Activities of cells Flashcards
What is passive transport
transport of substances that does not require energy as they move along the concentration gradient
What is active transport
transport that requires the input of energy to move substances against the concentration or electrical gradient.
What is diffusion
The random motion of particles resulting in a net flow of matter from a region of high concentration to a region of low concentration
What is osmosis
The movement of water molecules through a semipermeable membrane to a place with lower water concentration and generally high solute concentration
Define the terms, isotonic, hypotonic and hypertonic in regards to osmosis
Isotonic: two parts have the equal solute concentrations
Hypotonic (to something): has a lower concentration of solute
Hypertonic (to something): has a higher solute concentration
What are factors that affect the rate of diffusion
Distance: particles may have to travel further to reach equilibrium, diffusion takes longer
Temperature: higher temperatures mean particles have greater kinetic energy and diffusion occurs faster
Characteristics of subsstance: lower mass makes it easier to travel, also depends on whether it can fit through the lipid bilayer
Concentration difference: large concentration difference means a steeper gradient and a higher rate of diffusion
What is facilitated diffusion
Diffusion that is aided to help molecules cross the lipid bilayer barrier through a protein channel.
Why can’t saltwater fish swim in fresh water
They are hypertonic to the water, this causes water molecules through osmosis to travel into the fish and cause it to swell.
What is endocytosis
plasma protein folds around extracellular material forming a vescicle around a large particle. This is active transport. An example of this can occur when a cell needs a large molecule such as a polysaccharide carbohydrate.
What is exocytosis
This process is the reverse of endocytosis where materials such as hormones and waste products are expelled in vesicles that fuse with the membrane.
what are the three types of endocytosis
Phagocytosis: cells engulfing bacteria
Pinocytosis: endocytosis of liquid particles
Receptor-mediated endocytosis: two particles must bind to a cell membrane receptor to initiate their engulfment
what is the importance to SA to V ratio
a high SA:V means that substances that have to diffuse across a cell have to travel less distance to get to where it needs to be. As a result diffusion occurs faster and cells can operate more efficiently.
