Lecture 1 Flashcards
Give examples of macromolecules
lipids, carbohydrates, nucleic acids and proteins
What are structural proteins
-they provided mechanical support to cells and tissues e.g. collagen and elastin form tendons and ligaments
What are motor proteins
-they generate movement in cells and tissues eg. myosin in skeletal muscle cells provide the motive force for humans to move
What are signal proteins
-they carry extracellular signals from cell to cell
e.g. many of the hormone and growth factors that coordinate physiological functions in animals are protein e.g. insulin
What are transport proteins
-they carry small molecules or ions
e.g. in the bloodstream serum albumin carries iron
-many proteins embedded in cell membranes transport ions or small molecules across the membrane
What are gene regulatory proteins
-they bind to DNA to switch genes on or off
-the lactose repressor in bacteria silences the genes for enzymes that degrade the sugar lactose
What are receptor proteins
-they detect signals and transmit them to the cells response machinery
e.g. rhodopsin in the retina detects light: the acetylcholine receptor in the membrane of a muscle cell is activated by acetylcholine released from a nerve ending
What are special purpose proteins
-they are highly variable
e.g. organisms make many proteins with highly specialised properties
-these molecules illustrate the amazing range of functions that proteins can perform
What are proteins made out of?
-amino acids
Describe the structure of an amino acid?
-amino acids are linked end to end by covalent bonds in linear chains
What is a polypeptide?
-an amino acid chain
What is the structure of a polypeptide?
-polypeptides are folded into specific 3D shapes
What is formed when one more more polypeptides fold together?
-a protein is formed
What can a primary structure be described as?
a linear amino acid sequence
What can a secondary structure be described as?
-a polypeptide folds into regular shapes, different secondary structures can pack together to form domains
What can a tertiary structure be described as?
-the arrangement of one / multiple domains
-this results in a 3D structure
What can a quaternary structure be described as?
-the arrangement of multiple polypeptides
-this results in a protein complex with multiple subunits
What complexes are in an amino acid?
-the amino group (NH2)
-the alpha carbon
-the carboxyl group
-the side chain(R)
What is a zwitterion?
-an amino acid is a Zwitterion at pH7
-it has both positive and negative charges
Are amino acids chiral or achiral?
-amino acids are chiral, thus their image cannot be superimposed
(except glycine - as the sidechain of glycine is H)
Where are L amino acids found?
-L amino acids are found in proteins, in nature
What are examples of small and simple amino acids
-Glycine (Gly, G) and Alanine (Ala, A)
What are examples of amino acids with bulky, hydrophobic side chain?
-Valine (Val, V), Leucine (Leu, L), Isoleucine (Ile, I) and Methionine (Met, M)
-as these amino acids are hydrophobic they tend to be buried ‘inside’ the protein
Describe the amino acid Cysteine
-(Cys, C)
-contains a thiol (-SH) group which allows it to form a disulphide bond
