The Chemical Composition of Cells

Chapter 2

Rinorea niccolifera: Nickel-Eating Plant Discovered in Philippines

• Hyperaccumulator

plant species

• Phytoremediation

refers to the use of

hyperacccumulator

plants to remove

heavy metals in

contaminated soils

Rinorea niccolifera: Nickel-Eating Plant Discovered in Philippines

• Phytomining is the

use of

hyperacccumulator

plants to grow and

harvest in order to

recover

commercially

valuable metals in

plant shoots from

metal-rich sites.

The Chemical Composition of Cells

Elements of life

Chemical bonds

Inorganic compounds

Organic compounds

Key Terms: Atoms

Proton

positive electric charge, small mass

Neutron

uncharged, about same mass as proton

Electron

negative charge, extremely small mass

A Carbon Atom

Electrons

Move around the nucleus at

different energy levels

Allow elements to combine

chemically to form chemical

compounds

Ions are atoms which tend to gain

or lose electrons

Electron Configurations

KEY TERMS

IONIC BOND

An electrostatic attraction between

oppositely charged ions

Ionic Bonding

KEY TERMS

COVALENT BOND

A chemical bond involving one or

more shared pairs of electrons

Covalent Bonding in Hydrogen

Covalent Bonding in Methane

KEY TERMS

HYDROGEN BOND

An attraction between a slightly

positive hydrogen atom in one

molecule and a slightly negative

atom (usually oxygen) in another

molecule

LEARNING OBJECTIVE

Discuss the properties of water,

and explain the importance of

water to life

Water Has a strong dissolving ability

Molecules form hydrogen bonds with one another

(cohesion)

Molecules form hydrogen bonds to substances

with ionic or polar regions (adhesion)

Adhesion & Cohesion are particularly important

for transport

All living things require water to survive

Almost all chemical reactions that sustain life

occur in aqueous solution

High Melting & Freezing Points

Insulation Property after freezing (e.g., lakes)

Water Structure

Acids and Bases

Acids dissociate in water to form

hydrogen ions (protons, H+)

Bases dissociate in water to yield

negatively charged hydroxide ions

(OH-)

pH Scale

A measure of the relative

concentrations of H+ and OH- in a

solution

A solution’s acidity or alkalinity is

expressed in terms of the pH scale

LEARNING OBJECTIVE

Describe the chemical

compositions and functions of

carbohydrates, lipids, proteins, and

nucleic acids

KEY TERMS

CARBOHYDRATE

An organic compound containing

carbon, hydrogen, and oxygen in

the approximate ratio of 1C:2H:1O

Carbohydrates 1

Include sugars, starches, cellulose

Important fuel molecules,

components of molecules (nucleic

acids) and cell walls

Carbohydrates 2

Monosaccharides

simple sugars

Disaccharides

two monosaccharide units

Polysaccharides

many monosaccharide units

Common Monosaccharides

Sucrose Synthesis

Starch: A Storage Polysaccharide

Cellulose: A Structural Polysaccharide

KEY TERMS

LIPID

Any of a group of organic

compounds that are insoluble in

water but soluble in fat solvents

Lipids 1

Have a greasy consistency, do not

readily dissolve in water

Important fuel molecules,

components of cell membranes,

waterproof coverings over plant

surfaces, light-gathering molecules

for photosynthesis

Lipids 2

A neutral fat or oil molecule is

composed of a molecule of

glycerol plus one, two or three fatty

acids

Formation of a Neutral Fat or Oil

KEY TERMS

PROTEIN

A large, complex organic

compound composed of amino

acid subunits

Protein

A macromolecule composed of

amino acids joined by peptide

bonds

Order of amino acids determines

structure and function of a protein

molecule

Enzymes: Proteins that increase

the rate of chemical reactions

Amino Acids

Peptide Bonds

Organization of Protein Molecules

KEY TERMS

NUCLEIC ACID

Deoxyribonucleic acid (DNA) and

ribonucleic acid (RNA)

Large, complex organic molecules

composed of nucleotides

Nucleic Acids

Control the cell’s life processes

Deoxyribonucleic acid (DNA)

Transmits information from one

generation to the next

Ribonucleic acid (RNA)

Involved in protein synthesis

Nucleotides Repeating units that form nucleic acids

Order of nucleotides in a nucleic acid chain

determines the specific information encoded

Adenosine triphosphate (ATP)

A modified nucleotide compound important in

energy transfers in biological systems

Nucleic Acids

Nucleic Acids