Proteins Flashcards
What structure defines the three-dimensional shape of a protein?
The tertiary structure
What are essential amino acids? Give an example
Amino acids that cannot be synthesised by animals and are sourced directly from diet
Example: histamine
How many non-essential amino acids do humans produce? Give an example
11 out of 20 amino acids
Example: alanine
How are dipeptides produced?
When a carboxyl group of one amino acid reacts in a condensation polymerisation reaction with an amino group of another amino acid, forming a peptide link with excess water being produced
What does a primary structure of proteins involve?
The order of amino acids in a polypeptide chain
What are the two folded arrangements in the Secondary structure of proteins?
Alpha-helices and Beta-pleated sheets
What type of bonding occurs between the four different structures of proteins?
Primary - covalent bonding
Secondary - hydrogen bonding
Tertiary - hydrogen bonding, ionic bonding and disulphide bridges
Quaternary - hydrogen bonding, ionic bonding and disulphide bridges
Where do the hydrogen bonds attract in Secondary structures compared to Tertiary structure?
Secondary - the hydrogen bonds are within the same peptide chain
Tertiary - the hydrogen bond is between the R-groups
What is the difference between Fibrous and Globular proteins?
Fibrous proteins are long, narrow strands and are insoluble in water whereas globular proteins have compact round shapes and are usually soluble
State three functions of proteins in the body
1) Growth and repair of cells, 2) Acting as hormones, 3) Preventing infection as antibodies, 4) Forming muscle fibres, 5) Carrying atoms and small molecules around the body
What determines whether peptides formed are dipeptides, tripeptides etc.?
The number of amino acid residues per molecule
what are the nitrogen atoms from excess amino acids, broken down in the liver, removed from the body as?
CO(NH2)2
