extracellular matrix
      
      1. lamins, collagens, firbronectin
   3. mucins
      
      1. lubricants, surfactant
   4. plasma proteins
3. glycolipids
   
   1. myelin sheaths
   2. blood group antigen on surface
4. saccharides
   
   1. mono-glu, fru, gal
   2. di- two
      
      1. maltose
      2. sucrose
      3. lactose
   3. oligo-two or more
      
      1. starch

Question 27

compare glycoproteins and proteoglycans

Answer 27

1. glycoproteins
   
   1. proteins with oligosaccharides attached covalently
   2. DO NOT have repeating disaccharide units
   3. SMALLER than GAGs of proteoglycans
   4. function
      
      1. cell surface receptors/recognition molecules
      2. laminins, collagens, fibronectins
      3. mucins
2. proteoglycans
   
   1. proteins with at least one GAG
   2. GAGs are attached to the protein core through linkage of hydroxyl group on S or N
   3. function
      
      1. ell surface or ECM