Question of the Day 12-7 Homeostasis = ??? What kind of solution can cause a cell to burst (explode)? isotonic, hypotonic, or hypertonic? Water crosses through a ________ ____________ __________ during osmosis.

Review

12-7 Lab Pages 6 and 7 questions

12-8 Question of the Day Get out a clean piece of paper you can turn in Questions: What is osmosis? What is a hypertonic solution? What happens to the cell in this type of solution? What is a hypotonic solution? What happens to the cell in this type of solution?

Control egg – day 1 = 56. 5 grams Control egg – day 3 = 56 Control egg – day 1 = 56.5 grams Control egg – day 3 = 56.4 grams Control egg – day 4 = 56.4 grams

12-8 Lab Notes Page 8

Contractile Vacuoles – Organelle that excretes excess water from cells Uses ATP Usually found in unicellular freshwater organisms. This prevents them from bursting in a hypotonic solution. 7

Contractile vacuole 8

Plasmolysis – loss of turgor pressure in plant cell due to loss of water What happens to a plant during plasmolysis? The plant wilts The plants plasma membrane and cytoplasm will shrink away from the cell wall 9

REVIEW: What will happen to an Elodea Leaf in a hypertonic solution? Water will leave the cell… …which is called playsmolsis, which will cause the plant leaves to wilt Cell membrane Cell membrane

Review If we put Elodea leaves in a hypotonic solution, what happens? Water will move into the cell…. ….which will cause the cell to swell. If it’s an animal cell it will…. …burst, UNLESS the cell has a Contractile vacuole to pump the water out. to Cell membrane pushing against the cell wall

Summary of Hypo/Hypertonic solution changes on a RBC. 12

Review If the cell shrinks, it is in what type of solution? If the cell is at equilibrium with it’s environment, its in what type of solution? If the cell swells, it’s in what type of solution? Water –90% Salt – 10% Water 95% Salt 5% Water 64% Salt 36% Water 44% Salt 56% Water 50% Salt 50% Water 50% Salt 50% 13

Question of the Day 1. What is passive transport (notes page 2)? 12-9 1. What is passive transport (notes page 2)? 2. What’s an example?

HOMEWORK my.hrw.com – Chapter # 5 Self Check Quiz # 1 – 4 of these questions will appear on quiz (ignore #s 7 and 8) Username = dhe5n Password = p5e8n 15

Quiz Friday 12-10

page 9 review questions

Question of the Day Tell me everything you know about passive transport keep a numbered list. 12-10

Question of the Day In Lab: What was the purpose of the vinegar? What hypertonic solution did you put the egg in? What did you use for a hypotonic solution? 12-13

Objectives 12-13 Describe how the structure of the plasma membrane allows it to function as a regulatory structure and/or protective barrier for a cell.

Selective Permeability – plasma membrane to allow some materials to pass while keeping others out Why is selective permeability important? So the cell can allow important substances in (water, oxygen, glucose) and keep harmful substances out (bacteria). 21

Passive Transport Passive Transport – movement of particles across membranes by diffusion This process uses NO ATP Molecules moving from hi concentration  low concentration 22

Facilitated Diffusion – name for passive transport using proteins Does not use energy!!! Example: Glucose going from high concentration outside cell low concentration inside the cell Why doesn’t this need energy? Because it’s still along the concentration gradient carrier proteins 23

25

26

LAB

Homeostasis and Transport guided reading 5.1 HOMEWORK Homeostasis and Transport guided reading 5.1 28