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97 Cards in this Set

  • Front
  • Back
What is the most common monosacaccharide?
hexoses
What distinguishes an aldoses?
C==O...on end
What is distinguishing feature of a ketose?
C==O...in middle
What is second in importance to hexoses?
pentoses
Explain trioses, tetroses, pentoses, and hexoses?
distinguishes the number of carbons in an aldose or ketose monosaccharide
Where are pentoses found?
in nucleic acids
How do you figure out the possible number of stereoisomers of a monosaccharide as a function of it's chiral centers?
2^n (n = # chiral centers)
By convention, the stereisomers of monosaccharides are classified as D or L based on the configuration of what?
The chiral carbon farthest from the carbonyl group, with reference to D/L glyceraldehyde
In nature almost all monosaccharides are what isomers?
D (though there are some L sugars)
What group is D-glyceraldehyde in?
3 carbon D-Adlose
What groups is Dihydroxyacetone in?
3 carbon D-Ketose
Which group is D-ribose in?
5 carbon D-Aldose
Which group is D-glucose in?
6 Carbon D-Aldose
Which group is D-Fructose in?
6 carbon D-Ketose
Which group is D-mannose in?
6 carbon D-aldose
Which group is D-Galactose in?
6 Carbon D-Aldose
Glyceraldehyde is a what?
aldose, triose
Ribose is a what?
aldose, pentose
Glucose, Mannose, and Galactose are what?
aldoses, hexoses
Dihydroxyacetone is a what?
ketose, triose
Fructose is a what?
ketose, hexose
Rib
ribose
Glc
glucose
Man
mannose
Gal
galactose
Fru
fructose
What are epimers?
sugars that differ only in their configuration at one chiral center (when compared to glucose, not when compared to eachother) They are epimers at the #C of wherever the difference may occur.
Glucose configuration?
CHO
!
H-C-OH
!
HO-C-H
!
H-C-OH
!
H-C-OH
!
CH2OH
...but he says he will never ask structure
What do sugars spontaneously do in solution?
cyclize to form hemiacetals of hemiketals...hemiacetals have one H group off of C while hemiketals do not (only 2 R groups) see chpt 7 slide 22 for clarification
Pyranose vs Furanose?
pyranose = 6 member ring

furanose = 5 member ring, less stable
What is an anomer?
monosaccharides differing only in their configuration at the hemiacetal/hemiketal carbon (so they occur in pairs)
What are the two formations of anomers?
alpha and beta...alpha has hydroxy group on bottom and beta has the hydroxyl group on top
What is mutorotation?
interconversion of anomers (in aqueous solution) (at equilibrium, there may also be some linear molecules)
What is a Haworth perspective?
formulas that show the stereochemistry of the ring forms of monosaccharides (2 conformations)...includes pyranoses and furanoses
The 2 conformations of 6 member rings? Which one is favored?
chair and boat...boat is favored
What is N-acetyl-beta-D-glucosamine?
one of the many derivatives of hexose
What makes most monosaccharides reducing sugars?
the carbonyl group can be oxidized
When a disaccharide is formed...what needs to occur for the it to be considered a reducing sugar?
the anomeric carbon of at least one of the monomers remains free...anomeric is the hemiacetal group...so just look for the hemiacetal group (looks like they need to connect 1 to 4)
When a disaccharide is formed...what needs to occur for it to be considered a nonreducing sugar?
if both of the anomeric carbons are part of the O-glycosidic bond (looks like they are nonreducting if they are not connecting 1 to 4)
Maltose monomers and activity?
Glc-Glc (reducing)
Lactose monomers and activity?
Gal-Glc (reducing)
Sucrose monomers and activity?
Fru-Glc (non-reducing)
Trehalose monomers and acivity?
Glc-Glc (non-reducing)
Shorthand and activity for maltose?
Glc(a1-->4)Glc...reducing
Shorthand and activity for lactose?
Gal(B1-->4)Glc...reducing
Shorthand and activity for Sucrose?
Fru(B2<-->1a)Glc or
Glc(a1<--2B)Fru...non-reducing
Shorthand and activity for Trehalose?
Glc(a1<-->1a)Glc
Polysaccharides are also known as what?
glycans
What are the differences between homo and heteropolysaccharides?
homo are all the same units (ex. all glucose)...Hetero are 2 or more different substituents (often alternate)
4 types of polysaccharides?
1. storage homopolysaccharides

2. structural homopolysacch-

3. Structural heteropolysacc-

4. Glyconjugates (information carriers) (Carbohydrate and other molecule..like protein, lipid, etc)
What are storage homopolysacch.s?
food molecules stored in cell
What are structural polysacch.s?
stay in cell as framework
What kind of polymer (polysaccharide) are amylose and amylopectin?
starch
Amylose is what type of polysaccharide?
homo
Amylopectin is what type of polysaccharide?
homo
For starch in plants anomeric carbon is in what conformation?
the alpha conformation
Describe structure of amylose and linkage?
unbranched glucose polymer...(a1-->4 linkage)
Describe structure and linkage of amylopectin?
a1-->4 linkage, branched (every 24-30 residues) using a1-->6 linkage
Glycogen is found where?
animals
Describe structure and linkage of glycogen?
a1-->4 linkage branched every 8-12 residues using a1-->6 linkage
Glycogen, starch (amylose and amylopectin) are what types of glycans?
storage
Chitin and cellulose are what type of glycans?
structural
What is the most abundant polysaccharide in nature? Where is it found?
cellulose...in plants' cell walls
Cellulose is an unbranched polymer of what? Which configuration is the anomeric carbon in?
glucose monomers...the beta
What is the result of cellulose's anomeric carbon being in the beta configuration?
these polylmers are strong, straight chains
Cellulose are straight chains wht is amylose and why?
tightly coiled, compact helices...because it is in the alpha configuration
Most animals have what to digest amylose? What can they not digest? What are the exceptions?
most have alpha-amylase...cannot digest cellulose....important exceptions are cows and other ruminants
What is the 2nd most abundant polysaccharide?
chitin
Where is chitin found?
principal component of exoskeletons of lobster, insects, etc.)
Chitin structure?
unbranched polymer of N-acetylglucosamine
Storage polysaccharides have the anomeric carbon in what configuration?
alpha
Structural homopolysacchs. have the anomeric carbon in what configuration?
beta
Cellulose is made of what monomers?
glucose
The advantages of storing sugars as polymers rather than monomers?
1. polysacchs. are insoluble and do not contribute to osmotic pressure

...so we store less polysacchs.....without glycogen glc conc. would increase and lead to cell explosion...so more advantageous to store as glycogen
What is the advantage of branching in polysaccharides?
makes energy more accessible...quicker degradation by enzymes that attack only non-reducing sugars...
5 main structural features of peptidoglycans?
(strucutral heteropolymer..."peptides,carbs")

1. Alternating monosaccharide (repeating disaccharides)

2. Peptide-cross-linked linear polysaccharides

3. Hydrolyzed by lysozome (in tears) - prevents bacterial infections in eyes

4. Penicillin and related antibiotics prevent synthesis of cross-links (so you can still make polysaccharide chains)

5. Peptide links between disaccharides so polysaccharides in one direction and peptides in the other
4 structural features of glycosaminoglycans?
1. repeating disaccharides

2. with an amino side group

3. no cross-links-different then peptidoglycans

4. components of gel-like extracellular matrix-not parts of cell walls like peptidoglycans these are between cells
4 examples of glycosaminoglycans?
1. hyaluronate

2. chondroitin sulfate

3. keratan sulfate

4. heparin
Hyaluronate function?
viscous LUBRICANTs in synovial fluids (joints)...vitreous humor
Chondroitin function?
confers tensile STRENGTH on cartilage, tendons, ligaments, aorta walls
Keratan sulfate function?
in the cornea, cartilage, bone, horn-like structures...like chondroitin this is involved with strength
heparin function?
natural anticoagulant
The key structural features of glycoconjugates and 3 examples?
All are information carriers (markers on cells)...All consist of Oligosaccharides +
1. proteoglycans

2. glycoproteins

3. glycolipids
Key structural feature of proteoglycan?
1 or more glycosaminoglycan chains bound to a core protein
Strucural and functional aspects of proteoglycans?
1. found on cell surface or in extracellular matrix...major component of connective tissue

2. the glycosaminoglycan portion is often the main site of biological activity
Components of glycoproteins?
protein + carbohydrate...so protein + 1 or more oligosaccharides
The difference between teh carbohdrate components in glycoproteins vs. proteoglycans?
the oligosaccharides found in glycoproteins are smaller and more structurally diverse than proteoglycans
Where are glycoproteins found?
On the cell surface or secreted into extracellular matrix
Examples of glycoproteins?
Immunoglobulins, various hormones (FSH, LH, TSH)
The glycolipids (glycolipids and lipopolysaccharides) have what instead of protein/peptide?
lipid
Structure and function of glycolipid?
1. lipids covalently bond to oligosacchs.

2. on the outer surface of the plasma membranes

3. Often binding sites for proteins (eg. blood group determinants)
Glycolipids are information what?
carriers
Glycolipids determine what?
blood type
Lipopolysaccharides structure and function?
1. dominant surface feature of gram-negative bacteria (e.coli, salmonella)

2. prime targets of antibodies
Where are blood group determinants found?
on surface of cell
What is a Lectin?
not a carb...it is a protein that binds to carbs...proteins that specifically and strongly bind carbohydrates...found in all organisms

-Serve a wide variety of CELL-CELL RECOGNITION AND ADHESION PROCESSES
One type of Lectin?
selectins