Title: Jack Sparrow Biochem / Biochemistry / Biochemistry Chapter 4
Tags: #JackSparrow::#B/B::#Biochemistry::#Chapter.4

Q: Whaat is a monosaccharide and what are its types?
A: A monosaccharide is a single carbohydrate.
Monosaccharides can have 3 carbons (trioses), 4 carbons (tetroses), 5 carbons (pentose), or 6 carbons (hexoses).

Q: What is an aldose?
A: An aldose is a carbohydrate that contains an aldehyde group as its highest priority group.

Q: What is a ketose?
A: A ketose is a carbohydrate that containes a ketone group as its highest priority group.

Q: What are Carbohydrates?
A: Carbohydrates are a class of molecules in the body that consist mostly of carbon, hydrogen, and oxygen.

What is the structure of D-Fructose?

What is the structure of D-Glucose?

What is the structure of D-Galactose?

What is the structure of D-Mannose

Q: What is meant by D and L when naming carbohydrates?
A: D and L is an oldschool way of designating stereochemistry.  It predates R and S nomenclature.  D and L are enantiomers of one another, just like R and S, but a D configuration does not necessarily imply an R or an S configuration.  If you want to figure out the R or S configuration, you need to determine it independently of the D and L assignment.

Q: What is a Fischer Projection?
A: A fischer Projection is a simple two dimensional representation of a three dimensional object in which horizontal lines are wedges coming out at you and verticle lines are dashes going into the page.

Q: What is an enantiomer?
A: An enantiomer is a molecule with a mirror image exact opposite configuration of the molecule in question.

Q: What is a diastereomer?
A: A diastereomer is a molecule that is not an exact mirror image of the molecule in question, but is still different in its stereochemistry.

Q: What is an epimer?
A: An epimer is a special type of diastereomers.  It is a molecule that is different in configuration at only one carbon.

Q: What is the anomeric carbon?
A: When a sugar cyclizes, the carbonyl carbon becomes a stereocenter.  This is the anomeric carbon.

Q: What types of sugars exist in cyclic form in solution?
A: Six carbon pyranose rings or five carbon furanose rings.

Q: How do carbohydrates cyclize?
A: Carbohydrates cyclize by undergoing intramolecular reactions to form cyclic hemiacetals (from aldoses) and hemiketals (from ketoses).

Q: What is a hemiacetal?
A: A hemiacetal is a product of a hydroxyl group attacking an aldehyde.

Q: What is a hemiketal?
A: A hemiketal is a product of a hydroxyl group attacking a ketone.

Q: What is an anomer?
A: An anomer is a molecule that differes in the stereoconfiguration of the anomeric carbon.

Q: What is meant by alpha and beta anomerism?
A: Alpha anomeric carbons are trans to the CH_2OH substituent, which means they go axial and down.  Beta anomeric carbons are cis to the CH_2OH substituent, which means they go equatorial and up.

Q: What is a Haworth Projection?
A: A haworth projection is a 3 dimensional representation of a cyclic sugar.

Q: How does one convert a fischer projection into a haworth projection?
A: Represent the sugar with the fischer projection shown below.
Attack the carbonyl (wherever it is) with the last OH on the main chain (on the 5 carbon).  Then, all the substituents on the left end up above the ring while all the substituents on the right end up below the ring.  The position of the OH on the anomeric carbon is determined by whether or not the molecule is alpha or beta.

Q: What is mutarotation?
A: When hemiacetal rings are exposed to water, they will spontaneously cycle between the cyclic and the chain form.  Because the ring keeps reforming, the anomeric carbon's alpha or beta designation keeps changing.  This spontaneous change in the configuration on the anomeric carbon is known as mutarotation.

Q: What can you do to a solution to increase the rate of mutarotation?
A: Add acid OR base

Q: What is a reducing sugar?
A: A reducing sugar is any sugar with a free oxygen on its anomeric carbon or an aldehyde on the end of its chain.
These sugars are so named because they can be oxidized, and are thus considered reducing agents.

Q: What do you get when you reduce a sugar in its chain form?
A: You get an aldonic acid.

Q: What do you get when you reduce a sugar in its ring form?
A: You get a lactone, which is a ring with a double bond to oxygen at the anomeric carbon.

Q: What are the two standard reagents used to detect the presence of reducing sugars?
A: 1.  Tollen's Reagent
2.  Benedict's Reagent

Q: What is Tollen's Reagent?
A: Tollen's Reagent is [Ag(NH_3)_2]^+.  It must be freshly prepared when it is desired by mixing silver nitrate (AgNO_3) with sodium hydroxide (NaOH) to produce silver oxide (Ag_2O).  Silver oxide is then dissolved in ammonia to produce the Tollen's reagent.
The tollen's reagent is reduced to produce a silvery mirror when aldehydes are present.

Q: What is Benedict's reagent?
A: Benedict's reagent is a mix of Cu(OH)_2 and a special solution.  When it interacts with aldehydes, Cu_2O is produced, which is a reddish brown precipitate.  The appearance of the red precipitate therefore indicates the presence of large amounts of reducing sugars.
MNEMONIC:  Benedict's is Red like Bricks

Q: What is tautomerization?
A: Tautomerization refers to the rearrangement of bonds in a compound, usually by moving a hydrogen and forming a double bond.  Tautomerization is seen in carbohydrates in the form of Keto-Enol transitions when sugars ketoses are exposed to basic conditions.

Q: What is an enol?
A: An enol is a compound with a double bond and an alcohol group

Q: What is an alditol?
A: When the aldehyde group of an aldose is reduced to an alcohol, the compound is considered an alditol.

Q: What is a deoxy sugar?
A: A deoxy sugar is a sugar with hydrogens in place of one or more hydroxyls.  The most well known of these sugers is D-2-Deoxyribose, the carbohydrate found in DNA.

Q: What kinds of reactions can the hydroxyl groups on carbohydrates take place in easily?
A: 1.  Esterification with carboxylic acids and carboxylic acid derivatives.
2.  Phosphorylation in which the hydroxyl group attacks a phosphate.

Q: What is a glycoside?
A: A glycoside is a sugar with a glycosidic bond on its anomeric carbon.

Q: What is a glycosidic bond?
A: A glycosidic bond is the COC bond formed between the anomeric carbon of a sugar, the oxygen, and the carbon of the R group to which it is bound.  The R group can be a small moiety or an entire other sugar.

Q: What is an acetal?
A: An acetal is a molecule with an R group, 2 ether groups (-OR), and a hydrogen.

Q: What is a ketal?
A: A ketal is a molecule with two R groups and 2 ether groups (-OR)

Q: What is a disaccharide?
A: A disaccharide is the combination of two monosaccharides.  The disaccharide has a different name depending on what monosaccharides make it up.

Q: How do you appropriately name glycosidic bonds?
A: First, you name the monosaccharide on the left of the glycosidic bond.
Second, if an anomeric carbon is involved in the bond, state its alpha or beta configuration.  If both carbons in the glycosidic bond are anomeric, state the left anomeric carbon's configuration and then also state the right anomeric carbon's configuration.
Third, state what number carbon the left side molecule is linked by and then also state what number carbon the right side molecule is linked by.
Finally, name the sugar on the right side of the glycosidic bond.
For examples, look at the three disaccharides below.  Notice how only the left sided sugar is bound by the anomeric carbon, and so only the left side sugar's alpha or beta configuration is present.  Also notice the declaration of the carbon numbers and the monosaccharide names.

Q: What are three important disaccharides with which to be familiar?
A: 1.  Sucrose (glucose-a-1,2-fructose)
2.  Lactose (galactose-b-1,4-glucose)
3.  Maltose (glucose-a-1,4-glucose)

Q: What is a polysaccharide?
A: A polysaccharide is a long chain of monosaccharides linked together by glycosidic bonds.

Q: What is a heteropolysaccharide?
A: A heteropolysaccharide is a polysaccharide made up of more than one kind of monosaccharide.

Q: What is a homopolysaccharide?
A: A homopolysaccharide is a polysaccharide made up of only one kind of monosaccharide.

Q: What are the three most biologically important polysaccharides?
A: 1.  Cellulose
2.  Starch
3.  Glycogen

Q: What is cellulose and what is its characteristic bonding pattern?
A: Cellulose is the main structural component of plants.  Only animals with cellulase can digest cellulose.  Cellulose is composed of b-d-glucose molecules linked by b-1,4 glycosidic bonds.

Q: What is starch and what is its characteristic bonding pattern?
A: Starches are polysaccharides that are more digestible by humans.  There are two types of starch and they are both made of a-d-glucose monomers.  The first type of starch, amylose, is comprised of glucose monomers linked by a-1,4 bonds.  The second type of starch, amylopectin, is just like amylose, except it also has occasional branches of a-1,6 bonds.
The presence of starch can be tested for with iodine!

Q: What is B-amylase and A-amylase?
A: B-amylase and A-amylase are two different enzymes we have that help us break down starches.  B-amylase cleaves amylose at the non reducing end of the sugar (the end that is locked up in the glycosidic bond) to produce maltoses.  A-amylase just cleaves amylase randomly to yield shorter fragments.

Q: What is glycogen and what is its characteristic bond?
A: Glycogen is a carbohydrate storage unit in aminals.  It is similar to starch with it's a-1,4 bonded glucoses, but it has significantly more a-1,6 branches.  (For comparison, glycogen has a branch once every 10 molecules, amylopectin has one every 25 molecules.)

Q: What functional purpose does the branching of glycogen acheive?
A: 1.  Branching makes glycogen more soluble so more glucose in the same amount of space.
2.  Its branching pattern allows many enzymes to simultaneously cleave glucoses on different chains, which increases the speed at which glucose is liberated.

Q: What is glycogen phosphorylase?
A: Glycogen phosphorylase is an enzyme that cleaves glucose from a nonreducing end of a glycogen branching to produce a glucose-1-phosphate.  This enzyme plays an important role in metabolism.