2.4 proteins Flashcards
what is a monomer of a protein?
amino acid
draw an amino acid
see p. 155
polypeptide
long chains of covalently bonded amino acids joined together on the ribosome
how many amino acids are there?
20
peptide bond
a covalent bond that joins amino acids, at the carboxyl group of one amino acid to the amino group of the other amino acid, with the release of a molecule of water.
how can amino acids can be covalently joined together?
via condensation reaction, forming a dipeptide and water
how can polypeptide chains be broken?
via hydrolysis reactions
draw the formation of a peptide bond
see p. 155
primary structure
- determines the way the chain will fold
- Different amino acid sequences will fold into different configurations due to the chemical properties of the variable side chains
secondary structures (2 configurations)
- folding into repeat patterns (alpha-helix or beta-pleated sheet)
- By hydrogen bonds between amine and carboxyl groups
what happens if there is no secondary structure?
the polypeptide chain will form a random coil
tertiary structure
- Overall three-dimensional arrangement of a polypeptide
- Determined by interactions between variable side chains
quaternary structure
found in proteins that consist of more than one polypeptide chain linked together OR if they include inorganic prosthetic groups as part of their structure
An example of a protein with a quaternary structure
haemoglobin
- composed of four polypeptide chains (two alpha chains and two beta chains)
- It is also composed of iron-containing haeme groups (prosthetic groups responsible for binding oxygen)
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