Week 1B Tissues, Cytoskeleton, and Extracellular Matrix

Appreciate cellular diversity, the role of the cytoskeleton, and the ways that individual cells to come together to form a multicellular organism

cytoskeleton

a dynamic, interlinking network of protein fibers—microtubules, microfilaments, and intermediate filaments

determines the shape of the cell

“the cell’s internal skeleton + transport system”

Extracellular Matrix (ECM)

A network of proteins and molecules outside the cell that provides support, structure, and signaling.

“the environment or scaffold around cells”

What is the basic tissue types in animals

epithelial, connective, nervous, muscle

Microfilaments

Smallest most flexible made up of g-actin forming f-actin that makes a polymer 2 polyers make a double helix of your microfilament

Involved in…

Cell Migration: can change shape of cell to fit between things (ex diapedesis)

Cell Division: pinches 1 cell into 2 during cytokiesis

Cell Extensions: tiny finger-like on cells, makes up microvilli (for GIT) and stereocilia (ear)

Cell Junctions: helps make up adhernis and tight junctions

Muscle contraction: sticks to myosin to create a contraction

Membrane Transport: allow for things that are outside of the cell to come into the cell; helps with endocytosis (bring in) and exocytosis (things out)

Intermediate Filaments

Middle size but the toughest and the most resilient

can maintain the shape of the cell despite compressive forces

prevent cells like cardiac tissue and epithelial tissue from separating apart (cell junctions)

prevent the separation of the epithelium from the dermis

Microtubules

made up of Tubulin dimers

Hollow, “rail-road of the cell”

Function…

Cell shape and support

Cell movement - by cilia (the hair-like shits on eukaryotic cells move fluids (mucus), flagella (tails on the sperm)

Cell division (chromosome segregation) - they are the spindles

Vesicle transport (in neuron)- Kinesin → - to + (heading towards axon terminal) Dynein → − (heading toward nucleus)

Organelle arrangement

Cell Junction: Tight Junction

tightly hold the cells together

acts as a diffusion barrier

@ the apical surface of the cell

Major component: Claudins, occludins

Cytoskeletal attachment: Intermediate filament

Cell Junction: Adherens junction

Resting shearing/abrasive forces

more basial compared to tight

Major component: Cadherins

Cytoskeletal attachment: Actin filiments (Microfilaments)

Cell Junction: Desmosomes

More tensile strength then Adherens

Major component: Cadherins

Cytoskeletal attachment: Intermediate filament

Cell Junction: Hemidesmosome

Major component: Integrins

Cytoskeletal attachment: Intermediate filaments

Cell–extracellular matrix adhesion

Cell Junction: Gap Junctions

Major component: Connexins

Communication between animal cells