The Chemistry of Life

Chapter 2

Water makes up approx 70 to 95 percent of most organisms.

When the electrons in a covalent bond are not shared equally they form a polar molecule.

Polar Molecule: unequal distribution of charge, the molecule has a

distinct partial positive end and a partial negative end. Universal Solvent: “like dissolves like”

Water

H20 - Polar molecule

8p+8n0

1p+

1p+2e- 6e-

Hydrogen

Hydrogen

OxygenS+S+

S-

S+S+

S-

Properties• High Specific Heat – resists changes in temp.Water retains its state at temperature levels where other liquids would begin to turn into gas or evaporate.

• Cohesion – attraction of water molecules, provides surface tension.

• Adhesion – attraction of water to different substances….meniscus

http://www.youtube.com/watch?v=DAilC0sjvy0&feature=related

Role of CarbonCarbon has 4 electrons to share and it can

share these electrons in three different ways.

4 Covalent bonds it can form

1. Single C - C

2. Double C = C

3. Triple C C

Straight Branched Ring

Carbon-based molecules have three general types of structures.

ISOMERSIsomers - compounds that have the

same molecular formula but different structural formula.

Monomer - singular unit or molecule Polymer - a group of molecules or

units bonded together.

cellulose

FUNCTIONAL GROUPSMost organic compounds have functional

groups of atoms that carry out chemical reactions.

FUNCTIONAL GROUPS -NH2 Amine Proteins -PO4 Phosphate Nucleic

Acids -COOH Carboxylic Acid Fats -OH Hydroxyl or Lipids &

AlcoholCarbohydrates

ENDINGS -ose Sugars (Sucrose) -in Proteins (Pepsin) -ase Protein Enzyme (Amylase) -ol Lipid

(Glycerol)

CARBOHYDRATES- C, H, O

1 Carbon : 2 Hydrogens : 1 Oxygen 1:2:1 ratio

Example: Glucose C6H12O6

CARBOHYDRATE MONOMERSMonosaccharides - simplest

carbohydrate

Most common arrangement : C6H12O6

Names : Glucose, Fructose, Galactose

CARBOHYDRATE POLYMERS

Disaccharides - 2 monosaccharides covalently bonded

together.

Glucose + Galactose = Lactose (milk sugar) Glucose + Fructose = Sucrose (table sugar) Glucose + Glucose = Maltose (malt sugar)

Disaccharides

Polysaccharides - long chains (polymers) Glycogen- made and stored in animals

…highly branched compared to plant starches (store food in the liver as glycogen)

Starch – is made and stored by plants (potatoes)

Cellulose – straight rigid structure that makes up the cell wall in plants (celery, cotton)

Chitin – rigid structure that makes up exoskeleton of insects

CARBOHYDRATE POLYMERS

Polysaccharides

Processes of Forming and Breaking Bonds

1) Dehydration Synthesis/Condensation - put monomers together by removing water (H2O)

2) Hydrolysis - Add H20 to break covalent bonds

http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

Dehydration Synthesis

Hydrolysis

LIPIDS - C, H, O

Fats, oils, waxes, cholesterol (steroids), phospholipids (C57H110O6)

Nonpolar - insoluble in water, make up cell membrane, energy, used to make hormones, and Elle’s love for *all* her students.

Fat = 3 Fatty acids + glycerol (monomers)

Fatty acid : 1. Chain of C and H atoms 2. Carboxyl group -COOH

Glycerol : 3 Carbon molecule, backbone of a lipid.

(polymer)

LIPIDcarboxyl

Triglyceride http://

users.uma.maine.edu/SusanBaker/triglyceride.html

Phospholipid

1. Glycerol2. 2 fatty acids3. Phosphate head

Steroids

Cholesterol

2 KINDS OF FATS1. Saturated Fats - single carbon

bonds (solids)

2. Unsaturated Fats - double or triple carbon bonds (liquids)

PROTEINS-N, C, H, O sometime S, and always lovemade up of amino acids

(monomers/basic building blocks of a protein)

1 Carboxyl group

1 amino group (-NH2)

1 side chain (R)

Amino acids differ in side groups, or R groups.

PROTEINS

PEPTIDE BONDS : bonds formed between the amino group of

one amino acid and the carboxyl group of another, with

love.What process allows peptide

bonds to take place?

Dehydration Synthesis

H - N - C - C - OH + H - N - C - C - OHH O H O

H R H R

Proteins differ in the number and order of amino acids.– Amino acids interact to give a protein its shape.

– Incorrect amino acids change a protein’s structure and function.

hydrogen bond

Hemoglobin

PROTEINS

Polypeptides : proteins, long chains of amino acids

20 different amino acids

NUCLEIC ACIDSP, N, C, H, OHereditary Material1. DNA - 2 chains

- deoxyribose sugar- phosphate backbone

- nitrogeneous base

2. RNA - 1 chain- ribose sugar- phosphate backbone

- nitrogeneous base

NUCLEIC ACIDSNucleotides : monomer of a nucleic

acid.

Nucleotides are composed of 3 separate parts

5 Carbon + PO4 + Nitrogen

Base Sugar Phosphate Group

SP

N

Nucleotide

Nucleotides are made of a sugar, phosphate group, and a nitrogen base.

A phosphate group nitrogen-containing molecule,called a base

deoxyribose (sugar)

• Nucleic acids are polymers of monomers called nucleotides.

DNA Nucleotides

DNA Nucleotides

ATP Nucleotide

NUCLEIC ACIDS

Nitrogen Basesadenine (purine)guanine (purine)cytosine (pyrimidine)thymine (pyrimidine)uracil (pyrimidine)

*Only in DNA*Only in RNA

ENZYMESProtein catalysts necessary for most of

the chemical rxns that occur in living cells.

Catalysts : a substance that increase the rate of a chemical rxn.

HOW DO YOU RECOGNIZE AN ENZYME?

*Enzymes are usually named after the substrate with an -ase ending.

Substrate : the substance an enzyme acts upon

EXAMPLES : Enzyme that splits maltose into 2 glucose

molecules is maltase Proteins - Protease Lipids - Lipase

HOW DO ENZYMES WORK?1. The enzyme shape makes it able to do work. Active Site

2. The active site is the place on the enzyme where the rxn occurs.

3. The substance the enzyme act upon is the substrate

* The active site must fit the shape of the substrate

maltose

Enzyme

HOW DO ENZYMES WORK?4. The substrate and the active site of the enzyme come together briefly to form the enzyme - substrate complex.

*While temporarily together the enzyme may make or break bonds within the substrate.

Enzyme

OH OH

Enzyme* Note enzymes arenot changed by the rxn

QUESTION?

* What enzyme broke the bond between the disaccharide maltose in the previous slide?

HYPOTHESIS FOR HOW AN ENZYME WORKS (2)

1. Lock & Key Hypothesis : Proposes that the substrate fits exactly into

the active site on the enzyme. * Key - Active Site unlocks the lock - substrate

2. Induced Fit Hypothesis : Proposes that the enzyme changes shape

slightly to grasp the substrate at the active site.

* Hand grasping a baseball (molds to shape of object)

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__enzyme_action_and_the_hydrolysis_of_sucrose.html

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

DiffusionDiffusion : the net movement of

particles from an area of higher concentration to an area of lower concentration.

Key factors in the rate of diffusion: concentration, temperature, and pressure.

What is Equilibrium?Equilibrium : when concentrations

are equal and the net movement of particles is equal.