Biological Molecules

Carbohydrates, Lipids, Proteins, Food Tests, Enzymes and Enzyme Action

What is a polymer?

A long chain made from smaller repeating units called monomers

What is the opposite of hydrolysis?

A condensation reaction

What is a condensation reaction?

The reaction that joins two monomers together. It occurs every time a new-sub unit is added to a polymer

What extra molecule is produced in a condensation reaction?

Water

What is hydrolysis?

When polymers are broken down by the addition of water

What are the monomers that make up carbohydrates?

Monosaccharides

What is the general formula for a monosaccharide?

(CH₂O)_n

What do you call two bonded monosaccharides?

Disaccharide

What do you call more than two bonded monosaccharides?

Polysaccharide

What is a polysaccharide?

More than two bonded monosaccharides

What is a disaccharide?

Two bonded monosaccharides

What does glucose look like? Alpha and beta

What is the difference between alpha and beta glucose?

In alpha, the OH of carbon 1 is on the bottom, whilst in beta, OH of carbon 1 is on the top

What are 3 monosaccharides?

Alpha glucose

Beta glucose

Beta ribose

What is the bond form between two monosaccharides called?

Glycosidic bond

What does a glycosidic bond look like?

C - O - C

What are 3 disaccharides?

Sucrose

Lactose

Maltose

What monosaccharides make up sucrose?

Glucose and fructose

Where is sucrose produced?

Sugar cane and beet

What do glucose and fructose make?

Sucrose

What do glucose and galactose make?

Lactose

Where is lactose produced?

Mammalian milk

What monosaccharides make up lactose?

Glucose and galactose

What monosaccharides make up maltose?

Alpha glucose and alpha glucose

Where is maltose produced?

Germinating seeds

What do two alpha glucoses make?

Maltose

What are 3 polysaccharides?

Starch

Cellulose

Glycogen

What is starch used for?

Storage of glucose in plants

What are 3 features of starch?

Compact

Insoluble

Large

How does being compact help starch function?

Many glucose molecules can be stored in a small space

How does being insoluble help starch function?

It doesn’t affect the osmotic balance of cells

How does being a large molecule help starch function?

It can’t move out of cells

What two things is starch made of?

Amylose

Amylopectin

What type of glucose molecules is amylopectin made of

Alpha-glucose

What bonds are found in amylopectin?

Alpha 1-4 glycosidic bonds

with alpha 1-6 branches

Is amylopectin branched? How does that affect it?

Highly branched

There are more branch ends, which means it has a higher surface area, so can be hydrolysed more quickly

Is starch made mostly of amylopectin or amylose?

Amylopectin

Is amylose branched? How does this affect it?

Unbranched

Few branch ends so it is good for storing glucose

What type of molecule is amylose made of?

Alpha-glucose

What bonds are found in amylose?

Alpha 1-4 glycosidic bonds

What is amylose’s structure like? How does this help?

Alpha helix structure

Highly compact so good for storing glucose

What is the function of cellulose?

A structural component in plant cell walls

Is cellulose branched?

Unbranched/Straight

What molecule is cellulose made of?

Beta-glucose

What bonds are in cellulose?

Beta 1-4 glycosidic bonds

What is special about the glucose molecules in cellulose?

Alternate glucose molecules are inverted

What bonds are formed between chains of cellulose molecules?

Hydrogen bonds

What are lots of cellulose chains called?

Microfibrils

What are two features of cellulose?

Very strong

Fully permeable

Why is cellulose strong?

It is made of thousands of chains (and microfibrils) linked together

What does the permeability of cellulose allow?

The movement of substances to and from the membrane

What is the function of glycogen?

Storage of glucose in humans

Is glycogen branched?

Yes, highly branched

What molecules make up starch?

Alpha-glcuose

What bonds are in glycogen?

Alpha 1-4 glycosidic bonds

with alpha 1-6 branches

What elements are in lipids?

Carbon
Hydrogen
Oxygen

What are the 3 types of lipids?

Triglycerides
Phospholipids
Steroids

What make up steroids?

Four fused rings

What makes up triglycerides?

3 fatty acids
1 glycerol

What makes up phospholipids?

2 fatty acids
1 glycerol
1 phosphate group

What are the 3 parts of a fatty acid?

Carboxylic acid group (COOH)
Long hydrocarbon chain
Methyl group (CH3)

Depending on the bonds inside them, what 3 things can fatty acids be?

Saturated (no double bonds between carbons)
Monounsaturated (one double bond between carbons)
Unsaturated (multiple double bonds between carbons)

What state is a saturated fatty acid at room temp?

Solid

What state is an unsaturated fatty acid at room temp?

Liquid

How do fatty acids bond to glycerol? (What reaction)

Condensation reactions

What is the bond between a fatty acid and a glycerol?

Ester bond

What two substances are common forms of triglycerides?

Oil
Fat

What are the 3 uses of triglycerides?

Provide energy
Insulation
Protection for organs

How much energy do triglycerides provide in comparison to carbohydrates/proteins?

Twice as much energy

Draw a glycerol molecule

Draw a saturated fatty acid

Draw an unsaturated fatty acid

What is produced when a triglyceride is formed?

3 water molecules (from the condensation reactions)

Draw a triglyceride - you can simplify it a bit

What are phospholipids also known as?

Diglycerides

Draw a phospholipid - you can simplify it

What is the most important property of phospholipids?

They are polar

What does polar mean?

The distribution of charge across the molecule is uneven, so one end is slightly positive, while the other is slightly negative

What part of a phospholipid is the head?

The phosphate group

Which part of a phospholipid is the tail?

The fatty acids

Which part of a phospholipid is hydrophilic?

The head / The phosphate group

Which part of a phospholipid is hydrophobic?

The tails / The fatty acids

What is the chemical formula of the phosphate group?

PO4-

What can phospholipids form when in water?

Micelles (these little sphere things)
Phospholipid bilayers

Name 4 features of triglycerides

High ratio of C-H bonds to carbon atoms
Low mass to energy ratio
Insoluble in water
Release energy when oxidised

How does a high ratio of C-H bonds help in trigylcerides?

They store energy, making triglycerides good energy sources

How does a low mass to energy ratio help in triglycerides?

Lots of energy can be stored in small spaces
There is less mass that animals need to carry around

Why are triglycerides insoluble in water? (As in, how does this benefit them?)

So they don’t affect the water potential in cells

What are 3 features of phospholipids?

Polar
Have hydrophilic phosphate ‘heads’
Form glycolipids

What are glycolipids important for?

Cell recognition

What are 6 functions of lipids?

Protection of vital organs
Insulation of the body
Source of energy
Component of cell-surface membranes
Form the myelin sheath
Prevent evaporation in plants and animals

What are the monomers in proteins?

Amino acids

How many different amino acids are there?

20

What are amino acids coded by?

DNA

Draw an amino acid

What are the 2 groups all amino acids have?

Amine group
Carboxyl group

What reaction bonds amino acids together?

Condensation reactions

What is the bond formed between amino acids?

Peptide bond

What are two bonded amino acids called?

Dipeptide

What are more than two bonded amino acids called?

Polypeptide