Cell Membrane Transport

Cell membrane transport

There are 2 types of cell membrane transport:

Passive Transport Substance move fromHigh concentration to low concentration-no energy required

Active Transport Substance move fromlow concentration to high concentration-energy (ATP) required

Another perspective on passive and active transport

Passive Transport

DiffusionThe movement of particles from areas of high

concentration to low concentration

Diffusion

Factors that influence the rate of diffusionTemperaturePressure Electrical currentsMolecular size

Equilibrium

the concentrations of particles are the same on both sides of the membrane

Facilitated Diffusion

Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.

Facilitated diffusion

Osmosis

The diffusion of water across a selectively permeable membrane

Important in maintaining cell homeostasis Water flows to side of membrane where the water

concentration is lower until equilibrium is reached

Osmosis

Osmosis is controlled by the amount of solutes on either side of a membrane

Osmosis – Types of Solutions

When dealing with osmosis, water can either move into the cell or out of it.

The solute cannot move to equal out the concentration of solutions, so the water has to.

We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic.

Isotonic Solution

Isotonic solution – Concentration of solute is the same in the cell and the area around the cell.

Water moves in and out at equal rates.

Isotonic solution

Hypotonic Solution

Hypotonic Solution – Concentration of solute is lower in the solution than in the cell.

Net movement of water INTO the cell.

Hypotonic solutions

Since water moves into the cell the cell, animal cells can explodeCytolysis

Plant and animal cells in a hypotonic solution

Turgor Pressure – central vacuole is full; pressure against the cell wall

Hypertonic Solution

Hypertonic solution – concentration of solute is higher in the solution than in the cell.

Net movement of water OUT of the cell.

Hypertonic solutions

Since water moves out of the cell the cell will shrink

Plant and animals cells in a Hypertonic Solution

Plasmolysis: shrinking of cytoplasm due to osmosis

Active Transport

Molecules move from low concentration to high concentrationRequires energy….why?

Active Transport

Molecular TransportProtein Pumps

Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumps (low high)

Bulk TransportEndocytosis – in!Exocytosis – out!

Sodium Potassium Pump

Other membrane transport activities that require energy

EndocytosisEngulfing of large particles or liquids from

outside the cell

2 types of Endocytosis

PhagocytosisEngulfing of large particles from outside the cell

PinocytosisEngulfing of liquids from outside the cell

Other membrane transport activities that require energy

ExocytosisRelease of large particles or liquids from

inside the cell

Inside the cell

Outside the cell

Which of the following allows cells to recognize each other as self or foreign?

Channel Pro

tei...

Cholestero

l

Phospholip

ids

glyco

prote

ins

0% 0%0%0%

1. Channel Proteins

2. Cholesterol

3. Phospholipids

4. Glycoproteins

10

The inside of the cell membrane consists of

Phosphate head

...

Fatty acid

tai...

Extra

cellu

lar ...

Carbohydrate

c...

0% 0%0%0%

1. Phosphate heads

2. Fatty acid tails

3. Extracellular Matrix

4. Carbohydrate chains

10

Which of the following components of the cell membrane affects the fluidity of the cell membrane?

Glyc

oproteins

Glyc

olipids

Cholestero

l

Extra

cellu

lar ...

0% 0%0%0%

1. Glycoproteins

2. Glycolipids

3. Cholesterol

4. Extracellular matrix

10

Which type of protein is responsible for receiving messages from hormones?

Channel pro

tei...

Carrier p

rotei...

Cell Reco

gniti...

Recepto

r Pro

te...

0% 0%0%0%

1. Channel protein

2. Carrier protein

3. Cell Recognition Protein

4. Receptor Protein

10

The movement of particles from high concentration to low concentration is called

Osm

osis

Diff

usion

Endocy

tosis

Exocy

tosis

0% 0%0%0%

1. Osmosis

2. Diffusion

3. Endocytosis

4. Exocytosis

10

The diffusion of water is called

Active

transp

ort

Endocy

tosis

Exocy

tosis

Osm

osis

0% 0%0%0%

1. Active transport

2. Endocytosis

3. Exocytosis

4. Osmosis

10

The movement of particles across a membrane that requires energy (ATP) is called

Passive

transp

...

Active

transp

o...

Aquaporins

Semi-p

ermeable...

0% 0%0%0%

1. Passive transport

2. Active transport

3. Aquaporins

4. Semi-permeable

10

This diagram is an example of what membrane transport?

Diff

usion

Fac

ilita

ted

diffus

ion

Endoc

ytosi

s

Exo

cyto

sis

0% 0%0%0%

1. Diffusion

2. Facilitated diffusion

3. Endocytosis

4. Exocytosis 10

This diagram is an example of what membrane transport?

Diff

usion

Fac

ilita

ted

diffus

ion

Endoc

ytosi

s

Exo

cyto

sis

0% 0%0%0%

1. Diffusion

2. Facilitated diffusion

3. Endocytosis

4. Exocytosis 10