The cytoskeleton is a complex prtein frameework with protein filaments offering support in eukaryotic cells. The three-dimesional network of filamentous protein which fills the space between organelles and gives shape and structure to cells and acts as the 'bone and muscle' of the cell. The cytoskeleton supports and organizes the cell coponents and controls their movements. Different areas within cells are linked by transport systems made up by the cytoskeleton and different parts of the cytoskeleton are structrally linked.
There are 3 types of protein filaments that make up the cytoskeleton:
Microfilaments are the smallest of the cytoskeletal elements and consit of two chains of actin molecules wrapped around each other.
Intermediate filaments such as keratin -found in skin- are made up of three polypeptide strands wound around one another.
Microtubules are essentil for maintaining asymmetric cell shapes and are important in complex cell movements such as transport of secretory vesicles, movement of specialised cell projections (such as cilia and flagella) and distribution of chromsomes during cell division through the formation of a mitotic spindle. Microtubules are composed of tubulin which is made of alpha and beta proteni subunits, these stack to form protofilaments (which have polarity) and grow by addition of tubulin dimers to either end (but are added to positive end more rapidly). They grow out from an organising centre centrosome, basal body) in which the negative ends are embedded. Microtubules are in a state of dynamic instability brought about by hydrolysis of guanosine triphosphate (GTP) to guanosine diphosphate (GDP). Microtubules provide a high way forvesicular trafic and for mitochondria. Molecular motors are the transportrs- a protein attaches to the partickle to be transported and then it 'walks along' the microtubule with the particle. Kinesin (a motor protein) consists of two 'feet' and a stalk (tail) which binds to the vesicle to be moved. Kinesin mvoes its cargo to he cell membrane by using tubulin on teh microtubule as a stepping stone.
Cilia and flagella are specialized protrusions from cell surfaceand help in movent of materials across cel surface or to propel itself through its environment. Cila and flagella are the intracellular structures covered by plasma membrane and arise from centrioles. Ciliated cells are in teh respiratory tract and oviduct while the only vertebrate cells that bear flagella are sperm. Microtubules in cilia and flagella are arranged in an 9+2 pattern and a primary cilium lacks the central pair of microtubules.
Microfilaments are the smallest of the cytoskeletons. In most cells, the microfilaments are composed of actin, a protein molecule. Actin is assembled into two twisted strands to form a microfilament. Functions include the cellular contractile system (actin-myosin in muscle contractions, most cell locomotion) and mechanical stiffeners for several specific cellular projections (eg microvilli). Some of the microfilament contractile systems are assembled to perform a specific function in non-muscle cells such as the contractil ring formed during cytokineses and pseudopods which are formed in WBC's as organised assembly and disassembly of branching actin networks.
Intermediate filaments are fibrous proteins of great tensile strength and are irregular threadlike molecules fo proteins. THey are comprised of subunits with N- and C- terminal globular heads and central alpha-hlical domain. THey are highly stable structures with tough, durable fibres to maintain structural integrity of the cell and resist mechanical stresses to the cell. Neurofilaments (in thenerve cell) strengten and stabilise elongated cellular extensions and intermediatefilaments in skeletal musclse hold actin-myosin contractile units in proper alignment. Irregular netowrk of intermediate filaments are made up of keratin in the skin and interconnect with exctracullular filaments that tie adjacent cells together and extends thoughout the skin and gives its strength.
Cytoskeleton functions include supporting the plasma membrane, responsible for particular shape, rigidity and spatial geometry of different cell types, act as cells mechanical communication systm, directs intracellular tranport, assembly of cells into tissues and regulation of numerous cellular movements.
Learn More
Cell Biology: Cytoskeleton-Microtubules
The Cytoskeleton Song
Quizlet: Cytoskeleton Flashcards
Learn Biology: Cells- Cytoskeleton
Proprofs Quiz: Cytoskeleton
Cytoskeleton Multi-Choice Quiz
Questions
There are 3 types of protein filaments that make up the cytoskeleton:
- microtubules
- microfilaments
- intermediate filaments
Microfilaments are the smallest of the cytoskeletal elements and consit of two chains of actin molecules wrapped around each other.
Intermediate filaments such as keratin -found in skin- are made up of three polypeptide strands wound around one another.
Microtubules are essentil for maintaining asymmetric cell shapes and are important in complex cell movements such as transport of secretory vesicles, movement of specialised cell projections (such as cilia and flagella) and distribution of chromsomes during cell division through the formation of a mitotic spindle. Microtubules are composed of tubulin which is made of alpha and beta proteni subunits, these stack to form protofilaments (which have polarity) and grow by addition of tubulin dimers to either end (but are added to positive end more rapidly). They grow out from an organising centre centrosome, basal body) in which the negative ends are embedded. Microtubules are in a state of dynamic instability brought about by hydrolysis of guanosine triphosphate (GTP) to guanosine diphosphate (GDP). Microtubules provide a high way forvesicular trafic and for mitochondria. Molecular motors are the transportrs- a protein attaches to the partickle to be transported and then it 'walks along' the microtubule with the particle. Kinesin (a motor protein) consists of two 'feet' and a stalk (tail) which binds to the vesicle to be moved. Kinesin mvoes its cargo to he cell membrane by using tubulin on teh microtubule as a stepping stone.
Cilia and flagella are specialized protrusions from cell surfaceand help in movent of materials across cel surface or to propel itself through its environment. Cila and flagella are the intracellular structures covered by plasma membrane and arise from centrioles. Ciliated cells are in teh respiratory tract and oviduct while the only vertebrate cells that bear flagella are sperm. Microtubules in cilia and flagella are arranged in an 9+2 pattern and a primary cilium lacks the central pair of microtubules.
Microfilaments are the smallest of the cytoskeletons. In most cells, the microfilaments are composed of actin, a protein molecule. Actin is assembled into two twisted strands to form a microfilament. Functions include the cellular contractile system (actin-myosin in muscle contractions, most cell locomotion) and mechanical stiffeners for several specific cellular projections (eg microvilli). Some of the microfilament contractile systems are assembled to perform a specific function in non-muscle cells such as the contractil ring formed during cytokineses and pseudopods which are formed in WBC's as organised assembly and disassembly of branching actin networks.
Intermediate filaments are fibrous proteins of great tensile strength and are irregular threadlike molecules fo proteins. THey are comprised of subunits with N- and C- terminal globular heads and central alpha-hlical domain. THey are highly stable structures with tough, durable fibres to maintain structural integrity of the cell and resist mechanical stresses to the cell. Neurofilaments (in thenerve cell) strengten and stabilise elongated cellular extensions and intermediatefilaments in skeletal musclse hold actin-myosin contractile units in proper alignment. Irregular netowrk of intermediate filaments are made up of keratin in the skin and interconnect with exctracullular filaments that tie adjacent cells together and extends thoughout the skin and gives its strength.
Cytoskeleton functions include supporting the plasma membrane, responsible for particular shape, rigidity and spatial geometry of different cell types, act as cells mechanical communication systm, directs intracellular tranport, assembly of cells into tissues and regulation of numerous cellular movements.
Learn More
Cell Biology: Cytoskeleton-Microtubules
The Cytoskeleton Song
Quizlet: Cytoskeleton Flashcards
Learn Biology: Cells- Cytoskeleton
Proprofs Quiz: Cytoskeleton
Cytoskeleton Multi-Choice Quiz
Questions
- describe the growth of microtubules
- what is the function of microtubules, microfilaments and intermediate filaments?
- what are functions of the cytoskeleton?
- List two motor proteins, what are their functions and how do they work?