Which of the following accurately represents the compositions of eukaryotic cilia and flagella?

What happens at the minus-end of actin filaments when the concentration of G-actin is above its critical concentration?

In which of the following structures do actin microfilaments play a crucial role?

I. Contractile ring formed during cytokinesis

II. Sarcomeres

III. Adherens junctions

IV. Eukaryotic flagella

There are two models for the operation of the Golgi apparatus in eukaryotic cells. As it is difficult to visualize the operation of cells at the molecular level in real time, scientists typically rely on static electron micrographs to see the morphology of organelles. As a result, the dynamic operation of these organelles can sometimes be unclear.

Cisternal Maturation Hypothesis

In the cisternal maturation hypothesis, the cisternae of the Golgi apparatus evolve. Proteins leave the endoplasmic reticulum, and enter the cis-Golgi. The cisterna of the cis-Golgi then matures, with its enzymatic contents and internal environment changing as it becomes the medial-Golgi, and, eventually, the trans-Golgi.

In this model, the proteins never physically leave their membrane-bound cisternae during their transit across the Golgi. Instead, the entire unit of contents remains within the evolving cisternae.

Vesicular Transport Hypothesis

In contrast to the cisternal maturation hypothesis, the vesicular transport hypothesis posits that the cis-, medial-, and trans-Golgi cisternae are more static structures. Instead of evolving around their contents, the contents are physically shuttled via vesicular intermediates from each cisterna to the next.

In the case of vesicular transport, vesicles are shuttled along microtubules. Motor proteins facilitate this movement, with unique proteins being used for each direction of movement along a microtubule.

Which statement is true of microtubules and actin?

Desmosomes are specialized cell junctions that anchor cells to one another by connecting the __________ of the cytoskeleton to transmembrane proteins known as __________.

The cytoskeleton acts as a scaffold for the cell and maintains cellular integrity. Which of the following is a component of the cytoskeleton?

Actin is the major protein that composes which part of the cytoskeleton?

Which of the following choices describes a function of the eukaryotic centriole?

Which of the following statements is true about intermediate filaments?

I. Intermediate filaments display treadmilling

II. Intermediate filaments maintain a tightly regulated gradient of ADP/ATP bound monomers

III. Intermediate filaments play a crucial role in the function of desmosomes

IV. Intermediate filaments are a major component of the mitotic spindle

Which of the following is true of microtubules?