BIOL1020, cell membrane and lipids

A triglyceride consists of:

1. Glycerol backbone (hydrocarbon chain with alcohol groups at each carbon

2. Three fatty acid chains (long hydrocarbon chains with a carboxylic acid at the start)

How does a triglyceride come together?

Via dehydration synthesis, the OH and carboxylic acid take out an H2O molecule and turn into an ester linkage (O-O)

Saturated

Fully protonated hydrocarbon chain, all single bonds

• Solid at room temperature

• In hot environments, cell membranes prefer integrating saturated fats into themselves.

Unsaturated 

Not fully protonated hydrocarbon chain, has double carbon bonds

• Trans: Hydrogens are at OPPOSITE sides on the carbon bond

• Cis: hydrogens are at the SAME side on the carbon bond

Trans fats come to be when cis fat undergoes hydrogenation to break the double bond and flood it with hydrogens to turn it into a saturated fat, but when the double bond is broken and the hydrogens don’t properly bond, the bond fuses, creating trans fat.

Waxes

Composed of long fatty acid chains that have many wander vaal interactions between nonpolar hydrocarbons, making them extra hard.

Amphipathic

Contain both polar and nonpolar portions

Micele

A single small layer/bubble of phospholipids

• what lead to today’s cells

Cholestrol

• Steroid

• 4 rings, 17 carbons

• Regulates fluidity in the cell membrane

Low density lipoproteins (LDL)

Very poorly structured due to a lack of lipoproteins in the membrane vesicle that transports the lipids around the body, resulting in leaking cholesterol that can become plaque in the blood vessels

High density lipoproteins (HDL)

Better structured, more lipoproteins within protective membrane around lipid. Can collect outside (LDL) cholesterol.

In a cold environment, the cell membrane has more

unsaturated fats

In a hot environment, the cell membrane has more

saturated fats

Functions of the phospholipid bilayer:

1. Solute transport

2. Catalyzing chemical reactions

3. Communication (signal receptors)

4. Cell recognition (immune cells recognizing healthy cells, killing infected cells)

5. Adhesion (cells stick together to form tissues)

Simple diffusion

Neutral substances smaller than glucose (6 carbons) can cross freely through the membrane according to their concentration gradient (high to low)

Concentration gradient creates:

Potential energy, which moves solutes and water across the membrane

Hyperosmotic environment has:

higher solute concentration than the cell

Hyposmotic environments have

lower solute concentration than the cell

Osmolarity

Concentration of all solutes, sum of all solutes

Tonicity

Describes the effects of osmolarity on the cell (based on non-penetrating solutes ONLY)

A cell placed in a hyperosmotic solution will

shrivel

A cell placed in a hypotonic solution will

swell

A hyperosmotic solution has ____ solute than another solution

more

A hypoosmotic solution has ___ solute than another solution

less