1.4.1 Proteins Flashcards
Draw the general structure of an amino-acid
What is the only thing that differs in amino-acids
The R group
How many amino acids are there
20
How are dipeptides formed from amino-acids
- Condensation reaction between 2 amino acids
-
Peptide bond forms
*** Molecule of water released **
Where does a peptide bond form between 2 amino acids
The OH of the carboxyl group, and H from amine group
How are polypeptides formed
- Condensation reaction between many amino acids
- Many peptide bonds formed
- Many water molecules released
How are dipeptides broken apart
- Hydrolysis reaction
- Peptide bond broken
- Water molecule required
What is the primary structure of a protein
Order and sequence of amino acids, joined together by peptide bonds
What does the shape of a protein depend on
- What amino acids are present
- The order of amino acids
- So what bonds form between R groups
Describe the secondary structure of a protein
- Folding of polypeptide chain form alpha helixes or beta-pleated sheets
- Due to hydrogen bonding - between amine and carboxyl groups
Describe the tertiary structure of a protein
- Folding results in a complex shape
- Ionic bonds, disulphide bridges, hydrogen bonds, and London forces form between R groups of amino acids in different places
- Becomes 3D
Desribe the quaternary strucutre of a protein
Intermolecular forces between R groups holds 2 or more polypeptide chains together
Describe a functional protein
- 2 or more polypeptide chains and other molelcules (prosthetic groups)
- Held together by intermolecular forces
- Carries out a specific function
Describe the two types of proteins
- Globular - enzymes and hormones - have a specific shape for binding
- Fibrous - keratin (nails + hair) - structural
Describe the test for proteins
- Grind/crush sample, then add water to form solution
- Add biuret solution
- If positive will turn purple
- If negative will stary pale blue
