Unit 2 - Proteins Flashcards
Where can proteins be found?
Meat, fish, eggs, wool, silk, muscle tissue, skin, hormones such as insulin, hair and nails.
What does the body use proteins for?
Needed in diet for: growth and repair of body tissue and biological processes.
What elements do proteins ALWAYS contain?
Hydrogen
Oxygen
Nitrogen
Carbon
What are proteins?
Natural polymers made of amino acids.
What functional groups are in amino acids?
An amino group (NH2)
A carboxyl group (-COOH)
What is an essential amino acid?
Amino acids that must be obtained through diet.
How do you test that a protein is present in human hair?
Heat a test tube. In the test tube is protein, soda lime and mineral wool. Put wet pH paper in the gas leaving the test tube, it should turn blue.
How are proteins made?
When amino acid units join together through the elimination of water in a condensation reaction. The amino and carboxylic groups join to form an amide link.
How can proteins be hydrolysed in a laboratory?
Using a suitable enzyme such as pepsin. Pepsin breaks down proteins to amino acids and is most active in acid conditions.
What are enzymes?
Protein molecules that act as biological catalysts.
How are spirals/helix and sheet structures made?
Hydrogen bonds forming between the N—H bonds and the C=O bonds in a protein. The helix then twists and folds into the characteristic shape of the protein.
Describe the structure of an aldehyde.
A carbonyl group (C=O) which is at the end of the carbon chain.
What do aldehydes’ names end in?
-al
Describe the structure of a ketone.
Carbonyl group (C=O) in the middle (ketOne oxygen in middle).
What do ketones’ names end in?
-one
What is the general formula of aldehydes?
Cn H2n O
What is the general formula of ketones?
Cn H2n O
What ketones CAN’T you get?
Methanone and ethanone.
What is organic oxidation?
An increase in the oxygen to hydrogen ratio.
What is the symbol that means that an oxidising agent has been added?
[O]
What do you use to indicate that an oxidation reaction occurs?
Oxidizing agents
What 3 oxidizing agents can be used to oxidize an aldehyde and distinguish it from a ketone?
Fehlings solution, Tollens reagent, Acidified potassium dichromate solution
What is the colour change of fehlings solution?
Blue to orange
What is the colour change of tollens reagent?
Silver mirror effect
What is the colour change or acidified potassium dichromate solution?
Orange to green
What does volatile mean?
Easily releases gaseous molecules.
How does volatility work?
Stronger intermolecular forces = less volatile
Do compounds with low boiling points have high or low volatility?
High
In general, with a formula mass under ___ are likely to be volatile.
300
Polar molecules will be soluble in water since polar substances dissolve in ___ solvents.
Polar (like dissolves like)
Non-polar molecules will dissolve in ____ solvents such as _____.
- non polar
- oil/butter
(like dissolves like)
If you want to keep flavour when cooking a polar molecule, what should you cook it in?
Non-polar oil/butter.
(Non-polar molecules should be cooked in polar and water)
How does denaturing work?
Chains of proteins are held together in a particular shape by hydrogen bonds. The heat breaks the hydrogen bonds and the protein loses it’s shape.
What temperature will proteins normally denature at?
Around 60 degrees celsius.
What is the ‘“lock and key theory’?
Enzyme catalyse specific reactions in the body. Substrates go into the active site and take out products.
What happens when enzymes are heated?
The substrate molecule becomes denatured and is no longer suitable for the specific reaction, thus won’t work efficiently.
What is a primary alcohol?
1 C attached to the C—OH.
What is a secondary alcohol?
2 C attached to the C—OH.
What is a tertiary alcohol?
3 C attached to the C—OH.
What do you put in the name of an alcohol with 2 hydroxyl groups?
-diol
(3 = triol)
What is the colour change of hot copper (II) oxide?
Black to brown.
What oxidising agents can be used to oxidise a secondary alcohol?
Hot copper (II) oxide and Acidified potassium dichromate solution.
What is the process of the oxidation of a primary alcohol?
Primary alcohol ➡️ Aldehyde ➡️ Carboxylic acid
What oxidising agents are used for 1st step oxidation of a primary alcohol?
Hot copper (II) oxide or acidified potassium dichromate solution.
What oxidising agents are used for 2nd step oxidation of a primary alcohol?
Acidified potassium dichromate solution, fehlings solution or tollen’s reagent.
What is the process of the oxidation of a secondary alcohol?
Secondary alcohol ➡️ Ketone ➡️ ❌
Can you oxidise an tertiary alcohol?
No
Many foods are packaged in an __ atmosphere of ____ ____ to prevent ___.
- Inert
- Nitrogen gas
- Oxidation
What’s an antioxidant?
A compound that easily oxidises itself so that it protects other compounds from oxidation.
