Download is that you _understand______ life because it is only

Name _______________________________________________________________
Test Date _Fri, 9/9______
UNIT I – INTRODUCTION TO BIOLOGY
I. WHAT IS “LIFE”?
(pp.16-22, 35-36)
A. Complexity of Life
Biology is the study of _life____. To study “life” is to study a subject that is awesomely complex. Our common goal
is that you _understand______ life because it is only when you understand that you can truly _learn___ . . . And as
the wise Mrs. Rice says, “If you _memorize_____, you _forget______; when you _learn________, you
_remember______! ☺
To accomplish this, there are two important keys:
1. Active Listening – Listening is not a passive activity! An active listener
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2. Responsible Learning – A responsible learner takes care of business; that is, does what he/she needs to do to
truly learn!
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B. Characteristics of Life
1. Living things are made of _cells___ . A cell is the _smallest unit of life____________
2. Living things obtain and use _energy_____. Our ultimate source of energy is the _sun_____. Plants
can convert the sun’s energy into useable energy in a process called _photosynthesis__________. The chemical
processes that occur in an organism to convert food to _energy______ are known as _metabolism________.
3. Living things _respond to their environment____________________. Living things react to a
_stimulus__________; for example, _temperature, light________________________________.
4. Living things maintain a _constant____ internal environment. This is known as _homeostasis________
or __internal harmony_______.
5. Living things _grow and develop_______. Development describes _physical changes_____________
that take place during the _lifetime_________ of an organism.
6. Living things are based on a _universal genetic code_______ - _DNA_____.
7. Living things _reproduce________. If this did not occur, _species would die out__________
8. As a group, living things _evolve____; this means, _change over time________________.
C. Hierarchy of Life
1. _Atom_____ - Smallest unit of matter that retains its elemental properties
2. _Molecule________ - Groups of atoms bonded together
3. _Cell________ - Smallest working unit of life
4. _Organism______ - Individual living thing; depending on the complexity, an organism may be composed of:
a. _Tissue_________ - groups of cells working together
b. _Organ________ – groups of _tissues____ working together
c. _Organ system_____ - groups of _organs___ working together
5. _Population____ - Group of organisms of one _species___ in one area
6. _Community______ - Different populations that live together in a specific area
7. _Ecosystem_______ - A community and its _non-living components___________
8. _Biosphere________ - Earth
II. CHEMISTRY OF LIFE
Organisms are composed of _matter_____, which is anything that takes up space and has mass. All matter is
composed of _elements____, substances that cannot be broken down by chemical reactions.
A. Elements – There are 92 naturally occurring elements, 25 of which are essential to life. Four elements make up
96% of living matter. They are:
1. _Carbon_____
2. _Hydrogen___
3. _Oxygen_____
4. _Nitrogen______
B. Atoms – An atom is the smallest unit of _matter__ that still retains the properties of that _element_____. An
atom is composed of the following _sub-atomic______ particles:
 Protons - __+___ charge; located _in nucleus______
 Neutrons - _No___ charge; located _in nucleus_____
 Electrons - _-__ charge; found _orbiting around nucleus____________
Protons and neutrons are packed together to make up a dense core, the _nucleus___, and they have
approximately the same mass. Thus, the overall charge of the nucleus is _positive____. Electrons orbit around
the nucleus at nearly the speed of light. Their mass is so small that they are not used when calculating
_atomic mass____. It is the _charge attraction______ that holds an atom together.
C. Atomic Number – This is a number unique to each element that identifies the number of _protons____ in its
atoms. An atom is neutral or _uncharged_____________, therefore the number of _electrons___ = the
number of _protons_______.
D. Isotopes – Although all atoms of a given element have the same number of _protons_______, the number of
_neutrons_______ may vary. These different forms of an atom are called _isotopes________. An example of
an element that forms isotopes is _carbon_____.
 Carbon-12 → the most common & _stable___ form of carbon; has 6 protons and _6___ neutrons
 Carbon-13 → __6____ protons & __7____ neutrons
 Carbon-14 → __6____ protons & _8____ neutrons
Some isotopes are very unstable or _radioactive_______. These isotopes are very useful in
_research_________ and _medicine_____.
E. Chemical Bonds & Compounds (pp. 37-38)
Elements combine together in fixed ratios of atoms to form _compounds_______. Compounds are held together by
_chemical bonds______________. The reactivity of an atom and the type of chemical bond that it forms are
determined by the number of _electrons________ it has.
1. Ionic Bond – Weaker bond in which electrons are _transferred______- that is, one atom _strips_____ an
electron(s) away from the other. Results in 2 oppositely-charged particles called _ions____ that are
attracted to each other due to the difference in _charge____. Examples include _salt_____
2. Covalent Bond– Strong chemical bond in which electrons are _shared_____________. Results in a very
stable compound called a _molecule____. Examples include _water, glucose__________.
F. Chemical Formula - _Description______ of a compound. Identifies the _ratio__ of _atoms_____
of elements that make up the compound.
H2SO4 = _2 hydrogen atoms, 1 sulfur atom, 4 oxygen atoms _____________
 Total number of atoms = _7____
C6H12O6 = _6 carbon atoms, 12 hydrogen atoms, 6 oxygen atoms _______
 Total number of atoms = _24______
G. Chemical Equation – Provides the “_recipe______” for making a compound. The substances that
go into the reaction are known as the _reactants_________. The substance(s) formed is known as the
_product________.
2H2 + O2 2H2O
 Reactant = _ H2 and O2_________
 Product = _ H2O______________
III. WATER (pp. 40 – 43)
Water is essential for life. All organisms are composed mostly of water.
A. Polarity
1. Definition of Polarity – Polarity is the unequal _sharing_____ of _electrons__ in molecules formed
with covalent bonds. Water is a molecule with the chemical formula _ H2O ____. The atomic
number of hydrogen is _1___ and the atomic number of oxygen is _8___. This means the O nucleus
has 8 _protons__ and each H nucleus has _1__ _proton___. Due to this difference, the _oxygen__
nucleus has a much stronger positive charge than each hydrogen nucleus. Therefore, the shared
_negatively__- charged electrons are much more attracted to _oxygen___. Statistically, virtually all
_10__ electrons are orbiting around the oxygen end of the molecule just about all the time. Because
the oxygen nucleus has _8___ protons, this gives the oxygen end of a water molecule a slight
_negative__ charge and the two hydrogen ends of the water molecule a slight _positive__ charge.
2. Hydrogen “Bonds” - A hydrogen bond is not a true chemical bond because it does not result in the
formation of a new _compound__. This bond is simply an _attraction__ between the slightly positivelycharged _H_-end of one _polar___ molecule and the slightly- _--___ charged end of another polar
molecule. In water, hydrogen bonds form between the slightly _positively__-charged H-end and the slightly
_ negatively___-charged O end.
3. Hydrophilic vs Hydrophobic – Polar molecules are attracted to other polar__ molecules, while non-polar
molecules are attracted to _non-polar molecules_______. Any molecule attracted to water is described as
_hydrophilic_____; molecules repelled by water are described as _hydrophobic____________.
B. Properties – Polarity gives water some unique properties important in maintaining _homeostasis___
in organisms.
1. Water is "sticky" – Water molecules tend to stick together, called _cohesion___ and results in _surface tension__.
Water molecules also tend to stick to other surfaces - known as _adhesion___. This explains the phenomenon
known as _capillary_____ action.
2. Water is the solvent of life – Slightly-charged ends of water molecules _attract___ and
_separate___ atoms that make up other compounds, thus dissolving them. Anything dissolved in water is referred
to as a _solution_____. Many important compounds in cells are in solution.
3. Water has a high heat of vaporization – Perspiring cools us because it requires _heat energy____ to change
water from a liquid to a _gas____. When perspiration _evaporate___, the heat required is drawn from our
_skin________.
4. Water has a high specific heat – This allows large bodies of water to maintain a stable temperature.
5. Liquid water expands as it freezes – Ice is less dense than water so it floats which _protects_____ organisms
and _insulates lakes, rivers, oceans____________
IV. THE IMPORTANCE OF CARBON (pp. 44-45)
Although a cell is composed of 70% to 95% _water_________, most of the rest consists of carbon-based
compounds. Carbon can form very large, complex molecules called _biomolecules_____ compounds due
to its number of electrons. Organic molecules important in organisms are called _biomolecules (macromolecules)____.
A. Polymers - Most biomolecules are _polymers__________. The prefix “poly” means _many_____. A
polymer is a large molecule composed of _many_________ identical or similar building blocks. The sub-units,
or building block molecules, of a polymer are called _monomers_______.
B. Dehydration Synthesis – Reaction that occurs to _covalently__________ bond two or more
_molecules_____________ together. __Water______ is released as a waste product.
C. Classes of Biomolecules:
1. _Carbohydrates________________
2. _Lipids_______________________
3. _Proteins_____________________
4. _Nucleic Acids_________________
V. CARBOHYDRATES
(p. 45-46)
Carbohydrates are used for immediate and stored _energy____ and as a _building material____________.
Carbohydrates contain the elements _C_, _H__, and _O___. The ratio of _H___ atoms to _O___ is
_2 : 1____. In other words, for every _2 hydrogens__ in a carbohydrate, there is _1 oxygen____. There are
three groups of carbohydrates:
A. Monosaccharides – “_One__ Sugar”. Simplest of all sugars. Although they vary in the number of _C___ atoms that
make up the molecule, the ratio of _2 H : 1 O_____ is always present. Monosaccharides are the building blocks, or
_monomers______, for the more complex carbohydrates.
1. 5-carbon monosaccharides – Examples are _deoxyribose_____ and _ribose___.
These two sugars are a main component of _DNA___ and _RNA____, respectively.
Glucose
2. 6-carbon monosaccharides – There are three 6-carbon monosaccharides. They all have the
formula, _C6 H12 O6___ and are known as _isomers____. Isomers have the same chemical formula,
but the _atoms____ are arranged differently giving each molecule different properties.
 Glucose – Preferred _energy source__________ for most organisms, including _humans_________.
Found in _honey________.
 Fructose - _Very sweet!______. Found in _fruit_____.
 Galactose – Found in _milk______
B. Disaccharides - _Two__ monosaccharides _covalently____ bonded together
 Sucrose - _Table sugar___________. Composed of _glu + fru____________________
 Lactose - _Milk sugar_____________. Composed of _glu + galac_________________
 Maltose - _Found in seeds, grains___. Composed of _glu + glu___________________
C. Polysaccharides - _Many____ monosaccharides _covalently_________bonded together. They are
divided into two groups based on function
 _Storage_______ Polysaccharides
 _Structural_______ Polysaccharides
1. Storage Polysaccharides – Long _polymers_____ of _glucose_________ broken down as
needed for _energy_________
 Glycogen – Storage form of _glucose_______ in _animals_______. In humans, most glycogen is stored in
_liver______ and _muscle_____ cells.
 Starch - Storage form of _glucose______ in _plants________. Humans are able to break down starch for
energy.
2. Structural Polysaccharides – Used as a _building material________ in many organisms
 Cellulose – Major component of _plant cell walls_____________. Composed of monomers of
_glucose_________. Humans are unable to break the bonds in cellulose; therefore it cannot be used for
_energy____ but it is still important to our diet as a source of _fiber______.
 Chitin - Major component of _fungi____ cell walls and the _exoskeleton______ of insects and other
arthropods.
VI. LIPIDS
(p. 46-47)
_Non-polar______ molecules that are not _soluble________ in water. Made up of _C___, _H___, and _O___,
but lipids do not have the _2H : 1O______ ratio found in carbohydrates. Our bodies need lipids for
_insulation, cushioning, energy storage____________________. There are 3 important groups:
A. Fats & Oils – Characterized by presence of _three fatty acid tails____. Generally referred to as
_fat___ if lipid is solid at room temperature and an _oil___ if lipid is liquid at room temperature. Fats and oils are
classified as _saturated ___ or _unsaturated_, depending on the type of covalent bonds in the fatty acids.
_Saturated ___ fats have been linked to heart disease.
B. Phospholipids – Unique lipid because one end of the molecule is _non-polar____, but the other end is _polar___.
Phospholipids are a part of every living _cell membrane_____.
C. Steroids – An important example of a steroid is _cholesterol____. Cholesterol is found in animal
_cell membranes____ and is also used to synthesize some _hormones, including testosterone_______.
VII. PROTEINS
(pp. 47-53)
In addition to _C___, __H__, and _O___, proteins contain _N__.
A. Monomers
The monomers of proteins are _amino acids_____. There are _20_____ amino acids that combine together in
different _numbers__, _patterns___, and _arrangements______ to form proteins. All 20 amino acids are
identical, with the exception of a portion called the _R group________. The differences in the 20 amino
acids are due to the differences in the make-up of the R groups.
B. Protein Structure
The shape of a protein is very important to its function. Its shape is determined by interactions between R groups; for
example,
 _Covalent___________ bonds
 _Ionic______________ bonds
 _Hydrogen__________ bonds
 Van der Waals Forces – Similar in principal to H-bonds; intermolecular attractions between _non-polars_
C. Function
 Structure
 Transport
 _Hormones________
 Cell Identification & Communication
 _Metabolism______
VIII. NUCLEIC ACIDS
(p. 47)
Nucleic acids are _polymers___ composed of _monomers______ called _nucleotides______________.
Nucleotides contain __C___, _H__, _O____, _N__, and _P__. There are three important members of this
group:
Nucleotide
A. DNA
 Composed of __2__ strands of _nucleotides_____ _covalently_____-bonded together through _dehydration
synthesis_______
 Twisted together to form a _double helix______ structure.
 Contains the _genetic code___; the _working instructions___ for a cell.
B. RNA
 _Single___ strand of nucleotides
 _Carries out______ the instructions in DNA.
C. ATP
 Single _nucleotide_____
 Provides usable _energy__ for all cells