Unit #2: Biomolecules

NOTES.4: INTRO TO BIOMOLECULES & LIPIDS

Do Now:Here is the structural formula of phospholipid an

important structural that makes up parts of the cell membrane. Identify the hydrophobic (hates water) end and the hydrophilic end of this molecule and explain

why using the Claims, Evidence, and Reasoning Format.

PART I:All molecules are made of atoms.

Atoms are building blocks.Where do you get your building

blocks?

You Are What You Ate!Food is a mixture of biomolecules:

• Carbohydrates (sugars & starches)

• Proteins• Lipids (fats, oils, & cholesterol)• Nucleic Acids (DNA & RNA)• Vitamins• Minerals (Calcium, sodium, iron,

etc.)• Water

Your body breaks down food items and rearranges them to give you:

ENERGY and BUILDING BLOCKS

Biomolecules are ORGANIC molecules, because they contain the building block of CARBON.

Why is carbon so important?

Carbon atoms have four valence electrons.

Carbon atoms can make up to four bonds with other atoms.

Carbon atoms can make single, double, and triple covalent bonds.

Carbon atoms can easily bond with itself as well as other common elements, such as H, N, and O.

Carbon skeletons can:o vary in lengtho brancho make rings

In addition to carbon, the top four biomolecules also include the building blocks of…

Element

Carbohydrates

Lipids Proteins Nucleic Acids

C ✔ ✔ ✔ ✔

H ✔ ✔ ✔ ✔

O ✔ ✔ ✔ ✔

N ✔ ✔

P ✔* ✔

S ✔**

* Phospholipids ** Some proteins

Functional GroupsAll biomolecules have functional groups.

Functional groups are groups of atoms that give similar properties onto otherwise dissimilar molecules.

For example:(1) Alcohols are characterized by a hydroxyl group. This group makes the compound polar and hydrophilic. Therefore, alcohols dissolve in water easily. An example is ethanol.

(2) Carboxylic acids are characterized by a carboxyl group. These compounds are water soluble weak acids that are often aromatic. An example is acetic acid (vinegar).

Polarity is important! Functional groups of molecules helps us understanding interactions

between molecules!

Let’s investigate polarity:1. Part I & II: How does a Soap Molecule Work?

2. Part III: Hello Kitty Shaving Art Contest with Shaving Cream!

Part II:How does our body put these

building blocks together and take them apart in order to make and

break biomolecules?

How does the body build biomolecules?Biomolecules are examples of MACROMOLECULES, which are giant molecules in living things that are made from 1000’s of smaller molecules.

All macromolecules are made by the process of polymerization, which is simply making large molecules from smaller molecules.Monomers: single-subunits of a macromolecule

Ex. Glucose

Polymers: large molecules formed from repeating subunits of a smaller molecule

Ex. Starch

Monomers / subunitsCarbohydrate: Monosaccharide Protein: Amino Acid

Lipid: Fatty Acid Nucleic Acid: Nucleotide

Carbohydrate: Polysaccharide Protein: Polypeptide

Lipid: Triglyceride (specific example)

Nucleic Acid: DNA (specific example)

Polymers / macromolecules

Another View: Putting It All Together in Nature…

Amino Acid PolypeptideIntermediate Filament

Nucleotide DNA strandChromosome

Another View: Putting It All Together in Nature…Monosaccharide Polysaccharide

Starch grains in a chloroplast

Fatty Acid TriglycerideAdipose cells with fat droplets

A closer look at polymerization…

Polymerization occurs through the chemical reaction of dehydration synthesis:

Two molecules covalently bond by a removing water molecule.

One molecule loses a –OH, the other molecule loses a –H

Two monosaccharides bonding together to make a disaccharide:

Try it yourself:

Draw out dehydration synthesis of these two amino acids.

+

How does the body break down biomolecules?Biomolecules are broken down through the process of de-polymerization, which is simply breaking large molecules to form smaller molecules.

De-polymerization occurs through the chemical reaction of hydrolysis.

A water molecule is added to disrupt the bond linking monomers together.

One molecule gains –OH, the other molecule gains –H.

A disaccharide breaking apart into two monosaccharides:

Part III:What are the four main

biomolecules? How is each biomolecule structured? What are their roles in life? Where do

we find them in our body?

1. Lipids Large & Varied Group!

Fats, Oils, & Waxes

Do not dissolve in water!

Composed of: mostly C and H atoms

Functions: Energy storage Waterproofing Structure Hormones

What is a saturated vs. unsaturated fat?

Fatty acids that contain one or more double bonds between two carbon atoms are said to beUNSATURATED.

Fatty acids with only single covalent bonds between carbon atoms are said to beSATURATED.

Monounsaturated = 1 double bond

Polyunsaturated = 2 or more double bonds

Saturated fats are bad for you, because they are linear in shape. They easily stack upon one another to clog up blood vessels.

Monounsaturated Fats

Unsaturated FatsPolyunsaturated Fats

Only ONE double bond

TWO or MORE double bonds

http://www.youtube.com/watch?v=5aukVvYC-WA

Two Types of Unsaturated Fats

Cis-Unsaturated Fats• Occur naturally• Hydrogen atoms are on the SAME side of the double bond • the GOOD fats•Ex: Olive Oil

Trans-Unsaturated Fats•Do NOT occur naturally•Hydrogen atoms are on OPPOSITE sides of the double bond•The REALLY BAD fats•Ex: Crisco

Another look… Trans fats occur when H atoms are on opposite sides of the double bond, thus creating symmetry. As a result the fatty acid is linear, so it behaves like a saturated fat in your body.

Cis fats occur when H atoms are on the same side of the double bond, thus creating asymmetry. As a result, the fatty acid is bent in shape.

Let’s Watch A Video!

http://www.youtube.com/watch?v=EJa3E_zXrCo

Where do you find fats in your diet?

TriglycerideBody fat functions to:

Cushion organs Insulation Long-term energy storage

Composed of: Glycerol + 3 fatty acids

PhospholipidPhospholipids are the building blocks of a cellular membrane.

Phospholipids have a:

Polar head that is hydrophilic (“water-loving”).

Nonpolar tails that are hydrophobic (“water-fearing”).

SteroidsCarbon skeleton has:

Four interconnected rings Different functional groups attached

Group of lipids derived from cholesterolIncludes a variety of hormones:

sex hormones glucocorticoids, which regulate glucose metabolism mineralocorticoids, which regulate water and electrolyte levels in

blood