Chapter 5 Chapter 5 Section 3Section 3

LipidsLipidsMrs. KerstetterMrs. Kerstetter

BiologyBiology

LipidsLipids

LipidsLipids Lipids are generally not soluble in water.Lipids are generally not soluble in water.

Which means they are HYDROPHOBICWhich means they are HYDROPHOBIC

Lipids Lipids are made mostly from carbon and are made mostly from carbon and hydrogen atoms.hydrogen atoms.

Lipid structureLipid structure

LipidsLipids

The common categories of lipids are:The common categories of lipids are: fatsfats oils oils waxeswaxes steroidssteroids

LipidsLipids

What is the function of lipids?What is the function of lipids?

LipidsLipids

Lipids can be used to store energy. Lipids can be used to store energy. Some lipids are important parts of Some lipids are important parts of

biological membranes and waterproof biological membranes and waterproof coverings. In other words…coverings. In other words…BOUNDARIESBOUNDARIES

Some circulate in the body as chemical Some circulate in the body as chemical signals to other cellssignals to other cells

LipidsLipids

Many lipids are formed when a glycerol Many lipids are formed when a glycerol molecule combines with compounds molecule combines with compounds called fatty acids. called fatty acids.

If each carbon atom in a lipid’s fatty If each carbon atom in a lipid’s fatty acid chains is joined to another carbon acid chains is joined to another carbon atom by a single bond, the lipid is said atom by a single bond, the lipid is said to be SATURATED.to be SATURATED. The term The term saturatedsaturated is used because the is used because the

fatty acids contain the maximum possible fatty acids contain the maximum possible number of hydrogen atoms.number of hydrogen atoms.

LipidsLipids

If there is at least one carbon-carbon double If there is at least one carbon-carbon double bond in a fatty acid, it is UNSATURATED.bond in a fatty acid, it is UNSATURATED.

Lipids whose fatty acids contain more than Lipids whose fatty acids contain more than one double bond are polyunsaturated.one double bond are polyunsaturated.

Lipids that contain unsaturated fatty acids Lipids that contain unsaturated fatty acids tend to be liquid at room temperature.tend to be liquid at room temperature.

Saturated fats are SOLIDS at room Saturated fats are SOLIDS at room temperature.temperature.

SteroidsSteroids

= a lipid molecule in which the C = a lipid molecule in which the C skeleton forms 4 fused ringsskeleton forms 4 fused rings

-all steroids have a core set of 4 fused -all steroids have a core set of 4 fused rings, but they are different in the rings, but they are different in the kinds and locations of functional kinds and locations of functional groups attached to the ringsgroups attached to the rings

SteroidsSteroids

Classified as lipids because they are Classified as lipids because they are hydrophobichydrophobic

Functions:Functions:1.1. Circulate in body as chemical signalsCirculate in body as chemical signals2.2. Starting point for other steroidsStarting point for other steroids

Estrogen and testosterone are sex Estrogen and testosterone are sex hormones cause major differences in hormones cause major differences in female and male sexual female and male sexual characteristicscharacteristics

SteroidsSteroids

CholesterolCholesterol

Best known steroidBest known steroid Found in molecules that surround your Found in molecules that surround your

cellscells Starting point for making other hormonesStarting point for making other hormones

Bad Rep…Why?Bad Rep…Why? High levels of LDL and VLDL are linked to High levels of LDL and VLDL are linked to

increase risk of cardiovascular diseaseincrease risk of cardiovascular disease