week 1 Flashcards
L1-4
what are membranes made up
phospholipids
what are phospholipid polymers made up of
fatty acids, glycerol, phosphate and a terminal amine or alcohol group
define amphipathic and how it relates to phospholipids
a molecule with a polar and non-polar part
phospholipids have a non polar head and polar tail
what is the basic structure of a phospholipid
fatty acid tail and phosphate head
what is the result of being an amphipathic molecules
they form monolayers and bilayers
difference between a monolayer and bilayer
monolayer is singular, bilayer is a double layer of closely packed molecules
4 main important reasons for membranes
- to compartmentalise metabolic activities
- the separate and protect cellular components
- to provide a scaffold for signalling
- as a medium for cellular energy generation
what are the key properties of membranes
the ability to prevent exchange between compartments
w hat is diffusion driven by
chemical ad electrical gradients
what is generated by the ion imbalance across the membranes
biological energy, a process of bioenergetics
what is the importance of membrane transport
- prevents metabolic reactions within cell
from the environment - communicates and exchanges materials
- transport proteins in cell membrane allow for controlled interaction of the cell with the environment
what is the permeability of small hydrophobic molecules
high, eg for gases like O2
what is the permeability of water molecules
limited
what is the permeability of ion molecules
very low eg K+
what is the permeability of large solutes
very low
what do transport proteins create
a hydrophilic passage and a filter
provides possibility for energy coupling and regulation
how does facilitated diffusion work
transport proteins create a hydrophilic pore, molecules diffuse through this pore
what are the driving forces for solute transport
chemical gradient = conc gradient
electrical gradient = charge gradient
define electrochemical gradient
net driving force for the movement of a molecule resulting from the combination of the chemical and electrical gradient
what methods of movement are used in active transport
pumps and cotransport systems
what methods of movement are used in passive transport
channels and carriers
how do the pumps in the membrane work
ATPases consume ATP
pumps which allows the conformational change of the protein
what are plants primary pumps and role
proton pumps, used to export H+ out of the membrane ( so creates a ph gradient and electrical gradient)
what is a co-transport system
a system that couples the downward movement of one ion driver to the uphill movement of the substrate
what are the benefits of co-transport systems
they enable active transport without ATP, by using pre-established gradients
what is a symport co-transport system
the driver ion and substrate move in the same direction
what is an antiport co-transport system
the driver ion and substrate move in opposite directions
what are the common driver ions in plants and animals
sodium in animals, protons in plants
how important is transport coupling
is it extremely common, and is inherent to all forms of life. it occurs in different cells and organelles
how does passive transport work
moves substances down an electrochemical gradient
the channels provide an aquous pore for the passage of ions
the carrier channels undergo conformational change that exposes ion binding sites to different sides of the membrane
what are ion channels
not just pores, they exert a tight passage of control, they are selective and gated
