Proteins Flashcards
What are amino acids
The building blocks from which proteins are formed
What functional groups do amino acids contain
Contain the amino/amine group(-NH2)
And the carboxyl group(-COOH)
What are proteins
Condensation polymers
They are made of amino acid molecules that are linked together by condensation reactions
What happens to amino acids when they undergo condensation reactions
The amine group of 1 amino acid and the carboxyl group of another join and water is eliminated (similar to esters)
What is the link that forms during condensation reactions called
Peptide/amide link (-CONH)
What are essential amino acids
Amino acids that the body cannot make. They have to be supplied by our diet.
What are enzymes
Biological catalysts
What is hydrolysis
The process of breaking proteins into amino acids
Describe the structure of proteins
Long chain molecules that form sheets, spirals and other complex shapes. These shapes give it a specific job.
What happens when a protein is heated
Intermolecular bonds are broken allowing the protein to change shape. This is called denaturing (- stops it from being able to do its job)
What functional groups do aldehydes contain
Carbonyl functional group (C=O) on the END of the carbon chain
(Name as u would an alkane but with an -al on the end i.e. Propanal)
What functional groups do ketones contain
Carbonyl group (C=O)
In the MIDDLE of the carbon chain
For ketones names end in -one (must include carbon number of carbonyl group i.e. Propan-2-one)
What are oxidation reactions
An carbon compounds it involves an increase in an increase in oxygen to hydrogen ratio (losing an H or gaining an O)
Describe the oxidising agent hot copper (II) oxide
> its weak
changes from black to brown
1• alcohol ~> aldehyde
2• alcohol ~> ketone
Describe the oxidising agent Acidified Dichromate (VI) solutions (K2Cr2O7)
> its strong
changes from orange to green
1• alcohol ~> aldehyde ~> carboxylic acid
2• alcohol ~> ketone
Describe the oxidising agent Tollens Reagent
> its strong
Colourless solution to silver mirror
1• alcohol ~> aldehyde ~> carboxylic acid
Describe the oxidising agent Fehlings solution
> its strong
Blue solution to brick red precipitate
1• alcohol ~> aldehyde ~> carboxylic acid
Why do foods spoil
They contain edible oils which can spoil after being exposed to air
(O2 from air causes food to oxidise - increasing O:H ratio
Give an example of what happens when a food spoils
When butter spoils its due to the formation of butanoic acid as the butter is hydrolysed - its said to be rancid
What do antioxidants do
They prevent foods from spoiling too quickly by stopping oxidation reactions from taking place
How do antioxidants do their job
They are reducing agents and cause other substances to be reduced whilst being oxidised themselves
What are essential oils
Hydrophobic liquids containing mixtures of volatile aroma compounds that evaporate easily giving distint fragrances
How are essential oils extracted
From plants via steam distillation
(Look at diagram in booklet)
What difficulty is faced when extracting essential oils
Obtaining the liquid before it evaporates
How do you identify terpenes
They are unsaturated compounds thay form by joining isoprene units (therefore contain 5 carbon atoms per unit = isoprenes)
What is ultraviolet radiation
A high energy form of light present in sunlight
What are free radicals
Free radicals are atoms and molecules that are highly reactive due to the presence of an unpaired electron
How do free radicals form
When strong covalent bonds are broken by UV light
What three steps are in a free radical chain reaction
Initiation
Propagation
Termination
What is initiation
UV light provides energy for the splitting of diatomic halogen molecule into reactive halogen atoms or free radicals
( Cl2(g) ~> Cl•(g) + •Cl(g) )
What is propagation
Free radicals collide with other species but the number of free radicals is maintained
( H2(g) + •Cl ~> H•(g) +HCl (g) )
( H•(g) + Cl2(g) ~> HCl(g) + Cl•(g) )
What is termination
Free radicals are used uo by collision with each other
( H•(g) + •Cl(g) ~> HCl(g)
( H•(g) + •H(g)
