Section 3-3, 3-4, 3-5 Movement across the c ell membrane Write everything that is underlined.

Section 3-3, 3-4, 3-5Section 3-3, 3-4, 3-5

““Movement Movement across theacross the c cell ell

membranemembrane””

Write everything that isWrite everything that is underlinedunderlined

3.3 Cell Membrane / 3.4 Diffusion / 3.5 Transport

3.3 KEY CONCEPT3.3 KEY CONCEPT: The cell membrane is a : The cell membrane is a barrier that separates a cell from the barrier that separates a cell from the external environment.external environment.


Cell membranes are composed of two Cell membranes are composed of two phospholipid layers.phospholipid layers.• It forms a boundary between inside and It forms a boundary between inside and

outside of the celloutside of the cell • ……and controls passage of materialsand controls passage of materials

cell membrane outside cell

inside cell


cell membrane

• The cell membrane is made of a phospholipid The cell membrane is made of a phospholipid bilayer.bilayer.

• There are other molecules embedded in the There are other molecules embedded in the membrane.membrane.

• The fluid mosaic model describes the The fluid mosaic model describes the membrane.membrane.

protein

cholesterol

proteincarbohydratechain

protein channel


How many layers is the cell membrane made up of?

a.a. 11

b.b. 22

c.c. 33

d.d. 44


• The cell membrane is selectively The cell membrane is selectively permeable (only certain things get permeable (only certain things get through)through) like a screen doorlike a screen door


3.4 KEY CONCEPT: Materials move across membranes because of concentration differences.


PassivePassive transport does not transport does not require energyrequire energy• There are two There are two

types of passive types of passive transport: transport:

1.1.diffusiondiffusion

2.2.osmosisosmosis


1.1.DiffusionDiffusion: : Molecules Molecules move down a move down a concentration gradientconcentration gradient

• ““From an area of high From an area of high concentration to low concentration to low concentration”concentration”


•Osmosis is the diffusion of waterOsmosis is the diffusion of water

• There are three types of solutions: There are three types of solutions: isotonic, hypertonic, hypotonic isotonic, hypertonic, hypotonic


What is passive transport?

a.a. Does not require energy to move materialsDoes not require energy to move materials

b.b. Requires energy to move materialsRequires energy to move materials

c.c. Depends on your definition of movementDepends on your definition of movement

d.d. Only sometimes does it use energyOnly sometimes does it use energy


What is/are the different types of passive transport?

a.a. DiffusionDiffusion

b.b. IsotonicIsotonic

c.c. OsmosisOsmosis

d.d. A and CA and C


Diffusion is the movement of materials from an area of ___________ concentration to ______ concentration

a.a. Low to HighLow to High

b.b. High to HighHigh to High

c.c. Low to LowLow to Low

d.d. High to LowHigh to Low


Osmosis it the diffusion of ___________

a.a. MaterialsMaterials

b.b. SugarSugar

c.c. WaterWater

d.d. Amino acidsAmino acids


Some molecules can only diffuse through transport proteins.

•Facilitated diffusion: diffusion through transport proteins


3.5 KEY CONCEPT3.5 KEY CONCEPT: Cells use energy : Cells use energy to transport materials that cannot to transport materials that cannot diffuse across a membrane.diffuse across a membrane.


Active transport requires energy to Active transport requires energy to move a substance against its move a substance against its concentration gradient (from LOW to concentration gradient (from LOW to HIGH)HIGH)• PassivePassive transport requires no energy transport requires no energy

from the cellfrom the cell

• Active transport is Active transport is powered by chemical powered by chemical energy (ATP)energy (ATP)

• Cells use active transport Cells use active transport to maintain homeostasisto maintain homeostasis


A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis.

• Endocytosis is the Endocytosis is the process of taking process of taking material into the cell material into the cell – also called – also called PhagocytosisPhagocytosis


•ExocytosisExocytosis is the process of is the process of expelling (pushing out) expelling (pushing out) material from the cellmaterial from the cell

3.3 Cell Membrane / 3.4 Diffusion / 3.5 TransportWhat is the difference between active transport and passive transport?

a.a. Active requires energy and passive does notActive requires energy and passive does not

b.b. Passive requires energy and active does notPassive requires energy and active does not

c.c. Passive moves big materials into the cell and active Passive moves big materials into the cell and active does notdoes not

d.d. B and CB and C


What does the following picture show?

a.a. EndocytosisEndocytosis

b.b. ExocytosisExocytosis

c.c. DiffusionDiffusion

d.d. Osmosis Osmosis

Section 3-3, 3-4, 3-5 Movement across the c ell membrane Write everything that is underlined.

Documents

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