Chapter 3 Flashcards
Describe the structure of cell membranes
Thin/Delicate/Stretches Tiny folds on surface Lipids and proteins main substances Double layer of phospholipid molecules Phosphate forms outer layer Fatty acids form inner layer Hydrophobic tail regions hidden Hydrophilic tail regions exposed to water Hydro build a wall between outside and inside of membrane. Cholesterol in cell keeps cell stable Protein enclosed in oily background Proteins fibrous/globular/rod like On outer surface proteins may extend out marking cell as component of tissue/organ
What are the functions of cell membranes
Controls substances in and out of cell
Gives cell form
Membrane of cell adheres to others when forming tissue.
Permeable/non permeable
O2/co2 can pass
Amino acids/nucleic acids, some ions and sugars can’t pass.
Molecules form pathways receiving signals from outside cell transmitting inside.
Proteins can move in cell
Proteins form receptors for growth or hormone factors and transport substances across membrane.
Proteins form selective channels that decide what ions can enter/leave cell
Where much of cells biological activity is conducted
Describe the processes that transport substances across the membrane
Simple diffusion. Substances Spontaneously move from High to low. No o2 reqd.
Facilitated diffusion. High to low. No o2 reqd. Assistance from protein channel that decides what ions can enter or leave cell.
Osmosis. The movement of water molecules from high to low concentration.
Filtration. Forces molecules through membranes
Active transport. Particles move from Low to high requiring o2.
Carrier proteins assist movement.
Endocytosis. Secretion from cell membrane moving particles too large to enter by other processes within vesicle of cell
Exocytosis. Substance stored in vesicle is secreted from cell.
Compare passive and active transport
Passive require no energy
Active requires energy
What substances does simple diffusion include
O2
Co2
Fat soluble vitamins
What happens during simple diffusion
Substances cross the phospholipid membrane from high to low concentration
What substances are involved in facilitated diffusion
Amino acids
Ions
Glucose
Other sugars
How does facilitated diffusion occur
Substances bind to protein carriers
Substances move through water filled protein channels
How does osmosis occur
Osmotic pressure causes pressure to raise the level of water so that equilibrium occurs.
Water diffuses towards solutions of greater osmotic pressure.
Passes through lipid bilayer
How does filtration occur
Forces molecules through membranes.
Separates solids from water.
BP forces water and small dissolved substances through capillary wall forming tissue fluid.
Prevents oedema
What does active transport involve
Endocytosis
Exocytosis
What happens during active transport
Energy required comes from cellular metabolism ATP made in the mitochondria of cells.
Requires carrier proteins that have binding sites that combine with particles they’re carrying.
What type of molecules does active transport carry
Sugar Amino acids Sodium Potassium Calcium Hydrogen particles
What are active transporters known as and what do they move
Solutes and ions against concentration gradients.
Solute pumps
Explain primary and secondary active transport
Primary=energy comes from hydrolysis of ATP.
Secondary=stored energy is used from ionic gradients.
Two sub forms
Symport. Substances move across membrane in same direction.
Antiport. Substances move in opposite directions.
