Monosacchrides and disacchrides Flashcards
What is a monosaccharide?
It contains a single monomer, e.g, glucose, fructose and galactose
What is a disaccharide?
It contains two monomers joined together, e.g, maltose (2 alpha glucose molecules), sucrose (glucose and fructose) and lactose (glucose and galactose)
What is a polysaccharide?
It contains many monomers joined together, e.g, starch, cellulose and glycogen (all made of glucose joined together)
What are the uses of carbohydrates?
They make up 10% of a cells organic matter and are an energy source for respiration. Starch (in plants) and glycogen (in animals) are energy stores and cellulose is used for structure in plant cell walls
What are the elements in a carbohydrate?
Carbon, hydrogen and oxygen
What is a triose monosaccharide?
It is a monosaccharide made of 3 carbon sugars and it’s biological importance is intermediate in respiration, e.g, triose phosphate
What is a pentose monosaccharide?
A monosaccharide made of 5 carbon sugars and it’s biological importance is in nucleic acids (DNA and RNA), e.g, ribose
What is a hexose monosaccharide?
A monosaccharide made of 6 carbon sugars and it’s biological importance is respiratory substrates and blood sugar, e.g, glucose
Why are hexose monosaccharides soluble in water?
They are polar as the hydroxyl (OH) groups are slightly positive, forming hydrogen bonds between the hydroxyl groups and water molecules. This is important and it allows glucose to dissolve in the cytoplasm and blood stream.
What are the two forms of glucose?
Alpha and beta glucose. In beta glucose, the OH is above carbon - 1
What does beta glucose form?
Only cellulose, allowing for a structural polysaccharide
What does alpha glucose form?
Other polysaccharides such as starch
What are the two ways glucose can be drawn?
In a ring or a chain
What is furanose?
A ring with 5 members?
What is pyranose?
A ring with 6 members
What are the properties of fructose?
It is sweeter than glucose and is found in fruit and sugar
What are the properties of galactose?
It is sweeter than fructose and is found in milk and dairy products
What is an isomer?
Molecules with the same chemical formula but have different molecular arrangements, such as alpha and beta glucose or fructose and galactose
How are monosaccharides joined together?
They are joined by a condensation reaction where water is removed from the bond
What is a glycosidic bond?
When two monosaccharides are joined together to form a disaccharide
What kind of bond is between 2 alpha glucose molecules?
An alpha 1,4 glycosidic bond
Where is maltose found?
It is found in germinating grains
Where is sucrose found?
It is found in fruit and cane sugar
Where is lactose found?
It is found in milk
How are carbohydrates broken down in digestion?
Larger molecules are broken down by enzymes breaking the glycosidic bond between the monosaccharides through hydrolysis which adds water to break them.
