Cytoskeletal Systems: Microtubules Part 1

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Questions and Answers

What is the primary function of cytoplasmic microtubules in a cell?

Transporting genetic material between the nucleus and cytoplasm

Assisting in protein folding

Maintaining axons (correct)

Synthesizing ATP for cellular energy

In which cell structures are axonemal microtubules organized and stable?

Lysosomes and peroxisomes

Nucleus and Golgi apparatus

Cilia and flagella (correct)

Endoplasmic reticulum and ribosomes

What is the axoneme?

Highly ordered bundle of microtubules in a cilium or flagellum (correct)

Structure involved in photosynthesis

Specialized enzyme for cellular respiration

Component of the cell membrane

What are the two types of microtubules involved in various cell functions?

Cytoplasmic microtubules and axonemal microtubules Signup and view all the answers

What is the function of axonemal microtubules in eukaryotic flagella?

Formation of the central shaft of a cilium or flagellum Signup and view all the answers

Which of the following is NOT a function of cytoplasmic microtubules?

Synthesizing ATP for cellular energy Signup and view all the answers

What is the basic subunit of a protofilament in a microtubule?

Heterodimer of tubulin Signup and view all the answers

What is the inherent polarity of protofilaments in microtubules?

The two ends differ both chemically and structurally Signup and view all the answers

What type of microtubules contain one 13-protofilament tubule and one or two additional incomplete rings?

Doublet microtubules Signup and view all the answers

Which process is called nucleation in microtubule assembly?

The aggregation of dimers into oligomers Signup and view all the answers

What balances the assembly of microtubules when the mass reaches a point where the amount of free tubulin is diminished?

Disassembly Signup and view all the answers

What type of domain does each alpha and beta tubulin have?

GTP binding domain Signup and view all the answers

What are the tubulin heterodimers made of?

One alpha-tubulin and one beta-tubulin Signup and view all the answers

What do protofilaments in microtubules consist of?

Longitudinal arrays of polymers Signup and view all the answers

What serves as 'nuclei' from which new microtubules grow during assembly?

Dimers aggregation into oligomers Signup and view all the answers

What does the plateau phase of microtubule assembly represent?

A balanced state between assembly and disassembly Signup and view all the answers

Study Notes

Microtubules

The primary function of cytoplasmic microtubules in a cell is to provide structural support, shape, and movement.

Axonemal Microtubules

Axonemal microtubules are organized and stable in cilia and flagella.
The axoneme is the internal structure of cilia and flagella, composed of microtubules.
Axonemal microtubules in eukaryotic flagella are responsible for movement and motility.

Types of Microtubules

There are two types of microtubules involved in various cell functions: cytoplasmic microtubules and axonemal microtubules.
Cytoplasmic microtubules are not involved in cell motility.

Microtubule Structure

The basic subunit of a protofilament in a microtubule is a dimer of α-tubulin and β-tubulin.
Protofilaments in microtubules have an inherent polarity.
Cilia and flagella contain 13-protofilament microtubules with one complete tubule and one or two incomplete rings.

Microtubule Assembly

Nucleation is the process of microtubule assembly.
The dynamic equilibrium between assembly and disassembly balances the growth of microtubules when the mass reaches a point where the amount of free tubulin is diminished.
Microtubule-associated proteins (MAPs) and microtubule-organizing centers (MTOCs) serve as 'nuclei' from which new microtubules grow during assembly.
The plateau phase of microtubule assembly represents a state of dynamic equilibrium.

Tubulin

Each α-tubulin and β-tubulin has a globular domain.
Tubulin heterodimers are made of one α-tubulin and one β-tubulin molecule.
Protofilaments in microtubules consist of tubulin heterodimers arranged head-to-tail.

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Description

Test your knowledge on the first part of the lecture series by Kathleen Fitzpatrick at Simon Fraser University, covering the topic of microtubules as a component of the cytoskeletal system.