Biological Molecules Flashcards
A disaccharide is formed when two monosaccharides bond together, by what reaction and what is the bond?
A condensation reaction occurs (water molecule eliminated) to form a glycosidic bond.
What is a long chain of monosaccharides called and how?
A polysaccharide which is formed by lots of condensation reactions, held together by glycosidic bonds.
What is a glycosidic bond?
A sugar bond
What is a hydrolysis reaction?
Using a molecule of water to break a chemical bond (opposite of a condensation reaction)
Why are carbohydrates/monosaccharides a good energy source?
- Contain carbon, hydrogen, and oxygen
- Large number of carbon-hydrogen bonds
- Monosaccharides are hydrates of carbon
What is the difference between alpha and beta glucose structure (hexose sugar)?
In alpha, the -OH on carbon 1 is below, but its above in beta.
ABBA
What makes maltose?
Two glucose monomers
What makes sucrose?
Glucose and fructose
What makes lactose?
Glucose and galactose
What is the molecular formula of glucose?
C6 H12 O6
Describe glycogen
- A polysaccharide made from a-glucose monomers
- Is branched with 1-4 and 1-6 glycosidic bonds
- Compact, dense and insoluble
in a spiral shape - An energy store and source in animal cells
What types of starch are there?
Amylopectin: 70-80%
Amylose: 20-30%
Describe amylopectin (starch)
- Polysaccharide of a-glucose monomers
- Is branched, therefore as it makes up around 80% of starch, starch is classed as branched
- Has 1-4 and 1-6 glycosidic bonds
- Compact with spiral shape
Describe amylose (starch)
- Polysaccharide of a-glucose monomers
- Unbranched
- 1-4 glycosidic bonds
- Compact with spiral shape
Describe cellulose
- Polysaccharide of b-glucose monomers
- Polymers joined by hydrogen bonds, creating bundles called fibrils.
- 1-4 glycosidic bonds
- Is linear and every other one is rotated 180º to prevent spiralling
What is the function of starch?
Energy store and source for plant cells
What is the function of cellulose?
Is a structural unit for plants within the cell wall.
What is ribose?
A pentose sugar that is involved in respiration as it makes up ATP
What is deoxyribose?
A pentose sugar that is a component of a DNA nucleotide monomer
Briefly explain how you would test for a reducing sugar
- Add an excess of Benedict’s solution to the sample
- Gently heat in a water bath at about 80℃ for 5 minutes
- A positive result would show a colour change from blue→ green, yellow, or brick-red depending on the concentration
Briefly explain how you would test for a NON-reducing sugar
- Add and equal volume of and acid (HCL) to the sample
- Heat at 80℃ where the acid will hydrolyse the disaccharide
- Leave to cool and slowly add an alkaline (sodium hydrogen carbonate) to neutralise the acid
- Add in Benedict’s solution and heat again
- Sugar is non-reducing if there is a blue to green, yellow, or red change.
What sugar is NOT a reducing sugar?
Sucrose
Why is it easier and faster to hydrolyse a carbohydrate that has branched glycosidic bond (1,4 and 1,6)?
There are more ends to cut off from.
Why is it useful for a molecule to be insoluble?
It won’t decrease the water concentration inside of the cell, so water activity does not occur through osmosis
What can we use to test for starch, and what is the colour change?
Iodine
Orange→ Black
What is a triglyceride?
-Macromolecule
-Lipid