LipidsBy: Julianne, Madeline, Jade & Joy

Triglyceride

Structure of a Lipid

- Lipids are made of fatty acids including CHO

-The more C-C bonds a molecule has, the more energy it can store

-Hydrophilic head and hydrophobic tail

-A triglyceride is made of glycerol and fatty acids

Structure of Glycerol

Structure of Fatty Acid:

=Hydrophobic tail- hates water

Saturated and Unsaturated Fatty acids:

All “C”s have “H” attached

*Not all “C”s have an H attached.

*There is:

double bond between 2 carbons

Butter is a saturated fat because the tails of saturated fat can be close together to

form a solid.

Oil is not saturated because the tails “bump” together to

form a liquid.

If the fatty acid part of a lipid is saturated, then it is a saturated fat.

Isomer:-molecules with the same molecular formula, but different arrangements of atoms.

-physical and chemical

-properties may be very

different.

e.g. Isomer of C4H10O:

Structural isomerism :Positional: Due to a change in the arrangement of the atoms in a structure Functional: the atoms are arranged In such a way that there is a change in the functional group.

Stereoisomerism (Due to the spatial properties of the molecule itself):Geometrical: restricted rotation (often involving a carbon-carbon double bond)

Trans Isomer: 2 atoms that are locked on opposite sides of the double bond

Cis Isomer: 2 atoms that are locked on the same side of the double bond.

Fatty Acid in Cell Membrane

-The cell membrane is bilayer made out of phospholipids, cholesterol, and proteins.-Two fatty acids + a phosphate head= phospholipid -Fatty acids are hydrophobic (water-insoluble), the phosphate head is hydrophilic

Fatty acids orient inward, creating hydrophobic space in the center of the bilayer.

MEMBRANE FLUIDITY

-Decided by lipid composition and temperature

-Transition temperature: where gel becomes crystalline

-shorter or unsaturated fatty acids → lower trans. Temp.

CHOLESTEROL

-Doesn’t change membrane’s transition temperature, but broadens the transition range by reducing phospholipid movement

-Stiffens the membrane both below and above trans temp

MEMBRANE MODELSDavson-Danielli

-continuous bilayer

-polar head + protein ‘s beta sheet

-ionic electrostrostatic bonds

Singer-Nicolson-a.k.a the lipid globular protein mosaic model -discontinuous lipid bilayer

-glob of proteins -the membrane’s hydrophobic core is made up of nonpolar fatty acids and hydrophobic proteins-ionic electrostatic bonds aren’t the energy source

THREE FUNCTIONS OF LIPIDS

a) Energy Storage

-Long-term energy storage

-Energy stored in C-C bonds

-Fatty acid tails have a lot of C-C bonds

b) Cell Membrane

-Made up of phospholipids

-Glycerol, diglyceride, phosphate group

-Head is hydrophilic, tail is hydrophobic

c)Cholesterol

-Lipids are the precursor for cholesterol

-Functions of cholesterol:

Production of hormones

Stabilizes phospholipid bilayer

Aids in digestion

d)Other functions include: Protection & Insulation

IMPORTANCE OF LIPID SYNTHESIS FOR CELLULAR REPRODUCTION

-When cells reproduce, membrane divides, cell gets smaller

-Membrane is made up of lipids

-Lipid synthesis needed to maintain original cell size

Head is hydrophilic

Tail is hydrophobic

• Carboxyl group on end

H O

O

C H

H

Fatty acid tail

C C C

H H H

C

H H H H

H

C

HOCH

H

Glycerol

OCH

OCH

H

O

CH

H

OCH

CH

HH O

O

C H

H

C C C

H H H

C

H H H H

H

C

H

H

H

OH

Lipids form through condensation (Dehydration synthesis)

Anabolism

CONDENSATION

O

CH

H

O

CH

O

CH

H

H

O

O

C H

H

C C C

H H H

C

H H H H

H

C

H

H

H

H

O

O

C H

H

C C C

H H H

C

HH H H

H

C

H

O

O

C H

H

C C C

H H H

C

H H H H

H

C

H

H

H

Hydrolysis

Water is added back in

The tails come off

Energy is stored in C-C bonds

CH

H

CH

O

CH

H

H

O

O

C H

H

C C C

H H H

C

H H H H

H

C

H

H

O

O

C H

H

C C C

H H H

C

HH H H

H

C

H

O

O

C H

H

C C C

H H H

C

H H H H

H

C

H

OH

OH

H

H