Notes Membrane Structure and Function Check In 1

Notes – Membrane Structure and Function

Check In 1. What is an enzyme? 2. What do they do? Homework Study for your test, now on Friday Oct. 5. You may want to make flashcards and save the flashcards for your final exam.

Check In 1. What is an enzyme? 2. What do they do? Knowledge Rating: (finger survey) 1. I don’t know it or I’ve never seen it. 2. I’ve seen it before. 3. I know it, but I don’t know how to use it. 4. I can teach it to the class

Warm Up 1. Water is polar molecule. Define polar molecule. [1] 2. Outline how salt dissolves in water. [2] Homework

Check In 1. Water is polar molecule. Define polar molecule. [1] 2. Outline how salt dissolves in water. [2] Markscheme 1. A molecule that has a difference in charges from one side to the other 2. Slight positive charges on H attract Cl- and slight negative charges on O attract Na+

Notes – Membrane Structure and Function

Membrane functions • To control what moves in and out of a cell or organelle • To communicate with other cells

Membrane Terms • Hydrophilic = water-attracting – Charged or slightly charged parts of molecules • Hydrophobic = water-avoiding – Uncharged parts of molecules • Selectively permeable = some things can pass through but others cannot

Membrane structure

Cell Membrane Structure 1. Phospholipid Bilayer a. Cell membranes are made of two layers of phospholipids. b. Phospholipids: 1 phosphate head + 2 lipid tails Lipid tails Hydrophobic Charged =Phosphorous Hydrophilic Uncharged =

Phospholipids +N(CH ) Hydrophilic head CH 2 3 3 Choline CH 2 O P O – O Phosphate O CH 2 CH O O C CH 2 Glycerol O Hydrophobic tails Fatty acids (a) Structural formula Hydrophilic head Hydrophobic tails (b) Space-filling model (c) Phospholipid symbol

Why do phospholipids orient themselves like this in a watery environment? WATER Hydrophilic head WATER Hydrophobic tail

Cell Membrane Structure 1. Phospholipid Bilayer a. Cell membranes are made of two layers of phospholipids. b. Phospholipid: 1 phosphate head + 2 lipid tails c. Phospholipids form a bilayer around the cell

Cell Membrane Structure 2. Fluid Mosaic Model a. Membrane is flexible, like a fluid § Small molecules can “slip through” even if they are charged, like water. b. Membrane contains a mosaic of other molecules, like proteins § Channel proteins (transport proteins) act as tunnels that allow larger, charged molecules into the cell.

Draw and label a phospholipid Label: phosphate head, lipid tails, hydrophobic and hydrophilic

Check Outline the functions of membranes. [2] Homework Study for your test, now on Friday Oct. 5. You may want to make flashcards and save the flashcards for your final exam.

Check Out Draw a picture of a phospholipid and label the hydrophilic head and hydrophobic tails. [2] Homework Study for your test, now on Friday Oct. 5. You may want to make flashcards and save the flashcards for your final exam.