Let's discuss what each type is and what each type does. So let's begin with the microfiling. The microfilamentant is composed of a single protein known as actin. The protein is linear and so we form this linear type of structure and it's the thinnest type of structure. It's about six to 7 nm in length. Now, the function of our microfiling is in muscle contraction, in phagocytosis, in tensile strength and cytoplasmic streaming.