Mo Cell Exam 4 Study guide

What are the three components of the cytoskeleton? What do they do? What does the cytoskeleton do as a whole?

Three components of the cytoskeleton:

1. Intermediate filaments: help the cell with stand being stretched, great tensile strength, most durable of the filaments, helps anchor organelles.

2. Microtubules: the largest component of the cytoskeleton, they’re hollow tubes, they’re the most rigid, provide tracks for organelle and vesicle movement within the cell, form structural core of flagella and cilia in eukaryotic cells, help form mitotic spindles that separate chromosomes during mitosis.

3. Actin filaments: Enable cell movement (e.g., crawling, protrusions like lamellipodia and filopodia), Maintain cell shape via the cell cortex, drive muscle contraction through interaction with myosin motor proteins, assist in cytokinesis during cell division.

The cytoskeleton maintains cell shape and structural integrity, supports the plasma membrane through the cell cortex, enables movement of cells and internal components, coordinates cell division, and responds to external signals.

What are intermediate filaments? How do they assemble? What is their
function? Where are they found?

They are fiborous proteins that provide the cell with mechanical strength and help the cells withstand tensil stress.

Intermediate filaments are providee the cell with tensile strength and forms the nuclear lamina.

Intermediate filaments are found throughout the cytoplasm and nucleus of cells that experience mechanical stress such as:

1. Keratin filaments: epithelial cells

2. Vimentin and vimentin-related filaments: connective tissue, muscle cells, and glial cells

3. Neurofilaments: neurons

4. Nuclear lamins: strengthen the nucleus of all animal cells

How are microtubules assembled? What are they made of? What is
dynamic instability?

Tubulin dimers are made up of an alpha tubulin and a beta tubulin. Tubulin dimers stack together to form a long chain called protofilament. Each protofilament has directionality. The beta end is the plus end and it grows faster. The alpha end is the minus end. Thirteen protofilaments will combine to form a hollow micrutubule.

Microtubules are made of tubulin dimers, which are made up of an alpha tubulin and a beta tubulin.

Dynamic instability: Microtubules are constantly switching between polymerization (growing) and depolymerization (retracting).

What is a microtubule organizing center? To which end of the microtubule
does it bind? What is gamma-tubulin?

The microtubule organizing center in animals is the centrosome. Microtubules are found in the cell radiating from a centrosome. The microtubule organizing center binds to the minus end of microtubules at the centrosome. A gamma tubulin is a protein that caps the minus end and stabilizes it, allowing the addition (polymerization) of alpha/beta-tubulin dimers at the plus end.