Cell Structure and Function in Protists

Flashcards covering the structure and function of eukaryotic organelles, targeting mechanisms, the endomembrane system, motility, and reproductive processes in protists based on Principles of Modern Microbiology.

What is the primary function of the Endomembrane System?

It is responsible for the synthesis, modification, and transport of proteins and lipids within the cell.

Which organelle is responsible for sorting proteins produced in the endoplasmic reticulum?

The Golgi apparatus.

What is the role of 7-methyl-guanosine cap in mRNA?

It protects mRNA from degradation and assists in translation by facilitating ribosome binding.

In what way do signal sequences influence a protein's fate?

They direct proteins to their specific locations within the cell.

What is cotranslational targeting?

A process where the signal recognition particle halts protein synthesis until the ribosome attaches to the ER.

Posttranslational protein targeting typically involves which type of proteins?

Proteins that are destined for mitochondria or chloroplasts.

What key role does the nucleolus serve within the nucleus?

It is where ribosomal RNA (rRNA) is synthesized and ribosome subunits are assembled.

What is the Nuclear Localization Signal?

It is a sequence that facilitates the transport of proteins into the nucleus through the nuclear pore complex.

What is endocytosis?

A cellular process that captures external substances by enclosing them in vesicles.

Which structure facilitates water expulsion to maintain osmotic balance in cells?

The contractile vacuole.

How do kinesins function in cellular transport?

They transport cellular cargo towards the plus end of microtubules, typically towards the cell periphery.

Define endosymbiotic theory in relation to eukaryotic cells.

It proposes that mitochondria and chloroplasts originated from free-living bacteria that were engulfed by a primitive eukaryotic cell.

What are microtubules primarily composed of?

Tubulin dimers arranged in a hollow tube formation.

What is the function of the basal body in flagellar movement?

It serves as the anchoring structure for the basal part of cilia and flagella, composed of microtubule triplets.

Distinguish between kinesins and dyneins.

Kinesins move towards the plus end of microtubules, while dyneins move towards the minus end.

What cellular process is essential for moving vesicles along microtubules?

Motor protein activity, facilitated by kinesins and dyneins.

Identify the main cellular components involved in maintaining the structure of some protists.

The pellicle, a complex structure underneath the cell membrane.

What is the significance of the Poly-A tail in mRNA?

It enhances the stability of mRNA and aids in its transport from the nucleus.

How does microfilament structure contribute to cell function?

They support cell shape, facilitate movement, and are involved in intracellular transport.

What major process happens during closed mitosis in certain protists?

The nuclear envelope remains intact while the nucleus divides.