Tutorial - Week 7 - Carbohydrates and revision Flashcards
Key concept: Become familiar with the structure, function and nomenclature of carbohydrates (5 points)
- Ketoses vs aldoses
- L- & D monosaccharides (D-form is predominant)
- Cyclic structure of monosaccharides
- Epimers, mutarotation, anomeric forms
- Reducing sugars
Key concept: Recognise monosaccharides
Key concept: Distinguish monosaccharide isomers
Key concept: Recognise a glycosidic linkage
Key concept: Distinguish polysaccharides (energy storage vs structure)
Key concept: Functions of carbohydrate conjugates
What are the most abundant biomolecules on earth?
What percentage of human food does it represent?
Carbohydrates
50-60%
What do all carbohydrates contain and what is the empirical formula for most of them?
Carbon, Hydrogen and Oxygen and most have the empirical formula (CH 2 O)n
T/F: Some Carbohydrates also have some Nitrogen and Sulfur and Phosphorus
True
General name of carbohydrates normally ends in…? Examples?
–ose (e.g. glucose, sucrose, fructose)
Major functions of carbohydrates?
- Rapid source of energy
- Energy storage in plants as starch and in mammals as glycogen
- Structural components (e.g. ribose in nucleic acids, cellulose in plant cell walls)
- Cell surface recognition (as part of proteoglycan & glycoproteins)
Simple carbohydrates are often referred to as…? What is special about them?
sugars and are fast digesting
Complex carbohydrates refer to…? Example?
sugar that take longer to digest (e.g. starch)
What are the four major groups they are divided into?
Sugars can also be called _________
Saccharide comes from the Greek word for ______
saccharides
sugar
List all the functions of carbohydrates
What carbohydrates are in these foods?
T/F: Carbohydrates are very important for cognitive function. Why?
True
The brain needs glucose as an energy source, we need a continuous supply of glucose for our brain to work
Label these by name and group
Monosaccharides:
- Have at least how many carbons?
- What does one of the carbons contain?
- What do all the other carbons contain?
- Depending on where the _______ group is located they are divided into?
- How do you distinguish an aldose?
- How do you distinguish a ketose?
- What about a certain group is also important for the structure, properties, and naming of monosaccharides?
- Give the names for the different number of carbons from 3-7
1 Have at least 3 carbons ((e.g. (CH 2 O)3)
- One of the carbons contains a carbonyl group (C=O)
- All the other carbons contain a –OH group
- Depending where the C=O group is located they are
divided into aldoses and ketoses - Aldoses have the C=O group in the C1, it is an aldehyde
- Ketoses have the C=O group in another C, it is a ketose
- Orientation of –OH groups is also important for the
structure, properties and naming of monosaccharides
8.
Different number of carbons:
* Triose (3C)
* Tetrose (4C)
* Pentose (5C)
* Hexose (6C)
* Heptose (7C
What do the D and L in the names of carbons mean?
D (Dextro means ‘on the right side’)
L (Levo means ‘on the left side’)
Name these (mainly focus on D and L)
L-monosaccharide meaning?
-OH group is on the left side
D-monosaccharide meaning?
-OH group is on the right side
Which sugars (D or L) are more predominant in nature?
D- sugars
Define chirality
Chirality, or handedness, means that an object or molecule cannot be superimposed on its mirror image by any translations or rotations. Achiral (not chiral) objects are those objects that are identical to their mirror image
How do you spot an aldose?
- Aldoses with C=O in C1
- They have different numbers of carbons
- Different number of chiral centres
What are D-isomers in aldoses?
-OH is on the right in the chiral centre
What is the anomeric carbon in aldoses?
The anomeric carbon is the carbon with the double bond to oxygen.
In aldoses, this is the carbon that is only attached to one other carbon
What are epimers?
2 isomers that differ
in configuration of
one carbon
E.g: one carbon might have the OH on the opposite side
What are 1 & 2, and 2 & 3 examples of?
Epimers
1& 2 are two isomers that differ in the configuration of one carbon and same as 2 & 3
How do you determine if a monosaccharide is a ketose?
Ketoses with C=O in another C (not in C1)
Also have a different number of chiral centres
What is a constitutional isomer?
Aldose & ketose with
the same number of Carbons
Common monosaccharides have a _________ structure
cyclic
What is the process to this aldose becoming cyclic?
What do these create?
Formation of cyclic hemiacetal from aldoses
How does D-glucose look when it transforms into it’s cyclic form? What are the variations and final forms?
What does these result in?
Formation of cyclic hemiketal from ketoses
What does the process look like of D-Fructose turning into a cyclic structure? Name the parts and draw the final outcomes