Chapter 10 Carbohydrates Flashcards
What are three things that saccharides do?
-Energy transport and storage
-Structural support e.g. bacterial cell walls, cellulose
-Information e.g. signals on proteins and membranes
What is an Oligosaccharides?
it is a sugar with several sugar units
What is a polysaccharides?
It consists of Glycans in long chains of 100s which include 1000s of sugars
How many carbons is the smallest monosaccharide composed of
3 carbons
How do you tell if the structure is a D side or a L side structure
If the OH is on the right its a D side
If the OH is on the left its a L side
And you look at the chiral carbon furthest from the double C=O bond to determine this
What is an enantiomers?
They are non-superimposable mirror images
What is a Diastereomers?
-Non mirror image stereoisomers
What is a Epimers?
-Diastereomers that differ in configuration at 1C
What does a Aldehyde sugar look like?
It has a carbon double bonded to O and the same carbon single bonded to H
What does a Ketone sugar look like?
It has a carbon double bonded to O and a CH3Osingle bonded to the same carbon as well
What are the Aldoses derived from ?
D-glyceraldhyde
What are Ketoses derived from ?
Dihydroxyacetone
At which end does the carbon numbering begin from ?
It begins from the end of the molecule nearest the carbonyl carbon
An Aldehyde can react with alcohol to form what? and what happens if you react with second alcohol
A hemiacetal is formed with one and if second is added an Acetal is formed
A ketone can react with alcohol to form what? and what happens if you react with second alcohol?
A hemiketal is formed with one and if second is added a Ketal is formed
What is the ring formed by glucose in a intramolecular hemiacetal called?
Its a six carbon ring called pyranose
What is the ring formed by ketohexose fructose in a intramolecular hemiketal called
Its a five carbon ring called furanose
What is an anomer?
Its another diastereoisomeric form that is made from the formation of a cyclic hemiacetal
At the alpha form of the ring where is the OH at C-1
It is below the plane of the ring
At the beta form of the ring where is the Oh at C-1
It is above the plane of the ring
What is an anomeric form ?
The furanose form of fructose can exist in anomeric and this is when alpha and beta forms refer to the orientation of the OH at C-2
How many types of conformation can a pyranose ring adopt and what are they called?
-There are two conformations and they are called boat and chair
In the chair form, how many orientations of OH on the carbon ring atoms are there and what are they called?
there are 2 and they are called axial and equatorial
A solution of glucose contains approximately _________ alpha anomer,__________ Beta anomer, and ________ of the open-chain form.
One third, two third, <1%
What are sugars called that react with oxidizing agents and what are sugars called that aren’t reacting with oxidizing agents?
Reducing sugars, and nonreducing sugars
What is an O-glycosidic bond and what is the product of this bond called
This is a bond formed between the anomeric carbon atom of glucose and a hydroxyl group of another molecule and the product is called glycoside.
What is a N-glycosidic bond?
A bond formed between the anomeric carbon atom of glucose and an amine
Oligosaccharides contain _____or more _________________ linked by ____________bonds
2,monosaccharides, O-glycosidic bonds
The substrates for glycosyltransferases area activated by attachment to____________________
uridine diphosphate
Enzymes on the outer surface of intestinal epithelium cleave common _______________
disaccharides
Sucrase cleaves___________, lactase cleaves ___________ , Maltase cleaves__________
Sucrose, Lactose, Maltose
What is it called if all the monosaccharides in the polysaccharide are the same ?
It is called a homopolymer
Most glucose units in glycogen are linked by __________________, with branches formed by _______________every ___________ glucose units
alpha-1 4-glycosidic bonds, alpha-1 6-glycosidic bonds ,12
In plants glucose is stored as what and how many forms are there?
starch and there are 2 forms
What is an Amylose?
It is a linear polymer of glucose units linked by alpha-1,4-glycosidic bonds
What is an Amylopectin?
It is a branched polymer with an alpha-1,6-glycosidic bond for every 30 alpha-1,4-glycosidic bonds
What type of structure does a IAmylose form ?
it forms a tightly coiled helical structure stabilized by H-bonding with 6 residues per turn
what is II Amylopectin?
Up to 200 amylose chains linked alpha 1–>6 at branch points. So just like iso-maltose
what does saliva and pancreas secrete and what does it randomly cleave ?
Alpha-amylase is secreted and Alpha-1,4bonds are cleaved randomly
Plants and bacteria secrete ________________ that removes __________units starting at the _____________end
Beta-amylase, Maltose, Non-reducing
What do debranching enzymes hydrolyze?
alpha-1,6 bonds
Cellulose is a homopolymer of glucose units linked by_______________________
Beta-1,4-glycocidic bonds
The beta linkage yields a __________________ capable of interacting with other cellulose molecules to form ______________
Straight chain, strong fibrils
The alpha linkages of starch and glycogen form _____________________ suitable for accessible storage
compact hollow cylinders
