Cell Membranes Flashcards
what are eukaryotes
cell that have genetic material contained in a membrane bound nucleus and also contain a number of membrane bound organelles such as mitochondria and chloroplasts
What are prokaryotes
Organisms including bacteria that have few organelles and do not have genetic material contained in a membrane bound nucleus
What are organelles
sub celluar bodies found in the cytoplasm if cells
What do cell surface membranes do
controls what passes into and out of the cell and allowing the fluids wither side of it to have different compositions
What do membranes within cells do
makes it possible to have the right conditions for a particular reaction in one part of cell and different conditions to suit other reactions elsewhere in the same cell
Why do cell membranes have to be flexible
to allow the cell to change shape very slightly as its water content changes
What is the membrane made of
lipids and proteins
the lipids in the membrane are of what particular type
Polar lipid
What are polar lipids
lipids with one end attached to a polar group
how do phosoplipids form a bilayer
the hydrophillic heads point into the water and the hydrophobic tails stay protected in the middle.
What does a simple lipid bilayer do
allows fat solubale organic molecules to pass through it
Why can vital chemicals pass through cells
because the membranes consist of proteins and other molecules
Why does the proportion of
phospholipids contaning unsaturated fatty acids in the bilayer affect how freely the moving proteins about in the membrane
many of the proteins have a hydrophobic part which is buried in the lipid bi layer and a hydrophilic part which can be involved in a variety of activities
Wha can cell membrane proteins act as
specific receptor molecules e.g making cells sensitve to a particular hormone
What are vesicle
membrane ‘bags’ that hold secretions made in cells.
