cell membrane
DESCRIPTION
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 ? ____________ : The distance from one point to another. a.Tool - metric ruler - PowerPoint PPT PresentationTRANSCRIPT
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