plasma membrane and transport

plasma membrane

80% phospholipids, the surface encapsulating a cell

  hydrophilic heads of fluid mosaic model

P0₄ outside end "water" "loving" attracted to water on inner/outer parts of cell

hydrophobic tails

 face each other to exclude area that are in water. fatty acids "water" "fearing" attracted to each other on inside of bilayer

glycolipids

 some carbohydrates attached to outer lipids (involved in cell to cell recognition)

Missile

form a circle with all tails facing the center

cholesterol

regulates fluidity of membrane

receptors protein

hormones and neurotransmitter

enzymes

reactions in and out of cell

transport protein

ions and molecules

integral proteins

inserted into the bilayer

transmembrane

 across entire bilayer - form a transportation system, transfers ions

peripheral proteins 

on inner & outer surface, serve as anchors for cytoskeleton, messaging 

glycoproteins

 carbohydrates on outer surface

glycocalyx

outer carbohydrate coat made up of glyco proteins and glycolipids (cell recognition and identification

Cholesterol

 prevents plasma membrane from becoming too solid or liquid, helps maintain rigidity 

plasma membrane is fluid, importance

 it can easily shift & flow

a.  two layers can slide over one another

b.  some proteins float freely throughout

     membrane

c. many proteins attached to cytoskeleton

   i. allows for regional specialization- allows for difference in shapes 

microvilli of plasma membrane

ingerlike extensions of cell

i. found in kidney and intestine

ii. increases surface area for absorption

iii. actin filaments for support, cytoskeleton elements creating “wire framework” 

tight junctions

cell-cell adhesion proteins

i. generally at surface of epithelium

ii. prevent passage between cells

iii.  "seal" layer of cells into a sheet

desmosomes

 anchor cells to cells & basement 

  i.  carbohydrates of glycoprotein

     intermingle

ii. keratin filaments anchor to cytoplasm very strong, helps prevent tearing

hemidesmosome

(half of size) anchor to basement

     membrane

-gap junctions example

in heart is important, allows maximum pump

interstitial fluid 

- bathes all cells and tissues

interstitial fluid example

released by capillaries into organs/tissues

b. recaptured by lymph vessels back to heart

c. contains salts, nutrients, hormones, etc.

selectively permeable function

only certain things pass

 passive transport 

nature does the work

active transport

cell must use energy (ATP)

diffusion

 movement of particles from area of HIGH concentration to area of LOW concentration until equal

Concentration gradient 

difference in concentration between HIGH and LOW

    areas

 larger gradient

larger driving force,

fast gradient

higher temperature or smaller particle

oxygen simple diffusion

blood (high) → cells (low)

CO_{2 simple diffusion}

cells (high) → blood (low)

urea concentration gradient

ells (high) → blood (low)

fat soluble molecules

small fats and steroids

osmosis

the movement of a solvent (such as WATER) from an area of LOW solute (high free solvent) concentration (such as NaCl) to an area of HIGH solute (low free solvent) concentration

solution =

solvent + solute

                                                                             (dissolving liquid)   (dissolved particles)

1. molarity

1. moles of solute / liters of solution (moles/liter = Molar)

mole

grams of substance = mol. wt. substance

osmolarity

measure of concentration of particles in a solution

example of osmolarity 1 molar of NaCl =

2 osmol NaCl because Na+ and Cl- = 2 ions

isotonic

no net movement of water and concentration of solutes outside a cell is equal to the concentration inside

hypertonic

water moves inside the cell and an environment where a solution has a higher solute concentration than the fluid inside a cell

hypotonic

water moves outside the cell

osmotic pressure 

driving force generated by the concentration gradient

osmotic pressure example when larger concentration inside

*the larger the difference in concentrations between the INSIDE and OUTSIDE, the larger the osmotic pressure (driving force is greater)

hydrostatic pressure 

force of a fluid on itself

hydrostatic pressure example

; pressure of cell wall in plant cells that balances the osmotic pressure, preventing more water from entering the cell

crenate

water moves out and cell shrinks

lyse

water moves in and cell bursts

isotonic solution example

rings 0.9% NaCl, 5% glucose, humans require this

hypertonic solution example

to treat edema (water excess)

hyoptonic solution example

to treat dehyradtion

filtration

- hydrostatic pressure > osmotic

     pressure (Squeezing a leaky water balloon)

1. WATER moves from HIGHER osmo → LOWER osmo

facilitated diffusion

see-saw protein carries across or channels allow through (goes   with the concentration gradient so it is still a form of passive transport)

carrier protein

"open outside" <-> "open inside"

i. very specific for the molecule transported

ii. uses energy of natural diffusion (water-

    wheel)

iii. glucose carrier is typical 

 protein channels

passage of charged & polar

i.  Na⁺, K⁺, Cl^- channels are very specifi    can be opened or closed on command

active transport -

 transport solutes against a concentration gradient (goes against diffusion)

solute pumps

 Na⁺, K⁺, Ca⁺⁺, amino acids and relies on an energy source

uniport

one specific particle only

symport

same direction

antiport

opposite directions and uses ATP. Sodium potassium pump example

Na⁺-K⁺ ATPase Pump

 creates ion concentration gradient for cell [Na⁺]_OUT HIGH; [K⁺]_IN HIGH, ATP is used by this pump to move 3 Na+ out of the cell and bring 2 K+ into the cell

what moves into cell in sodium potassium pump

Na⁺ will want to move INTO cell; K⁺ will want to move OUT of cell- very important

blk transport

cell membrane pouching process

exocytosis

cell vesicle moves to membrane with contents, merges, then releases material

example of exocytosis

hormone/neurotransmitter release; mucus secretion; expulsion of extracellular proteins (collagen, elastin, matrix)

endocytosis

engulfment by cell membrane pouch which then buds off into the cytoplasm

phagocytosis

("eat" "cell"" process") - plasma membrane raps around large mass

(bacteria, dead cell, cell debris)

phagosome →

lysosome

pinocytosis

 "drink" "cell"" process"

receptor-mediated endocytosis 

receptors on the cell surface bind to desired molecule before the  engulfment

The Resting Membrane Potential 

voltage across the membrane)

-basis for all electrical signals

voltage

electrical potential energy that results from separation of charges across the plasma membrane (also called potential difference - potential)

The Na⁺-K⁺ ATPase Pump create

concentration gradients for both Na⁺ and K⁺

a. [Na⁺]_OUT > [Na⁺]_IN

b. [K⁺]_IN > [K⁺]_OUT

what does The Na⁺-K⁺ ATPase Pump result in

1. Results in NET flow of positive charge out of the cell

1. cycle =   3Na⁺ out & 2K⁺ in

Results of pump

1. NET flow of positive charge out of the cell

1. cycle =   3Na⁺ out & 2K⁺ in

Na⁺ Channels

normally closed so that Na⁺ cannot easily move back into the cell.

K⁺ Channels normally

slightly open so that K⁺ can slowly leak out

resting membrane potentials for cells generally range

-20 mV to -200mV

electrochemical gradient -

 charge & concentration

i. Na⁺: {electro-IN; chemical-IN}

ii. K+: {chemical-OUT = electro-IN

A. Determination of ABO Blood Types

• Red blood cells have glycoproteins (and glycolipids) on their surface.

• Attached to these molecules are specific carbohydrate (sugar) chains.

• Those sugar chains act as the A or B antigens that the immune system recognizes.

Binding of Dangerous Toxins

proteins of cholera and tetanus bind to cell by identifying specific carbohydrate  on proteins

  C.     Identification of Specific Cell Types examples

Sperm knows egg by specific glycoproteins

2. Cell-cell interaction during embryogenesis and tissue differentiation

3. Immune cells identifying foreign cells and material such as bacteria, viruses, and cancer cells

Potassium linkage channel

allows a little bit of potassium to go out at a time, making the inside more negative since more positive are going out.

Sodium channels- 

closed at rest (needs to regulate excess sodium from coming inside because then we can’t kick it out then inside becomes positive middle),  but still allows sodium in. Prevents positives from coming in (most important concept)

Sodium potassium ATP pump

 uses ATP to get rid of 3 sodium for every 2 potassium , kicking out more positive so inside becomes more negative