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EXAM2 Chapter 5A: Cell Membranes - Coggle Diagram
EXAM2 Chapter 5A: Cell Membranes
How do we know about cells?
Technology enables discoveries (late 17th century microscope) --> humans draw the implications (Theodore Harvey, mid 18th century)
Why are all living organisms composed of cells?
Define a place where living things can do the processes of life
store/use information
store/use energy sources
make things happen in a non-random way
A place that can be copied/propagated through time
cells divide and divide and divide and divide
A place that's different from the surrounding environment - need a barrier
to keep some things out/some things in
to do things and make things happen
membranes also used for transformation of energy and info (ATP synthase; G-Protein coupled receptor)
Cell membranes are a mix of lipids, proteins, carbohydrates
lipid bilayer
Phospholipids
are AMPHIPATHIC: has BOTH polar heads and nonpolar tails
have SHAPE
saturated (cone shape): NO double bonds, straight tails, make micelles
micelles: lipids with bulky heads and ONE tail are wedge-shaped, pack into spherical structure
unsaturated (cylinder shape)
Phospholipids with unsaturated tails form DOUBLE membranes
Phospholipids shape influences shape that comes from interaction with water: liposomes
liposome: an enclosed spherical bilayer structure spontaneously formed by phospholipids in environments with neutral pH (i.e. water)
liposomes are aqueous INSIDE
proteins: transport vesicle
carbohydrates: outer surface on the membrane
Membranes are not static - they are FLUID
continual movement of lipids, what controls fluidity?
temperature
higher temp: MORE fluid
lower temp: LESS fluid
Ratio of saturated vs. unsaturated tails
Van Der Waals are strongest when they're closer together (STRAIGHT TAILS ARE MORE TIGHTLY BONDED)
unsaturated: MORE fluid
saturated: LESS fluid
Length of fatty acid tails
Van Der Waals: the longer the tail, the more chances to interact, more tightly bonded
long: less fluid
short: more fluid
Cholesterol stiffens membranes
cholesterol sits in spaces between unsaturated lipids, fill up space, tighten membrane
Membranes are stuffed with proteins
Integral membrane proteins
include transmembrane proteins that span the entire membrane
3 regions: transmembrane, extracellular, cytoplasmic
Peripheral membrane proteins
temporarily associated with either the internal or external side of the membrane (ATTACHED to membrane, NOT IN the membrane)
holding on tightly to the membrane by hydrophobic regions
Membrane proteins could be a: transporter, receptor, enzyme, anchor
