Lecture 1

Question 1

Give examples of macromolecules

Answer 1

lipids, carbohydrates, nucleic acids and proteins

Question 2

What are structural proteins

Answer 2

-they provided mechanical support to cells and tissues e.g. collagen and elastin form tendons and ligaments

Question 3

What are motor proteins

Answer 3

-they generate movement in cells and tissues eg. myosin in skeletal muscle cells provide the motive force for humans to move

Question 4

What are signal proteins

Answer 4

-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

Question 5

What are transport proteins

Answer 5

-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

Question 6

What are gene regulatory proteins

Answer 6

-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

Question 7

What are receptor proteins

Answer 7

-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

Question 8

What are special purpose proteins

Answer 8

-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

Question 9

What are proteins made out of?

Answer 9

-amino acids

Question 10

Describe the structure of an amino acid?

Answer 10

-amino acids are linked end to end by covalent bonds in linear chains

Question 11

What is a polypeptide?

Answer 11

-an amino acid chain

Question 12

What is the structure of a polypeptide?

Answer 12

-polypeptides are folded into specific 3D shapes

Question 13

What is formed when one more more polypeptides fold together?

Answer 13

-a protein is formed

Question 14

What can a primary structure be described as?

Answer 14

a linear amino acid sequence

Question 15

What can a secondary structure be described as?

Answer 15

-a polypeptide folds into regular shapes, different secondary structures can pack together to form domains

Question 16

What can a tertiary structure be described as?

Answer 16

-the arrangement of one / multiple domains
-this results in a 3D structure

Question 17

What can a quaternary structure be described as?

Answer 17

-the arrangement of multiple polypeptides
-this results in a protein complex with multiple subunits

Question 18

What complexes are in an amino acid?

Answer 18

-the amino group (NH2)
-the alpha carbon
-the carboxyl group
-the side chain(R)

Question 19

What is a zwitterion?

Answer 19

-an amino acid is a Zwitterion at pH7
-it has both positive and negative charges

Question 20

Are amino acids chiral or achiral?

Answer 20

-amino acids are chiral, thus their image cannot be superimposed
(except glycine - as the sidechain of glycine is H)

Question 21

Where are L amino acids found?

Answer 21

-L amino acids are found in proteins, in nature

Question 22

What are examples of small and simple amino acids

Answer 22

-Glycine (Gly, G) and Alanine (Ala, A)

Question 23

What are examples of amino acids with bulky, hydrophobic side chain?

Answer 23

-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

Question 24

Describe the amino acid Cysteine

Answer 24

-(Cys, C)
-contains a thiol (-SH) group which allows it to form a disulphide bond

Question 25

Give examples of amino acids with aromatic (ring) side chain?

Answer 25

Phenylalanine (Phe, F), Tyrosine (Try, T) and Tryptophan (Trp, W)

Question 26

Give examples of amino acids with polar side chain(s)

Answer 26

(amino acids with polar side chains contain a hydroxyl (OH) group)
e.g. Serine (Ser, S) and Threonine (Thr, T)