17 Flashcards by naj n

What are the functions of the Cytoskeleton?

Dynamic Scaffold for structure
internal framework for organelle positioning
creates a network of tracks for molecular movement within the cell
participates in cell division and acts as force-generating apparatus for cell motility

(strength, structure, organization)

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What are the 3 types of Cytoskeletal Filaments?

Intermediate Filament (IF)
Microtubules
Actin Filaments

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What is the function of Intermediate filaments?

Provides strength and resistance to mechanical stress

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Intermediate Filaments are found where?

In the Cytoplasm and Nuclear Envelope

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What are 2 examples of Cytoskeletal Filaments?

Keratin
Lamins

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Function of Keratin?

skin cells; that provide mechanical stability through desmosomes

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Function of Lamins?

Nuclear Envelope support; Disassembles during cell division via phosphorylation

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How and when do Lamins disassemble?

During cell division via phosphorylation

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Describe the composition of Intermediate Filaments?

Rope-like structure made of a-helical proteins
made stable by non-covalent bonds

-globular head and tail regions (which vary allowing diff functions)

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Mutation in IFs that makes skin prone to mechanical injury is known as what?

Epidermolysis Bullosa Simplex

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Defective Lamins that cause premature aging due to nuclear instability is known as what?

Progeria

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Describe the structure of Microtubules.

Hollow tubes composed of Tubulin Dimers (alpha and beta tubulin)

Walls formed by 13 protofilaments

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Describe the structural polarity, growth and shrinkage of Microtubules.

the plus (+) end grows
the minus (-) end shrinks

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What are the functions of Microtubules?

Organizes cell’s interior
Acts as tracks for motor proteins to transport cargo
aids in chromosome movement and organelle positioning

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Which type of Cytoskeletal Filament is found in Cilia and Flagella for motility?

Microtubules

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The Microtubule-Organizing Center is known as what?

Centrosome

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The Microtubule-Organizing Center is located where?

near the nucleus

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The Centrosome is located where?

Near the Nucleus

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The Centrosome is composed of what?

y-tubulin rings that nucleate microtubule growth

The y-tubulin rings in Centrosomes do what?

Nucleate Microtubule growth

True or False: Microtubules grow and shrink independently.

True

Microtubules grow/shrink due to what?

GTP Hyrdrolysis

In Microtubules, GTP-Tubulin dimers cause what to occur?

growth of microtubules

In Microtubules, GDP-Tubulin dimers cause what to occur?

disassembly of microtubules

In Microtubules, how does the plus end become stabilized?

via attachment to cellular structures which enables polarization

Nuclear Lamina is formed by which Cytoskeletal Filament?

Intermediate Filament

Nuclear Lamina, formed by IFs, support what?

the Nuclear Envelope

Intermediate Filaments are disassembled and reassembled during _______ via lamins' _________

Mitosis ; Phosphorylation

The Microtubule plus end (+) undergoes _______ growth and does what?

Rapid; interacts with cell structures

The Microtubule minus end (-) undergoes _______ growth and does what?

Slower; stays anchored to centrosomes

Describe the process of Transport in Neurons.

1. Microtubules are polarized along the Axon 2. Motor Proteins transport cargo directionally along these tracks

What is meant by Dynamic Instability in Microtubules?

- Individual Microtubules exhibit independent growth / shrinkage cyles Regulated by GTP-hydrolysis: - GTP-tubulin promotes stability+ Growth - GDP tubulin destabilizes + shrinks

What is the Epidermolysis Bullosa Simplex?

A genetic disorder that is caused by mutations in keratin which makes the skin prone to blistering and mechanical injury

What is Progeria?

A genetic condition that is linked to defective nuclear lamins, which lead to premature aging and nuclear instability

What is Keratin?

A type of IF that is found in Epithelial Cells that provides mechanical strength to tissues (like skin)

What are Lamins?

IFs that form a meshwork (scaffold) that supports the nuclear envelope, disassembling and reassembling during cell division

What is Tubulin?

A protein dimer that consists of a-tubulin and b-tubulin that assembles into microtubules

What is Dynamic Instability?

The process by which microtubules grow and shrink GTP-Tubulin Addition = grow GTP Hydrolysis to GDP-Tubulin = shrink

What is a Centrosome?

A microtubule-organizing center (MTOC) located near the nucleus that contains y-tubulin rings that nucleate microtubule growth

What is GTP Hydrolysis?

A chemical reaction that converts GTP into GDP ; regulating the stability of Microtubules

Which end are Tubulin Dimers added?

Plus (+) End

What are Motor Proteins?

Proteins that move cargo along microtubules which enables intracellular transport

What is Selective Stabilization?

The process by which microtubules are stabilizes by attaching their plus ends to cell structures, aiding in cell polarization

What is Cell Polarization?

The asymmetric organization of cellular components,

What is Axon Transport?

Movement of proteins and organelles along microtubules in a neuron which is facilitated by Motor Proteins.