ch 14 actin motor and cell motility & ch 15 intraxellular junction and extracellular matrix

skeletal muscle movement is done by

thick filaments (myosin) and thin filaments which is actin

sarcomeres are surrounded by

beta actin filaments

when the muscle contracts the thick and thin filaments come together making the ____ shorter

sarcomere

thick filament is made of a lot of ___ ___ and are all independent from each other

myosin heads

when there is a contraction of the muscle the _____ (btwn actin and myosin) is smaller

H zone

Describe the myosin cycle

1. cross-bridge formation

2. Pi released

3. power stroke; myosin undergoes a conformational change

4. ADP is released

5. ATP binds myosin, causing detaching of myosin from actin; cross brodge dissociates

6. ATP hydrolysis occurs cocking myosin

regulation of contraction is done by

tropomyosin

___ sits on top of actin and blocks where myosin is going to bind

tropomyosin

Describe the regulation of contraction of the skeletal muscle

TnT is bound directly to tropomyosin. once there is high amounts of calcium, the calcium will bind to TnC and that will cause a conformational change. the tropomyosin will moved away from binding site and myosin can bind now.

smooth muscle is made of

intermediate filaments

the regulation of smooth muscle does not have

tropomyosin

describe the regulation of smooth muscle

1. calcium ions triggered by nerve impulse or hormonal signal go into the cytosol

2. calcium bonding activates

3. calmodulin binds myosin light-chain kinase and activates it

4. myosin light-chain kinase phosphorylates myosin light chains and myosin is activated

5. dephosphorylation happens right after it’s phosphorylated

forward cell motility is done by

microfilaments polymerization

backward cell motility is done by

motor protein

epithelial cells attach to a basement membrane of extracellular matrix on base of their

basolateral membrane

T or F connective tissue forms a lot of cell-cell attachments

F. It does not

Most connective tissue cells make extensive contact with their

extracellular matrix

cell-cell junction types

tight, gap, adherens and desmosomes

cell-cell junctions are used for

recognition, communication and attachment

tight junction is done by the transmembrane

claudin

___ forms a barrier between cells and defines interior and exterior of the epithelial cells

Claudin

T or F the tight junctions on the epithelial cells allow for transport between the cells

F. it does not allow it

gap junctions are found in the

cardiac muscle

the intercalated disks in the cardiac muscle is made of a lot of

gap junctions

___ ___ allow for soluble molecules filled with water to pass through

gap junctions

___ are transmembrane proteins interacting with each other

ex: cadherins to cadherins

adherins

the interaction between cadherins is ___ dependent

Ca++

cadherins bind to catenins p120, alpha and beta which binds to

microfilaments

desmosomes are transmembrane proteins in adjacent cells that interact with each other. they are called

desmosomal cadherins

2 types of desmosomal cadherins are

desmocollin and desmoglein

the desmosomal cadherins attach to catenins which bind to

intermediate microfilaments

3 types of catenins are

plakophilin, plakoglobin and desmoplakin

connective tissue is made of

loose, dense, cartilage, bone and blood

fibroblast make

loose and dense connective tissue

chondrocytes make

cartilage

matrix is made of proteoglycans which have many o-linked polyssaccharides called

glycosaminoglycans

most of the amino sugar in glycosmainoglycans have a __ group attached

sulfate

Because glycosaminoglycans have sulfate attached that attracts a sodium which attracts

water

collagen provides high-tensile strength and is organized into

fibrils and sheets

fibronectin are produced by alternate splicing of the

mRNA

fribronectin possesses multiple binding sites for other components of the ECM which help cell

anchor

laminin has multiple ___ ___ for other ECM components

binding sites

the cell- ECM junctions are

hemidesmosomes, focal adhesions, and costameres

integrins are transmembrane heterodimers capable of binding ECM proteins such as

fibronectin or laminin

integrins bind directly to ___ ___ in the cytosol

cytoskeletal proteins

different combinations of ___ and ___ subunits provide different binding specificities

alpha, beta

integrins anchor and make the framework more ___

rigid

focal adhesions are found in motile cells such as ___ and non-epithelial cells

fibroblast

focal adhesions is a cluster of integrins that bind ___, ___, _____ and bind directly to microfilament bundles

talin, viculin and alpha actin

focal adhesions provide attachment points between ___ ___ the responsible for movement and the surrounding tissue

cytoskeletal proteins

hemidesmosomes are found in ____ cells as they attach to extracellular matix

epithelial

hemidesmosomes are a cluster of ___ and ____ bind to plakins which bind directly to intermediate filaments

integrins, BPAG2

hemidesmosomes provide strong connections in ___ and ___ ____

skin, mucus membrane

lectins are proteins that bind to

carbohydrates

____ mediate attachment between leukocytes and vascular endothelial cells and the leukocytes migrate along the wall of the blood

selectins

inflammatory mediators trigger the leukocytes to adhere more strongly using ___ attaching immunoglobulin-like Cell Adhesion Molecules

integrins

when the leukocytes are attached to integrins, they are able to

squeeze though and migrate toward the site of inflammation

Costameres are found in

striated muscle cells

costameres are located on the ___ in alignment with Z discs

sarcolemma

Costameres connect contractile proteins in the muscle cells directly with _____ ____ and with the surrounding extracellular matrix

plasma membrane

integrins and dystroglycans bind ___, ____, ___ plus ____ which directly bind microfilaments

talin, vinculin and alpha actinin plus dystrophin

dystroglucan also bind laminin

extracellularly

if there is a mutation on dystroglycan it will cause

muscle dystrophy