cell membrane & transport

• what is a cell membrane?

  they are like the cells gatekeepers, they handle movement coming in and out and keeps the cells gate in shape
• is cholesterol a normal component in our cell membranes?

  yes
• what is a plasma membrane?

  it controls what goes in and out for balance
• what happens if the internal part of a cell isnt balanced ? (if the plasma membrane doesnt do its job of balancing the cell)

  it can lead to dysfunction or cell death
• the plasma membrane has a selective permeability barrier that ensures that...

  the inside of the cell is different from the outside
• why must cells use a lot energy?

  to maintain the chemical balance of the right mix of stuff, inside and wrong stuff, out
• what are transport proteins?

  Proteins that transport molecules across cell membranes.
• what is passive transport?

  movement of molecules across a cell membrane without the use of energy
• what is active transport?

  Movement of molecules across a cell membrane that requires energy
• what is diffusion?

  The movement of particles from an area of high concentration to an area of low concentration
• what is an equilibrium?

  it is when things are evenly spread, like mixing sugar in water until it stops dissolving
• what can increase the rate of diffusion?

  heat
• do small substances diffuse faster than larger substances?

  yes
• what is osmosis?

  water moving through a barrier to balance out the concentration levels
• what is a hypotonic solution?

  it is when there is a less of a concentration outside the cell, so water rushes in making it swell
• what is a hypertonic solution?


  it is when there is more stuff outside of the cell, so water leaves making it shrink
• what is an isotonic solution?

  it is when the stuff inside and outside of the cell is balanced and equal
• what are ways in which substances can move across membranes?

  by passive(without) or active transport(with energy) and/or simple(without) or facilitated diffusion (with proteins)
• what can easily pass through cell membranes without assistance?

  O2 and CO2 through simple diffusion (without transport protein)
• what is facilitated diffusion?

  the passive transport of molecules across a cell membrane with the help of transport proteins.
• what are the two transport proteins that makes up facilitated diffusion?

  channel proteins and carrier proteins.
• what are channel proteins?

  they help substances move through the membrane without needing energy
• what are carrier proteins?

  they carry specific molecules across the membrane based on their shape
• what are two types of carrier proteins?

  passive and active carrier proteins
• what is exocytosis?

  it is when substances from a cell is sent out by merging transport vesicles with the membrane
• what is endocytosis?

  it is when the cell brings stuff in by wrapping it in a membrane section
• what are the 3 main cell junctions in animal cells?

  tight, anchoring and gap junctions
• what is a tight junction?

  tight belts of proteins that make leak-proof sheets in the body
• what is an anchoring junction?

  like protein patches that connect cells under a lot of stress
• what are gap junctions?

  like tunnels between cells made of proteins for direct connections
• what is plasmodesmata?

  like tunnels connecting cells through the cell wall for communication
• what is a target cell?

  it gets a signal through a receptor protein on the surface or inside of a cell
• what is signal transduction?

  signals at the cell surface that need a pathway to be relayed inside