2. cell surface membrane Flashcards
what is number 1?
glycolipid
what is number 2?
carbohydrate chain
what is number 3?
extrinsic protein
what is number 4?
glycoprotein
what is number 5?
cholesterol
what is number 6?
Phospholipid
what is number 7?
channel/transport protein
label the structure from top to bottom?
- phosphate group
- phosphoester bonds
- glycerol
- ester bond
- fatty acids
what is the function of the cell surface membrane?
- controls which substances enter and leave the cell (partially permeable membrane)
- membranes allow recognition by other cells
- site of cell communication (cell signalling)
Are all organelles in plant and animal cells membrane bound?
yes
what is the function of membranes within cells?
- separates the content from the cytoplasm
- can form vesicles to transport substances through the cytoplasm
- allowing selected molecules to enter and leave the cell
- a site for biochemical reactions
- allows the organelle/cell to change shape
- provides attachment site for enzymes
what is this called?
phospholipid bilayer
what is the head? (water)
hydrophilic. It attracts water
what is the tail? (water)
hydrophobic. It repels water
what does the membrane not allow through it via simple diffusion?
water-soluble substances
(fat-soluble substances can travel through the the membrane via simple diffusion down a concentration gradient)
why can’t water and lipids mix?
water and lipids can’t mix because lipids can not form hydrogen bonds with water
what is this called?
Micelle
what is this called?
Bilayer
Do you know this?
what are the different types of intrinsic proteins?
- channel proteins
- carrier proteins
- glycoproteins
what are the different types of extrinsic proteins?
- peripheral proteins
how does diffusion occur through the membrane?
diffusion occurs through the membrane by moving from a high to low concentration. Down a concentration gradient
channel proteins
- form (water-liking) pores/channels in the membrane
for charged particles (smaller ions and polar
molecules) to diffuse through. - Down their concentration gradient.
- Different channel proteins facilitate the diffusion of
different charged particles.
carrier proteins
- moves large molecules (including polar
molecules and ions) into or out of the cell. - Down their concentration gradient.
- Different carrier proteins facilitate the diffusion of
different molecules. - Carrier proteins change shape when a specific
molecule binds.
glycoproteins
- Glycoproteins are intrinsic proteins with an
attached carbohydrate chain. - Stabilise the membrane by forming
hydrogen bonds with surrounding water
molecules. - They are also sites where drugs, hormones
and antibodies bind – cell recognition. - They act as receptors for cell signalling.
- Cell adhesion.
glycolipids
- Glycolipids are lipids with an
attached carbohydrate (sugar)
chain. - Act as receptor molecules
- They act as cell markers or
antigens. - Can be recognised by the cells of
the immune system as self (cells
of the organism) or non-self (cells
from another organism).
got it ;)
what are extrinsic proteins involved in?
- Cell signalling
- Cell recognition
- Act as receptors for other molecules e.g. hormones
Cholesterol
- Cholesterol is a type of lipid.
- It is present in all cell membranes (except
bacterial membranes). - Cholesterol molecules fit between
phospholipids. - This makes the membrane less fluid and
more rigid, therefore stabilising the
membrane.
why is cell fluidity essential?
Phagocytosis
what is cell signalling?
- Cell signaling is how cells communicate with each other.
- Cells need to communicate with each other to control processes inside the body and respond to changes in the environment. E.g. low blood glucose levels.
Receptors in the cell surface membrane
- Proteins in the cell surface membrane (e.g. glycoproteins act as
receptors for the messenger molecules e.g. drug/hormone. - They are called ‘membrane bound receptors’.
- Membrane bound receptors have a specific shape so only
messenger molecules with a complementary shape can bind to
them. - A cell that can respond to a particular messenger molecule is
called a ‘target cell’.
what is the model of the cell surface membrane called?
fluid mosaic model
