plasma mebrane and organelles Flashcards
what are the 5 key functions of cells
- Manufacture cellular materials
- Obtain raw materials, often from outside the cell brought inside
- Remove waste from outside of the cell or destroy it
- Generate the enrgy required to poerform different tasks
- Control over the fuctions
what are the key functions of the plasma mebrane?
- Semi permeable barrier
- Allows passage of oxygen, nutrients, waste, all come from outside of the cell or to be moved inside or outside e.g. waste expelled
- Controls movement of substances in and out of the cell, distinguishes what should and shouldn’t come in
what is the effect of surface area on the cell
the ration of the volume of the inside of the cell to plasma membrane is very important, a bigger cell is less functional as the molecules must travel further thus a smaller cell is more efficient
the plasma mebrane controls how big a cell can get
what is the structure of the plasma membrane?
hydrophyllic phospahte groups on the outside, with hydrophobic tails, inside has another layer of phospholipids with hydrophyllic heads and hydrophobic tails
what is the effect of a saturated plasma mebrane?
: when it is saturated it is tightly packed together resulting in less fluidity and makes the mebrane really viscous and makes it very difficult to allow movement in the space inside and out., when it is unsaturated the tails prevent tight packing which means there is more fluidity, prevent phospolipids from packing in tightly together
what is the effect of temperature on the plasma membrane?
high temperatures result in more fluidity, low temperatures result in less fluidity
what is the effect of cholesterol on the plasma membrane
cholesterol stabilises the membrane fluidity, stops it from being too viscous or too fluid
what are the functions of plasma membrane proteins?
determine the function of the cell as there are thousands of different types of membrane proteins, often specific to a cell type with different proteins all with different functions (each cell can have many different types of membrane proteins)
what is signal transduction?
Relay messages and coordinatwe functions from the body or environment into the cell. The signalling molecule is a messgae for the cell to do something eg, divide, grow, move, make soemthing, die
This message must be relayes into cell, the receptor passes from one protien to another and so on until the function is completed
what is cell recognition?
Often involves glycoprotiens, immune system uses this to find viral cells and attacm if they don’t want it near and draw it in if they do etc
what is intercellular joining?
some proteins in once cell attach to a protein in another cell and can form long term connections between these cells.
why do proteins link cytoskeleton and Extra cellular matrix
this allows cells to physically attach to protein structures outside the cell to connect and anchor to other things outside the cell
what is diffusion?
diffusion is a form of passive transport where molecules move down their concentration gradient , membranes are permeable to hydrophobic lipid soluble molecules such as gases and steroid hormones, membrane restricts free movement of water soluble and charged moleculessuch as glucose, ions and water which cannot freely enter due to the hydrophobic phospholipid tails
what is facilitated diffusion?
also passive transport. movement of hydrophyllic molecules require membrane proteins which are either channels or carriers.
allow specific molecules or substances down the concentration gradient
although no energy, some channels open of close in responce to signals
e.g. osmosis moving water across the cell membrane is facilitated by specific channels called aquaporins
what is active transport?
requires transport proteins that are carriers requiring ATP,
move specific substances across their concentration gradient so has to be forced across using carriers and energy, there are specific shaped carriers for specific molecules
e.g. sodium potassium pump which requires active transport to regulate levels of each of these molecules inside the cell
what is co - transport / indirect active transport?
uses atp but not where the sunstance is being moved
we have to create tge concentration gradient
e.g. sucrose needs hydrogen ti come in with it as the hydrogen is being moved down the concentration gradient so we create the concentration gradient in order for the hydrogen to get in by using a different membrane protein to force them out using ATP
