Ch 5 cell membrane and transport
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Ch. 5 Cell Membrane and Transport. LIPID BILAYER. cytoplasm. extracellular fluid. Cell Membrane —thin, flexible membrane that surrounds all cells. . Selectively permeable - regulates what enters and exits the cell. Made up of a phospholipid bilayer . Double layer of phospholipids

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Ch. 5 Cell Membrane and Transport

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Ch 5 cell membrane and transport

Ch. 5 Cell Membrane and Transport

LIPID BILAYER

cytoplasm

extracellular

fluid


Cell membrane thin flexible membrane that surrounds all cells

Cell Membrane—thin, flexible membrane that surrounds all cells.

  • Selectively permeable - regulates what enters and exits the cell.

  • Made up of a phospholipid bilayer.

    • Double layer of phospholipids

    • Gives cells flexible but strong barrier between itself and its surroundings.


Phospholipids

Phospholipids

Hydrophilichead

  • Phospholipids are a lipid that have a

    • Glycerol

    • Phosphate

    • Two fatty acid chains

Hydrophobictail


Ch 5 cell membrane and transport

Hydrophilic

Hydrophobic


Phospholipid bilayer

PhospholipidBilayer

hydrophilic

head

hydrophobic

tails

Water (outside of cell)

hydrophilic

head

Water (inside of cell)


Fluid mosaic model

Fluid mosaic model


Fluid mosaic model1

Fluid mosaic model

Fibers of extracellular matrix

Carbohydrate (of glycolipid)

Glycolipid

Glycolipid

Phospholipid

Microfilaments of cytoskeleton

Protein

Steroids


Membrane proteins

Membrane Proteins

  • > 50 kinds of proteins found in human red blood cells so far

  • Carry out many different functions

    • Structural, external, identification tags, form junctions between cells

    • Enzymes – catalytic teams for molecular assembly lines

    • Receptors – receive chemical messages from other cells

      • Message transfer is called signal transduction

    • Help move substances across membrane


Ch 5 cell membrane and transport

Cell Transport: movement of substances across the cell membrane based on concentration gradient.

Concentration Gradient: Difference in concentration over a distance.

No Gradient

HIGH concentration

LOWconcentration

Gradient


How the cell membrane does its thing

How the Cell Membrane does its thing…

  • Two categories of cell transport:

    • Passive transport – Requires NO energy

      • High to low concentration

    • Active transport – Requires energy

      • Low to high concentration


3 types of passive transport

3 types of passive transport:

  • Simple Diffusion

    • High to low concentration

    • Small, lipid soluble molecules like CO2 and O2

    • Example:

      • Oxygen enters bloodstream from the lungs


2 facilitated diffusion

2) Facilitated Diffusion

  • Large, charged, or polar substances move across membrane in this way.

  • Always moves from high to low concentration

  • Requires a transport protein

Transport Protein


2 facilitated diffusion1

2) Facilitated Diffusion

  • Water can move through because it is small, buttransport is slow, aquaporins allow for faster diffusion

Transport Protein


3 osmosis

3) Osmosis:

  • Diffusion of water through a selectively permeable membrane until equilibrium occurs.

  • High to low concentration

  • Water will cross membrane until solute concentrations(molecules/mL) are _______________on both sides of membrane


What words do you know that start with

What words do you know that start with……

  • Iso______________

    • Definition:

  • Hyper___________

    • Definition:

  • Hypo____________

    • Definition:


Tonicity

Tonicity

  • A term used to describe the tendency of a cell in a given solution to lose or gain water.


Ch 5 cell membrane and transport

Isotonic Solution—Concentration of solutes is equal in and out of the cell.

  • No net movement of water.

  • Cell maintains shape.


Ch 5 cell membrane and transport

Hypertonic Solutions—Concentration of solutesis higher outside the cell.

  • Water exits the cell.

  • Animal Cell: shrinks which is known as crenation

  • Plant Cell: cell membrane collapses away from cell wall. This is known as plasmolysis.


Ch 5 cell membrane and transport

D. Hypotonic Solution—Concentration of solutes is lower outside the cell.

1. Water enters the cell.

2. Animal cell swells and

may burst which is known as Cytolysis.

3. Plant cell—cell wall prevents breaking. (Turgor Pressure)


Tonicity in animals

Tonicity in animals

  • Osmoregulation: or an animal to survive changes in salinity it must have a method to prevent excessive uptake of water or excessive loss of water

    • Ex: freshwater fish live in hypotonic environment

    • Ex: saltwater fish live in a ___________________ environment


Ch 5 cell membrane and transport

  • Have evolved to have kidneys and gills that constant work to flush water out of the body


Tonicity in plants

Tonicity in plants

  • Turgidity: When a plant cell has a net inflow of water.

  • Plasmolysis: When a plant cell loses water, plasma membrane pulls away from cell wall.

    • Also happens in bacteria and fungi


Ch 5 cell membrane and transport

HYPOTONIC HYPERTONIC

ISOTONIC


What type of solution is each cell in

What type of solution is each cell in?

HYPERTONIC

HYPOTONIC

ISOTONIC


Ch 5 cell membrane and transport

Ticket out Quiz

2M sucrose

solution

1 liter of

pure water

10M sucrose

solution

2M sucrose

solution

1)

2)

3)

HYPOTONIC

CONDITIONS

HYPERTONIC

CONDITIONS

ISOTONIC

CONDITIONS

Fig. 5.14, p. 88


Active transport

Active Transport

  • Substances move against

    concentration gradient

    -low to high concentration

  • Requires energy (ATP)

  • Requires a transport protein.


How do large molecules enter and exit the cell

How do LARGE molecules enter and exit the cell?

  • BULK TRANSPORT: Movement of particles into or out of a cell without passing through the plasma membrane.

  • Requires energy!


Ch 5 cell membrane and transport

Endocytosis – Large materials move into cell.

  • Cell engulfs large materials such as macromolecules.


Phagocytosis

Phagocytosis

  • Cell engulfs large particles, microbes, and cellular debris

  • “Cell eating”


Pinocytosis

Pinocytosis

  • Cells receive bulk amounts off liquid

  • “Cell drinking”


Ch 5 cell membrane and transport

  • Exocytosis - vesicle fuses with the membrane and exits the cell.

    • Expels materials such waste and hormones.


Lorenzo s oil

Lorenzo’s Oil

ALD

Can not digest FAT

Fat builds up and destroys his nerves

Fat enters body in 2 ways – food and biosynthesis

Oil stops biosynthesis!

Oil keeps the body from building up the bad fat

COMPETITIVE inhibition


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