cellular movement Flashcards
What is extracellular fluid in multicellular organisms?
They have an outside layer that creates an internal environment and is very regulated.
What is extracellular fluid in unicellular organisms?
Their external environment which they are exposed to the changes made in this environment.
What is homeostasis?
It is where multicellular organisms create a stable internal environment that is different from their external environment.
How are internal environments regulated?
list 4 factors
temperature, pH levels, osmotic pressure, concentrations of oxygen, carbon dioxide, nitrogen waste, glucose
What is the key function of the plasma membrane?
to separate the interior of the cell from the external environment.
Describe the cell membrane.
function + material
semi-permeable and mad eup of a phospholipid bilayer
Describe the structure of the two layers of phospholipids.
hydrophobic tails pointing inwards, hydrophilic heads pointing outwards
What does cholestrol do in the plasma membrane?
fatty molecules that provide stability
What do proteins do in the plasma membrane?
aid in transportation of materials, chennel proteins that allow water soluble particles (ions and polar molecules) to enter cells
What do carbohydrates do in the plasma membrane?
bound to lipids / proteins, play a role in cell adhesion, recognition of hormones, antibodies, viruses
What can diffuse through the bilayer?
- small molecules: water, gases like o2, co2
- lipid soluble molecules: drugs, vitamins, hormones
What cannot pass through the membrane directly?
- large, water soluble molecules
- hydrophilic substances: ions, sugars, amino acids
three ways that substances can move
simple diffusion, facilitated diffusion, active transport
definition of diffusion.
when something travels from an area of high to low concentration
along/down the concentration gradient
three factors that affect the rate of diffusion.
concentration of particles, temperature (kinetic energy), particle size
What is simple diffusion?
The process which solutes pass through pores in a cell membrane.
What is net flow?
Molecules always diffuse in both directions at once. (in and out) Net Flow is when they move from a greater to lesser concentration.
What molecules does facilitated diffusion allow the passive movement of?
ions (K+), polar water-soluble molecules (amino acids, glucose)
differences between simple and facilitated diffusion.
3
faster, may get saturated when channels are full, selective, trasnportation of one molecule may inhibit another
similarities between simple and facilitated diffusion.
2
down the concentration gradient, no energy required,
describe the two types of facilitated diffusion.
channel proteins - act like pores that transport small polar molecules (ions)
carrier proteins - bind to the particle, changing the shape of the channel to allow transport
What is active transport?
substances moving from a low to high concentration, needs ATP as energy
move substances against the concentration gradient
What similaries does active transport have with facilitated diffusion?
selective, may get competitive, saturation may occur
What substances does bulk active transport assist the transportation of?
hormones, nutrients, bacteria
