Biology I

Chapter 6

The Chemistry of Life

 

Ch 6 Terms:

acid                                      disaccharide                isotope                              peptide bond

amino acid                      DNA                                       lipid                                     pH

atom                                   enzyme                               metabolism                    polar molecule

base                                     glycogen                         mixture                             polymer

carbohydrate             hydrogen bond           molecule                         protein

cellulose                        ion                                        MONOSACCHARIDE       nucleic acid

polysaccharide         compound                       ionic bond                       nucleotide

RNA                                       covalent bond            isomer                               

solution                          starch                               nucleus                            

 

 

Element - a substance that cannot be broken down into ____________ substances.

90 naturally occurring elements

4 elements make up 96% of a human

-C-H-O-N-

Only 25 elements are essential elements needed for ____________

Trace Elements – elements present in living things in very ___________ amounts

(although in small amounts, they are very important in maintaining a healthy cell)

 

Atom- the smallest particle of an element that still has the ____________ of that element

Atomic Number – number of ____________

Atomic Mass Number - number of protons plus ____________

 

Structure of the Atom:

 

 

 

 

 

 

 

 

 

 

 


3 subatomic particles – protons, neutrons, electrons

 

 

nucleus - the center of the atom, nucleus contains:

proton (+)-____________ charged particles

neutrons (o)- particles with ____________ charge

\ all nuclei are positively charged because of the presence of protons

 

Electron cloud - a “cloud” or area around the nucleus where e(-) move in _______ levels

contains electrons(-)____________ charged particles, they are the smallest of the

subatomic particles

 

Energy level - an area surrounding the ____________ that an electron will travel in

the farther away from the nucleus the energy level, the ____________ the energy

each energy level can only hold a specific number of electrons

the first level is the smallest, therefore it can only hold ____________ electrons.

 

Atoms contain equal numbers of protons and electrons; \they have no net charge

 

Isotope - atoms of the same element which have different numbers of ____________

 

Example:

 

              C612                C613                C614

                Most commonly          6 protons                       6 protons

                        found in nature  7 neutrons                    8 neutrons

                        6 protons

                        6 neutrons

 

All of the above are isotopes of ____________

 

Isotopes are useful because some are unstable which means they tend to break apart, so we call them ____________.  Science has developed some very useful ways to use radioactive isotopes.

 

Compound - a substance that is composed of 2 or more different elements joined by ____________ bonds ( H20, NaCl2)

the characteristics of a compound are different from its individual ____________

 

How do compounds form?

 

            Bonds

1. Covalent Bond - a bond between elements where the electrons are __________ most compounds in organisms have covalent bonds

Molecule - 2 or more atoms held together by covalent bonds.

            - they have no net charge

                                H- O-H    (H20)

2. Ionic Bond – a bond between elements where one element “____________” an electron and the other element “____________” an electron resulting in a charged particle. (\a transfer of electrons)

 

Bond Energy – the energy needed to ____________ a chemical bond

 

Matter – anything that occupies space and has ____________: 3 states of matter – solid, liquid, gas

 

Mass – the ____________ of matter an object has

 

Weight – mass + ____________

 

Mixture – 2 or more substances blended together with each other but keeping their  original properties (i.e.: sand and water)

 

Types of Mixtures:

            1. Solution – molecules or ions are spread evenly in a solvent (i.e.: Kool-Aid)

                        a. solvent – the substance doing the ____________ (water)

                        b. solute – the ____________ being dissolved (Kool-Aid powder)

                        c. saturated – the point at which no more solute can be ____________

d. supersaturated – if solvent is heated it can hold more solute, but when solvent ____________, the solute will precipitate out.

2. Suspension – a mixture in which large particles are held up before settling out (i.e.: orange juice, blood)

 

Water – (H2O) most ____________; makes up 70-90% of a human cell.

a very versatile ____________

 

3 Properties of H2O

            a. Polar Molecule – has uneven ____________, O (-) and H (+)

b. Capillarity – ability to spread through tubes or pores against the pull of ____________ (adhesion – water attraction to solid surfaces – (i.e. the meniscus in a graduated cylinder)

c. Cohesion–water bonding to _______: it helps cells regulate temperature

 

Metabolism -all the ____________ reactions that occur within an organism

 

Chemical Reactions -the process of making or ____________ of chemical bonds.

 

Chemical Equations – a diagram used to show how reactants change and form new ____________

                        CO2 + H2O ΰ C6H12O6 + O2

                       

Balanced          6CO2 + 6H2O ΰ C 6H12O 6 + O2

 

CH4 + O2 ΰ CO2 + H2O

                        (reactants)     (products)

 

Balanced          CH4 + O2 ΰ CO2 + 2H2O

 

Activation Energy – the amount of ____________ required to start a reaction

 

Endothermic reaction – requires a steady input of energy to keep going.  These use more electrons than they ____________ (i.e. human metabolism)

 

Exothermic reaction – releases more ____________ than they use (quick action, i.e. wood burning)

 

Acids & Bases:

 

          The functioning of the cells in living organisms is very dependent on pH level.

 

pH – the measure of how ____________ or ____________ a solution is

             pH scale – from 0- 14 with 7 as neutral

             acidic – numbers < 7; basic numbers > 7

 

Acid – any substance that forms ____________ ions (H) in water (pH below 7, tastes sour, reacts with metals, tingling or burning of skin)

 

Base – any substance that forms ____________ ions (OH) in water (pH above 7, tastes bitter, feels slippery) (NADH)

 

Organic Compounds – come from and make up living things; contain ____________

 

Carbon – has ____________ electrons available for bonding therefore it will form ____________ covalent bonds with other element producing macromolecules

 

3 Shapes of Carbon Molecules can Form

1.      straight chains

 

 

2.      branched chains

 

 

3.      ringed chains

 

 

 

Biosynthesis – the building of organic ____________ by living organisms

 

 

Isomer – molecules with the same molecular ____________, but different structure.

            2 kinds of isomers:

                        a. structural isomer – different __________ sites ((galactose & fructose)

                        b. steroisomer – 1 group __________ 180° in space (galactose & glucose)

 

Monomer – a single ____________

 

Polymer – a large molecule formed by ____________ small (monomer) molecules

 

Polymer macromolecule – large complex molecules essential for life

             these could be a large polymer, or a set of polymers connected together

 

 

Types of Macromolecules

1. Carbohydrates – an organic substance composed of C, H, O, in a 1:2:1 ratio (i.e.: starch, sugar, cellulose)

                        a. Monosaccharide – simplest ____________—simple sugar

                                    1) glucose – main fuel source

                                    2) fructose – sweetest sugar, from fruits

                                    3) galactose – comes from milk

                        b. Disaccharide – a 2 sugar ____________

                                    1) sucrose = fructose + glucose (table sugar)

                                    2) maltose = glucose + glucose

                                    3) lactose = galactose + glucose

                        c. Polysaccharide – the ____________ carbohydrate molecules

                                    -- complex molecules made up of 3 or more monosaccharides

1) starch – highly ____________ glucose units, used as food storage by plants

2) glycogen – used as ____________ storage for human

3) cellulose – used for structural support in ___________ cell walls

4) chitin – used in the cell walls of fungi and insect exoskeletons

Condensation reaction – the ____________ of a water molecule (dehydration) allowing the formation of  complex compounds.

Hydrolysis reaction – the breakdown of a complex compound into monomers by ____________ water

 

2. Lipids – (fats & oils)

-- organic compounds with large proportion of C – H bonds and low amounts of ____________ (beef fat C57H110O6)

-- insoluble in ____________

-- cells use lipids for ____________term energy storage, insulation and protective coatings (lipids are the major component that make up cell membranes)

 

hydrophilic – water ____________

hydrophobic – water ____________

 

a. Triglycerides – 3 fatty acids + glycerol – may be oils from plants – may be ____________ from animals (oils = liquid; fat = solid)

b. Waxes – waterproof protective barriers ( i.e.: honey combs, fruit peel, earwax)

c. Steroids – ____________ in water (i.e.: hormones, nerve tissue, toad venom, plant poisons)

            3. Proteins – most ________ compound in living cells (composed of C, H, O, N)

                        a. Amino acid – basic building blocks of life

                                    -- 20 found in nature

                                    -- distinct structure

                                                 H

                                           R – C – COOH

                                                NH2

R= ____________ skeleton, different R groups represent different ____________

 

NH2 – amine group

COOH – carboxyl group

                                    Peptide bond = ____________ bond between 2 amino acids

Polypeptide = a chain of amino acids connected by ____________ bonds ranging from 50 – 3000 amino acids long

b. Enzymes – proteins that ____________ (catalyst) a chemical reaction

--catalyst – enzymes that speeds up a reaction without being ____________ themselves

--substrate – the ____________ that the enzyme catalyzes.

(enzymes and substrates fit like puzzle pieces)

 

4.  Nucleic Acids – complex macromolecules that store ____________ in cells in the form of a code

            2 Types of Nucleic Acids

1. DNA – deoxyribonucleic acid – contains ____________ codes and controls all cell functions \ transfers hereditary information

2. RNA – ribonucleic acid – aids in protein ____________ nucleotides – smaller subunits of nucleic acids.

            Consists of 3 parts:

                        a. nitrogen ____________

                        b. simple ____________

                        c. ____________group

5 types of nucleotides (bases)

            a. Adenine

            b. Guanine

            c. Thymine

            d. Cytosine

            e. Uracil – found ONLY in RNA

 

 

 nucleotides pair only one way!

DNA               RNA

A – T               A – U

C – G              C – G

 

                        purines – bases with a ____________ ring structure

                                     ____________sized bases (Adenine & Guanine)

                        pyrimidines – bases with a ____________ ring structure

                                     ____________ sized bases (Thymine, Cytosine, Uracil)