Cytoskeleton (Biomedical Science)

Cells To Systems - Cytoskeleton
The Cytoskeleton

Cytoskeleton:
Cytoskeleton - Structures which come together

 Made up of 3 components
 Organised in a cell to specific structures
 Their structure organisation define their function
 They are macromolecules (very large molecules)
 Cytoskeleton components are essential to form the structure, maintain the structure, shape, and the structural cells
which define the structure of tissues
 Forms the framework of every cell

Actin - Structure that forms all of the components/organisation of the body and is essential for all cells in the body

 Non-muscle found in all cells

Cytoplasm & Cytoskeleton:
Cytoplasm:

 An aqueous environment where many proteins are together, as well as the nucleus
 A lot of protein form the backbone
 Has a framework which maintains cell structure and organisation e.g. if it was composed of water, liquid,
membranes, nucleus without the framework, the cell won’t be able to structure them
 Regarded as a gel-like substance in which organelles and the nucleus were suspended

Cytoskeleton:

 Provides an architectural framework for cells
 Cytoskeleton has a dynamic changing nature (unlike the skeleton)
 Cytoskeleton and all structures of the cytoskeleton have dynamic structures, they can assemble and disassemble
very efficiently

Size Matters:

 Cytoskeleton proteins form polymers/fibres built from small protein subunits that are held together by non-covalent
bonds
 Cytoskeleton proteins are able to interact with each other to form macromolecules

3 Proteins/Molecules Which Come Together To Form Specific Structures:

1. Microfilaments
2. Intermediate filaments
3. Microtubules

Microfilaments:

 F-actin (fibular/filamentous)
 G-actin (globular)

Intermediate Filaments:

 Create specific subsets of filaments as they follow certain structures and requirements to be classified in this family
of proteins
 4 major types
 The proteins vary in size and sequence

Microtubules:
1

, Cells To Systems - Cytoskeleton
 2 proteins coming together to form a dimer
 α-tubulin
 β-tubulin
 Because α and β-tubulin are slightly different, they become a heterodimer (HO dimer)
 These proteins are very small
 By binding together, they can form structures which are long or large

 Nerve cells or neurons form axons
 Axons are ½ - 1 metre long
 Axons are extended like this due to cytoskeleton proteins, which allow the axons to function properly

Cytoskeleton - Common Themes:
Filaments - Architecture and framework which hold and make the cells the way they are

 Unlike the bones in the body, filaments are very easily disassembled and organised in change in structure
 Filamentous structures are polymers of subunit proteins
 State of assembly is dynamic (constantly changing)
 Specific changes in assembly are due to interaction with other proteins
 Molecular motors allow for intracellular transport and cellular movement
Cytoskeleton proteins are small molecules that can form into large sedimental
polymers/macromolecules/filamins

Reversible pattern = Subunits assemble to form filaments and filaments can disassemble
to form subunits
= process is very efficient and quick

Small molecules can diffuse rapidly within the cytoplasm

1. Large amounts of filaments are organised on 1 side of the cell. However, there is a
source (yellow arrow) which triggers the cell and tells it to act
= as a consequence, this phase is facing the wrong way and needs to reorganise
itself very efficiently
2. Filaments are disassembled
3. Promotes the organisation, reassembly, and polymerisation of these filaments
where it’s required)

 Dynamic process where dynamicity is essential (things can act and can be act upon
very efficiently
 For this process to take place, energy is required for many events to take place at
the same time and certain molecules e.g. mottos to work
 The rate of assembly into polymers, the site of assembly and the stability of the
polymer, once formed, are tightly regulated events
Typical Organisation Of The Cytoskeleton Filaments Within Cells:

 Filaments are organised in a specific pattern and cellular localisation which is key function of these molecules
working together
 Diameter is important, not length



Actin Filaments:

 Smallest diameter
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