Form and function: Cells Flashcards
Osmosis
Net movement of water across a partially permeable membrane from an area of lower solute concentration to an area of higher solute concentration
Diffusion
The net movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient
This directional movement along a gradient is passive and will continue until molecules become evenly dispersed
Only small and non polar molecules will be able to freely diffuse
integral proteins
proteins that penetrate the phospholipid bilayer to remain permently attached to the membrane
these trans membrane proteins cannot be readily isolated without disrupting the bilayer
Peripheral proteins
Only temporarily linked to the membrane
are either attached to integral proteins, linked to polar phospolipid heads or held by the cytoskeleton
Membrane proteins
What does JETRAT stand for in membrane transport?
Junctions
Enzymes
Transport
Recognition
Anchorage
Transduction
Membrane proteins
Junction
serve to connect and join two cells
Membrane proteins
Enzymes
fixing to membrane to localises metabolic pathways
Membrane proteins
Transport
Responsible for facilitated diffusion and active transport
Membrane proteins
Recognition
Many functions as markers for cellular identification
Membrane proteins
Anchorage
attatchment point for cytoskeletons and extra celluar matrix
Membrane proteins
Transduction
function as receptors for peptide hormones
Aquaporins
Channels that allow the passage of water but not other substances
Faciliated diffusion
the passive movement of molecules across a cell membrane via the aid of a membrane protein. used by molecules that are unable to freely cross the phospholipid bilayer
Chanel Proteins
have tiny pores which act as pathways for ions
these chanels are highly selectie due to the binding sites of the hydrophilic amino acids side chains lining the chanels being highly specific and the size of a pore
What are some stimuli for gated chanel proteins?
changes in voltage across the membrane (voltage gate chanels)
binding a small molecules to the channel protein (ligand-gated channels)
mechanical forces
Carrier proteins
bind to solute molecules
undergo a comformational change
transfer molecules to the otherside of the membrane
Active transport
uses ATP to move molecules against a concentration gradient
Membrane transport
Protein pumps
used to move molecules against the contration gradient
Direct active transport
where the energy released by a reaction is used for directly for active transport
Process of direct active tranport
a specific solute will bind to the protein pump on one side of the membrane
the hydrolysis of ATP causes a comformation change in a protein pump
the solute molecule is translocated across the membrane
Indirect active transport
where the movement of one solute down it’s concentration gradient drives the movement of the second solute against it’s concnetration gradient
Functions of Glycoproteins/glycolipids
Cell recognition
act as markers and help regonise each other, it also helps the immune system regonise forgein cells
Functions of Glycoproteins/glycolipids
Cell adhesion
both glycolipids and glycoproteins help cells attach and bind to other cells to form tissues
Functions of Glycoproteins/glycolipids
Cell signalling
they act as receptors for an enzymes and other molecules in helping in cell signalling
Glycolipids
they are attached to the phospholipids/fatty acid chains
they are amphipatic (hydrophobic and phylic at the same time) - the carbohydrate group of these molecules are polar and extend into the extra cellular enviroment and the nonpolar lipid is in the bilayer
Glycoprotein
the covalent bonding of short carbohydrate chains to the protein molecules results in formation of glycoprotein. the carbohydrate groups of the glycoproteins often stick out into the extracellular enviroment
Glycocalyx
the sticky layer formed y carbohydrate group of the gycolipids and glycoproteins that protrude from the cell surface. Glycocalyx in addition to its roles in cell signalling, cell adhesions, and cell recognition, helps in protecting the cell surface
