transportation cells Flashcards
(22 cards)
define diffusion?
the spreading out of particles from high concentration to a low concentration until evenly distributed over the available space.
what effects the diffusion rate?
higher concentration gradient= faster the rate of diffusion
smaller particles= faster diffusion rate
define osmosis
movement of water across a semi permeable membrane from a high conc to a low conc to balance conc,
what is facilitated transport?
water soluble molecules must pass through proteins.
what is a channel protien?
provide a pathway for hydrophilic elements to travel across the cell without coming into contact with hydrophobic. they can fit large molecules
what are carrier protiens?
to bind molecules and transport them across membrane
- only one side opens up at a time and when specific protein binds it changes shape and opens the other side.
3 characteristics of carrier proteins?
specific- will only bind with particular molecules
saturated- once all carries are full, any increase in concentration of molecules will not speed up the movement.
hormones- carrier activity is regulated by hormones.
molecules that pass through carrier protiens.
amino acids, glucose, na, k, ions
what is facilitated diffusion?
occurs when substances are transported through a protein along concentration gradient. passive
what is active transport?
requires energy in form on ATP because they are going through membrane against gradient.
what is vesicular transport?
active
the movement of substances across the cell membrane in vesicles
what is endocytosis?
taking liquids or solids into cell by vesicular transporting
what is exocytosis?
when contents of a vesicle are transported outside
what is pinocytosis?
taking fluids into the cells by surrounding the droplet until it pinches off
what is phagocytosis?
talking solids into cell by completely surrounding particles and pinching off
what are the 3 basic transport materials?
simple diffusion -passive
facilitated(channel+carrier) passive or active
vesicular transport -active
what is the structure of the cell membrane?
composed of phospholipids molecules which are lipid molecules containing a phosphate group, arranged in 2 layers known as a bilayer.
-each phospholipid molecule has a head that is hydrophilic( water loving) and a tail that is hydrophobic(water hating)
-arranged in 2 layers with their heads on outside and tails on inside
- drift from place to place with heads& tails moving, keeping membrane fluid.
-embedded in the phospholipids bilayer of membrane are cholesterol and protein molecules, cholesterol wedged between phospholipids ( act as cell identity marker)
what does isotomic mean
the conc is equal
functions of cell membrane?
-physical barrier- separates cytoplasm from extracellular fluid around cell.
isolation of cytoplasm is important due to compositions being different.
-regulates passage of materials- controls what goes in and out of cells
-sensitive to changes- first part of cells to be affected by any changes by extracellular fluid, it has receptors that are sensitive to particular molecules in immediate environment.
- helps support the cell- internal part of membrane is attached to microfilaments of the cytoskeleton, also connects to adjacent cells giving support to whole cell.
what is homeostasis?
body systems work together to ensure that cellular environment is kept constant
what is the function of the cell membrane?
act as a physical barrier, regulates the passage of materials, helps support cell.
