cilia and microvilli set 2

CILIA AND MICROVILLI

presented by Afifah Amry

START

CONTENT

01

CILIA

DEFINITION FUNCTIONSTRUCTURE

02

MICROVILLI

DEFINITION FUNCTIONSTRUCTURE

03

SUMMARY

DIFFERENCES

1. CILIA

CIlia (singular; cilium) and flagella (singular; flagellum) have identical structure . They are whip-like, beating extension of many eukaryotic cells. Each is surrounded by an extension of the cell surface membrane. FLagella are long and found usually one or two per cell, while cilia are short and often numerous.

STRUCTURE OF CILIA

• Have two central microtubules and a ring of nine microtubules doublets (MTDs)
• This is referred to as '9+2' structure
• Each MTD contains an A and B microtubule
• Wall of the A microtubule is a complete ring of 13 protofilaments.
• B microtubule attached is an incomplete ring with only10 protofilaments.
• Each A microtubule has inner and outer arm which is made up of the protein dynein.
• They connect with the B microtubules of neighbouring MTDs during beating.
• If you imagine the microtubules in 3D, there are two rows of several hundred dynein arms along the outside of each A microtubule.
• The whole cylindrical structure inside the cell surface membrane is called the axoneme
• At the base of Cilia is a structure called the basal body which is identical in structure to centriole .
• Now, we know that centrioles replicate themselves to produce this basal body and that cilia grow from basal body.

BEATING MECHANISM

The beating mechanism of cilia and flagella is caused by the dyneine (protein) arms making contact with, and moving along, neighbouring microtubules. This produce the force needed for cilia to beat. As neighbouring MTDs slide past each other, the sliding motion is coverted into bending by other parts of the cillium.

FUNCTION

LOCOMOTION

If the cell is attached to something, so that it cannot move, fluid will move past the cell. If the cell is not attached, the cell will swim through the fluid. Single-celled organism can therefore use cilia and flagella for locomotion. In vetebrates, beating cilia are found on some epithelial cells, such as those lining the airways. Here, more than 10 million cilia may be found per square milimetre. They maintain the flow of mucus which removes debris such as dust and bacteria from the respiratory tract.

2. MICROVILLI

Microvilli (singular; microvillus) are finger-like extensios of the cell surface membrane. They are typical of certain animal cell, such as epithelial cells.

STRUCTURE OF MICROVILLI

CLICK ON THE LINK OR SCAN THE CODE

https://microbenotes.com/microvilli-structure-and-functions/

FUNCTION

1. Increase surface area of cell surface membrane

• efficient absorption and secretion; eg reabsorption in the proximal convoluted tubules of the kidney and for absorption of digested food into the cells lining the guts.

2. Motility

• The microvilli on the cell surface may sweep unwanted materials toward a resorptive area of the cell.

3. Increase number of digestive enzymes that can be present on the cell surface.

• For example, enzymes that digest carbohydrates, called glycosidases are present at high concentrations on the surface of enterocyte microvilli.

3. SUMMARY

CILIA VS MICROVILLI

1. Microvilli mainly occur in the columnar epithelial cells of the small intestine and kidney tubules.
2. Do not arise from basal granules.
3. Increase absorption
4. Non-motile
5. Made up of microfilaments, they lack (9+2) ultrastructure.
6. Numerous
7. Shorter compared to cilia.

1. Cilia occur in columnal epithelial cell in the respitory and uterine tube.
2. Arise from basal granules
3. Involved in movement
4. Motile
5. Made up of microtubules; they contain (9+2) ultrastructure.
6. Occur in fewer numbers.
7. Longer than microvilli

VS