Biochemistry

Chapter 3

Water

Section 2.3

Structure of Water

Held together by covalent bonds 2 atoms of H, 1 atom of O

Water is a Polar Molecule

Definition: a molecule with an uneven distribution of charge but a net charge of zero

Water bonds at an angle

Water’s ability to dissolve

“Like Dissolves Like”

Polar substances can dissolve polar substances, nonpolar substances can dissolve nonpolar substances

Questions:

Why don’t oil and water mix?

Why can water dissolve sugar or salt?

How does water dissolve a polar substance?

Answer:

The + end of water attracts to the – ion of the substance

The – end of water attracts to the + ion of the substance

This breaks the ionic bond of the substance thus dissolving it

Water’s special bond:

Hydrogen Bond: a weak chemical bond that exists between the H atoms and a – charged part of a different molecule

Water’s special properties:

Due to H-bonds:

1. Water can cling to itself and other substances

2. Water is able to absorb large amounts of energy without changing temperatures quickly

Cohesion:

Definition: When like molecules are attracted to each other

Ex) surface tension in water

Adhesion:

Definition: the attractive forces between unlike substances

Capillarity:

Definition: cohesion and adhesion working together to move water molecules up a narrow tube against the force of gravity

Homeostasis?

1. The H-bonds in water are the first bonds to break when an increase in energy (temp) is applied

2. It takes a LARGE amount of energy to break/move water molecules

3. Thus, the temperature of water stays fairly constant in a cell even though there might be a drastic temperature change outside

Lab time….yeah!

Carbon Compounds

SECTION 3.1

Organic Compounds

Organic compounds contain carbon atoms

Form covalent bonds with other C atoms or to other elements - N, H, and O.

Carbon Bonding

C readily covalently bonds (a bond forms when electrons are shared)

Each C forms 4 covalent bonds

Large Carbon Molecules

Polymers are made up of many small, repeating molecules called monomers.

Macromolecules- large polymers

Condensation Reaction

A chemical reaction that links monomers to form polymers

One water molecule is produced

Ex) Glucose and Fructose combine to make Sucrose, table sugar

Hydrolysis

A chemical reaction that breaks down polymers

Reversal of condensation reaction

Usually done by adding water

ATP – Adenosine Triphosphate

All of life’s functions require energy Energy compounds found in cells

Biochemistry

The stuff life is made of!

Section 3.3

The Four Molecules of Life

1. Carbohydrates 2. Proteins 3. Lipids 4. Nucleic Acids

All of your body is made up of these four types of molecules!

The Building Blocks

Each type of molecules is made up of smaller parts called monomers.

When 3 or more monomers are linked together, they form a polymer.

How to make a macromolecule.

How do you make a polymer from many monomers?

CONDENSATION REACTION!

Condensation Reaction:

The formation of larger molecules by removing a H+ from one monomer and a OH- from the other monomer.

The H+ and the OH- combine to form the bi-product H2O.

What will break up a large molecule?

The opposite reaction of condensation……

HYDROLYSIS REACTION!

The use of water to break apart polymers back into monomers.

Condensation/Hydrolysis

Monomers of the 4 Life Molecules

1. Carbohydrates - Monosaccharide 2. Proteins – Amino Acids 3. Lipids – Fatty Acids 4. Nucleic Acids - Nucleotides

How do you make macromolecules of each monomer?

CONDENSATION REACTION

1. Carbohydrates Monosaccharide = monomer, simple

sugar, ex) fructose, galactose, & glucose C6H12O6

Disaccharide = 2 monomers, double sugarex) sucrose (table sugar)

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Examples)

Polysaccharide = 3+ monomers ex) starch & cellulose (in plants)

glycogen (in animals)

2. Protein

Amino Acid = monomer, 20 different types

Peptide bond holds amino acids together

Polypeptide = chains of amino acids

Most DIVERSE group of moleculesMany structures such as muscles, skin, hair, and biological catalysts (enzymes) are made of proteins.

Enzymes Protein molecules that catalyze

(increase the rate of) biochemical reactions

How Do Enzymes Work? Animation: How Enzymes Work

3. Lipids

Fatty Acids = monomer

•Hydrophilic Head - polar

•Hydrophobic Tail - nonpolar

Complex Lipids

Saturated Fats - bad Unsaturated Fats - good Phospholipids (cell membrane) Waxes Steroids

4. Nucleic Acids

Nucleotide = monomer

Found in the genetic material DNA & RNA

carries out all of the functions of the cell