Cell Science - Cellular Process 1 & 2 Flashcards
What does intracellular mean?
Within the cell
What does Extracellular mean?
Between the cells
E.g in blood vessels = plasma
What does solvent mean?
It’s the liquid doing the dissolving
What does solute mean?
It’s the dissolved material (particle or gas)
What does concentration mean?
It’s the amount of solute in a given amount of solvent
What does Concentration Gradient mean?
It’s the Difference in concentration between 2 area of solution
What does selective permeability mean?
Allows a living cell to maintain different concentrations of certain substances on either side of plasma membrane
What does concentration gradient mean?
Difference in the concentration of chemical from one place to another
- From inside to outside of plasma membrane
What is the Electrical gradient?
Difference on electrical charge between two regions
What is membrane potential?
It’s the electrical gradient that occurs across the plasma membrane
Why is the concentration gradient and electrical gradient important?
They are important because they help move substances across the plasma membrane
What is the electrochemical gradient?
It’s the concentration gradient and the electrical gradient on movement of a particular ion
What is the electrochemical gradient?
It’s the concentration gradient and the electrical gradient on movement of a particular ion
Name 4 types of movement across the membrane
- Passive transport
- Active transport
- Endocytosis
-exocytosis
Name 3 types of passive transport
- Simple Diffusion
- Facilitated Diffusion
- Osmosis
What is diffusion?
It’s a passive process involving the random mixing of particles in a solution due to a particles kinetic energy
What factors affect Diffusion?
- steepness of the concentration gradient:
- Temperature: higher temp means faster diffusion
- Mass of diffusing substance: larger mass of diffusing particle, slower diffusion rate
- Surface area: Larger membrane area, faster the diffusion
- Diffusion Distance: Greater distance the longer it takes
Describe Simple Diffusion
- No energy required
- Moves due to gradient: difference in concentration, pressure, charge
- Moves to equalize gradient: High moves toward low
- Depends on lipid soluability
What is Facilitated Diffusion?
It’s when solutes are too polar or highly charged to move through lipid bilayer by simple diffusion across the plasma membrane
- Requires a carrier
- goes down the concentration gradient
What does Facilitated diffusion go through
- Ion Channels
- Protein Transporters (AKA carriers)
What is the Ion Channel (Facilitated Diffusion)
Channel mediated facilitated diffusion of potassium ions (K+) through a gated K+ channel
What is a carrier in Facilitated Diffusion
- a carries is used to move a solute down its concentration gradient across the plasma membrane
What are the substances that move across the plasma membrane by carrier mediated facilitated diffusion
Glucose, Fructose, Galactose and some Vitamins
What do the carriers exhibit when the maximum transport is reached
Saturation
How does Glucose enter the cells by diffusion?
- Binds to specific carrier protein
- Transported undergoes a change in shape, Glucose passes the membrane
- transporter releases glucose on the other side of the membrane
What is Osmosis
The diffusion of water through a semi-permeable membrane
What is osmosis impermeable to?
Solute
What is osmosis permeable to?
Solvent
What are the two ways water passes through a plasma membrane via osmosis?
- By moving through the lipid bilayer via simple diffusion
- by moving through aquaporins (integral membrane protein) that function as water channels
What is Osmolarity?
It’s the total solute concentration of a solution
What is one osmol equal to?
1 mol of solute particles
What does osmolarity determine?
It determines the water concentration in the solution
What does Tonicity mean?
It’s the ability of a solution to change the shape or tone of cells by altering their internal water volume
Explain Active transport
- uses energy to move molecules against the concentration gradient
- the transporters are often called pumps
- these pumps can also be saturated
What are the two types of energy sources the pumps use?
- Direct use of ATP in primary active transport
- The use of electrochemical gradient across a membrane , driving the process in secondary active transport
What is the primary transporter
Na+/K+-ATPase
What does the primary transporter do?
Maintains the membrane potential of the cell
What are the major primary active protein found in most cells?
- Ca2+ - ATPase
- H+ - ATPase
- H+/K+ - ATPase
Describe the stages of Primary active transport
- Cytoplasmic Na+ bunds to pump protein
- Binding of Na+ promotes phosphorylation of the protein by ATP
- Phosphorylation causes the protein to change shape, moving Na+ to the outside
- Extracellular K+ binds to pump protein
- K+ binding triggers release of the phosphate, the pump reverting to its original form
- K+ is released from the pump protein and Na+ site is ready to bind to Na+
-The cycle repeats
How is the secondary active transport different to the primary active transport?
By its use of an electrochemical gradient across a plasma membrane as its energy source
