active + co-transport

active transport?

substance movement from area of low concentration to area of high concentration via ATP + a carrier protein

process of active transport?

• complementary substance binds to specific carrier protein

• ATP binds, hydrolyses → ADP + Pi, releasing energy

• protein changes shape, releases substance on side with higher concentration

• Pi released so protein returns to original shape

process of co-transport glucose/amino acids in the ileum?

• Na+ AT out of ileum epithelial cells into blood via Na+/K+ pump

• forming conc gradient as Na+ conc in lumen>epithelial

• Na+ diffuses into epithelial cells, down its conc gradient with glucose, against its gradient

• via a co-transporter protein

• glucose conc gradient formed as conc in epithelial>in blood

• glucose diffuses into blood, down its gradient via facilitated diffusion

why is co-transport used to transport glucose/amino acids?

higher conc. of glucose in epithelial than in the lumen, so co-transport required

co transport?

2 substances bind to move simultaneously via a co-transporter protein

one substance moves against, and the other moves down its gradient

how can rate of movement across cell membrane be increased?

• increased SA

• increased no. channel/carrier proteins increases rate of facilitated diffusion/AT

• greater conc. gradient increases rate of S/F diffusion, until all proteins saturated (LF)

• greater WP gradient increases rate of osmosis

specialised cell adaptations to increase rate of movement across their membranes?

• epithelial cell membrane have microvilli increasing SA

• large no. mitochondria → more ATP for AT