chapter 4 - cells exchange materials Flashcards
(18 cards)
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)
what are the types of endocytosis
- pinocytosis: ingestion of liquid particles
- phagocytosis: ingestion of solid particles
active transport: define exocytosis
movement of substances out of the cell through a vesicular membrane (forms a vacuole around it)
examples of exocytosis
milk from breast cells, enzymes from a small intestine, saliva from salivary glands, lipids, proteins, cell wastes
