1. Notes – Membrane Structure and Function

2. 1. What is an enzyme? 2. What do they do?
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.

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

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

5. 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+

6. Notes – Membrane Structure and Function

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

8. 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

9. Membrane structure

10. Membrane structure

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

12. (a) Structural formula (b) Space-filling model
Phospholipids
Hydrophilic head
CH2
N(CH3)3 O P CH C
Choline
Phosphate
Glycerol
(a) Structural formula
(b) Space-filling model
Fatty acids
(c) Phospholipid
symbol
Hydrophobic tails
Hydrophilic
head
Hydrophobic
tails + –
Phosphate bearing “head” is hydrophilic (attracted to water)
Hydrocarbon tail is hydrophobic (repelled by water)

13. Why do phospholipids orient themselves like this in a watery environment?
Hydrophilic
head
WATER
Hydrophobic
tail
Bilayer structure formed by self-assembly of phospholipids in an aqueous environment

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

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

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

17. Outline the functions of membranes. [2]
Check Out
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.

18. Study for your test, now on Friday Oct. 5.
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.