reading 17-09- macromolecules

folded proteins are held by

non covalent interactions

protein exposed to certain conditions

it will denature

unfolding due ot

non covalent interactions being disrupted

some proteins can refold once

conditions return to normal

changing the non covalent interactions can affect

how stable a protein is

greater umber of stronger interactions within a protein

makes it more stable

stronger interactions

more stable protein

weaker interactions

less stable protein

why triglycerols are hydrophobic

mostly non polar covalent bonds

triglycerols electrons are

distributed relatively equally, few partial charges

triglycerols are uncharged so

dont interact well with water

tricylglycerols can be packed closely because

theyre stored without water

triacylglycerols are good

energy molecules

the longer chain of hydrocarbon

the more van der Waals

the more van der Waals

more energy required to pull molecules apart —> higher melting point

cholesterol

steroid lipid

anabolic reaction

build larger molecules from smaller

building macromolecules requrires

new covalent bonds

macromolecule synthesis reactions require

input of free energy

macromolecule synthesis is endergonic

products have more free energy than reactants

cells couple an energy requiring reactions with an

energy releasing reaction, allows overall process to proceed

cell membrane main commponent

lipids

phospholipid head

phosphate containing

hydrophilic

polar

phospholipid tails

fatty acid

hydrophobic

non polar

amphipathic

contains nothing hydrophobic and hydrophobic parts

phospholipids in water

form into organized structures

hydrophobic effect

tendency of nonpolar (hydrophobic) molecules or parts of molecules to come together in water.

hydrophobic effects drives

lipid self assembly in water

micelle

lipids with 1 fatty acid form

circular

liposomes

phospholipids can spontaneously form closed bilayer structures

liposomes bilayer can

enclose an aqueous compartment

small disruptions in bilayer can

spontaneously close

exposing hydrophobic tails to water is

energetically unfavourable

membrane fluidity

ability of membrane components to move within membrane

non covalent interactions between lipids can

break and reform

lipids can

move sideways within layer

rotate

fatty acid tail can flex

interactions break/reform

flip flopping

movements between the layers

flip flopping is uncommon, would require

polar head to cross hydrophobic interior

longer fatty acid Tail

more van der Waals interaction

more van der waals interactions in tail

less lipid movement —> less fluid

saturated fats acids are straight

pack tightly —> less fluid

unsaturated tails have kinks

pack less tightly —> more fluid

cholesterol is

amphipathic

cholesterol effect on membrane depends on

temperature

at high temp

phospholpids move more

cholestrol restricts movement

decreases fluidity

at low temp

phospholipids pack more tightly

cholesterol prevents tight packing

increases fluidity

hydrophilic head + water

hydrogen bonds

other polar/charge interactions

hydrophobic tails + water

poor interactions

hydrophobic efect

fatty acid tail + tail

van der Waals

transporters

move substances across

receptors

receive signals

enzymes

catalyse reactions

anchors

connect structures + maintain cell shape

integral membrane protein

permmentatly associated with membrane

embedded in lipid bilayer

peripheral membrane proteins

temporarily associated with membrane

interact with lipid head or integral membrane proteins

help by weak non covalent interactions

bilayer interactions within membrane

hydrophobic amino acids

interact with hydrophobic fatty acid tails

hydrophobic effect + van der Waals interaction

bilayer interactions at membrane surface

polar/chagred amino acids

interact with water and polar head

hydrogen bonds + other polar/charge interactions

fluid mosaic model

membrane is dynamic not rigid

fluid

lipids and many proteins can move laterally within membrane

mosaic

membrane contains many different components