chapter 4 - cells exchange materials Flashcards
what is the structure of the cell membrane
fluid mosaic model, phospholipid bilayer (phosphate heads, lipid tails, proteins)
what is the function of the cell membrane
- physical barrier
- regulation of passage of materials
- sensitivity
- support
what is transport
proteins in the membrane help form openings / channels and lipids which allow substances to pass through the membrane
why is transport of materials important
- provides cells with essential materials
- maintains constant internal environment for efficient functioning
- removal of wastes
passive transport: define simple diffusion
random net movement of molecules through a semi permeable membrane from a region of high concentration to a region of low concentration through lipids
what is the concentration gradient
the difference in concentration between two regions (large diffusion gradient = faster flow)
what are factors affecting simple diffusion
- difference in concentration
- surface area
- large concentration gradient
- temperature
- distance particles need to move
- permeability
examples of simple diffusion
alcohol, steroids, fat soluble substances, oxygen, carbon dioxide
passive transport (carrier mediated): define facilitated diffusion
diffusion which is accomplished through the use of carrier proteins (protein changes shape, one at a time)
passive transport: define osmosis
random net movement of water molecules from a high water concentration (low solute concentration) to a low water concentration (high solute concentration) through a semi permeable membrane or protein channel
what is the cell membrane
semi permeable membrane regulating what enters and leaves cells
what is a hypertonic, hypotonic and isotonic
- hypertonic: more solute and less water outside the cell, water leaves cell = shrinks
- hypotonic: less solute and more water inside the cell, water enters the cell = swells / may burst
- isotonic: same solute and water inside and outside cell, cell stays the same
active transport: define active transport
random net movement of molecules against the concentration gradient, from an area of high concentration to an area of low concentration through a carrier protein (changes shape)
examples of active transport
sodium / potassium pump
active transport: define endocytosis
movement of liquids and solids into the cell through a vesicular membrane (forming a vacuole around it)
