Biological Molecules

What are the elements present in carbohydrates?

carbon, hydrogen, oxygen

What is the monomer for carbohydrates?

monosaccharides

What is the polymer for carbohydrates?

polysaccharides

What are the bonds in carbohydrates?

glycosidic

What is the test for sugars?

Benedicts

What do you add for a non-reducing sugar to the benedicts test?

hydrochloric acid - to hydrolyse the disaccharide

sodium hydrogencarbonate - to neutralise as benedict's needs neutral conditions 

What is maltose made of?

Glucose + glucose

What is sucrose made of?

Glucose + fructose

What is lactose made of?

Glucose + galactose

Name three disaccharides

maltose, sucrose, lactose

What is a reducing sugar?

possess a highly reactive unbonded functional group at their active centre

Are maltose, lactose and sucrose reducing or non-reducing?

maltose: reducing

lactose: reducing

sucrose: non-reducing

What does alpha DUDD and beta DUDU describe?

the positioning of the OH molecules around the ring starting with C4 and going to C1 

What type of glucose makes starch?

alpha glucose

What bonds are present in starch?

1-4 glycosidic bonds present, 1-6 when branched 

What forms of starch are there?

amylose and amylopectin

How is starch’s structure related to function?

• Insoluble - doesn't affect osmotic potential

• Large - doesn't diffuse out of cell 

• Compact - lots can be stored 

• Branched form has many ends so can be acted on by lots of enzymes at once - released fast 

What form of glucose makes glycogen?

alpha glucose

what bonds are in glycogen?

1-4 glycosidic bonds with 1-6 where branched 

Describe the structure of glycogen

Long chains of alpha glucose with branches 

How is glycogen’s structure related to function?

• Insoluble - doesn't affect osmotic potential of the cell 

• Large - doesn't diffuse out of cell 

• Compact - lots can be stored 

• Branched form has many ends so can be acted on by lots of enzymes at once and released fast – important because animals have a high metabolic rate 

What is the function of cellullose?

Makes plant cell walls and provides rigidity 

What type of glucose is cellulose made from?

beta glucose

What bonds does cellulose contain?

1-4 glycosidic bonds and hydrogen bonds 

Describe the structure of cellulose

Layers of beta glucose chains with hydrogen cross links between layers

How is the structure of cellulose related to its function?

• Straight unbranched chains - provide support and rigidity 

• Cross links - provide extra strength 

• Molecules are grouped into microfibrils and then fibres - provides even more strength 

What elements make up lipids?

carbon, hydrogen and oxygen 

What are triglycerides made from?

one molecule of glycerol and three fatty acids

what bonds are present in lipids?

ester bonds

What are saturated lipids?

don't contain any carbon carbon double bonds 

What are unsaturated lipids?

contain at least one carbon carbon double bond  

How is the structure of triglycerides related to function?

• High ratio of carbon hydrogen bonds to carbon atoms - good energy store 

• Low mass to energy ratio - good storage molecule 

• Large and non-polar so insoluble - don’t affect the osmotic/water potential of the cell 

• Release water when oxidised - provide a source of water for animals in dry environments (e.g. a camel) 

What is the structure of phospholipids?

Glycerol backbone with 2 fatty acids and a phosphate containing group

What is a polar molecule? (give an example)

a molecule that has a partial positive charge on one end and a partial negative charge on the other end - E.g. phospholipids

What is the function of phospholipids?

• Makes cell membranes as it forms a phospholipid bilayer 

• Can form glycolipids with carbohydrates which are important on the cell surface membrane for cell recognition  

What is the emulsion test?

• Shake with ethanol

• Add water and shake again  

• Cloudy white suspension indicates the presence of a lipid 

What does emulsion mean?

a mixture of two or more liquids that normally do not mix where tiny droplets of one liquid are scattered throughout the other 

What is the test for lipids?

the emulsion test