14. They get pollinated by animals, and birds that come to
These three groups are monotremes, marsupials, and the largest group, placental mammals.
An electron is transferred from an electron to the other
Both are composed as cells the basic unit of life with each cell surrounded by a cell membrane
Answer: Microtubules
Explanation:
The cytoskeleton is a three-dimensional network of proteins that provides internal support in the cells, organizes the internal structures and intervenes in the phenomena of transport, traffic and cell division. In eukaryotic cells, it consists of actin filaments, intermediate filaments and microtubules.
<u>The microfilaments maintain the shape of the cell.</u> Other functions are the formation of cytoplasmic protuberances such as pseudo and microvilli, participating in intercellular or cell-matrix junctions, signal transduction, cell mobility (in the case of muscle cells, and together with myosin, they allow muscle contraction) and in animal cell cytokinesis, the formation of a contractile ring that divides the cell in two.
<u>Intermediate filaments are fibrous protein filaments which constitute the most stable (supporting organelles by their strong bonds) and heterogeneous components of the cytoskeleton.</u> Their main function is to organize the internal three-dimensional structure of the cell (for example, they are part of the nuclear envelope and the sarcomers). They also participate in some intercellular junctions (desmosomes).
<u>Microtubules are tubular structures that originate in microtubule organizing centers and extend along the cytoplasm. They can be polymerized and depolymerized according to the needs of the cell</u>. They are found in eukaryotic cells and are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulins. Each microtubule is composed of 13 protofilaments formed by the tubulin dimers. <u>They are involved in various cellular processes involving displacement of secretion vesicles, movement of organelles, intracellular transport of substances, as well as in cell division (mitosis and meiosis), since they form the achromatic spindle. In addition, they constitute the internal structure of cilia and flagella. </u>
Microtubules are composed of a protein called tubulin and they are the largest type of filament and its diameter is about 25 nanometers (nm). While actin filaments are made of actin and they are smaller, with a diameter of about 6 nm. And intermediate filaments have a diameter of about 10 nm, which is intermediate between the diameters of the two other principal elements of the cytoskeleton.
