Biology-Chapter 6-Lipids, Membranes and the first Cells

Plasma membrane can also be referred to as what?

cell membrane

Plasma membrane is composed of ( ) and separates life from nonlife

lipids

The lipids in cell membrane serves as ( ) barrier

selective

Lipids in plasma membranes allow entry of ( ) needed by the cell and keeps ( ) out of cell

materials

damaging materials

The lipids in the cell membrane allows for the ( ) of a particular environment inside the cell compared to outside the cell

maintenance

The lipids in the cell membrane ( ) chemical reactions necessary for life, they allow ( ) to occur by sequestering appropriate chemicals

facilitate

chemical reactions

what does sequester mean?

isolate

( ) proteins, nucleic acids and carbohydrates, most lipids are ( ) polymers

unlike

not

lipid structure ( ) widely

varies

Fats, oils, waxes, phospholipids and steroids are all ( )

lipids

Are lipids hydrophobic or hydrophilic?

hydrophobic

Lipids are hydrophobic compounds due to their high ( ) content

carbon-hydrogen

Why are hydrocarbons hydophobic?

They’re nonpolar, the difference between their electronegativities is small

lipids are ( ) in water

insoluble

Are lipids hydrocarbons?

Mostly yes

Hydrophobic lipids in the fur of aquatic mammals- ( ) them from the elements

protects

Fatty acids are simple lipids made of ( ) chain bonded to polar ( ) function group

hydrocarbon

carboxyl

Fatty acids can be saturated or ( )

unsaturated

Fatty acids are ( ) hydrocarbon chains joined to a ( ) group

unbranched

carboxyl

What is a carboxyl group?

COOH

In ( ) fatty acids kinks may form in hydrocarbon chains

unsaturated

What does saturated mean?

carbons in the long chain are all ‘saturated’ with hydrogens

What does unsaturated mean?

carbons in the long chain are not ‘saturated’ with hydrogens

Unsaturated carbons are caused by what?

double bonds exist between carbons

Name some saturated lipids

butter

beeswax

Name some unsaturated lipids

Safflower

Olive oil

Canola oil

What hydrogenation?

manufacturing process that takes polyunsaturated fats and turns them into saturated fats

Hydrogenation makes ( ) fats

trans

Cis means what?

same side

Trans means what?

opposite side

What are essential Fatty acids?

“essential”- body cannot produce, and one must consume to obtain

Give an example of an essential fatty acid

alpha-linolenic acid, an example of an omega-3 fatty acid

Fats ( ) energy than carbohydrates

store more

Glycerol + fatty acids are joined by

Ester linkages

Fats and oils are polymers

false, they are not

What is another name for triacyclglycerols?

triglycerides

Glycerol + Fatty acids make what?

triacyclglycerol

Glycerol + fatty acids is caused by hydrolysis or dehydration reaction?

condensation reaction

A fatty acid as increased ration of bonds with higher ( ) energy than a carbohydrate

potential

Steroids are in the family of ( )

lipids

Steroids are distinguished by bulky, ( )

four-ring structure

Steroids differ from one another by ( ) attached to carbons in rings

functional groups

cholesterol is a component of ( )

plasma membranes

Give some examples of steroids

estrogen

testosterone

cholesterol

Phospholipids are made of what?

glycerol

two fatty acids

phosphate

charged or polar molecule

phospholipids have a ( ) head and ( ) tail

hydrophilic

hydrophobic

Are phospholipids amphipathic?

yes

What does amphipathic mean?

having both hydrophilic and hydrophobic parts

Lipid micelles are what?

tiny spherical aggregates of a phospholipid with single fatty acid chain

What is cell aggregation?

binding of cells of the same type

What are lipid bilayers?

from when phospholipids align in paired sheet, have two tails

Lipid micelles and lipid bilayers both form ( )- no energy is needed to occur

spontaneously

Hydrophilic heads of lipid micelles and bilayers interact with ( )

water

Hydrophobic tails of lipid micelles and bilayers interact with ( )

one another

Liposomes are ( ) membrane bound vesicles

artificial

phospholipids form a spherical structure when added to ( ) solution

aqueous

Two phospholipid layers are called what?

phospholipid bilayer

Phospholipid bilayer creates a barrier that does what

Separated the outside from inside

Molecules are in constant ( )

motion

Molecules will not move to occupy the space provided

false

molecules in constant motion is an example of what energy?

kinetic energy

What is Brownian motion?

the erratic random movement of microscopic particles in a fluid, as a result of continuous bombardment from molecules of the surrounding medium.

This is an example of what concentration gradient ?

no concentration gradient

From left to right what is the concentration gradient? Is it a concentration gradient?

low concentration to high concentration

yes its a concentration gradient

When a substance goes from high concentration to an area where it is low concentration, we say it goes ( ) or ( ) its concentration gradient

down

with

When a substances goes from where it is in low concentration to a region where it is in high concentration, we say that it goes ( ) or ( ) its concentration gradient

up

against

What is electrochemical gradients?

occurs when both concentration gradients and electrical gradients are present and drive the movement of ions

Electrochemical gradients do what?

create a difference in charge across the membrane

Electrochemical gradients are another form of ( ) energy

potential

What is diffusion?

The movement of molecules from an area of high concentration to an area of low concentration

In diffusion what moves, the solute or solvent?

solute

What is diffusion driven by?

driven by random movement (kinetic energy)

Is diffusion spontaneous or nonspontaneous

A passive process-it is spontaneous-no energy needed

The cell membrane is not dynamic

False it is dynamic

phospholipids are ( ) in place, but are fluid

NOT fixed

Phospholipids are in constant lateral motion, but rarely ( ) to the other side of the bilayer

flip

Phospholipids move ( ) about the bilayer

laterally

Phospholipids bilayers have ( ) permeability

selective

( ) or ( ) molecules move across phospholipid bilayers quickly

small

nonpolar

( ) or ( ) substances cross slowly, if at all

charged

large polar

Oxygen a ( ) molecules moves ( ) across bilayers

small nonpolar

quickly

Glucose a ( ) molecule moves ( ) across bilayer

large polar

slower

Small ions have a ( ) permeability

low

Many factors influence a membranes ( )

permeability

What affects a membranes permeability

-Length of hydrocarbon tails

-Saturation state of hydrocarbon tails

-Temperature

-Presence of cholesterol molecules in membrane

Lipid bilayer with short and unsaturated hydrocarbon tails have ( ) permeability

higher

Lipid bilayer with long and saturated hydrocarbon tails have ( ) permeability

lower

Membrane fluidity ( ) as temperature drops

decreases

As temperature drops molecules in bilayer move more ( ), and hydrophobic tails do what?

slowly

hydrophobic tails pack together more tightly

As temperature drops this causes decrease membrane fluidity which causes ( ) permeability

decreased

The presence of cholesterol embedded in the membrane ( ) fluidity when cold and ( ) fluidity when warm

increases

decreases

What is equilibrium?

occurs when molecules or ions are randomly distributed throughout solution, but there is no more net movement and molecules are still moving randomly

If we added some blue pigment and 20 ml of water what which would be the solvent and which would be the solute? what would it make?

solute= blue pigment

solvent= water

makes solution

Osmosis is the diffusion of ( ) across a selectively permeable membrane

water

Osmosis is a type of ( )

diffusion

Water will move ( ) its own concentration gradient; from where water is in ( ) concentration to where water is in ( ) concentration

down

high

low

Water moves from regions of ( ) solute concentration to regions of ( ) solute concentration

low

high

The amount of ( ) on the opposite side of the membrane will determine what water does

solute

What is tonicity ?

The ability of a solution to attract water into or out of the cell

The concentration of solution outside cell may ( ) from concentration inside cell

differ