Biological compounds 1.1

Name 4 key organic ions in living organisms

Magnesium ions

Iron ions

Calcium ions

Phosphate ions

What is the role of phosphate in living organisms?

Used to produce nucleotides

What is the role of magnesium in plants

It is used to produce chlorophyll

What is the role of calcium in living animals

It is used to strengthen tissues such as bones

What’s is the role of iron in animals

Iron is found in haemoglobin and is involved in the transport of oxygen

Why is waters high specific heat capacity important for organisms

Waters needs a large amount of heat to raise the temperature, enabling endothermic to resist fluctuations in core temperature and to maintain optimum enzyme activity

Why does water have high surface tension?

Due to ordered arrangement and cohesion at the surface of water

Why is waters high latent heat of vaporisation important for organisms

When water evaporates it has a cooling effect. This is important in homeostasis organisms can loose heat through sweating or panting

Why is the high surface tension of water important for organisms

-Enables the transport of water and nutrients through plant stems and small blood vessels in the body

-Allows small insects to walk on water

What is a monosaccharide?

Simple sugar

Give examples of monosaccharides

Alpha glucose

Beta glucose

fructose

Galactose

What is a disaccharide?

Molecule formed by the condensation of two monosaccharides forming a glycosidic bond

What are examples of disaccharides

Sucrose

maltose

lactose

What is the name of the bond formed when two monosaccharide react?

Glycosidic bonds

What is the reaction for lactose?

Glucose + galactose → lactose + water

What is the reaction for maltose?

Glucose + glucose → maltose + water

What is the reaction for sucrose

Glucose+ fructose → sucrose + water

What is a polysaccharide?

A polymer of monosaccharides formed by many condensation reactions

Give some examples of polysaccharides

Starch

cellulose

Glycogen

How is starch formed?

By two polymers of alpha glucose - amylose + amylopectin

What is the function of cellulose

Provides structural strength to cell wall

Describe the structure of amylose.

Alpha glucose- glycosidic bond + coiled+ unbranched

Describe the structure of amylopectin

Alpha 1,4 and alpha 1,6 glycosidic bond + branched

How is glycogen produced?

By many condensation reactions between alpha glucose

How does the structure of glycogen relate to its function?

It is highly branched

Easily hydrolysed to alpha glucose which can be transported to where ever the energy is needed

What is the function of starch and glycogen?

Insoluble store of glucose

Differentiate between monounsaturated and polyunsaturated fatty acids

Monounsaturated fatty acids contain only one double carbon bond

Polyunsaturated fatty acids have more than one double carbon bond

Why is water polar?

Because the oxygen end of the molecule has a negative charge and the hydrogen atoms have a positive charge.

The uneven distribution of charge is called a dipole

what is a metabolite?

A molecule formed or used in metabolic reactions

Describe hydrogen bonding between water molecules

When two molecule are in close contact the opposing charges forming a hydrogen bond.

The attraction between water molecules is called cohesion

Explain how a triglyceride is formed

One molecule of glycerol forms ester bonds with three fatty acids via condensation reactions

What are properties of triglycerides

Energy store -

Protection- fats often stored around delicate organs

Thermal insulator- when stored under skin acts as thermal insulator which reduces heat loss

What is a phospholipid?

A typed of lipid formed by condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group

Describe the positive result of an emulsion test

White cloudy emulsion forms

Define a protein

Proteins are polymers made of the monomer animo acids

How are polypeptides formed

Many amino acid monomers joined together in condensation reactions forming peptide bonds

Describe the general structure of an amino acid

What is the primary structure of a protein?

The individual sequence of amino acid in a polypeptide chain

Describe the secondary structure of a protein

The sequence of amino acids cause parts of a protein molecule to bend into alpha helix or fold into beta pleated sheets

Describe the tertiary structure of protein

The further folding of the secondary structure to form a unique 3D shape. Held in place by ionic Hydrogen and disulphide bonds

Describe the quaternary structure of a protein

Interactions of more than one polypeptide chain

May involve the addition of prosthetic groups

Describe how the structure of fibrous proteins relates to their function

-Long polypeptide chains folded parallel

-Little tertiary structure aside from cross links for strength

-This makes them insoluble and good for structural roles

Describe how the structure of globular proteins relates to their function

Spherical compact highly folded with complex tertiary/ quaternary structures

Hydrophilic R group table outwards

hydrophobic R group faced inwards

Name the food test used to identify to identify proteins

Biuret test

What is the difference between reducing and non reducing sugar?

A reducing sugar has a free aldehyde or ketone functional group so can act as a reducing agent

A non reducing sugar doesn’t have a free aldehyde or ketone functional group so it cannot act as a reducing agent

Describe the positive result for reducing sugars

Colour change from green to yellow to brown to orange to brick red

Describe the positive result for non reducing sugars

Colour change from green to yellow to orange brown to brick red

Describe the result of a positive buiret test

pale blue to purple

Describe the iodine potassium iodine test for starch

Add iodine KL solution

Colour change from orange to blue black in the presence of starch

What is meant by a low density lipoprotein?

-A combination of triglycerides from saturated fats and protein

-Blocks receptor sites reducing cholesterol absorption

-“bad” lipoproteins

How do LDLs contribute to the risk of cardiovascular disease?

High blood cholesterol level caused by LDLs leads formation of atherosclerosis plaques

How is cellulose formed?

By many condensation reactions joining beta glucose by 1,4 glycosidic bonds

Relate the structure of phospholipids to their functions

Glycerol backbone attached to two hydrophobic fatty acid tails and one hydrophilic polar phosphate head

Forms phospholipid bilayer in water-component of cell membrane

Tails are outward- waterproofing

Describe the structure of cellulose

Long straight chains lie parallel together by many hydrogen bonds. This is a fibril