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Properties of Proteins
Concept Questions
Question #1

The interior and the exterior of cells is liquid, usually a solution or suspension of ions, small molecules and large molecules dissolved in water. Proteins must therefore be hydrophilic ("water loving") in order to be suspended in this environment.

The bilayer of molecules that surround cells, however, is mostly made up of phospholipids arranged in such a way that their hydrocarbon "tails" are all pointing into the center of the structure.

In which of the following links are the special properties of proteins that have to exist in both a hydrophilic and hydrophobic environment discussed?

Link-#61 Link-#22 Link-#11 Link-#23

Question #2

Those regions of the protein that must interact with the strongly hydrophobic center of the lipid bilayer have sequences of polypeptide that are made up of amino acids with hydrophobic R-groups, such as alanine, leucine, glycine, serine and tyrosine.

In which of the following links is it thought that these hydrophobic lengths of polypeptide coil up into a alpha-helical shape?

Link-#23 Link-#93 Link-#56 Link-#86

Question #3

Humans have two different kinds of muscle, one of which, cardiac and smooth muscle, is not connected to bone, and is not usually under the conscious control of the animal.

In which of the following links are the protein molecules responsible for the lateral movement of actin filaments in these muscles discussed and described?

Link-#23 Link-#81 Link-#39 Link-#77

Question #4

In between the arrays of actin filaments in muscle cells are a set of myosin thick filaments, which point in both directions. On the other side of the myosin thick filaments are a second set of actin filaments, which are also attached to a second Z-disc.

In which of the following links is there an illustration of the ways in which proteins interact with and to the Z-disc of muscle?

Link-#23 Link-#51 Link-#45 Link-#49

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© 2003, Professor John Blamire