Good Morning 1 1/13

• Do Now : effects of acid sprayed tomato plants

• Take out notebook • Discuss size of a cell and why they

are the size that they are • Volume to surface area ratio –

activity

1

How Big is It? • http://www.cellsalive.com/howbig_js.htm

2

3

The Plasma Membrane -

Gateway to the Cell

Allows molecules to move in and out of the cell

What needs to get into and out of the cell?

4

CO2 and Oxygen

5

Blood cells take Oxygen and nutrients to every cell in the body and CO2 is removed

Wastes, Carbon dioxide and Urea pass out of cells

through membrane

6

Cells are limited to size due to its

Volume to Surface area Ratio

7

8

9

Photograph of a Cell Membrane

10

Cell Membrane

The cell membrane is flexible and allows a unicellular organism to move

11

Homeostasis

• Balanced internal condition of cells

• Also called equilibrium• Maintained by plasma

membrane controlling what enters & leaves the cell

12

Functions of Plasma Membrane

Protective barrier

Regulate transport in & out of cell (selectively permeable)

Allow cell recognition

Provide anchoring sites for filaments of cytoskeleton

13

Structure of the Cell Membrane

copyright cmassengale

14

Structure of the membrane is Made up of phospholipids, Proteins and cholesterol

15

FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid.

MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above

http://www.dnatube.com/video/360/Fluid-Mosaic-Model

FLUID MOSAIC MODEL

16

Polar heads are hydrophilic “water loving”Nonpolar tails are hydrophobic “water fearing”

Cell Membrane

Makes membrane “Selective” in what crosses

17

Cell Membrane

Hydrophobic molecules pass easily; hydrophilic DO NOT

The cell membrane is made of 2 layers of phospholipids called the lipid bilayer

18

Small molecules and larger hydrophobic molecules move through easily.e.g. O2, CO2, H2O

Semipermeable or selectively permeable

Membrane

19

Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own.

Semipermeable Membrane

http://www.bing.com/videos/search?q=Cell+Membrane+animation&go=Submit&qs=n&form=QBVR&pq=cell+membrane+animation&sc=8-23&sp=-1&sk=#view=detail&mid=7FC1F9FD1D31B1EAB2057FC1F9FD1D31B1EAB205

20

Types of Transport Across Cell Membranes

21

Passive TransportSimple Diffusion

Doesn’t require energy

Moves high to low concentration

Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.

22

Simple Diffusion

• Requires NO energy

• Molecules move from area of HIGH to LOW concentration

23

DIFFUSION

Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

Diffusion through a Membrane

Cell membrane

Solute moves DOWN concentration gradient (HIGH to LOW)

Solute= anything that is dissolved (in water)

25

Diffusion of Liquids

26

Passive TransportFacilitated diffusion

Doesn’t require energy

Uses transport proteins to move high to low concentration

Examples: Glucose or amino acids moving from blood into a cell.

27

Active Transport

Requires energy or ATP

Moves materials from LOW to HIGH concentration

AGAINST concentration gradient

28

Carrier Proteins• Other

carrier proteins change shape to move materials across the cell membrane

29

Endocytosis – Phagocytosis

Used to engulf large particles such as food, bacteria, etc. into vesicles

Called “Cell Eating”

30

31

Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)

copyright cmassengale

32

Moving the “Big Stuff”

Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.

Exocytosis-

moving things out.

This is how many hormones are secreted

33

Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in

the cell are released through the cell membrane.

Inside Cell Cell environment

34

Three Forms of Transport Across the Membrane

35

Osmosis

• Diffusion of water across a membrane

• Moves from HIGH to Low

Diffusion across a membrane

Semipermeable

membrane

36

Diffusion of H2O Across A Membrane

High H2O potentialLow solute concentration

Low H2O potentialHigh solute concentration

37

Aquaporins• Water Channels• Protein pores used during

OSMOSISWATERMOLECULES

copyright cmassengale

38

Cell in Isotonic Solution

CELL

10% NaCL90% H2O

10% NaCL

90% H2O

What is the direction of water movement?The cell is at _______________.equilibrium

ENVIRONMENT

NO NET MOVEMENT

39

Cell in Hypotonic Solution

CELL

10% NaCL90% H2O

20% NaCL

80% H2O

What is the direction of water movement?

40

Cell in Hypertonic Solution

CELL

15% NaCL85% H2O

5% NaCL95% H2O

What is the direction of water movement?

ENVIRONMENT

Isotonic Solution

NO NET MOVEMENT OF

H2O (equal amounts entering

& leaving)

Hypotonic Solution

CYTOLYSIS- cell busts

Hypertonic Solution

PLASMOLYSIS- shriveling of cell

42

Cytolysis & Plasmolysis

Cytolysis Plasmolysis

43

Osmosis in Red Blood Cells

Isotonic Hypotonic

Hypertonic

44

hypotonic hypertonic isotonic

hypertonic isotonic hypotonic