bio exam 2 Chapter 11 cell cell interactions

cell walls in plants

long strands of cellulose and other gelatinous polysaccharides

middle lamela

plant cells are glued together by this.

plasmodesmata

plant cells are connected by gaps in their cell walls called

extracellular matrix ECM

most animal cells secrete the extracellular matrix, collagen (protein) and the ground substatnce is made of proteoglycans

Animal cells have a variety of membrane proteins that attach cells together

tight junctions- seal cells together

desmosomes-connect the cytoskeletons of cells\

gap junctions-act as channels between cells

how do distant cells communicate

neurotransmitters

horomones

neurotransmitters

open or close channels in distant cells

horomones

information carrying molecules

• secreted from a cel

• small moloecules (peptides steroids)

• acts on target cells far from the signaling cell

Binds to signal receptor moelucles, receptors change shape and activity after binding

Lipid soluble signaling molecules

diffuse across plasma membrane

receptors are in the target cells cytoplasm

like estrogen and cortisol

lipid insoluble

do not cross the plasma membrane, have to be recognized at cell surface

bc cannot diffuse across plasma membrane, bind to receptors on the membrane, signal that arrives produces intracellular signal, triggers signal transduction

message may be amplified as signal changes

Signal transduction systems

g-protein coupled receptors , initiate production of inracellular second messengers, amplify signal

enzyme linked recpetros- phosphorylate proteins inside target cell

g protein coupled receptors

trans membrane receptors that work with the help of a g protein

when activated by a signal receptor they trigger the production of a second messenger

regulated by guanine nucleotides

second messengers

small molecules that diffuse rapidly throughout the cell

produced quickly

some second messengers activate protein kinases

enzyme linked receptors

Receptor tyrosine kinases (RTK’s) best known group of enzyme linked receptors

-are trans membrane proteins.

directly catalyze a reaction inside the cell

signal response

change in which genes are being expressed in the target cell

change in the activation or deactivation of a particular target protein that already exists in the cell