Atoms, Molecules, and Life

electron shell

Carbon (C) Oxygen (O) Phosphorus (P) Calcium (Ca)

Phosphorus (P) Calcium (Ca)

(b)

Sodium ion (+) Chlorine ion (–)

Attraction between opposite charges

(c)

An ionic compound: NaCl

II. Matter

A. Elements

92 naturally occurring elements

Biologically important elements: Carbon (C) Hydrogen (H)

Oxygen (O) Nitrogen (N)

Phosphorous (P) Sulfur (S)

II. Matter

B. Atoms 1. Nucleus

• a. Protons and neutrons • b. Atomic number and atomic mass

2. Electrons • a. Electron shells, orbitals, energy level

electron

nucleus

Hydrogen (H) Helium (He)

II. Matter

C. Molecules and compounds Atoms usually exist chemically bonded

to other atoms to form molecules and compounds 1. Inert atoms 2. Reactive atoms

II. Matter

D. Types of chemical bonds 1. Bonds between individual atoms

• a. Ionic • b. Covalent

• 1) Nonpolar • 2) Polar

(a)

Sodium atom (neutral) Chlorine atom (neutral)

Electron transferred

(a)

(b)

(c)

Sodium atom (neutral)Chlorine atom (neutral)

Sodium ion (+) Chlorine ion (–)

Electron transferred

Attraction between opposite charges

An ionic compound: NaCl

II. Matter

D. Types of chemical bonds 1. Bonds between individual atoms

• a. Ionic • b. Covalent

• 1) Nonpolar • 2) Polar

(a)nonpolar covalentbonding

(b)polar covalentbonding

(slightly negative)

(slightly positive)

Water (H–O–H or H2O),a polar molecule

Hydrogen (H–H or H2),a nonpolar molecule

Oxygen (O=O or O2),a nonpolar molecule

(a)nonpolar covalentbonding

Hydrogen (H–H or H2),a nonpolar molecule

Oxygen (O=O or O2),a nonpolar molecule

(b)polar covalentbonding

(slightly negative)

(slightly positive)

Water (H–O–H or H2O),

a polar molecule

II. Matter

D. Types of chemical bonds (cont.) 2. Bonds between parts of polar molecules

• a. Hydrogen bonds

hydrogenbonds

III. Water and life

A. Water and chemical reactions 1. Hydrolysis 2. Dehydration synthesis 3. Photosynthesis 4. Respiration

III. Water and life

B. Water, the solvent of polar and ionic molecules

C. Water and cohesion D. Water and pH

hydroxide ion(OH – )

hydrogen ion(H+)

water(H2O)

stomach acid, lime juice

lemon juice

“acid rain” (2.5-5.5), vinegar, cola,orange juice, tomatoesbeer

black coffee, tea normal rain (5.6),

pure water (7.0), saliva, blood, sweat (7.4)seawater (7.8-8.3)

baking soda

phosphate detergents chlorine bleach, milk of magnesia household ammonia, some detergents (without phosphates) washing soda

oven cleaner

1-molar sodium hydroxide (NaOH)

1-molar hydrochloric acid (HCl)

urine (5.7)

IV. Carbon and life

A. Carbon is versatile 1. Each atom can form four covalent bonds 2. Carbon atoms are joined in short, long chains

or rings 3. Organic molecules

electron shell

Carbon (C) Oxygen (O)

V. Complex biological molecules are synthesized from simple subunit molecules

A. Polymers form from bonding two or more subunit molecules in a dehydration synthesis reaction

Dehydration synthesis

V. Complex biological molecules are synthesized from simple subunit molecules

B. Polymers can be broken down into individual subunit molecules in a hydrolysis reaction

1. Food we eat is hydrolyzed to provide the raw materials to build new polymers

Hydrolysis

VI. Four classes of biologically important organic compounds

A. Carbohydrates

Monosaccharides (glucose, fructose) combine to form Disaccharides (sucrose) and Polysaccharides (complex carbohydrates: starch and cellulose))

glucose fructose sucrose

Dehydration synthesis

individualcellulose

molecules

bundle ofcellulose

molecules

hydrogen bondscross-linking

cellulose molecules

cellulosefiber

VI. Four classes of biologically important organic compounds

A. Carbohydrates (cont.)

3. Functions

• a. Energy storage (starch, glycogen, simple sugars)

• b. Structural support (cellulose, chitin)

VI. Four classes of biologically important organic compounds

B. Lipids

1. Fatty acids combine in dehydration synthesis with glycerol to form triglycerides

2. Are nonpolar

fatty acidsglycerol

3 watermolecules

Beef fat (saturated)

carbon

hydrogen

oxygen

Peanut oil (unsaturated)

Cardiovascular diseases

Evidence is accumulating that increasing omega-3 fatty acid intake can decrease the risk of cardiovascular diseases by 1) preventing arrhythmias that can lead to sudden cardiac death, 2) decreasing the risk of thrombosis (blood clot formation) that can lead to heart attack or stroke, 3) decreasing serum triglyceride levels, 4) slowing the growth of atherosclerotic plaque, 5) improving vascular endothelial function, 6) lowering blood pressure slightly, 7) decreasing inflammation. The American Heart Association found the evidence discussed below convincing enough to recommend that all adults eat a variety of fish, particularly oily fish, at

least twice weekly, in addition to consuming vegetable oils rich in ALA

fatty acid tails

(hydrophobic)

polar head

(hydrophilic)

glycerolbackbone

estradiol

cholesterol testosterone

VI. Four classes of biologically important organic compounds

B. Lipids (cont.)

3. Functions

• a. Energy storage (fats, oils)

• b. Protection (oils, waxes) • 1) Waterproof coating of body surfaces

• c. Component of cell membranes

• d. Hormones

VI. Four classes of biologically important organic compounds

C. Proteins

1. Amino acids combine in dehydration synthesis to form polypeptides

2. Proteins are functional units made of one or more polypeptide chains

aminogroup

carboxylgroup

variablegroup

hydrogen

aminogroup

amino acidamino acid

aminogroup

carboxylgroup

carboxylgroup

peptidebond

peptide water

Peptide chain of amino acidsfolds into complex shape

two or more folded chains may join to form a complex protein

Peptide chain of amino acidsfolds into complex shape

Two or more folded chains may join to form a complex protein.

VI. Four classes of biologically important organic compounds

C. Proteins (cont.)

3. Protein structure is based on the amino acid sequence

4. Have varying degrees of polarity based on amino acid composition

VI. Four classes of biologically important organic compounds

C. Proteins (cont.)

5. Functions

• a. Structural components (cells, tissues) • b. Enzymes• c. Transport O2 in blood (hemoglobin)

• d. Receptors for hormones (insulin receptor)• e. Contractile proteins (actin and myosin in muscle)• f. Immunoproteins (antibodies)

VI. Four classes of biologically important organic compounds

D. Nucleic acids

1. Nucleotides combine in dehydration synthesis to form nucleic acids

2. Functions • a. Hereditary material (genes) • b. Direct the production of proteins

phosphate

base

Deoxyribose nucleotide

sugar

phosphate base

Nucleotide chain

sugar