Cytoskeleton Flashcards
Cytoskeleton
Dynamic network of fibers throughout the cytoplasm
Cytoskeleton function
Support, maintains shape, and anchors organelles
Movement
Regulation
Transmits forces from the surface to the interior of the cell (signal)
Types of filaments
Microtubules, microfilaments, and intermediate filaments
Motor protein function
Use ATP to power movement in interaction with plasma membrane molecules or cytoskeleton tracks, one foot maintaining contact wile the other releases and attaches one step further
Responsible for bending movements of cilia and flagella
Motor protein structure
Microtubule doublets held in place by cross linking proteins
Receptor connects motor protein to vesicle for transport
Microtubule structure
Hollow tubes made of protein tubulin dimers (globular proteins made of an α-tubulin and a β-tubulin)
Microtubule diameter
25nm
Microtubule subunit
Tubulin
Microtubule function
Cell support (compression resistance)
Cell movement (cilia and flagella)
Chromosome movement in cell division
Organelle movement
Vesicle movement
Microtubules grow from…
Centrosomes
Centrioles
Cylindrical structures containing 9 sets of 3 microtubules
Exist in perpendicular pairs in the centrosome
Cilia and flagella structure
Hair-like structures with 2 central microtubules and an outer 9 sets of 2 microtubules with dynein motor proteins extending from the outer microtubule and walking along the adjacent microtubule
Anchored by a basal body
Surrounded by an extension of the plasma membrane
Basal body structure
Cylindrical structures containing 9 sets of 3 microtubules (same as centrioles)
Basal body function
To anchor cilia and flagella to the cell
Cilia and flagella function
Move the cell or move things past the cell
Cilia
Many and short
Flagella
Few and long
Primary cilia
Nonmotile signal receiving cilia in many vertebrate animal cells
Microfilament structure
Solid fibers made of two intertwined strands of actin
Microfilament function
Cell support (bearing tension via pulling forces)
Cytokinesis
Cell movement (creeping)
Muscle contraction
Cytoplasmic streaming
Microfilament diameter
7nm
Microfilament subunit
actin
Cytoplasmic streaming
Cortical microfilaments
Network of supportive microfilaments just inside the cell membrane that gives the cell its shape and gives the cortex a gel-like consistency
Cortex
Outer cytoplasmic layer of the cytoplasm with a gel-like consistency
Microvilli
Finger-like projections made of microfilaments that increase a cells surface area
Microfilament (actin) interaction with myosin
Myosin and actin filaments driven past each other drawing actin filaments towards each other in order to shorten a muscle cell for contraction
Pseudopodia
Microfilament cellular extension that allow for creeping cell movement
Intermediate filament structure
Fibrous proteins coiled into cables
Intermediate filament function
Cell support (bear tension)
Cell adhesion (DESMOSOMES)
Hold organelles in place
Formation of the nuclear lamina (supporting the nuclear envelope)
Intermediate filament diameter
8-12nm
Intermediate filament subunit
Various proteins
Some are repeating keratin subunits
Cell wall structure
Supportive layer outside cell membrane
Cell wall function
Cell and organism structural support and protection
Prevents excess water uptake and loss
Cell walls exist in…
All plants and fungi
Many bacteria and protists
Plant cell wall structure
Cellulose and other carbohydrates (pectin and hemicellulose)
Primary cell wall
First thin cell wall layer
Able to stretch
Secondary cell wall
Thicker cell wall layer formed afterwards and on the interior of the primary cell wall
Middle lamina structure
Made of pectin; highly hydrophilic carbohydrates that take a sticky gelatinous texture in water
Middle lamina function
Cement adjacent cells together
Cell wall structure (outside in)
Middle lamina, primary cell wall, secondary cell wall, cell membrane
Plant cell wall main component
Cellulose
Fungi cell wall main component
Chitin
Bacteria cell wall main component
Peptidoglycans (netlike sugar and amino acid macromolecule)
Archaea cell wall
No peptidoglycans
Protist cell wall
Highly variable structure
Extracellular matrix structure
Glycoproteins and other carbohydrate containing molecules
Integrins
Fibronectins
Collagen
Proteoglycans
Extracellular matrix function
Tissue support
Tracks for cell movement
Cell signaling
Coordinating behavior between cells in tissues
Integrin
Protein with two subunits embedded in the cell membrane to connect the ECM to the cell
Binds to fibronectins in ECM and microfilaments in cortex
Fibronectin
One kind of extracellular protein that binds to integrins
Plasmodesmata structure
Areas of the cell wall in which the cytoplasm of one cell is directly continuous of that of another
Lined by plasma membrane and filled with cytosol
Plasmodesmata function
Cell to cell communication
Passing macromolecules between cells using
Central desmotubule of ER
Tubules running through the plasmodesmata and connecting to the endoplasmic reticulum’s of adjacent cells
Types of junctions in animal cells
Tight junctions
Desmosomes
Jap junctions
Tight junction structure
Membranes of neighboring cells are fused with the help of proteins
Tight junction function
Cell adhesion
Holds cells together tightly and forms a seal
Prevents leakage of extracellular fluids across a layer of epithelial cells
Gap junction structure
Protein channels lined up between cells (similar to plasmodesmata but no membrane lining)
Gap junction function
Cell to cell communication
Desmosome structure
Plates on the inside of each cell membrane anchored by keratin intermediate filaments
Desmosome function
Cell adhesion
