Proteins Flashcards
What is the structure of an amino acid?
Central carbon group connecting to R group, carboxyl group, amine group and an extra H
How many amino acids are in the human body?
- 8-10 of these are vital for life
All exactly the same apart from the R group
What is a dipeptide made of?
2 amino acids
What is a polypeptide made of?
Over 10 amino acids
What is a protein made out of?
Over 100 amino acids
How are proteins made?
-Protein synthesis in ribosome.
Hydroxyl from carboxylic acid group reacts with H in amine group of another amino acid
-Joined by a peptide bond, is a condensation reaction
What enzyme catalyses the formation of a polypeptide?
-Peptidyl transferase
What is the primary structure of a protein?
-Only peptide bonds
-End structure determined by amino acids and their sequence here
What is the secondary structure of a protein?
-O,H,N interact forming H bonds between NH and C=O groups
-Either a beta pleated sheet or alpha helix
What is the tertiary structure of a protein?
-Folding protein into its final 3D structure, determines its function
-Interactions between R-groups maintain tertiary structure, 4 types
- Disulphide bridges
- Ionic bonds
- Hydrogen bonds
- Hydrophobic+phillic interactions
What is a disulphide bridge?
Strong covalent bond ONLY between R-groups with SULPHUR(cysteines)
What are ionic bonds?
Between opposite charged R-groups, stronger than H bonds
What are hydrogen bonds?
Weak bond between two slightly charged molecules
What are hydrophobic+hydrophillic interactions?
Weak interactions between polar and non-polar R-groups
What is the quaternary structure of a protein?
NOT ALL PROTEINS HAVE IT as it only happens if the protein is made of MULTIPLE POLYPEPTIDE SUBUNITS)
-2 or more individual proteins called subunits interact
What are the properties of a fibrous protein
-Insoluble
-Strong
-Elongated filaments
-Flexible
What are the functions of fibrous proteins?
-Structure eg collagen in skin
-Protection eg keratin in skin
-Elasticity eg alveoli
-Contraction eg muscle
-Microtubules eg cilia
What are the properties of globular proteins?
-Soluble
-Spherical
-Tertiary structure, specific to other molecules
-pH/temp sensitive
-Hydrophilic on the outside
What are the functions of globular proteins?
-Hormone/receptors for cell signalling eg insulin
-Enzymes eg lipase lowers activation energy to digest lipids
-Haemoglobin
