17 Flashcards
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)
What are the 3 types of Cytoskeletal Filaments?
- Intermediate Filament (IF)
- Microtubules
- Actin Filaments
What is the function of Intermediate filaments?
Provides strength and resistance to mechanical stress
Intermediate Filaments are found where?
In the Cytoplasm and Nuclear Envelope
What are 2 examples of Cytoskeletal Filaments?
- Keratin
- Lamins
Function of Keratin?
skin cells; that provide mechanical stability through desmosomes
Function of Lamins?
Nuclear Envelope support; Disassembles during cell division via phosphorylation
How and when do Lamins disassemble?
During cell division via phosphorylation
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)
Mutation in IFs that makes skin prone to mechanical injury is known as what?
Epidermolysis Bullosa Simplex
Defective Lamins that cause premature aging due to nuclear instability is known as what?
Progeria
Describe the structure of Microtubules.
Hollow tubes composed of Tubulin Dimers (alpha and beta tubulin)
Walls formed by 13 protofilaments
Describe the structural polarity, growth and shrinkage of Microtubules.
the plus (+) end grows
the minus (-) end shrinks
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
Which type of Cytoskeletal Filament is found in Cilia and Flagella for motility?
Microtubules
The Microtubule-Organizing Center is known as what?
Centrosome
The Microtubule-Organizing Center is located where?
near the nucleus
The Centrosome is located where?
Near the Nucleus
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.
- Microtubules are polarized along the Axon
- 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.
