Proteins

Question 1

How do myosin and actin work?

Answer 1

1. Myosin heads are bound to Actin to from cross bridges.
2. The binding of ATP to the myosin causes a conformational change, making the myosin head detach from the actin and swings forward.
3. The ATP is broken down into ADP and Phosphate. These stat bound to myosin causing a second confromational change.
4. The myosin head rebinds to the actin which causes yet another conformational change.
5. The ADP + Pi are released from the myosin. The myosin head swings back to its original conformation, dragging the actin filament along. Then the cycle starts again.

Question 2

Types of membrane proteins?

Answer 2

Integral proteins - these form strong hydrophobic interactions, tethering the protein to the tails of the phospholipids in the membrane’s interior. Some integral proteins only extend partly into the bilayer while others are transmembrane proteins that span the width of the membrane.

Peripheral proteins are not embedded in the phospholipid bilayer, but instead, they form weak bonds to the surface, either with the heads of the phospholipids, or, more usually, to the exposed parts of the integral proteins.