CELL MEMBRANE

Measurement

In science the Metric System is used when collecting data or taking measurements. It can also be called SI units ( ___________________________ ). What and How Do We Measure?1. ____________: The distance from one point

to another. a.Tool- metric ruler

b.Unit- __________________ 2. ____________: The amount of space an

object takes up.a. Tools- beaker, graduated cylinder, pipette,

ruler, etc.b. Unit- _________ (liquids) & __________ (solids)

International System

Length

MetersVolume

L Cm3

*** How do you read a graduated cylinder?

1. Place cylinder on table.

2. Read @ eye level

3. Read bottom of curved line (meniscus)

3. _____________: The amount of matter in an object. a. Tool- triple beam balanceb. b. Unit- _________________

4. ________________: average kinetic energy (____________ of particles).c. Tool- thermometer d. b. Unit- _____________________

Mass

Grams

TemperatureMovement

Celsius

Understanding Metric Units_________________, ________________ and _______________ are the 3 base units. Prefixes can be added to the base units to show larger or smaller amounts.

Common Prefixes:

Kilo(k)=1000centi(c)=1/100milli(m)=1/1000 micro(μ)=1/1,000,000

MetersLiters Grams

In science, our measurements must be both ______________ and _____________. Precision: how _________ a measurement is.

Accuracy: how _________ the measurement is to _______________.

Precise Accurate

exact

closetruth

An Analogy:

X X

Precise, but not accurate

X

X

x

Accurate, but not precise

Hit the Bull’s Eye

Precision is limited by the ________ you use. You can guess ____ decimal place beyond what is labeled on the measuring device.

tool1

The Cell Membrane

Remember: The job (function) of the cell membrane is to control what _______________ and _________________ the cell in order to help the cell maintain __________________.

***Why do cells need to maintain homeostasis?

Enters Leaves

Homeostasis

The external environment changes constantly, but cells need a stable internal environment to function properly.

Structure of the Cell Membrane (Plasma Membrane)The cell membrane is made of 2 macromolecules: ______________ and _____________.

Phospholipid: basic building block of the _________ (___________) _______________.

•The head is ___________ (_________) and is therefore attracted to _________.

•The 2 tails are ___________ (____________)and are repelled by ___________.

ProteinsLipids

Cell PlasmaMembrane

Polar ChargedH2O

NonpolarUncharged

H2O

http://www.aquaculture.ugent.be/coursmat/online%20courses/ATA/analysis/lip_phos.htm

Most of the interior of a cell is ________. Most of the fluid around the cell is _________.

Problem: How can phospholipids be arranged so that both the polar head and the non- polar tail are in the “correct” environments?

H2O

H2O

http://www2.chemistry.msu.edu:80/faculty/reusch/VirtTxtJml/lipids.htm

•This double layer of phospholipids is called a ____________ __________________.

•______________________—gives the membrane its ability to be_________________. Can be found _____________________the phospholipids.

•___________________—________________ the cell and can be used to help cells ________________________ with each other.

•_________________—set in the bilayer and act as ________________or __________________ to move materials in and out of the cell.

Lipid Bilayer

CholesterolFluid

between

Glycoproteins identify

communicate

Transport Proteinschannels pumps

http://keep3.sjfc.edu/students/cmg03165/e-port/vsg/VSG.htm

Characteristics of the Lipid Bilayer•The lipid bilayer is fluid--______________ and ________________ can move throughout the cell membrane.

Why is this important?

LipidsProteins

Allows cells to change shape!

•The lipid bilayer is self-sealing. Why is this important?

•The lipid bilayer is _____________ permeable—only certain substances are able to pass through the membrane.

Cells can repair themselves!

Selectively

Most _______________ substances cannot cross through the lipid bilayer. Why?

Why is this important?

How could this be a problem?

Polar

They are repelled by the nonpolar part!

Keeps unwanted particles out!

Sugars (food) are polar!

Figure 8.Permeability of the cell membrane phospholipid bilayers. Gases, hydrophobic molecules and small polar uncharged molecules can diffuse through phospholipid bilayers. Larger polar molecules and charged molecules such as ATP cannot. Reprinted with permission from Cooper GM, Ed. The Cell. A molecular Approach. ASM Press, Washington, D.C., 1997: 478.

Solution: Cell surface proteins in the membrane connect cells to their environment.

http://219.221.200.61/ywwy/zbsw(E)/edetail5.htm

Passive Transport

Cells need to maintain __________________ (balanced internal conditions). In order to do this they must move ___________ and _____________ __________________out of the cell and ________________ into the cell. We can describe the way molecules move across the cell membrane in and out of the cell based on two characteristics: _______________________ & ____________________ of molecule movement.

Homeostasis

waste

protein productsnutrients

Energy requireddirection

1.Passive Transport- moves particles from _______ to ________ concentration to reach _____________. _________________ is required.

2.Active Transport- moves particles from ______ to ______. __________ is required.

high lowequilibrium No energy

low high Energy

PASSIVE TRANSPORT1. ________________ - particles randomly move from ________ to_______ concentrations. The goal of diffusion is to reach ___________________: the point at which the ________________ of a substance is the same everywhere.

Diffusionhigh low

equilibriumconcentration

*** What happens at equilibrium?

Molecules continue to move randomly in ALL directions!

a. Role of Diffusion is to aid in the maintenance of_______________.

b. Remember the membrane is ________________. Not all molecules can _______________ across the membrane. These molecules cannot cross the membrane _______:

i. Molecule is too_____. ii. Molecule is strongly________.

Examples: _______ passes easily through most membranes.

___________ do not.

homeostasis

Selectively permeablemove (diffuse)

alonelarge = Glucose

ChargedH2O

Ions (Na+,K+,Cl-)

2.__________________ is the diffusion of large molecules across the membrane with the help of proteins.

a. Large molecules need a __________ or ____________ called ____________________.

b. Protein channels only guide _______________ molecules across the cell membrane.

c. Molecules still move from __________ to _________ concentrations.

d. Is energy required? ______

Facilitated Diffusion

guidepath A protein channel

Specific

highlow

No

3.______________- diffusion of __________ through a selectively permeable membrane.

Water still moves from ___________ to _______ concentrations. ____________________ is required.

OsmosisWater

highlow

No energy

Review

A. Parts of a Solution a.______________- substance being dissolved. b.______________- substance in which solute

is being dissolved.

B. _________________- the amount of solute in a solvent. a.Formula: concentration = mass/ volume b.Unit: ___________

Example: Sugar water solution contains 5 g of sugar and 1 L of water. What is the concentration? ________________

SoluteSolvent

Concentration

g/mL or g/L

5 g/L

C. Effect of Temperature on Solutions a. As

temperature_____________, it becomes easier to ___________the solute in the solvent.

Increasesdissolve

http://www.iun.edu/~cpanhd/C101webnotes/aqueoussolns/solandtemp.html

Movement of water into or out of a cell depends on the ____________ the cell is in. There are _____ different types of solutions.

a. Isotonic- _________, solute concentrations are ___________ inside and outside the cell. Water ________________stop moving, it moves equally in and out of the cell.

Solution 3

sameequal

does not

b. Hypertonic- ________, solute concentration of the solution is _________________ the solute concentration of the cell. This means there is a higher water concentration __________ the cell. Water will go _________ of a cell placed in this solution.

Highhigher

insideout

c. Hypotonic-_________, solute concentration of the solution is __________________ the solute concentration of the cell. This means there is a higher water concentration __________ the cell. Water will go __________ a cell placed in this solution.

Lowlower

outsideinto

Active Transport

Active Transport: (___________________________)Needs Energy1. Example: Molecular Transport- done by

_______________________ that act like a _________.

a. This process moves _______________ molecules and ________. i. Examples:

b. Molecules are pumped _____________ the concentration gradient or from _________ to __________ concentrations.

c. Proteins change their _________ in order to ________________ or _________________ the pumping process.

proteins pump

largeions

againstlow high

shapeTurn on Turn off

Example:

2. Endocytosis - take material ________ the cell when _________________ or ____________ of the cell membrane surround the object.

a. The cell takes in ____________ molecules, _________, or even ______________.

b. After taking the object in, the pocket _____________________ and becomes a ______________.

There are two types of Endocytosis: i._____________________- the cell takes in

solid material (cell__________). ii.______________________ - the cell takes

in liquid material (cell___________).

intoinfolds pockets

largefood Whole cells

Breaks awayvacuole

phagocytosiseating

Pinocytosisdrinking

3. Exocytosis- ______________ of large amounts of material from the cell.

Opposite of Endocytosis. a.The vacuole ___________with the cell

membrane.

b.Then the membrane opens up and the contents are _________________.

c. Examples:

export

fuses

released

Cell removing waste or hormones