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
Give examples of amino acids with aromatic (ring) side chain?
Phenylalanine (Phe, F), Tyrosine (Try, T) and Tryptophan (Trp, W)
Give examples of amino acids with polar side chain(s)
(amino acids with polar side chains contain a hydroxyl (OH) group)
e.g. Serine (Ser, S) and Threonine (Thr, T)
