Forms bilayers in cell membranes

Forms micelles in aqueous solutions

Hydrophilic

Hydrophobic

Has a sugar head - often called an antigen

 lipid tail - important in immune response and cell recognition

Have specific sugars attached to outer surface

Function along with glycolipids in immune response and cell recognition

Sugar head often called an antigen

Recognition proteins & Glycoproteins

Ex:  Major histocompatibility comples (MHC)

       ABO blood groups

       Cell junctions (like desmosomes) are also often

       formed from glycoproteins

Structural Support

Inside - to cytoskeleton

Outside - to other cells or fibers

Often important in integral membrane proteins, where they play a role in cell-cell interactions.

Occur in the cytosol

Molecules randomly move through the opening in a process called diffusion

Requires no energy

Molecules move from an area of high concentration to an area of low concentration

These proteins are used in intercellular communicaiton.

(lock and key)

Forms impermeable junction

Molecules cannot cross epithelial sheet by slipping between cells

Anabolism

constructive metabolism

Catabolism

destructive metabolism

Activation Energy

Increasing

Allosteric Regulation

• The availabilty of substates and cofactors usually determines how fast the reaction goes.  As product accumulates, the apparent rate of the enzymatic reaction will decrease due to lack of substate
• covalent modification
• allosterically
• modulator proteins
• genetic regulation

• body temperature - heat is generated by the cellular respiration reaction, combining oxygen and ATP and creating heat, carbon dioxide and water.  The Hypothalamus monitors body temperture and regulates that temperature by increasing or decreasing cellular respiration reactions which keeps the body temperture maintained within a few degrees of normal

• Glucose is the form of sugar that is found in blood and provides energy for cellular respiration.  When glucose levels are high - insulin is secreted by the pancreas.  Insulin stimulates the absorption of glucose by cells and the liver's conversion of glucose into glycogen (stored in the liver and blood cells).As glucose levels decrease, less insulin is secreted, glucagon is produced which causes the liver to convert glycogen back to glucose.

Glycolysis

• Carbohydrates start to breakdown
• Occurs in the cytoplasm/cytosol
• Does not require Oxygen - can occur anaerobic
• Requires 2 ATP produces 4 ATP = gain of 2 ATP

• Carbohydrates
• Fats
• Proteins
• Pyruvate - which changes to acetyl coenzyme A before Krebs during the linking step
• Oxygen

NADH + H⁺ ---->   NAD⁺

OIL RIG

Oxidation is loss of electrons

Reduction is gain of electrons

Since NADH is becoming more positive (or less negative), then it must be losing electrons, and therefore is being oxidized to NAD⁺

(Oxidation is Loss of eletrons)

• carbohydrates continue to breakdown
• some fatty acids begin breakdown
• uses products of glycolysis and krebs cycle
• occurs in the mitochondria
• requires oxygen (aerobic)
• produces H₂O
• produces 34 ATP

Where is glycogen stored?

What two hormones are secreted to stimulate  the conversion of glycogen to glucose?

What is this process called?

Liver and Muscles

eqinephrine and glucogon

glycogenolysis

Carbohydrates are broken down into __________

which then enters _____________

glucose

glycolysis (breaking down sugar)

cytoplasm

glycerol

fatty acids

• glycogen storage
• decomposition of red blood cells
• plasma protein synthesis
• hormone production
• detoxification
• produces bile

Low-density lipoprotein

Enables lipids like cholesterol and triglycerides to be transported within the water-based bloodstream

High density lipoprotein

HDL particles are able to remove cholesterol from atheroma within the arteries and transport it back to the liver for excretion or re-utilization

Ammonia

which is converted into urea in the liver which is then transported to the kidneys to be excreted

Most polar molecules ____ ____ diffuse into cells, or very slowly

Why?

do not

Electrical charge/polarity:  strongly-charged ions are polar and not lipid soluble and cannot cross directly through the lipid portion of the membrane; often cross through specific channel proteins

_____ _____ molecules diffuse very well across membranes

Why?

non polar

Membranes are lipid-soluble (non-polar)

Ions (NA⁺, K⁺, Cl-) diffuse across plasma membranes very fast even though they are very ____

Why?

polar

They have specific channel proteins

Facilitated diffusion

EX:  the exchange of oxygen and carbon dioxide in the alveoli of the lungs

exergonic process

Energy is released

Endergonic Process

Uses energy from an outside source

What type of transport does not involve any

• chemical energy
• relies on the innate permeability of the cell membrane
• proteins and lipids

• Diffusion
• Facilitated
• Osmosis
• Filtration

filtration

the size of the membrane pores dictate the molecules that may pass

• polarity - (Hydrophobic vs Hydrophylic)
• charge - (charge vs uncharged)
• size - (large vs small)

Endocytosis

By three slightly different processes

Phagocytosis

Pinocytosis

Receptor-mediated endocytosis

facilitated

Active Transport

Use ATP

Primary active  transport

• Requires ATP
• From low to high
• An accumulation of particles on one side of the membrane
• Requires carrier proteing and ATP
• Carrier protein pumps particles from one side to the other
• Carrier is shape-specific

Secondary Active Transport

Describe the first step

carrier protein moves two substances at the same time in the same direction

for instance - first substance moves into cell from it high to low by facilitated diffusion through a carrier protein

second substance tags along

Secondary Active Transport

describe the second step

first substance is actively pumped out of cell to maintain low in ICF - ACTIVE TRANSPORT

During secondary active transport

 if the two substances are moving opposite direction it considered

Chemical gradients

High ___ in the extracellular fluid exerts a pressure pushing ____ to the inside

High ____ in the intracellular fluid exerts a pressure pushing ____ to the outside

Na+

Na+

K+

K+

Electrical Gradients

The intracellular negativity tends to pull ____ into the cell

Electrical Gradients

The intracellular negativity tends to ______ the movement of ____ out of the cell

Hinder

K+

The chemical gradient pushes Na+ into the cell

The electrical gradient pulls Na+ into the cell

The chemical gradient pushes K+ out of the cell

The electrical retards the movement of K+ out of the cell

i.e. K+ is attracted by the intracellular protine (-)

K+ is repulsed by the accumulation of positive chages extracellularly

Transport across an epithelial sheet

(lining the intestine)

• Lumen
• Apical surface
• Epithelial cell ICF
• Basolateral surface (and basement membrane)
• Interstitial fluid
• Capillary wall
• Blood plasma

Diffusin

Primary Active Transport

blood plasma

• Sodium moves into the body through the digestive tract, it comes in contact with an epithelial sheet
• Na+ diffuses through a protein channel from the lumen of the digestive tract organ into epithelial cell
• Na/K pump transports Na+ into the ISF
• Na+ diffuses passively into blood plasma

• Na+ diffuses through protein carriers from lumen of organ into epithelia cell and carries with it glucose, which is being moved against its concentration gradient
• the second molecule is moving into the epithelial cell by secondary transport
• the second molecule is then transported across basal surface and into the ISF, by facilitated diffusion and then into the blood
• Na+ is then pumped out of epithelial cells by primary active transport

• Water moves into cells through special protein channels called aquaporins
• water passes through tight junctions
• water follows the movement of solutes across epithelium
• as Na+ goes from apical to basal surface, it generates osmotic pressure gradient and pulls water with it

negatively charged

• concentration gradients
• electrical gradients
• gated channels
• leak channels in the membrane

but not directly through the lipid portion of the membrane

Potassium

Potassium

down

Chemical concentration - from high to low

Electrical gradient - toward an area of opposite electrical charge

"electrochemical gradient"

have electrical difference between the sides of the membrane

Outside surface of cell membrane is slightly postive

Inside surface of cell membrane is slightly negative

Closed

Open

First, many of the voltage-gated sodium channels begin to close

Second, many more potassium channels open, allowing positive charges to leave the cell

This causes the membrane potential to begin to shift back towards the resting membrane potential

voltage-gated potassium

What type of Potentials have these types of origins

• arise mainly in dendrites and cell bodies
• arise at trigger zones and progagate along axon

Graded

Action

What type of potentials have these types of channels

Chemical, mechanical or light

Voltage gated ion channels

Graded

Action

May be hyperpolarizing (inhibitory to generation of action potential)

or

Depolarizing (excitatory to generation of action potential)

Reduction in membrane potential

• occurs when gated Na+ channels open and Na+ rushes inside cell
• Inside of cell membrane and potential moves closer toward zero than -70mV
• May continue until inside of membrane is postive

Membrane potential increases

• occurs when an excess of K+ moves outside of cell, leaving a slight excess of negatively charged proteins trapped inside
• Membrane potential goes below -70mV
• Inside of cell membrane becomes more negative

membrane potential moves back toward -70mV after depolarization occurs

• Short-lived local changes in membrane potential
• Local flow of current that decreases with distance traveled, goes a short distance then dies out
• Called "graded" because magnitude of current varies with intensity of stimulus that sets it off
• Occur in all cells
• May be depolarizing or hyperpolarizing 

slows down

speeds up

voltage-gated sodium channels are open or inactivated and voltage-gated potassium channels may alos be open

low K+ in ECF

Concentration gradient for K+ is steeper than usual so more K+ moves out of the cell which causes a hyperpolarized cell (-90mV)(inside more negative, outside more postive)

Harder to depolarize so no action potential can happen

What are some of the symptoms of hypokaleima

What causes hypokaleima

muscle weakness, fatigue, sluggish reflexes, cardiac arrhythmias

decreased intake, persistent vomiting, diarrhea, diuretics, hormone imbalance

High K+ in ECF

• increased intake, especially when coupled with kidney insufficiency
• death by lethal injection
• severe and extensive damage to cell membranes, burns for example allow K+ to leak out
• hormone imbalance (aldosterone)

• nerves and muscles have spontaneous, inappropriate action potentials
  • cramps
  • spasms
  • exagerrated reflexes
  • convulsions
  • tetany

• decreased intake
• lack of vitamin D
• low parathyroid hormone
• high calcitonin

concentration gradient for Na+ not as steep as it should be

causes the cell to have a harder time to depolarize

• muscle weakness
• nausea
• profound osmotic effect on water content of all cells
• brain cells sell causing dramatic neurological symptons (act crazy)
• low plasma volume
• hypotension

• decreased take
• excessive sweating
• vomiting
• diarrhea
• diuretics
• kidney failure
• hormone imbalance
• poor diet combined with alot of beer
• ecstasy (most common electrolye imbalance)