Transport Mechanism Across Membrane: Passive and Active Transport

plasma membrane

plasma membrane

• semi-permeable layer surrounding the cell

• consists of phospholipid bilayer with several types of sugars and proteins embedded

• protects all components of the cell from the outside environment as

  structure

• separates the cytoplasm

• provides structural support to the cell

fluid mosaic model

• phospholipids

• cholesterol

• proteins

• glycolipid and glycoprotein

phospholipids

• fatty acid chain and phosphate group

• fatty acid tails - inwards

• phosphate heads - outwards

cholesterol

sterol to stabilize the membrane and reduce fluidity

proteins

integral or peripheral, variety of roles

glycolipid and glycoprotein

surface of membrane

phospholipids

• contains hydrophilic head

• saturated fatty acids contain single bonds only

• unsaturated contains double bonds producing kinks on chains (healthier)

passive transport

• does not require cell energy

• high to low concentration

• molecules more randomly

passive transport

• diffusion

• facilitated diffusion

• osmosis

active transport

• requires cell energy (ATP)

• low to high concentration

ative transport

• carrier mediated active transport

• endocytosis

• exocytosis

diffusion

• spontaneous movement of particles (high to low)

• continues until all molecules are evenly spaced (equilibrium is reached)

simple diffusion

• small and nonpolar molecules can pass through the plasma membrane easily

• temperature and size are factors that can affect the rate of diffusion

simple diffusion

• food coloring

• perfume

• tea

• breathing

• soda

• calcium

facilitated diffusion

• diffusion with the help of transport proteins

• specific!! they “select“ only certain molecules to cross the membrane

• transports larger or charged molecules

facilitated diffusion

• glucose and amino acid transport

• gas transport

• ion transport

• cholesterol molecules

passive transport

osmosis

• diffusion of water (high to low)

isotonic solution

• concentration of solute inside and outside of the cell is the same

• water goes in both directions

• water in = water out

• molecules in equilibrium

• normal state for animal cells

• cell in homeostasis

hypotonic

• water enters the cell

• cell swells and bursts

• give plant cells shape and support

cytolysis

cell swells and bursts

hypertonic

• water moves out of the cell

• cell shrinks due to water loss

plasmolysis

shrinking of cell due to water loss

osmosis

• blood cells shrinking in a hypertonic solution

• fruits and veggies shrinking

• can kill slugs or snails

• reason behind getting thirsty

• plants survival

importance of transport mechanisms

• plays an important role in homeostasis

• movement of substances into and out of the cell enables to keep cell conditions within normal ranges