the chemistry of life. 2.1 introduction to chemistry

The Chemistry of Life

2.1 Introduction to Chemistry


elements - make up earth & organisms (O, C, H, N, S, P, K, Si, Al, Fe, Ca)

cannot be broken down by a chemical process into a simpler substance


Compounds - combinations of elements (ex. Hemoglobin

(compound) contains Fe (element)

Organic compounds - all contain carbon -ex.

Carbohydrates, lipids, proteins, nucleic

acids


inorganic compounds - do not contain carbon (ex. Table salt = NaCl)

C6H12O6 – 24 total atoms6 carbon atoms12 hydrogen atoms6 oxygen atoms

How many atoms are in this molecule?

C55H72MgN4O5

137


Atoms - smallest particle of an element that has the elements properties

protons (+) = Atomic number neutrons (no charge)Protons and neutrons together

make up the nucleuselectrons (-) – used to form bonds

with other elements


Changes in the number of electrons causes atoms to become + or –

Outer most energy level (orbit) likes to be full – more stable that way

Atoms will give up, gain, or share electrons to fill the outer orbit

1st level – 2 electrons 2nd level – 8 electrons 3rd level – 8 or 18 electrons


Sodium – 11 protons and 11 electrons 2 electrons in the 1st level 8 electrons in the 2nd

1 electron in the 3rd


Chlorine – 17 protons, 17 electrons 2 electrons in the 1st level 8 electrons in the 2nd level 7 electrons in the 3rd level

Sodium wants to give up the last electron whereas Chlorine wants to gain an electron to fill the 3rd level with 8 electrons

Atoms bond with other atoms to become more stable

21. Introduction to Chemistry

IONIC BOND


Ions - atoms that gain or lose an electron and have a

charge


Chemical Bond -The force that holds atoms together

When a chemical bond is broken, energy is

absorbed or released

IONIC BONDING

Electrons are lost by one element and gained by another

Outer energy level in both elements is full (stable)


Ionic bond- a bond b/w oppositely charged molecules

One element loses e- & the other element gains e-

Covalent bond – a bond where electrons are shared (carbs, lipids, proteins & nuc. Acids); three types: single, double, triple

COVALENT BONDING

Electrons shared in a chemical bond (each atom donates one electron)

Outer energy level in both elements is full (stable)

Double covalent bonds have four electrons

Triple covalent bonds have six electrons

COVALENT BOND


Polar Covalent – bond w/ unequal sharing of electrons that

results in slightly positive & slightly negative ends

Water – example of covalent

POLAR COVALENT

NONPOLAR COVALENT

COVALENT VS. IONIC


Hydrogen Bonds – bonds that hold molecules together rather

than atomsThese bonds are weaker

than ionic or covalent bonds

* like in water – hydrogen bonds are the force that holds water molecules together


Isotopes - atoms of the same element that have a

different number of neutrons


Isotopes - have an unstable nucleus that breaks

apart giving off energy in the form of radiation

used to tell age of fossilspreserve foodtreat cancer


Water is found in all living organisms Water is a polar molecule Being polar allows water to dissolve ionically

bonded compounds easily When compounds dissolve in water they form

a solution Living things are composed of 70-90% water


Solutions --Water is known as the universal solvent

Chemical properties of water are important b/c they allow it to form solutions (aka. Uniform mixtures)


Solute --That which is being dissolved (sugar)

Solvent --That which does the dissolving (water)


Ionic Compounds --dissolve readily in water

b/c water is polar

Polar covalent compounds --dissolve in water


Cohesion – “sticking together” b/c of hydrogen bonding

surface tension – Like a water strider walking on water

Plants --have a xylem (straw-like tubes that carry water)

where the water is pulled up!


Expansion – water expands when it freezes, which is opposite to most substances

results in ice having a lower density than liquid water so the ice floats


-ponds “freeze on top” so organisms are able to live underneath

-Problem for roads


Acids & Bases --Formed by ionic compounds in

solution

Acids – release Hydrogen ions (H+) in water

(ex. HCl in stomach acid)


Bases – Produce hydroxide (OH-) ions in solution (ex. NaOH in soap & egg whites)

Salts – yield other ions (ex. NaCl and KCl)When salt is dissolved in water; sodium & chlorine “disassociate” or temporarily separate


pH --“power of H+”

-pH scale measures the concentration of

Hydrogen ions

Scale 0-14

acid: 0 to < 7bases: > 7 to 14


Blood - 7.4 (lethal if more acidic than 7 and more basic than 7.8)

Stomach acid - 2

A change in pH --in your body results in halting some enzyme functions


Acid rain --contains sulfuric acid and nitric acid

Acid rain pH < 5.6

Acid rain washes away vital minerals from soil, kills aquatic

organisms & strip nutrients from plants

2. 3 The Compounds of Life (most contain carbon)

Carbohydrates - store energy & provide shape (composed of C,H&O)

Starch - plants stored energy that is made of sugars

(monosaccharides, disaccharides &

polysaccharides)

CARBON

Carbon is important biological element because it can form four bonds with other elements and long chains or rings

Polymer – large molecule made up of many smaller units like starch

Monomer – unit that makes up polymer; glucose is the monomer for starch

2. 3 The Compounds of Life

Glycogen - animals stored energy made from sugars (same saccharides)

Cellulose - simple sugars that make structural

carbos in plants

GLUCOSE

Monomer of starch, glycogen, and cellulose


Lipids - long term energy storage; four types; not

soluble in waterFats - provide insulationWax - repel waterPhospholipids - give

structure to cell membranes

2. 3 – The Compounds of Life

Steroids - cholesterol in cell membranes


Proteins - large, complex molecules composed of many smaller molecules called amino acids (only 20 amino acids make

different combinations & proteins)Amino acids are held together by

peptide bonds to form proteins


Proteins - make enzymes that help control

chemical reactions (ex. Speed up digestion, releasing energy during cellular

respiration, building up proteins

2.3 The Compounds of Life

1. Defense2. Movement3. Structure

4. Regulation5. Transport6. nutrition


Nucleic Acids - large, complex molecules that contain

hereditary or genetic info – two types

monomer – nucleotide (made up of nitrogen base, phosphate, and sugar)


DNA - carries instruction that control activities of cell (blueprint)


RNA - make the proteins (builder)

2.4 Chemical Reactions and Enzymes

Chemical Reaction – creation of new substances by

breaking or forming chem. bonds

Carbs broken for energy

All chemical reactions involve energy (absorbed or released)


2H2 + O2 2H2O

_C6H12O6 + __ O2 __C02 + __ H2O


Reactions happen in living & nonliving things all the time

can be sped up by increasing temp or by involving a catalyst

Catalyst - in organisms are called enzymes (see sucrose

example, fig. 2.15) Enzymes - break bonds others help

form bonds


*Type of protein

*Act as a catalyst, speeding up chemical reactions

1. Substrate- substance being changed by enzyme

2. Active site- region on enzyme where substrate attaches (this is the enzyme substrate complex)


3. Substrate is altered (bond weakened) so that bond is broken

4. Products released and enzyme is unchanged (only the substrate changes)

5. Enzyme is free to bond with another substrate

*Enzymes catalyze specific reactions- only specific substrates will fit into the active site

*Enzymes work by either breaking or forming compounds

*Enzymes work only within specific ranges of temperature and pH.


*Enzyme affected by high temperature

*Enzymes are also affected by the concentration of the substrate and the enzyme

Application: bee sting home remedy- meat tenderizer (enzyme) on bee

sting (protein in venom)

the chemistry of life. 2.1 introduction to chemistry

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