Carbohydrates Flashcards
(24 cards)
What are macromolecules?
Large molecules containing 1000+ atoms (high molecular mass)
What is a monosaccharide?
Single sugar monomer
(all are reducing sugars)
What is a disaccharide?
A sugar formed from TWO monosaccharides joined by glycosidic bond in a condensation reaction
What is a polysaccharide?
A polymer formed by MANY monosaccharides joined by glycosidic bond in a condensation reaction
What are 3 examples of disaccharides?
Maltose
Sucrose
Lactose
What are 3 examples of polysaccharides?
Cellulose
Starch
Glycogen
What are 3 examples of monosaccharides?
Glucose
Galactose
Fructose
What are the two isomers of glucose?
Alpha glucose
Beta glucose
Which two monosaccharides make maltose?
Glucose and Glucose
What two monosaccharides make sucrose?
Glucose and Fructose
What two monosaccharides make lactose?
Glucose and Galactose
What is the main function of Starch?
Energy store in plant cells
What is the main function of Glycogen?
Energy store in animal cells
(stores glucose)
What is the main function of Cellulose?
Provides strength and structural support to plant/algal cell walls
What is amylose and amylopectin?
The two polysaccharides which make up starch
- Amylose is a long unbranched chain of aglucose joined by 1,4 glycosidic bonds so it is coiled and compact (storing lots of energy), several thousands
- Amylopectin is branched, made of aglucose joined by 1,4 and 1,6 glycosidic bonds and due to many side branches, can be acted on by many enzymes and broken down to release energy, more complex, 50,000 molecules
What is the test for starch? (SIMPLE)
Add iodine and shake/stir
Orange/brown sugar= Blue/black
Describe STARCH
Energy store in plant cells - made of a-glucose
Can be amylose 1,4 glycosidic bonds (unbranched) OR can be amylopectin 1,4 and 1,6 glycosidic bonds (branched)
Helical - compact for storage in cells
Large and insoluble - can’t leave cell and won’t affect water potential
Insoluble - no osmotic effect
Describe GLYCOGEN
Energy store in animal cells - made of a-glucose joined by 1,4 glycosidic bonds AND 1,6 glycosidic bonds (highly branched)
Large and insoluble - can’t leave cell
Branched - more ends for faster hydrolysis
Insoluble in water
Branched and compact to fit more molecules in smaller area
Describe CELLULOSE
Provides strength and structural support to a plant - made of b-glucose joined by ONLY 1,4 glycosidic bonds so straight and unbranched
Chains linked in parallel by H bonds forming microfibrils
H bonds strong in high numbers
What is amylose?
An unbranched chain of glucose molecules joined by 1,4 glycosidic bonds
As a result amylose is coiled, thus a very compact molecule storing a lot of energy
What is amyloceptin?
Branched and made up of glucose molecules joined by 1,4 AND 1,6 glycosidic bonds
Due to many side branches, these can be acted on by enzymes, thus broken down to release energy
How do we test for reducing sugars?
Benedict’s reagent (alkaline solution of copper sulfate)
Add to food sample (must be liquid form)
Add Benedict’s reagent
Heat in water bath for 5 minutes
Brick red
What are common reducing sugars?
All monosaccharides and some disaccharides (e.g maltose) so therefore they are sugars that can donate an electron to the Benedict’s reagent
How do we test for non-reducing sugars?
Benedict’s test is altered
Do original test and if it stays blue, reducing sugar isn’t present
Another food sample taken and add dilute hydrochloric acid, and place in water bath for 5 minutes. Dilute HCl will hydrolyse disaccharides and polysaccharides into monosaccharides.
Then add some sodium hydrogencarbonate to neutralise the test tube. pH paper used to check solution is neutralised.
Now solution can be retested by adding Benedict’s reagent to solution and water bath
Brick red
