Carbohydrates Flashcards
What are carbohydrates? What does the name carbohydrate mean?
Molecules that only contain the elements carbon, hydrogen and water. Carbohydrate literally means ‘hydrated carbon’
What are carbohydrates also known as? What is a single unit of this called?
Also known as saccharides or sugar. A single sugar unit is known as a monosaccharide, e.g. fructose and glucose.
What is it called when these units link together?
When two monosaccharides link together they form a disaccharide. When two or more monosaccharides are linked they form a polymer called a polysaccharide, e.g. glycogen and cellulose.
What is the chemical formula for glucose?
C6H12O6
Is this α-glucose or β-glucose?
What is the difference between α-glucose and β-glucose?
β-glucose
The difference between α-glucose and β-glucose is the location of the -OH group of the first carbon (the carbond that is furthest right)
In α-glucose it is located beneatht the first carbon as seen here:
What are the properties of glucose?
Are polar and soluble and water due to the hydrogen bonds that form between the hydroxyl groups and water molecules.
This solubility in water is important, because it means glucose is dissolved in the cytosol of the cell.
What is a condensation reaction and how does this occur in glucose?
Condensation reaction - a reaction where water is released.
When to α-glucose molcules are side by side, two hydroxyl groups interact. New bonds are broken and new bonds reformed in different places, producing new molecules.
Which carbonds does this occur on and what name is given to the bond?
Glycosidic bond on the carbon 1 and 4 of two glucose molecules.
Water is released in the process of making this molecule.
What are the two types of starch and what are its uses for plants?
Used to store glucose
Amylose and amylopectin
What are the differences between amylose and amylopectin?
Amylose is formed by α-glucose molecules joined together by 1-4 glycosidic bonds. Twists to form a helix, stabalised by h-bonds, makes molecules compact and much less soluble than glucose itself.
Amylopectin is also formed by 1-4 glycosidic bonds, however some glycosidic bonds occur between 1 and 6 on glucose molecules, this means that amylopectin has a branched structure.
How do organisms release glucose from carbohydrate stores?
Hydrolysis, requires addition of water
catalysed by enzymes
What is the structure of cellulose?
β-glucose molecules are unable to join together in the same way that alpha glucose molecules can.
Hydroxyl groups on carbon 1 and 4 are too far apart to react.
The only way for them to join together and form a polymer is if alternate beta glucose molecules are turned upside down.
How are fibres formed?
Cellulodr molecules make hydrogen bonds with each other forming microfibrils.
These microfibrils join together to form macrofibrils which combine to produce fibres.
