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Carbohydrates
The structure of Sugars
67
Biochemistry
Undergraduate 1
12/18/2012

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Term
What atoms do all carbohydrates contain?
Definition
Carbon, Hydrogen and Oxygen
Term
What atoms do some (but not all) carbohydrates contain?
Definition
Sulphur and Nitrogen
Term
Which groups define a carbohydrate?
Definition
A hydroxyl group AND either a ketone of aldehyde group
Term
What is the general formula for a carbohydrate?
Definition
(CH2O)n
Term
Which are the two most common carbohydrates?
Definition
Glyceraldehyde and Dihydroxyacetone
Term
What is a chirally active carbon?
Definition
A carbon atom with four different groups bonded to it
Term
How many sterioisomers can one chirally active carbon have?
Definition
Two (D and L)
Term
How do carboydrates form ring structures?
Definition
The aldehyde or ketone group combines with one of its many alcohol groups.
Term
What is the name given to a five carbon ring?
Definition
Furan
Term
What is the name given to a six carbon ring?
Definition
Pyran
Term
Pyranose sugars assume what 'visual' structure?
Definition
A Chair
Term
What orientation of atoms would result in a physical clash within the molecule?
Definition
If the axial atoms pointed in the same direction of the carbon atoms
Term
How many asymmetric carbons does glucose have?
Definition
Four
Term
Which isomer of glucose is naturally found in nature?
Definition
D-glucose
Term
Which asymmetric carbon in sugars determines the stereoisomerism of the sugar?
Definition
The asymmetric carbon furthest from the aldehyde/ketone group
Term
Why are sugars referred to as 'D' or 'L'?
Definition
In the direction to which the sugar rotates polarized light
Term
What does the 'D' in a D sugar stand for?
Definition
Dextrorotatory (Clockwise)
Term
What does the 'L' in a L sugar stand for?
Definition
Laevorotatory (Anticlockwise)
Term
What is an epimer?
Definition
Sugars that are isomers at more than one asymmetric carbon
Term
During the formation of a hemiacetal which carbon also becomes asymmetric?
Definition
C1
Term
What determines the formation of alpha and beta sugars?
Definition
The stereochemistry on C1 in comparison to C5
Term
What is an animer?
Definition
A sugar that has either an alpha or beta conformation
Term
What determines a beta anomer?
Definition
Same stereochemistry at C1 and C5
Term
What determines an alpha anomer?
Definition
Different sterochemistry at C1 and C5
Term
What determines a L-sugar?
Definition
Axial -OH groups
Term
What determines a D-sugar?
Definition
Axial Hydrogen groups
Term
What is a polysaccharide?
Definition
A polymer made of repeating sugar monomers
Term
What is an ogliosaccharide?
Definition
A polymer made of a small number (10-20) repeating sugar monomers
Term
What is the name given to the link between sugar monomers?
Definition
A glycosidic bond
Term
Glycosidic bonds can have different orientations. What are the different orientations?
Definition
Sticking down from the plane or equatorial on the plane
Term
What is the disaccharide generated from starch?
Definition
Maltose
Term
Which main monosaccharide in milk?
Definition
Lactose
Term
Which organism/s synthesise starch?
Definition
Plants AND Bacteria
Term
Which family of the animal kingdom synthesise glycogen?
Definition
Mammals
Term
What is the function of cellulose?
Definition
Maintaining structure in plant cell walls
Term
What organism/s synthesise cellulose?
Definition
Plants
Term
Which polysaccharide is present in bacteria cell walls?
Definition
Peptidoglycans
Term
What is a reducing sugar?
Definition
The sugar at the end of a polysaccharide that has it's aldehyde group exposed and is able to be opened to reduce its adjacent sugar
Term
What type of glycosidic bonds are present in glycogen
Definition
1,4 glycosdic bonds AND 1,6 glycosidic bonds
Term
What is a reducing sugar?
Definition
The sugar at the end of a polysaccharide that has it's aldehyde group incorporated into the glycosidic bond and therefore is unable to be open unless the adjacent sugar is reduced
Term
What causes the helical structure in glycogen and starch?
Definition
The 1,4 glycosidic bonds
Term
What is the advantage of glycogen and starch having a helical structure?
Definition
It makes the molecule more compact and therefore easier to store
Term
What is the advantage of glycogen being branched?
Definition
Lots of non-reducing sugars that can be forced open and hydrolysed to produce glucose more quickly
Term
What gives strength to cellulose fibres?
Definition
The -OH groups forming hydrogen bonds
Term
What causes cellulose to have a highly crystalline structure?
Definition
The interconnection of hydrogen bonds
Term
Which enzyme synthesises sugars?
Definition
Glycosyltransferase
Term
Which enzyme determines our blood group?
Definition
Glycosyltransferase
Term
Which glycosyltransferase/s creates blood group A?
Definition
GTA
Term
Which glycosyltransferase/s creates blood group B?
Definition
GTB
Term
Which glycosyltransferase/s creates blood group AB?
Definition
GTA AND GTB
Term
Which glycosyltransferase/s creates blood group O?
Definition
None, the glycosyltransferase is inactive
Term
Which sugar does GTA add?
Definition
GalNac
Term
Which sugar does GTB add?
Definition
Gal
Term
What factors contribute to the difference in blood groups?
Definition
Pathogens AND Parasites
Term
Which two key surface proteins are present on the influenza virus?
Definition
Hemagglutinnin AND Neuraminidase
Term
What does the hemagglutinnin receptor do?
Definition
Recognises the sugar sialic on the surface of target cells
Term
What does the neuraminidase receptor do?
Definition
Allows the release of the new virus by removing sialic acid
Term
What are glycoproteins?
Definition
A protein embedded in the plasma membrane that has a carbohydrate chain attached
Term
What are the two types of bacteria cell wall?
Definition
Gram-negative and Gram-positive
Term
What two monosaccharides make up a peptidoglycan?
Definition
N-Acetyl-B-D-Glucosamine (NAG) AND N-Acetyl-muramic acid (NAM)
Term
What is a tetrapeptide?
Definition
A chain of four amino acids
Term
Which amino acids are present in the tertapeptide of N-Acetyl-muramic acid (NAM)?
Definition
L-Alanine, D-Glutamic Acid, DAP (Diaminopimelic acid), D-Alanine
Term
What is the purpose of the tetrapeptide in peptidoglycan?
Definition
It forms cross links with other tertapeptides to give strength and flexibility to the bacterial cell wall
Term
Which enzyme forms the cross links in peptidoglycan?
Definition
Transpeptidase
Term
How does Penicillin destroy bacterial cell walls?
Definition
It inhibits transpeptidase, this prevents tetrapeptide crosslinks forming making the cell wall osmotically sensitive which allows cell lysis to occur
Term
Which bacterial cell wall contains more peptidoglycan?
Definition
Gram-positive cell walls
Term
Which bacterial cell wall contains less peptidoglycan?
Definition
Gram-negative cell walls
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