10/15/13

Objective: What are the properties of Lipids?

Chapter 5: The Molecules of Life

Do Now: What can happen to sugar if not used for energy?

Lipids

• lipids: class of compounds that are hydrophobic (water-fearing) and nonpolar– Made of glycerol and

fatty acid– Part of cell membrane– store energy

Fatsfats(triglyceride):) made of glycerol attached to 3 fatty acids(long

hydrocarbon chains)– Solid or liquid– Fatty tissues cushion organs and provide body with insulation

• saturated fats: all fatty acid chains contain the maximum possible number of hydrogen atoms– All single bonds– Animal fats (solid at room temp)

• unsaturated: less than max. number of H atoms in one or more fatty acid chains

– Some double bonded– Most plant and fish oils

(liquid at room temp)

Steroids

steroids: carbon skeleton forms 4 fused rings– Different functional

groups attached to rings

• Examples: Cholesterol, Sex hormones

Cholesterol

• cholesterol: essential molecule found in cell membranes– Help maintain membrane

structure

Phospholipids

• Major part of cell membrane

5.4 Proteins

• protein: a polymer constructed from monomers called amino acids.– Ex: Enzymes, hormones,

cell receptors, immune defense

Protein Structure

• amino acid: monomer that consists of a central carbon atom bonded to four partners (carbon forms 4 bonds)- a carboxyl and amino group

• Polypeptide: chain of amino acids that make up a protein– Made by dehydration synthesis

Shape

• polypeptides are precisely twisted, folded, and coiled into a unique shape for each protein

• Shape of protein determines how it will function

Denaturation

• Denaturation: unfavorable change in pH, temperature, or other quality of the environment that causes the protein to unravel and lose shape– (ex. frying an egg;

albumin is egg white which turns from clear to white)

Enzymes

• enzymes: proteins that act as organic catalysts– Lowers activation energy

• pH and temp can affect function

Catalysts

• Catalysts: compounds that speed up chemical reactions

How Enzymes Work

• substrate - a specific reactant acted upon by an enzyme

the shape of the enzyme fits the shape of only particular substrate

• active site - where enzymes binds to substrate

Substrates are the reactants. Lactose is the substrate, lactase is the enzyme.

Enzyme Function

Describe what is occurring in the picture:

Enzyme Function

Nucleic Acids

• DNA: dexoyribose nucleic acid

• RNA: ribose nucleic acid