U1B cell transport mechanisms

what are fluid mosaic model used to describe

arrangement of biological membranes

what are all biological molecules made from?

phospholipid bilayers

what are phospholipids made from

• phospholipid head

• 2 fatty acid tails

what happens when phospholipid mixed with water

the heads stick into the water

what happens when fatty acid tails mixed with water

fatty acid tails stick up out of water

why is it important that all membranes are permeable

• important for survival

• cells get supply of nutrients that they need

• any waste is removed from cell

what layer do phospholipids have

hydrophobic layer formed by fatty acid tails

what do hydrophobic layers do

creates barrier that help separate cell content from outside

what is diffusion

movement of molecules from area of a high concentration to low concentration gradient down a concentration gradient

diffusion is a passive process what does passive process mean?

when molecules only rely on their kinetic energy and concentration gradient for movement

name example's of passive transport by diffusion

steroid hormones- diffuse through phospholipid membrane

what is facilitated diffusion?

large molecules not able to pass through phospholipid bilayer so they need channel proteins/carrier proteins to cross memebrane

what is osmosis?

diffusion of water molecules from region of low water potential down a water potential gradient across partial permeable membrane

when will osmosis stop?

water potential same on both sides

what is active transport?

when cell uses carrier proteins to pump substances across membrane

what is bulk transport

large substances moved across cell membrane

what are the 2 types of bulk transport

• Endocytosis

• Exocytosis

what is Endocytosis

bulk transport of materials in cell

name 3 split processes of Endocytosis

• phagocytosis

• pinocytosis

• receptor-mediated endocytosis

what is Exocytosis

bulk transport of materials out of cell

what is the significance of SA:V ratio in organisms

• o2 enters and co2 leave more easily

• transport more effective when SA:V larger

• diffusion happen faster