e2 cell bio

epithelial tissue

cells lined up side by side, usually outside of organs and attached to EM on their basal lamina side

connective tissue

cells scattered throughout the ECM & ECM fills the space btwn cells

extracellular matrix

composed of fibers, proteins, and water

functions of the ECM

support, adhere, movement, & regulation

collagen

protein that makes fibers that spread throughout the ECM

functions of collagen

provide structural support, reduce tension & stress, hold connective tissue together

structure of collagen

3 alpha helix chains bound very tightly together due to glycine amino acids every 3 amino acids

ground substance

amorphous gel-like substance that is composed of water and proteoglycan aggregates

functions of ground substance

forms gel-like matrix that allows cells/fibers to embed

acts as a protective barrier

lubricates the cell from drying out

adhesive platforms for cells to migrate

provides solid yet fluid medium

proteoglycan

a core protein w/multiple glycoaminoglycans (GAGs) that are covalently attached to the core protein

glycoaminoglycans (GAGs)

a highly hydrophilic carbohydrate that is made up of repeating disaccharide units. GAGs are about 70-200 sugars long

functional groups added onto GAGs

carboxyl, sulfate, & hydroxyl

their charges make it easier to bind

Proteoglycan aggregates

a lot of proteoglycans link to a central hyaluronic acid. Proteoglycans link non-covalently to the central hyaluronic acid

hyaluronic acid

made with beta glycosidic linkages making them very rigid and they are very long so they can attach to many proteoglycans to make a big proteoglycan aggregate

integrins

cell surface glycoproteins that act as receptors for the ECM

main role of integrins

attach a cell to the ECM

active integrin

talin attached to it

basal domain

side of the epithelial cell that is facing the ECM and connective tissue

lateral domain

part of the epithelial cell that is facing other epithelial cells to the sides

apical domain

side of the epithelial cell that is facing the space

basolateral domain

proteins can move across basal and lateral & tight junctions are the only restrictions

tight junction

Found on very top of apical side, goes all the way around the cell

protects cell from outside

occluding jucntion

tight junction that seals the gap between epithelial cells to regulate permeability

claudins

proteins interacting w/each other in between cells to create a tight junction

adhering junction

anchoring junctions that either anchor a cell to cell or anchor cell to ECM

cadherin

protein in adhering junction

cytoplasmic domain of cadherin attached to the MF cytoskeleton that anchors to the MF cytoskeleton on another cell

communicating junctions

create a hydrophilic channel between cells for exchange of materials

connexon

6 connexins & regulates whether the junctions are open/close

proteins tight junctions use

occludins and claudins

adherens junctions proteins

cadherins

desmosomes

anchoring junctions that anchor two cells together and act as little screws that meet in between cells to strengthen their stability

use cadherins

gap junctions

allow direct diffusion of ions and small molecules between adjacent cells

use connexons

plasmodesmata

form of gap junction found in plant cells & are formed from the ER

focal adhesions

attach to epithelial cells to the ECM & use integrins to do this

junctions that are associated with MFs

tight, adherens, focal

junctions that are associated with intermediate filaments

hemidesmosomes, desmosomes

junctions that are associated with MTs

plasmodesmata associate

occluding junction involved in

regulating the permeability of the tight junction by adding more claudin or different types of claudin

transcellular route

material going through the cell

paracellular route

material going around the cell btwn the cracks

2 junctions that anchor 2 cells together

adhering junctions & desmosomes

2 junctions that anchor cells to the ECM

focal adhesions & hemisdesmosomes

belt-like adhesive junction

adhering

disc-shaped adhesive structures

desmosomes

cell wall

rigid layer of polysaccharides used by plant and fungi that surround the plasma membrane

cell wall functions

provides tensile strength, protection against mechanical & osmotic stress

what goes through the cell wall?

plasmodesmata goes through to form a gap junction btwn plant cells

functions of cell membranes

compartmentalization

scaffolding for biochemical activities

selectively permeable barrier

responding to external signals

intracellular interaction

energy transduction

fluid mosiac model

refers to a mosaic of components like carbs, cholesterol, proteins, and phospholipids that give the membrane a fluid character to move laterally

cholesterol

rigid, flat planar rings that have hydroxyl groups attached making them slightly amphipathic

cells change membrane permeability by

changing the amt of sat/unsaturated membranes to amt of cholesterols

more unsaturated FA in membrane,

more fluid

membrane fluidity depends on

how well proteins are able to move throughout the membrane and affects the permeability of the membrane

integral membranes

span the entire membrane. one part inside the cell, one in the membrane, one outside the membrane

peripheral proteins

associated w/one side of the membrane through noncovalent interactions w/integrated proteins or the lipid bilayer

lipid-anchored proteins

proteins that are covalently linked to a lipid in the membrane

transmembrane domain

domain of the integrated protein that is within the lipid bilayer of the membrane

glycoproteins

oligosaccharides attached to peripheral proteins

glycolipids

oligosaccharides attached to the polar ends of the phospholipid molecule in the outer membrane

glycocalyx

layer of carbs that are attached to proteins on the outer membrane

diffusion

net directed movement of molecules driven by thermal energy that move down an electrochemical gradient

passive transport

requires no additional energy

facilitated diffusion

passive movement of particles across the plasma membrane with the help of transport proteins embedded within the membrane

channel-mediated diffusion

large molecules use a channel protein to pass through the membrane

creates hydrophilic channels for specific molecules to pass through after binding to receptor to open the gate

ion channels

gated protein channels that cause a rapid movement of ions across a membrane

transporter-mediated diffusion

help large hydrophilic molecules across a membrane & these molecules are too large for the hydrophilic channels of the channel proteins

Active transport

passes molecules through the membrane against their gradient using the fuel of ATP hydrolysis

primary active transport

uses direct fuel of ATP to move across a membrane

secondary active transport

piggybacks off another molecule’s gradient to move across a membrane

electrochemical gradient

takes into account 2 things for whether an ion or molecule crosses a membrane

concentration and charges

easiest molecules to diffuse

hydrophobic. CO2, O2, N2

small, uncharged polar molecules that diffuse

water and glycerol sneak through the gaps

large, uncharged, polar molecules

use facilitated transport like glucose or sucrose

tonicity

the ability of an extracellular solution to make more water move into or out of a cell by osmosis

osmosis

the diffusion of water across the cellular membrane

isotonic

the solute concentration inside and outside the cell is the same so water will not diffuse anywhere and the cell will remain the same size.

hypertonic

when the solution has a higher solute concentration than the cell. So water (the solvent) will leave from the cell to the solution

hypotonic

when a solution that the cell is in has less of a concentration than the cell so water will diffuse out of the solution into the cell causing the cell to swell

osmoregulation

the process by which the cell regulates how much water it has in it compared to its outside environment

carrier proteins

materials that are too big for hydrophilic channels & require molecules to bind to undergo conf change to push molecule thru membrane

GLUT

aquaporins

channel proteins that allow water molecules through in a single file manner

acetylcholine receptor

gated ion channel for Na & binds to the receptor on the channel to open the ion channel and causes Na to flood into the cell causes muscle contractions

lysosome

membranous sac of hydrolytic enzymes that can digest macromolecules and worn out organelles

autophagy

breaks down things inside the cell

ribosome

makes proteins, translates DNA, free & rough ER ribosomes

smooth ER

no ribosomes, makes lipid hormones, carbs, stores Ca, detoxifies poisons, medications, & alcohols

rough ER

contains ribosomes, makes phospholipids, proteins, & modifies proteins

glycosylation