W3 - Monosaccharides (lecture) Flashcards
What is the empirical formula of a carbohydrate?
[CH2O]n
What are polyhydroxy aldehydes/ketones referred to?
Aldose sugars and ketose sugars
Glucose is the most abundant carbohydrate absorbed in the bloodstream even though starch is the most ingested, why is this?
Due to digestion, breakdown of starch
Glucose is a major fuel for all tissues but where is it the only fuel molecule?
Brain and RBCs
What is it that can cause diabetes, galactosaemia, fructose/lactose intolerances?
Abnormal carbohydrate metabolism
Give 4 examples of monosaccharides
Glucose, fructose, galactose, ribose
What molecules make up maltose, sucrose and lactose (disaccharides)?
Maltose - glucose x2, Sucrose - glucose + fructose, Lactose - glucose + galactose
How many monosaccharide units are in an oligosaccharide and polysaccharide?
O - 3-10, P - 11 and up
Are cellulose or glycogen/starch linear/branched?
Cellulose - linear, glycogen/starch - branched
Simple polysaccharides such as aldose/ketose sugars can act as what in reactions?
Alcohols and aldehyde/ketone
What is the minimum number of Cs a monosaccharide can have (no max)?
3
What are all aldose sugars derived from?
Glyceraldehyde
When drawing a fisher projection of glyceraldehyde does the CHO or the CH2OH group go at the top or the bottom?
CHO - top, CH2OH - bottom
Which series of glyceraldehyde is encountered in human metabolism?
D- series ONLY
What is the general rule for calculating the number of isomers for a monosaccharide when you know the number of Cs? Use glucose as an example
2 to the power of number of asymmetric Cs, Glucose = 2^4 = 16
Glucose contains OH groups and is therefore water soluble, it can also have amine groups on C2, what is it called when this happens?
Glucosamine
When a hydroxyl on glucose is replaced with a H what type of sugars does this produce?
Deoxysugars
When glucose acts as an alcohol reacting with an acid/phosphoric or sulfuric acid what does it produce?
Acid - ester, phosphoric/sulfuric acid - phosphates + sulfates
Can the aldehyde group on glucose be oxidised/reduced or both?
Both
What type of rings form when pentoses and hexoses cyclise?
Pent - furanoses, Hex - pyranoses
D- glucose is the open chain form, what are the two cyclic forms called?
Alpha/beta-D-Glucopyranose
D-Fructose is the open chain form, what are the two cyclic forms called?
Alpha/beta-D-fructofuranose
Pyranose and furanose rings can be drawn in chair, envelope and boat form, what does this tell us about it’s structure?
The rings aren’t planar
What forms when glucose reacts with alcohols or amines?
Alcohols - glucosides with O-glycosidic bonds, Amines - Glucosamines with N-glycosidic bonds
Can glucose or glucosamine be readily oxidised?
Glucose
Phosphorylated sugars are key intermediates in energy generation and biosynthesis but why? (2 reasons)
-ve charge means they cannot cross membrane and they become more reactive in important pathways
