Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 12/16/10 Objective: To understand the structure and function of the cell membrane

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings

12/16/10

Objective: To understand the structure and function of the cell membrane

Do Now:What is meant by “fluid mosaic” model as a description for the membrane?

Today:1. Do Now/Sign - up for presentations2.Discuss/Collect Evidence for life article3.Cell Membrane Note4.Osmosis/Diffusion LABS


12/17/10


Do Now:What is diffusion? How do molecules flow?

Today:1. Do Now/Collect Evidence for Life Article2.Osmosis/Diffusion LABS3.Membrane Notes


1/3/11 – “E” day


Do Now:What is osmosis? How do cells behave in a hypotonic solution?hypertonic solution?isotonic solution?

Today:1.Do Now2.PJAS/MCSRC announcements3.Did you hand in your diffusion lab?4.Homework - Chapter 5 Review Handout5.IRP Presentations:

1. Sean2. Nick M.3. Sarah4. Rose5. Bjay6. Stephen

Tomorrow:1.Lindsay2.Patrick3.Matt B.4.Jeremy

MCSRC Meeting WEDNESDAY – Jan. 5th

D20 Mrs. Biondo


1/3/11 – “E” day


Do Now:What is osmosis? How do cells behave in a hypotonic solution?hypertonic solution?isotonic solution?

Today:1.Do Now2.PJAS/MCSRC announcements3.Did you hand in your diffusion lab?4.Homework - Chapter 5 Review Handout5.IRP Presentations:

1. Marissa2. Suzie3. Sang

Tomorrow:1.Jess Q.2.Bea3.Jen4.Stephanie5.Paul6.Andy

MCSRC Meeting WEDNESDAY – Jan. 5th

D20 Mrs. Biondo


1/6/11 – “B” day


Do Now:What is active transport across a membrane? Passive transport?

Today:1.Do Now2.Complete IRP presentations3.Complete Membrane Notes4.Value of Villi Activity5.Homework - Chapter 5 Review Handout


1/10/11 – “D” day

Objective: To understand the function of enzymes in metabolism

Do Now:What is ATP, what is it used for?

Today:1.Do Now2.Did you try the Enzyme Packet?3.Go over Enzyme Packet4.Review


Plantcell

H2O

H2OH2O

H2O

H2O

H2O

H2O

H2OPlasma

membrane

(1) Normal (2) Lysed (3) Shriveled

(4) Flaccid (5) Turgid(6) Shriveled (plasmolyzed)

Isotonic solution Hypotonic solution Hypertonic solution

Animalcell


MEMBRANE STRUCTURE AND FUNCTION

5.10 Membranes organize the chemical activities of cells

• Membranes

– Provide structural order for metabolism


• The plasma membrane of the cell is selectively permeable

– Controlling the flow of substances into or out of the cell

Figure 5.10

Cytoplasm

Outside of cell

TE

M 2

00,0

00


5.11 Membrane phospholipids form a bilayer

• Phospholipids

– Have a hydrophilic head and two hydrophobic tails

• Fatty Acid chains!

– Are the main structural components of membranes

Figure 5.11A

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

CH2

CH2

CH3

CH3

CH3N+

O

O O–P

O

CH2CHCH2

C O C O

O O

Phosphategroup

Symbol

Hydrophilic head

Hydrophobic tails


• Phospholipids form a two-layer sheet

– Called a phospholipid bilayer, with the heads facing outward and the tails facing inward

Figure 5.11B

Water

Water

Hydrophilicheads

Hydrophobictails


5.12 The membrane is a fluid mosaic of phospholipids and proteins

• A membrane is a fluid mosaic

– With proteins and other molecules embedded in a phospholipid bilayer

Figure 5.12

Fibers of the extracellular matrix

Carbohydrate(of glycoprotein)

Glycoprotein

Microfilamentsof cytoskeleton

Phospholipid

Cholesterol

Proteins

Plasmamembrane

Glycolipid

Cytoplasm


Fibers of the extracellular matrix

Carbohydrate(of glycoprotein)

Glycoprotein

Microfilamentsof cytoskeleton

Phospholipid

CholesterolProteins

Plasmamembrane

Glycolipid

Cytoplasm


5.13 Proteins make the membrane a mosaic of function

• Many membrane proteins

– Function as enzymes (biological catalysts – speed up reactions)

Figure 5.13A


• Other membrane proteins

– Function as receptors for chemical messages from other cells

Figure 5.13B

Messenger molecule

Receptor

Activatedmolecule


• Membrane proteins also function in transport

– Moving substances across the membrane

Figure 5.13C

ATP


5.14 Passive transport is diffusion across a membrane

• In passive transport, substances diffuse through membranes without work by the cell

– Spreading from areas of high concentration to areas of low concentration

EquilibriumMembraneMolecules of dye

Equilibrium

Figure 5.14B

Figure 5.14A


• Small nonpolar molecules such as O2 and CO2

– Diffuse easily across the phospholipid bilayer of a membrane


5.15 Transport proteins may facilitate diffusion across membranes

• Many kinds of molecules

– Do not diffuse freely across membranes

• For these molecules, transport proteins

– Provide passage across membranes through a process called facilitated diffusion

Figure 5.15

Solutemolecule

Transportprotein


1/7/11 – “C” day


Do Now:What would likely happen to an animal cell placed in a hypotonic solution? A hypertonic solution? Why are animal cells different?

Today:1.Do Now/Homework Check - Chapter 5 Review Handout2.Complete Membrane Notes3.Value of Villi Activity4.Enzymes and Metabolism POGIL


5.16 Osmosis is the diffusion of water across a membrane

• In osmosis

– Water travels from a solution of lower solute concentration to one of higher solute concentration

Figure 5.16

Lowerconcentration

of solute

Higherconcentration

of solute

Equalconcentration

of solute

H2OSolutemolecule

Selectivelypermeablemembrane

Watermolecule


5.17 Water balance between cells and their surroundings is crucial to organisms

• Osmosis causes cells to shrink in hypertonic solutions

– And swell in hypotonic solutions

• In isotonic solutions

– Animal cells are normal, but plant cells are limp

Figure 5.17

Plantcell

H2O

H2O H2O

H2O

H2O

H2O

H2O

H2OPlasma

membrane

(1) Normal (2) Lysed (3) Shriveled

(4) Flaccid (5) Turgid(6) Shriveled (plasmolyzed)

Isotonic solution Hypotonic solution Hypertonic solution

Animalcell


• The control of water balance

– Is called osmoregulation


PP PProtein

changes shapePhosphatedetaches

ATPADPSolute

Transportprotein

Solute binding1 Phosphorylation2 Transport3 Protein reversion4

5.18 Cells expend energy for active transport

• Transport proteins can move solutes against a concentration gradient

– Through active transport, which requires ATP

Figure 5.18


Fluid outside cell

Cytoplasm

Protein

Vesicle

5.19 Exocytosis and endocytosis transport large molecules

• To move large molecules or particles through a membrane

– A vesicle may fuse with the membrane and expel its contents (exocytosis)

Figure 5.19A


• Membranes may fold inward

– Enclosing material from the outside (endocytosis)

Figure 5.19B

Vesicle forming


• Endocytosis can occur in three ways

– Phagocytosis

– Pinocytosis

– Receptor-mediated endocytosis

Pseudopodium of amoeba Food being ingested

Phagocytosis Pinocytosis Receptor-mediated endocytosis

Material bound to receptor proteins

PIT

Cytoplasm

Plasma membrane

TE

M 5

4,00

0

TE

M 9

6,50

0

LM 2

30

Figure 5.19C


CONNECTION

5.20 Faulty membranes can overload the blood with cholesterol

• Harmful levels of cholesterol

– Can accumulate in the blood if membranes lack cholesterol receptors

LDL particle

Protein

Phospholipid outer layer

CytoplasmReceptorprotein

Plasmamembrane

Vesicle

Cholesterol

Figure 5.20


5.21 Chloroplasts and mitochondria make energy available for cellular work

• Enzymes are central to the processes that make energy available to the cell


• Chloroplasts carry out photosynthesis

– Using solar energy to produce glucose and oxygen from carbon dioxide and water

• Mitochondria consume oxygen in cellular respiration

– Using the energy stored in glucose to make ATP

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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 12/16/10 Objective: To understand the structure and function of the cell membrane