BIO2102

Chapter 2 THE CHEMICAL LEVEL OF ORGANIZATION

I.How Matter is Organized

A. matter

1.anything that occupies space and has mass

2.solid, liquid, gas

3.mass is constant, weight includes the effect of gravity

B. all matter is composed of elements

1.elements cannot be broken down and retain their physical and chemical

characteristics

2.Example: Hg, Na, K, Ca, Cl

3.C,O,H,N make up 96% of body weight

C.An atom is a single unit of an element

D.Molecule

1.atoms joined together

2.H₂O - 2 atoms of H and 1 atom of O

3.O₂ - 2 atoms of O

a.diatomic molecule

E.A compound is a pure substance containing identical molecules.

F.Periodic Table

1.gives most information about elements

2.Subatomic particles of an atom

a.Neutron

(1)in nucleus

(2)has atomic mass of 1

(3)no charge (neutral)

b.Proton

(1)in nucleus

(2)has atomic mass of 1

(3)positive charge

c.electrons

(1)circling in orbits about the nucleus

(2)has negligible mass (0)

(3)negative charge

3.Atomic Number

a.# protons

b.also is # electrons

4.Atomic Weight (or Mass Number)

a.mass of an atom due to protons and neutrons

b.since mass = 1, AW=#protons+#neutrons

5.Isotope

a.atoms that differ in the #neutrons

b.same atomic number, different atomic weight

c.Radioactive isotopes

(1)give off energy as they break down to a more stable molecule

(2)used in diagnostic procedures

(3)used to damage rapidly dividing cells (cancerous cells)

(4)Half-life

(a)how long it takes for 1/2 of the element present to become

stable

(b)short half-lives rapidly degrade

(c)minutes to thousands of years

(d)Particles or Rays emitted:

i)alpha - large particle can block with a sheet of paper

ii)beta - smaller particle

iii)gamma - ray and most damaging

requires very thick material to block (lead); similar to x- ray

G. Free radicals

a. atom or group of atoms with an unpaired electron

b. unstable and searches for substance to react with

c. DNA and proteins can be damaged by free radicals

d. Associated with many diseases (cancer) as well as with aging

e. Superoxide

f. Purpose of antioxidants in diet

II.Chemical Bonds

A.Electrons in outer shell allow interactions between atoms

B.Outer shell = valence shell

1.Octet rule or Rule of eights

a.wants 8 electrons in outer shell except first

(1)H and He filled with 2

b.needs electrons to fill outer shell

(1)- oxidation number (valence #)

(2)anion

(3)nonmetals

c.needs to give up electrons

(1)+ oxidation number

(2)cation

(3)metals or nonmetals

C.Combine atoms to make molecules

1.metal + nonmetal

2.nonmetal + nonmetal

3.always write as cation,anion (+ oxidation # first, - oxidation # last)

4.# atoms that join is a molecule depends on the oxidation number

a.must add up to zero

b.(# atoms)x(oxidation # of cation)=

( " )x( " anion)

D.Types of Chemical Bonds

1.Ionic

a.transfer electrons

b.weak

c.example: salts like NaCl

d.If element in group 1 in Periodic Table and an element in Group 7 bond, will always be ionic

e.depends on electronegativity

2.Covalent

a.sharing of electron pairs

b.makes a strong bond

c.O=O

d.polar

(1)unequal sharing

e.nonpolar

(1)equal sharing of electrons

3.Hydrogen

a.weak bonds

b.between H of one molecule and O or N of another

c.water

III. Chemical reactions

A. reactants are the starting substances

B. products are formed from the reaction

C. metabolism is the sum of all chemical reactions

D. Law of conservation of mass

1. sum of mass of reactants equals mass of product(s)

E. reactions have energy changes

1. energy : the capacity to do work

2.potential energy due to position

3.kinetic energy is energy of motion

4.chemical energy is stored in bonds

a.ATP

(1)used most often in living cells for energy

(2)organic molecule

(3)adenosine triphosphate

(4)high energy phosphate bond

(5)breaking bond releases energy

5.electrical energy

a.flow of ions

b.in body ions are electrolytes

c.charged particals move across membrane to generate an electrical current

d.important in excitable cells

(1)nerve

(2)muscle

6. Law of conservation of energy

a. energy is neither created nor destroyed in a reaction but can be converted to a different form

7. Activation energy – energy needed to get reaction started

E. Rate of reactions- moving of particles and collision

1.increased with temperature

2.increased with decreased size of molecule

3.increase rate when concentration of molecules increases

4. increase rate with catalyst (enzyme is a biological catalyst)

G. Types of Reactions

4.synthesis

a.anabolic

b.make bonds

c. A + B = AB

5.decomposition

a.catabolic

b.break bonds

c. AB ->A+B

II.Mixtures

A.Solution

1.2 or more compounds mixed

2.solute is dissolved in solvent

3.homogenous mixture

4.example:sodium chloride solution

B.Colloid mixture

1.heterogenous mixtrue

2.large molecules (often proteins)

3.each molecule retains identity but does not separate

4.proteins in milk

C.Suspension

1.settles out

2.sand mixed in water, Metamucil

D.Concentrations of compounds in a mixture

1.% - grams per 100ml

2.Molar (M)

d.moles/liter

(3)1 mole= molecular weight in grams

(4)relates number of molecules

e.Calculate the molecular weight of KCl and determine how to make a 1M solution

3.Normal (N)

a.used with acids and bases need to know number of H or OH ions that can react

b.not the same as normal saline which is similar to plasma or body fluids thereby called 'normal'

III. Inorganic compounds

A.Definition

1.generally molecules without carbon

B.water

1.70% of cell

)

2.universal solvent

3.polar molecule (polarity)

a. cohesion

a.polar substances dissolve in water (nonpolar do not)

4.salts dissociate into ions in water

5.transports nutrients, wastes

6.important for chemical reactions

8.absorbs heat without greatly changing temperature (high heat capacity

9. has high heat of vaporization (sweat to cool body)

10. acts as a cushion to protect cells and as a lubricant

C.salts

1.electrolytes

a.conduct an electrical current

b.cations + charge

(1)Na, K, Ca

c.anions

(1)- charge

(2)Cl, CO₃, PO₄

d.help maitain body fluid balance

e.water goes with Na

D. acids and bases

1.ionize and dissociate into ions in water

2.pH

a.-log of the H ion concentration (M)

b.scale of 0 to 14, 7 is neutral

c.lower pH has more H ions present

3.acids

a.release H ions (+ cations)

b.pH < 7

c.example

(1)HCL

(2)H₂CO₃ (carbonic acid)

4.bases

a.accept H ions

b.many dissociate into OH^- ions

c.also referred to as alkaline

d.pH >7

e.examples

(1)NaOH -> Na⁺ + OH^-

f.acids + bases -> neutrilization

g.NaOH + HCl -> Find the products

h.Bicarbonate (HCO₃^-)

(1)important in body fluids

5.buffers

a.regulate pH and resists large fluctuations

in pH

b.Carbonic acid/bicarbonate ion

(1)carbonic acid can donate H⁺ if pH is high

(2) bicarbonate ion can accept if pH is low

c.buffers are always weak acids and its conjugate base

d.do not completely dissociate in water as strong acids and bases do

IV. Organic Compounds

A.Definition

1.have carbon as an element in the molecule

2.generally large molecules with many C

3.carbon can form 4 covalent bonds

B.Carbohydrates

1.Sugars and starches

2.contain elements C, H, O in ratio 1:2:1

3.Monosaccharides

a.simple sugars with 3-7 carbons

b.building blocks of carbohydrates

c.hexoses

(1)six carbons

(a)what is its formula

i)C H O

(2)glucose, fructose, galactose

d.pentoses

(1)deoxyribose in DNA

(2)ribose in RNA

4.Disaccharides

a.two monosaccharides bonded together

b.glu+fru = sucrose (table sugar)

c.glu+glu = maltose

d.glu+gal = lactose (milk)

5.Polysaccharides

a.starch (plant carbohydrate)

b.glycogen

(1)animal storage form of glucose

6.Functions of Carbohydrates in the body

a.chief source of energy

b.structure

c.communication between molecules

C.Lipids

1.include

a.fats (solids at room temperature)

b.oils ( liquid at room temperature)

c.sterols

(1)cholesterol

(2)steroid hormones

d.lipid soluble vitamins

(1)A,D,E,K

2.fatty acids are simple units of lipids

a.long chains of carbon with H and less O than in carbohydrates

b.not an acid but have a carboxylic acid group attached (COOH)

c.may have double bonds (=) between adjacent carbons

(1)saturated

(a)saturated with H and no =

(2)unsaturated

(a)remove hydrogens and replace with =

(b)trans fatty acids

i)in margarines

ii)H removed on opposite sides

iii)implicated as lowering HDL and raising LDL cholesterol levels (opposite of desired)

d.concentrated source of energy

e.body stores in adipose tissue (adipocytes)

3.fats transported and stored as a glycerol molecule linked with the fatty acids

a.monoglyceride - 1 fatty acid

b.diglyceride - 2 fatty acids

c.triglyceride - 3 fatty acids

4.fats are nonpolar molecules and do not mix with water

D.Protein

1.basic structural material C,H,O,N

2.many functions

a.enzymes

b.contraction

c.hemoglobin

d.thousands of proteins with different functions

3.DNA codes for proteins

1 gene for each protein

4.amino acids are the building blocks of proteins

a.amine - NH₂

b.carboxylic acid - COOH

c.have neutral, basic and acidic amino acids

d.join amino acids together with peptide bond

e.peptides

(1)small number of amino acids <100

f.proteins

(1)more than 100 amino acids</