3.13 Amino Acids, Proteins and DNA Flashcards
What are amino acids?
The monomers of proteins
20 naturally occurring alpha amino acids (alpha due to only 1 carbon in between the end groups)
Chiral molecule
What is an amino acid made up of?
Carbon bonded to
A carboxyl group
An amine group
A hydrogen
A variable R group (alkyl group)
In pH 1-6, acidic conditions what happens to the amino acid?
The amine group NH2 accepts a hydrogen ion (H+)
The base acts as a proton acceptor (protonated)
REMEMBER the positive charge on the nitrogen
In pH 8-14, basic conditions what happens to the amino acid?
The carboxyl group COOH loses a hydrogen ion (H+)
The acid acts as a proton donor (deprotonated)
REMEMBER the negative charge and the lone pair of electrons on the oxygen
In neutral conditions what happens to the amino acid?
It forms a zwitterion
The amine group accepts a H+
And
The carboxyl group loses a H+
Leaving a permanent positive and negative charge = neutral overall
How is a dipeptide formed?
2 amino acids join together in a condensation reaction with a water molecule being eliminated forming a peptide or amide bond
How can 2 different dipeptides form from the same 2 amino acids?
Each amino acid has an amino end and a carboxyl end and depending on which amino end reacts with which carboxyl end depends on the dipeptide that forms
What is the primary structure of a protein?
The sequence of amino acids joined together in a condensation reaction with peptide links
What is the secondary structure of a protein?
The 3D arrangement of amino acids in the polypeptide chain by coiling or folding held in place by hydrogen bonds between the amine group and carboxyl group on opposite monomers
The R groups point out
What is the tertiary structure of a protein?
The folding of the secondary structures to create a precise 3D structure
Held in place by peptide, hydrogen, di-sulfide bridges and ionic bonds
With van der waals
What are some features of wool?
A helical structure
Held together be hydrogen bonds
The hydrogen bonds can stretch so the fibre extends
Washing at high temperatures can permanently break the hydrogen bonds
After proteins are hydrolysed how can we separate the amino acids?
Using thin layer chromatography
Plate covered with silicon dioxide (white powder) or the stationary phase
Rf values are taken after ninhydrin is sprayed and heated for 10 minutes due to the amino acids being transparent- resulting in red or blue spots
General information about DNA?
Deoxyribonucleic acid
Monomer = nucleotide
Nucleotide is made up of: deoxyribose, phosphate group and a nitrogenous base
What are the bases, pairings and bonds of DNA?
Adenine = Thymine
Cytosine ≡ Guanine
AT - 2 hydrogen bonds
GC - 3 hydrogen bonds
How is the sugar phosphate backbone formed?
The OH group on the phosphate reacts with the OH group on the deoxyribose to eliminate a molecule of water
