Question

1. Complete the following table:

	Kinesin	Dynein
Structure
Function(s) in a cell
Direction that this motor protein moves

*Highlight or use a different text color for similarities shared between kinesin and dynein.

2. Complete the following table:

	Cilia	Flagella
Structures
Function(s)
Types of movements, and how these occur

*Highlight or use different text colors for similarities shared between cilia and flagella.

Answer 1

1.

Structure of kinesin :-

The heavy chain of kinesin-1 comprises a globular head (the motor domain) at the amino terminal end connected via a short, flexible neck linker to the stalk – a long, central alpha-helical coiled coil domain – that ends in a carboxy terminal tail domain which associates with the light-chains.

Structure of dynein :-

  Each heavy chain has a globular motor domain with a doughnut-shaped structure believed to resemble that of other AAA proteins, a coiled coil "stalk" that binds to the microtubule, and an extended tail (or "stem") that attaches to a neighboring microtubule of the same axoneme.

Function of kinesin :-

Kinesins moving along microtubules usually carry cargo such as organelles and vesicles from the center of a cell to its periphery.

Function of dynein :-

Dyneins are important in sliding microtubules relative to one other during the beating of cilia and flagella on the surfaces of some eukaryotic cells.

Direction in which kinesin motor protein moves :-

kinesin move cargo towards the plus (+) end of a microtubule.

Direction in which dynein motor protein moves :-

  dynein toward the minus end.

2.

Structure of cilia :-

A cilium is made up of microtubules coated in plasma membrane. Each cilium contains nine pairs of microtubules forming the outside of a ring, and two central microtubules. This structure is known as an axoneme, and the arrangement as '9+2', an arrangement ubiquitous in motile cilia.

Structure of flagella :-

made up of the protein flagellin. Its shape is a 20-nanometer-thick hollow tube. It is helical and has a sharp bend just outside the outer membrane; this "hook" allows the axis of the helix to point directly away from the cell.

Function of cilia :-

cilia are found in the lungs, respiratory tract and middle ear. These cilia have a rhythmic waving or beating motion. They work, for instance, to keep the airways clear of mucus and dirt, allowing us to breathe easily and without irritation. They also help propel sperm.

Function of flagella :-

Flagella performs the following functions:

• They help an organism in movement.
• They act as sensory organs to detect temperature and pH changes.
• Few eukaryotes use flagellum to increase reproduction rates.
• flagella are also used as a secretory organelle. For eg., in Chlamydomonas.

Types of movement in cilia :-

It move the cell itself or to move substances over or around the cell.

Types of movement in flagella :-

Flagellar movement, or locomotion, occurs as either planar waves, oarlike beating, or three-dimensional waves. All three of these forms of flagellar locomotion consist of contraction waves that pass either from the base to the tip of the flagellum or in the reverse direction to produce forward or backward movement.