Biology notes-Chapter 2-The Chemistry of Life
Biology notes-Chapter 2-The Chemistry of Life….
I. The nature of matter-
· Derived from Greek word Atomos,which means “unable to be cut”
As described by _____________________,2300 years ago
· 100 million atoms would make a room about 1 cm long
· DOES contain__________________particles that are smaller than an atom
1/1840th of mass of a proton(amu)
Energy levels in an electron cloud
· Calculating subatomic particles:
PROTONS=Atomic Number=electrons(in a neutral atom)
MASS NUMBER=p + n
· Since atoms tend to have p=electrons ,the + and – charge balance ,making them neutral
· _________________center of atom bound by STRONG FORCES.
· Electrons are attracted to + nucleus ,but are held in levels by the energy of their motion
B. Elements and Isotopes
· ____________________=PURE SUBSTANCE CONSISTING OF ONE KIND OF ATOM
· More than 100 in existence but ~24 compose living things
· Represented by 1 or 2 letter symbol
· Common symbols:
· Isotopes-atoms of the same element with a different number of neutrons----example:C-12,C-13,C-14----all averaged together for the atomic mass
· Isotopes are identified by ____________________.
· Radioactive Isotopes have unstable nuclei and break down at a constant rate over time…
· Radioactive Isotopes uses:_______________________________________________________________________________________-
· All isotopes of an element have the same chemical properties because they have the same # of ______________-.
· ‘WEIGHTED MASS”-ie .Atomic weight=average mass of all isotopes for an element
C. Chemical Compounds=______________________________________________________________________
· Shown by a chemical formula
· Physical and chemical properties for an element differ a lot when they are bound in a compound
· What is the ratio of H:O on H2O?____________________________
· Physical properties:__________________________________________________________________________________
· Chemical properties:_________________________________________________________________________________
D. Chemical Bonds hold together atoms in a compound
1. Ionic Bonds-electrons are transferred from one to another creating an electrical ,ionic charge that binds the atoms
· Tends to happen between metals and nonmetals
· Looking @ p.37 ,draw what happens in a NaCl bond
2. Covalent Bonds-_____________________
· The moving electrons of both atoms travel in the orbits of both atoms
· Double or triple bonds occur when 4 or 6 electrons are shared
· ____________________-smallest unit of a compound
· See drawing 2-4 on p.37 and draw the bond of H2O
E. Van der Waals Forces_intermolecular forces that result from
unequal sharing that results in tiny + or – charges in covalent bonds
· Help hold a molecule together a little more….see example of gecko on p.38
· Rapid movement of electrons can create regions of tiny (+) and (-) charges/As some molecules are close together,slight attraction between oppositely charged regions of nearby molecule-esp. when molecule is large
II. Properties of water
· Single most abundant compound in most living things
A. The Water Molecule
· _____________-because of an uneven distribution of electrons between O and H atoms
· O side is more – pole because it has more electrons
· It is ,essentially ,neutral ,but has a more – and more + end
· Because of this polarity water molecules can attract one another
· Polar charges are written in ( ) to show they are weaker than ionic charges
· H bonds not strong ,but water can form___________ H bonds…..causing many of its properties/bonding with itself O,N, and F
· A single water molecule can be involved in as many as 4 H-bonds
· __________________-attraction between molecules of the same substance…water is cohesive-example-surface tension allows spiders to walk on water
· ___________________-attraction between molecules of different substances-example-water creating meniscus as attaches to sides of graduated cylinder
· H20 bonding in H2O is Unique orientation that enables expanding as freezes
· HEAT CAPACITY---because of H-bonds ,takes a lot of heat to get water molecules moving faster, creating high heat capacity….helping organisms maintain body temp’s
· Look @ ppt and describe the effect of capillary action and how it is used in nature:_____________________________________________________________________________________________________________________________________________________________________________________________________________________
B.Solutions and Suspensions
· Water is often in a ________________________,where 2 or more elements or compounds are PHYSICALLY combined
· 2 types;
1) __________________mixture where components evenly distributed
· Ions are surrounded by water molecules and evenly distributed
· _____________-substance dissolved
· ______________-substance that does dissolving
2) ____________________-mixtures of water and non dissolved materials—blood cells in a suspension of water in vessels
B. Acids,Bases and pH-
· Water molecule can react to form ions.Draw reaction as shown @ bottom of p.42:
· _________________indicates concentration of H ions in solution
· Each step represents a power of 10-example-pH of 5 has 10 x as many H+ ions as same qty of ph 6
· ______________-higher concentrations of H+ ions and pH 7
· ________________weak acids or bases that react w/ strong ones to prevent sharp pH changes
· Buffers are dissolved in life’s fluids ,playing an important role in maintaining homeostasis in organisms
III. Carbon Compounds
· In the 1800’s,chemists thought compounds created by living things –organic compounds-were much different than others
· In 1838 a German chemist made the organic compound,urea ,from nonorganic ammonium cyanate…Thus principles of chemistry governing nonliving could be applied to living things
· _________________________is actually the study of almost all C-compounds-many not having anything to do w/ living things.
A. The Chemistry of Carbon
· Why is carbon special?---1) It has 4 valence electrons and can make 4 bonds 2)It can bond w/ many other elements. Includes H,O,P,S,N to make molecules of life
3)C can bond to other C’s in single,double or triple bonds
4)C can form chains and rings
· Forms millions of different complex structures.
· “Giant molecules found in organisms “
· Formed by _________________________________,in which large compounds are built by joining smaller ones.
· ______________________-small units –join to form __________________________-large molecules
· The 4 groups of macromolecules are________________________________________________________
· Made up of C,H and O in ,uaually, a ratio 1:2:1.
· Used by organisms for energy-main source.
· Used for structure-by plants and some animals.
· Break down of sugars,like glucose(C6H12O6)provides immediate energy for cell activities
· Starches are complex carbohydrates-stores extra energy
· Single sugars are called ______________________,like glucose,galactose and fructose.
· Sucrose=disaccharide-made of 2 sugars(notice structure in picture)
· ______________________________are large molecules formed from monosaccharides
-such as glycogen or animal starch—glycogen from the liver helps out when glucose levels run low.This is also stored in muscles for energy.
· Plants have plant starch and cellulose ,which gives plants their structure----major component of wood and paper.
· Large ,varied group of macromolecules that are generally are ________ in water
· Includes fats ,oils,waxes
· Made mostly of C,H and O
· Groups are ____________________.
· Can be used to store energy
· Some are parts of biological membranes or waterproof coverings
· Many are formed when glycerol is combined w/ fatty acids
1) If each C atom is joined to another C atom by a single bond it is called ________________________.This is because it has the max # of H-atoms.These are________________.
2) If there is at least 1 C-C double bond ,it is called ___________________________.These are ______________________@ room temp.example-olive oil
· If there is more than 1 C-C double bond,it is__________________________________examples:oils such as corn,sesame,canola and peanut
· Monomer basically glycerol and fatty acids….see analyzing data,p.48
E. ____________________=macromolecules containing C,H,O,N and P
· Polymers assembled from monomers called_________________________________, which contain 3 parts:
1. 5-C sugar
2. phosphate group
3. nitrogenous base
· Nucleic Acids store and transmit ______________or genetic info…2 types of nucleic acids
1. __________________________________-,involved in protein synthesis and has the sugar_________________.
2. Single strand
3. ___________________________________-contains genetic code and has the sugar ____________________________.
· Double helix
· Contains deoxyribose
· For heredity
F. _________=macromolecules containing C,H,O and N and composed of amino acids (monomer)
· _______________________ are compounds w/ an amino group(-NH2) on one end and a carboxyl group(-COOH) on the other end.
· Look @ Fig 2-17 on p. 48
basic amino acid formula
· More than 20 amino acids in nature
· All amino acids alike in region where they may be joined by covalent bond.Thus any amino acid can be joined to any amino acid-by bonding an amino group to a carboxyl group
· The portion of each amino acid that is different is the side chain called a ____group.Some of these R groups are acidic and some are basic…some polar and some nonploar.Some have C rings .
· The instructions for assembling amino acids into different proteins is stored in____.
· Each protein has a specific role….various functions include:
1. control _____________rates(enzymes).
2. regulate cell processes .
3. forming bones and muscles
4. transporting substances into and out of cells
5. fighting diseases
· up to 4 levels of organization
1st –sequence of amino acids in a protein chain
2nd –amino acids within a chain can be twisted or folded
3rd –chain itself is folded—If there is more than one chain,each chain has a specific arrangement in space.
4th –Van der Waals forces and H-bonds help maintain a protein’s shape.
IV. Chemical Reactions and Enzymes
A. Chemical reactions=_______________________________________________________________________________________________
· Some are fast and some are slow
· The elements entering into the reaction are ________________and that which is produced are the ________________________.
Co2 + H2O(H2CO3 reaction that allows release of CO2 from the bloodstream
The above reaction is reversed in the lungs.
· Chemical reactions always involve the breaking of bonds in ____________ and the formation of new bonds in _____________.
B. Energy in Reactions
· Energy is released or absorbed in chemical reactions.
1. Energy Changes-
· Chemical Reactions that release energy are called ______________________ and often occur spontaneously.
Example: 2 H2 + O2( 2 H2O….energy released as heat/sometimes as light and sound
· Chemical reactions that require energy are called_________________ and usually doesn’t occur by itself
Example: 2 H2O( 2H2 + O2 requires an electrical current---NEEDS AN ENERGY SOURCE
· Organisms must have a source of energy to carry out necessary reactions.Plants get this from products of _____________________and animals get it from consuming plants or other animals….thus from metabolizing food
2. Activation energy-____________________________________________________
· A ______________ is a substance that speeds up the rate of a chemical reaction by lowering activation energy.
· Enzymes speed up reactions that take place in a cell
· ________________________speeds up the release of CO2 from the bloodstream.
· Enzymes are specific to the reaction they speed up and usually named on the basis of the reaction.
C. Enzyme Action-
· Reactants must collide w/ sufficient energy to make _____________.
1. ENZYME-SUBSTRATE COMPLEX-enzymes provide a site where reactants can be brought together to react,thus reducing energy needed for the reaction.-made of proetein
· Reactants of enzyme-catalyzed reactions are called _____________________________.
· Enzymes themselves unchanged in a reaction
· Often end in –ase/sugars in -ose
· Substrates bind to a site on the enzyme called the ______________________________.These are complementary shapes..These are bound together by intermolecular forces making an_______________________________These are bound together until the reaction is done.
2. REGULATION OF ENZYME ACTIVITY
· Affected by many variables,such as temperature ,pH
· Cells can regulate enzymes in many ways—often w/ a protein that turns the key enzymes on and off.