Chapter 7 Flashcards
what are the 7 physiological functions of carbohydrates
1) source of energy
2) energy storage
3) structural roles
4) cellular interaction
5) cellular identification
6) information transfer (DNA and RNA)
7) signalling
what does carbohydrates mean
hydrate of carbon
what are the empirical formulas of carbohydrates
(CH2O)n where n is greater then or = to 3 (usually 3-6)
what are the two major classes of carbohydrates
-aldose (which have aldehyde group)
-ketoses (which have ketone group)
most monosaccharides have multiple…
asymmetric carbons
what designates a D or L sugar configuration
based on the configuration of the chiral carbon most distant from the carbonyl oxygen
what is the reference molecule for designation of D or L
D-glyceraldehyde
what group do all carbohydrates have
a carbonyl
what is contained in a ketone and a aldehyde
ketone is just a C double bond O and a aldehyde is a C double bond O and a H
what is the L and D configuration based on
the configuration of the chiral carbon most distant from the carbonyl oxygen
what side does the OH have to be on to be a D configuration
the right side
what side does the OH have to be on to be a L configuration
the left side
molecules with n chiral centers will have ____ sterioisomers
2^n
what are epimers
sugars that differ in configuration at one and only one chiral carbon
draw out a D-ribose
draw out a D-deoxyribose
draw out a D-glucose
draw out a D-mannose
draw out a D-galactose
draw out a D-fructose
draw out a dihydroxyacetone
draw out a D-glyceraldehyde
what has more chiral Cs aldose or ketosis
aldose has one more chiral C
what do longer carbohydrates tend to do in solution
longer carbohydrates (5 Cs and more) tend to be cyclized
what is longer C cyclized structures the result of
formation is the result of a reaction of an internal alcohol (hydroxyl group) with either:
1) an aldehyde (aldose) to form a hemiacital
2) a ketone (ketoses) to form a hemiketal
what is a stereoisomer
atoms are connected in the same order but differ in spatial arrangement
what is a epimer
they differ at one of several asymmetric carbon atoms
what is a isomer
they have the same molecular formula but different structures
what are constitutional isomers
they differ in the order of attachment of atoms
what is a enantomer
non superimposible mirror images
what are diastereoisomers
isomers that are not mirror images
what is anomers
isomers that differ at a new asymmetric carbon atom formed on ring closure
are all anomers epimers?
yes
are all epimers anomers?
no
what does cyclization of glucose involve
the C5 hydroxyl and the C1 aldehyde
in cyclization what happens when a C1 chiral is rendered
it produces two stereoisomers a and B
what is a anomeric carbon
the carbon that becomes chiral as a result of cyclization
what are the a and B forms of cyclization of eachother
they are a and B forms of each other
how can you tell if a carbohydrate molecule is a or B
you look at the carbon 1
if the OH is above the plane of the sugar its B
if the OH is below the plane of the sugar its a
cyclization produces a new ____ at the ____ resulting in two _____
chiral carbon, anomeric carbon, new stereoisomers (a and B)
what happen to a and B configurations in solution
they interconvert by a process called mutarotation
what is mutarotations intermedeate
it does from cyclization to linear intermediate back to cyclization
what does mutarotations represent
a change in configuration
what conformation fraction does glucose tend to be in solution
2/3 B-glucopyranose
1/3 a-glucopyranose
and less then 1% linear
what does the cyclization of fructose involve and what does it render
it involves the C5 hydroxyl and the C2 ketone
it renders C2 chiral (anomeric carbon) producing a and B sterioisomers
what ring does fructose exist in
both pyran and furan
where is B-fructopyranose found
in honey and its extreamly sweet
what happens when you heat B-fructopyranose
it promotes its conversion to B-fructofuranose (which is less sweet)
why is corn starch which contains lots B-fructopyranose used to sweeten
cold but not hot drinks because it would go to its less sweet form B-fructofuranose
what doe carbohydrates derivatives do to the glucose formula
it breaks from the empirical formula
what things can sugar derivatives contain
they can include nitrogen, phosphate, and sulphur groups
what things do sugar derivataves indicate
they usually indicate specialized functions
i.g muscle lubrication
what is myrosinase and glucosinolate
-found in plants as a survival defence
-myronose is an enzyme
-they are produces and stored separately but come together upon tissue damage
-when they come together they produce glucose and isothiocyanate (has a sharp, bitter taste)
-discourages herbivores from eating
what does myrosinase and glucosinolate come together to create
glucose and isothiocyanate
what can oxidize linear forms of monosaccharides
mild oxidizing agents like iron and copper
what happens when linear forms of monosaccarides are oxidized
the carbonyl group os oxidized into a carboxyl group
what does oxidizing linear forms of monosaccharides allow us to do
-allows for the quantifications of sugars present in blood or urine
-also defines the end of the sugar with the carbonyl carbon as being the reducing end
what are glycosidic bonds and what are the different ones
-primary structural linkage in all polymers of monosaccharides
-O-glycosidic bonds occur through oxidation
-N-glucosidic bonds occur through nitrogen
what things does the nomenclature of disaccharides specify
-the monosaccharides involved in the disaccharide
-their ring types (puran, furan)
-their configurationd (alpha or beta)
-their linkages (C1-C4 etc…)
-the end of the chain with a free anomeric carbon called the reducing end of the polymer
the end of the chain with a free anomeric carbon is called…
the reducing end of the polymer
monosaccharides have multiple hydroxyl groups what does this mean
there are many different glycolic linkages possible
how many different structures could just 3 monosaccharides create? (glucose, galacose and mannose)
12000 different stuctures
what are higher order carbohydrate structures in (disaccharides) generated through
-the action of glycosyltransferases
-glycosyltransferases uses monosaccharides that are activated through linkage with UPD
how do you use nomenclature to distinguish the configuration of cyclic carbohydrates
identify if its alpha or beta at the anomeric carbon
what nomenclature would you use to specify ring form of cyclic carbohydrates
furan or pyran
how would you use nomenclature to indicate reducing sugars or nonreducing sugars
non reducing has the suffix osyl
reducing sugar has the suffix ose
how do you use nomencature to determine how the disaccharides are bonded togeter
indicate in parentheses the two different carbon atoms joined by the glycosidic bond with an arrow
what are the two steps the prof gave to thing about when naming disaccharides
1) look at carbon 1 and see if its alpha or beta
2) look at carbon 4 and see if its glucose or galactose
what do lactose intolerant people lack
they have insufficent levels of the enzyme (lactase) that catalyses the hydrolysis into a glucose and galactose
what happens if lactose intolerant people consume dairy
it can lead to bloating, diarrhea, bloating, cramps, nausea
are mammals suposed to be able to drink milk
mammals cease to produce lactase after weaning but some human populations developed lactase persistence
what are some biological functions of polysaccharides
energy storage, structural roles and specialized roles such as cushioning and lubrication etc
what are homopolysaccharides
polymers contining A single type of monosaccharide
what are heteropolysaccarides
polymer containing more than one type of monosaccharide
what is branched hetero or homopolysaccharides
both of them can be unbranched or branched
what are energy storage polysaccharides
starch and glycogen (both homopolysaccharides)
what are structural polysaccharides
cellulose
chitin
dextran
(homo)
peptidoglycan
agarose
(hetero)
what is a specialized structural polysaccharides
hyluronate (hetero)
where and how is glucose stored in plants and animals
glucose is stored intracellularly in polymeric forms in both plants (starch) snd animals (glycogen)
both starch and glycogen are heavily hydrated structures
what is starch and where is it found
it is a mixture of two molecules, amylose (unbranched) and amylopectin (branched)
its found in plants and fungi
where is glycogen found
its stored in the liver and skeletal muscles of animals
is glycogen a long term energy storage
-you have about 24 hours of storage
-its not a very long term storage due to its polarity
-it can also be used in the case of extreme exersize hence why its also found in muscle
what is amylose and amylopectin
amylose: its a linear polymer of glucose residues through alpha(1-4) bonds
amylopectin: consists of alpha(1-4) linked glucose residues with alpha(1-6) branch points every 24-30 residues (on average)
what cuts the amylose and amylopectin branches
alpha(1-4) is cut by amylase
alpha(1-6) branche points by debranching enzymes
branches create more…
non reducing ends
the more reducing ends you have the faster you can…
mobilize your energy storage
how do amylose and amylopectin compare interms of reducing and non reducing ends
both have a single reducing ends
amylose has a single non-reducing end
amylopectin has multiple non reducing ends
where is glycogen found
in all cells but most prevalent in skeletal muscles and liver
what is glycogen like structrally
its structrally identical to amylopectin and consists of alpha (1-4) linked glucose residues with alpha(1-6) branch points but with a higher frequency of branch points (every 10 residues)
when and how is glycogen mobilized
its mobilized in times of need by glycogen phosphoralase which sequential cleaves glucose residues from non reducing ends
in polysaccharides greater frequency is branching allows for…
rapid mobilization
why is rapid mobilization of energy storage beneficial in humans and not plants
because for use being able to access that energy helps us to fight or run faster which determines our survival. plants dont use this as survival mechanism.
for humans the more densely branched structure =…
faster access to our energy
what is the primary component of plant walls
cellulose (fiber)
how much of the carbon in the biosphere does cellulose account for
over half
how is cellulose made up
its linear, homopolysaccaride of glucose residues
and has a linear arrangement of beta(1-4) glycosidic residues
can amylase break down cellulose
no it cannot cut the beta(1-4) glycosidic residues
where do we see the use of chitin
as the principal component of hard exoskeletons (insects, lobsters, etc)
how is chitin made up
its a linear, homopolysaccharide of N-acetalglucosamine residues
what is the chemical difference between cellulose and chitin
the replacement of hydroxyl group at C2 with acetylates amino groups
what does the beta linkages of cellulose and chitin allow for
the formation of long straight chains called fibrils this fiber generates a digid supportive structure of high tensile strangth
how are fibrils formed
by parallel chains that are linked through hydrogen bonds
what structure does the alpha(1-4) linkages of starch and glycogen form. and what does these structures do
they form hollow, helical structures
the hollow helix provides a compact, accessible storage structure of glucose
what are glycolipids
sugars can also be covalently linked to lipid molecules to form glycolipids
what is a central function of glycolipids
is in the blood groups antigens
how does the body use glycolipids in blood to help determine if its itself or not
different patterns of sugars presented on the surface of cells by the glycolipids help the body to discriminate self from non self
what enzyme have scientist created to make blood tranfusions easier
an enzyme that snips off the sugars found in type A and B blood, making it more like type O
what are glycoproteins
-proteins with covalently attached sugars
-the protein constituent is the largest component by weight
-serves in a variety of biological roles
what are proteoglycans
-protein component is linked to a particular type of carbohydrate called a glycosaminoglycan
-the carbohydrate constituent is the largest component by weight
-often serves structural and lubricating functions
what post translational mods do proteins undergo to become glycoproteins
post-translational glycosylation (additions of sugar groups)
how many proteins are modified with sugar groups
almost half biological proteins
what does post translational glycosylation regulate
-modifications regulate the structure and function of the protein
what does post translational glycosylation involve when it comes to sugar attachment
-modifications often involve complex, specific patterns of sugar attachment
-sugars are attached to either:
the amide nitrogen of the side chain of an asparagine (N-linked)
the hydroxyl oxygen of the side chain of serine or threonine (O-linked)
what is erythropoietin (EPO)
-it simulates red blood cell production
-its highly effective in the treatment of anaemia
-has three N-liked and O-linked glycosylations
-its also exploited by the endurance athletes to increase oxygen carrying capacity
-the patterns of glycosylation associated with the synthetic version of EPO differ from those of the endogenous proteins
how many membered rings are pyranose and furansose
pyran is a 6 membered sugar ring
furan is a 5 membered ring
how do you calculate the number os stereoisomers in a carbohydrate
First determine the number of chiral carbons then follow the formula 2n where n is the number of chiral carbons. If n =1 there are 2 stereoisomers, n=2 there are 4 stereoisomers, n= 3 there are 8 stereoisomers and n =4 there are 16 stereoisomes.
what molecule are the designation of D and L relative to the reference of
D-glyceraldehyde
what designates a D or L sugar configuration
based on the configuration of the chiral carbon most distant from the carbonyl oxygen
