Movement in and out of cells Flashcards
Why do substances have to go in & out of cells?
For cells to survive, they need to be able to exchange materials between themselves and the environment.
How do nutrients get into our cells and wastes get out?
They must cross the plasma membrane.
Diffusion
the random movement of gas or dissolved molecules from higher to lower concentration
SIMPLE DIFFUSION there is __ energy required
no energy required
what is the plasma membrane
- is the boundary that separates the living cell from its nonliving surroundings
- controls the movement of substances entering and waste products to leave.
- is able to change shape easily, grow and expand.
Plasma Membrane is called a
- selectively permeable
- partially permeable
- differentially permeable
- semipermeable membrane
Plasma Membrane is made up of
• two layers of phospholipids
also known as a phospholipid bilayer
why are plasma membranes known as Fluid Mosaic Models?
- as the membrane is like oil, and mosaic because it has proteins and carbohydrates moving around in this oily liquid.
what does the steroid cholesterol have effects on?
membrane fluidity
Hydrophilic?
‘water-loving’ heads that are attracted to water.
Hydrophobic?
‘water-repelling’ tails will
orientate themselves away from water.
what is a plasma membrane made of?
two layers of lipid molecules come together to form a BARRIER
A range of different proteins are?
- embedded within the membrane.
- rest on the surface or
- penetrate throughout the whole membrane
Transport proteins ?
which have openings on both sides of the membrane, forming channels, that allow some substances to move through the membrane
Receptor proteins ?
these bind hormones & other substances that cause changes to the cell’s activities
Recognition proteins ?
these attach to carbohydrate molecules and act as markers, called ANTIGENS which allow the immune system to distinguish between ‘self’ and foreign invaders
Adhesion proteins ?
link cells together
Osmosis?
diffusion that only involves the movement of water molecules
What does osmosis occur across?
a semipermeable membrane which has tiny holes in it which are small enough for water molecules to pass through but larger molecules cannot pass through.
Where do water molecules move from?
a region of high water concentration to a region of low water concentration across a semipermeable membrane
What is the movement of water molecules affected by?
the concentration gradient of dissolved substances (SOLUTES) or the concentration of water molecules.
what __ energy does osmosis require?
no energy , no atp
Isotonic Solutions?
- The concentration of solution is the same outside as it is inside the cell
- There will be NO NET movement of WATER
Hypertonic Solution?
- The concentration of solutes is greater outside the cell than it is inside the cell
- The cell will lose water and Shrink.
What is Crenation ?
when an animal cells Shrink in a Hypertonic solution
Plasmolysis?
when a plant cell loses water→ cytoplasm will pull away from cell wall → cytoplasm shrinks.
Hypotonick Solutions
- The concentration of solutes outside the cell is less than it is inside the cell
- The cell will gain water
What happens when a plant cells are in a HYPOTONIC solution?
the cell wall will stop the plasma membrane from bursting
What happens when a red blood cells are in a HYPOTONIC solution?
it will take in water until it swells and bursts. This is known as HAEMOLYSIS
Facilitated Diffusion?
it is diffusion when large molecules need to move across a plasma membrane the process of diffusion requires the assistance of other molecules such as as proteins eg. glucose
what is the function of Channel proteins ?
- provide corridors that allow a specific molecule or ion to cross the membrane
What is the function of Carrier proteins?
bind to molecules or ions on one side, change shape & release the particular molecule/ion on the other side.
What is active transport?
It is when Sometimes substances move into cells from a low outside concentration to a high internal concentration
- Active transport needs energy to make it happen. The cell uses ATP (Adenosine Triphosphate)
how do minerals enter the root cell?
- Minerals enter a root cell by active transport.
- The plant uses energy to move minerals up the concentration gradient from the soil into its root cells.
ENDOCYTOSIS ?
is the movement of very large particles INTO a cell
PHAGOCYTOSIS ?
is the ingestion of large solid particles INTO the cell
PINOCYTOSIS ?
is the ingestion of liquid particles – known as ‘cellular drinking’
Exocytosis
vesicles transport molecules OUT of the cell
In diffusion where does it occur and what is transported and is energy required?
Bilayers of phospholipids , lipid soluble molecules , no energy
In osmosis where does it occur and what is transported and is energy required?
Bilayers of phospholipids , water and solvent, no energy
In facilitated diffusion where does it occur and what is transported and is energy required?
carrier proteins and protein channels , water and large molecules, no energy
In active transport where does it occur and what is transported and is energy required?
carrier proteins , glucose and specific molecules, yes energy
