The image below shows part of a structure of a protein, with several amino acids highlighted in ball and stick representation.

Which one statement concerning this region of the structure is true?

The graph below shows data for the fractional saturation of a protein with varying concentrations of ligand.

Using the graph and your knowledge of Kd, determine the concentration of ligand (in nM; nanomolar) required to achieve 1% of protein bound.

A hydropathy plot of the amino acid sequence of a membrane protein begins with a region of high negative hydrophathy, followed by three regions of high positive hydropathy, and ends with a region of high negative hydropathy. Each of the regions of high positive hydropathy spans around 25 residues. The first two regions of high positive hydropathy have a short region of negative hydropathy between them. The second two regions of high positive hydropathy have a far longer region of negative hydropathy between them.

Which (terribly sketched by Nathan) schematic below best fits with the description above?

An enzyme, E, displays negative cooperativity (allosteric behaviour) for its substrate, S, in the presence of a modulator, M.

Which curve below (A, or B) represents the dependence of the initial velocity of E on the concentration of S in the presence and absence of M.

The velocity of each of these reactions:

Shown below are the sequences of two strands that are adjacent to each other in an antiparallel β-sheet.

The strands are labelled “A” and “B” and the amino acids are labelled A1-A2-A3…A8 and B1-B2-B3…B8 so that we can unambiguously refer to each amino acid.

The side chains of amino acids Asp-A3 and Lys-B6 (underlined) form a salt bridge on one face of the β-sheet.

Shown below is a ribbon representation of a protein.

Shown below is a ribbon representation of the enzyme triosephosphate isomerase.

True or False, The region labelled "J" is the C-terminus.

The following sequence forms an amphipathic α-helix:

Ala-Val-Asn-Asp-Glu-Ile-Ser-Thr-Leu-Met-His-Arg-Val-Lys-Ser-Phe-Phe-Gly

In your mind (or by taking a photo, sketching it out, annotating on the screen, or doing-whatever-you-need-to-do-because-this-isn't-a-paper-exam-so-I'm-adapting-it-here-for-this-revision-quiz...), map the sequence onto the helical wheel shown below. The position of Ala-1 is already shown.

Which side of the helical wheel diagram represents the hydrophobic side of the helix?

Isoelectic focussing is an old but nevertheless useful technique of separating proteins along a gel strip containing an immobilised pH gradient.

In an experiment utilising this technique, a mixture of four proteins (with known pI values of: 9.3, 8.1, 6.5, and 4) was added to the gel strip and an electric field applied. Then, the gel was stained so that proteins could be visualised.

From the image below (where black ovals represent the stained and visualised proteins), which gel strip represents the one corresponding to the above mixture of proteins?