C.P. BIOLOGY
Unit 2 - Structure and Function of Living Things
Disciplinary Core Idea: From Molecules to Organisms: Structures and Processes
OBJECTIVE 1: DEFINE THE TERM BIOLOGY
A. Biology is the organized study of living things and their interactions with their natural and physical
environments.
1. In biology you will study the origins and history of life and once-living things, how living things
interact with one another, and how living things function. This will help you understand how we
as humans have a vital role in preserving the natural environment and sustaining life on earth.
OBJECTIVE 2: CHARACTERISTICS OF LIVING ORGANISMS
A. Life is the quality that distinguishes living things – composed of cells – from nonliving things or those
that have died.
1. All living things, all organisms, can be characterized by common aspects of their structure and
functioning.
2. Organisms are complex, organized, and built on a hierarchical structure, providing the foundation
for the next, from the chemical foundation of elements and atoms, the cells and the systems of
individual organisms, to species and populations living and interacting in complex ecosystems.
B. All living things possess specific characteristics. An organism is anything that has or once had all of
these characteristics. (see page 7)
1. they are organized (arranged in an orderly way) and made of cells (from one to billions). Cells
are the basic units of structure and function.
2. they use energy (energy in food is changed into chemical energy by cells).
3. and grow (add mass and in many organisms form new cells and structures).
4. to a specific size and form during development ( the process of natural changes that take place
during the life of an organism.
5. they reproduce which is not essential for the survival of the individual but is essential to continue
the species(a group of organisms that can breed with one another and produce fertile offspring)
6. respond to stimuli (anything that causes some sort of reaction in the organism) to maintain
homeostasis (regulates an organism’s internal conditions to maintain life.
7. they adapt (an inherited characteristic that results from changes to the species over time and in
many instances evolve.
8. All living things eventually die
OBJECTIVE 3: IDENTIFY THE PARTS OF A CHEMICAL REACTION
A.
A chemical reaction is the process by which atoms or groups of atoms and substances are
reorganized into different substances. It is these chemical reactions that occur inside an
organism’s cell that maintain homeostasis and keep the organs and systems functioning.
1. Indications that chemical reactions have taken place include the production of heat or light, and
the formation of a gas, liquid or solid.
2. When writing chemical equations, chemical formulas describe the substances in the reaction
and arrows indicate the process of change.
3. A chemical reaction shows the reactants, the starting substances, on the left side of the arrow,
and the products, what was made during the reaction, on the right side of the arrow.
a. ReactantsProducts
b. C6H12O6 + O6  CO2 + H20 (Glucose and oxygen react to form carbon dioxide and water)
4. In chemical reactions, matter cannot be created or destroyed (conservation of mass). So, all
chemical reactions must show this balance of mass by having equal number of atoms for each
element on both sides of a chemical equation.
OBJECTIVE 4: RELATE ENERGY CHANGES TO CHEMICAL REACTIONS
A. The minimum amount of energy needed for reactants to form products in a chemical reaction is called
the activation energy. Some reactions don’t happen because the activation energy is too high.
B. Exothermic reactions release energy (heat or light) and the energy of the product is lower than the
energy of the reactants.
C. Endothermic reactions absorb heat and the energy of the products is higher than the energy of the
reactants.
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D. In every chemical reaction, there is a change in energy due to the making and breaking of chemical
bonds as reactants for products.
OBJECTIVE 5: SUMMARIZE THE IMPORTANCE OF ENZYMES IN LIVING ORGANISMS
A. All living things are chemical factories driven by chemical reactions. In living organisms additional
substances must be present to lower the activation energy and allow the reaction to proceed quickly.
1. A catalyst is a substance that lowers the activation energy needed to start a chemical reaction.
Catalysts do not increase how much product is made nor are they used up in a reaction.
B. Special proteins called enzymes are the biological catalysts that speed up the rate of reactions in
biological processes.
1. Enzymes are essential to life. Once used in a chemical reaction, it can be used again because
enzymes are catalysts.
2. An enzyme’s name describes what it does and most are specific to one reaction.
3. Substrates, reactants that bind to the enzyme, interact with enzymes at specific places called
active sites.
a. The substrate and active site have complimentary shapes.
b. When the substrate binds to the active site, the active site changes shape and forms the
enzyme-substrate complex. This complex helps chemical bonds in the reactants to be
broken and new bonds to form.
c. pH, temperature and other substances affect enzyme activity.
d. Enzymes affect many biological processes; they are the chemical workers of the cells.
OBJECTIVE 6: DESCRIBE THE ROLE OF CARBON IN LIVING SYSTEMS
A. The element carbon is found in living organisms or in their products. Organic chemistry is the study
of organic compounds, those compounds containing carbon.
1. Organic compounds usually also have hydrogen, oxygen and nitrogen.
2. Inorganic compounds: all compounds that are not organic, do not usually contain carbon.
Ex. H2O, salts, some acids and bases. An exception is CO2.
3. Chemistry: a carbon atom can form four covalent bonds with other atoms, as a result, organic
compounds can be very complex. They can form straight chains, branched chains or rings.
B. Most cells store small carbon compounds that will be the building blocks for large molecules called
macromolecules.
1. Formed by joining smaller organic molecules together.
2. Polymers are molecules that are made from repeating units of identical or nearly identical
compounds called monomers that are linked together by covalent bonds.
OBJECTIVE 7: LIST THE FOUR IMPORTANT MACROMOLESCULES, AND DESCRIBE THEIR
FUNCTIONS IN LIVING ORGANISMS
A. Four important organic molecules found in your body:
1. Carbohydrates
2. Lipids
3. Proteins
4.. Nucleic Acids
B. Carbohydrates
1. Defined: compounds of carbon, hydrogen, and oxygen, with two hydrogens for every oxygen
(CH2O).
2. Function: main source of energy; can be stored by both plants and animals. In plants the
cellulose is used as structural support.
3. Examples:
a. Simple: monosaccharides like glucose, fructose and galactose
b. Complex: disaccharides like maltose or polysaccharides like starch, glycogen or cellulose.
4. Dehydration synthesis: a reaction in which two molecules are bonded together by the removal of
a water molecule.
5. Hydrolysis: the opposite of dehydration synthesis, molecules are broken apart by the addition of a
water molecules
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C. Lipids
1. Examples: fats, oils, and waxes. All have a large proportion (much greater than 2 to1) of C-H
bonds and less oxygen than carbohydrates. Ex. C57H110O6
2. Function:
a. Cell structure
b. Reserve energy supply, in plants it is stored as oils, in mammals it is found under our skin and
it cushions and insulates against heat loss
3. Formed: by dehydration synthesis, joining long fatty acid chains to a glycerol molecule.
4. Types:
a. Saturated: all carbon bonds in the fatty acid chain are single, usually a solid at room
temperature
b. Unsaturated: one or more double bonds found in the fatty acid chain, usually a liquid at room
temperature.
5. A special kind of lipid, called a phospholipid, is responsible for the structure and function of the
cell membrane. Lipids are hydrophobic, they do not dissolve in water. This lets lipids serve as
barriers in biological membranes.
6. Steroids are a group of lipids that include substances like cholesterol and hormones. Cholesterol
is the starting point in the formation of vitamin D and the hormones estrogen and testosterone.
a. Cholesterol can be a problem if it builds up in the artery walls, can lead to heart attacks and
strokes
b. Saturated fats found in butter and meat can increase cholesterol
C. Proteins
1. Contain: nitrogen plus carbon, hydrogen and oxygen but can vary greatly in their structure
2. Functions:
a. Structural: cells and body tissues like hair, nails, cartilage and connective tissue
b. Pigments: blood, skin, eyes, chlorophyll
c. Hormones: chemical messengers
d. Contractile materials of muscles
e. Antibodies: immune system
f. Transport molecules
g. Enzymes: used during reactions
D. Amino Acids: structural building blocks of proteins
1. Peptide Bonds
a. Formed by dehydration synthesis
2. Polypeptide: chain of amino acids held together by peptide bonds
3. Protein: a polypeptide chain(s)
4. Protein shapes: coils, sheets, and globules
E. Nucleic Acids
1. Two types: DNA and RNA
2. Both types are made of nucleotides. A nucleotide consists of a base, a sugar and a phosphate
molecule all joined together.
3. DNA
a. DNA structure: two chains of nucleotides in the shape of a double helix
(1) Possible bases: adenine, thymine, guanine and cytosine
(2) Sugar: deoxyribose
(3) Phosphate molecule
b. Purpose: hereditary material transmitted from one generation to the next during reproduction,
it directs and controls the cell
4. RNA
a. RNA structure: a single chain of nucleotides
(1) Possible bases: adenine, uracil, guanine, and cytosine
(2) Sugar: ribose
(3) Phosphate molecule
b.
Purpose: to copy the DNA code and take it out into the cell to direct protein synthesis
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5. Summary
Sugar
Base difference
# of chains
types
DNA
Deoxyribose
Thymine
Double
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RNA
Ribose
Uracil
Single
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OBJECTIVE 8: DIFFERENTIATE BETWEEN A PROKARYOTE AND A EUKARYOTE CELL
A. Cells differ in their shapes and sizes and vary in their functions that they perform. Organisms and
their parts are made of cells which are structural units of life and which themselves have a molecular
substructures that support their functioning..
B. Organisms range from a single cell (unicellular) to multi-celled organism. Cells are grouped into two
broad categories, prokaryotic and eukaryotic cells.
1. Eukaryotic cells contain a nucleus and other membrane bound organelles
a. Occur mostly in multicellular organisms
b. Organelles allow many chemical reactions to occur at the same time although in different
locations in the cell.
2. Prokaryotic cells lack internal membrane bound structures.
a. Mostly occur in bacteria (unicellular) so smaller than eukaryotic cells
b. May be similar to first organisms on Earth
C. Specialized structures within cells are responsible for specific cellular functions. These essential
functions of a cell of a cell involve chemical reactions between many types of molecules, including
water, proteins, carbohydrates, lipids, and nucleic acids.
D. Within multi-celled organisms, different groups of large numbers of cells work together to form
systems of tissues and organs that are specialized for particular functions.
OBJECTIVE 9: DESCRIBE HOW A CELL’S PLASMA MEMBRANE FUNCTIONS
A. All cells have a plasma membrane, which is a special boundary that controls what moves into and
out of a cell.
B. The survival of a cell depends on its ability to maintain the proper conditions within itself (homeostasis).
1. Fundamental life processes of plants and animals depend on a variety of chemical reactions that
occur in specialized areas of the organisms cell.
C. The job of the plasma membrane, the boundary between the cell and its environment, is to allow a
steady supply of nutrients to come into the cell and to remove the excess and waste products.
D. The plasma membrane is selectively permeable – it allows some molecules into the cell (water,
sugars, oxygen) while keeping others out (bacteria). (See page 187)
E. The structure of the plasma membrane is a phospholipid bilayer , in which two layers of
phospholipids are arranged tail to tail along with proteins on its surface or embedded in the
membrane.( see page 188 Fig. 7.6)
F. The structure of the plasma membrane is a phospholipid bilayer , in which two layers of
phospholipids are arranged tail to tail along with proteins on its surface or embedded in the
membrane.( see page 188 Fig. 7.6)
1. Two layers of lipid molecules are organized with the polar heads of the molecules forming the
outside of the membrane and the nonpolar tails forming the inside of the membrane
a. Water soluble substances will not move easily through the plasma membrane because they
are stopped by the nonpolar middle, allowing the cell to separate the environment inside the
cell from the environment outside the cell.
2. Proteins are a component of the plasma membrane.
a. Proteins that span the entire membrane are transport proteins, regulating molecules that
b. Proteins on the outside of the cell act as receptors and transmit signals to the inside of the
cell.
c.
Proteins on the inner surface anchor the plasma membrane to the cell’s internal support
structure, giving the cell its shape.
3. Cholesterol molecules helps to keep the fatty acid tails of the phospholipids from sticking together
so it is needed to maintain the structure of the plasma membrane and maintain homeostasis.
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4. Carbohydrates stick out of the plasma membrane help cells identify each other.
E. The fluid mosaic model refers to a plasma membrane with substances that can move around within
the membrane.
OBJECTIVE 10: LIST THE STRUCTURES OF A TYPICAL EUKARYOTIC CELL AND THEIR
FUNCTIONS
A. Each component of a eukaryotic cell has a specific job, and all the parts of the cell work together to
help the cell survive. (See summary of cell structures on page 199)
B. Some organelles act as specialized boundaries
1. Plasma membrane – selectively permeable. Controls movement into and out of the cell.
2. Cell wall – found in plants, fungi, and most bacteria. Located outside the plasma membrane and
provides additional support and locomotion. Made of cellulose.
C. Some organelles are involved in cell control and protein synthesis
1. Nucleus – leader or director of the cell. Contains DNA. Surrounded by a porous membrane.
2. Nucleolus – found within the nucleus and makes ribosomes
3. Chromatin/chromosomes – chromatin is threads of DNA that can be wound on protein spools
to form rod-shaped chromosomes.
4. Ribosomes – located outside of the nucleus in the cytoplasm; site where the cell assembles
enzymes and other proteins according to the directions of the DNA.
5. Cytoplasm – clear, gelatinous fluid inside the cell.
D. Some organelles assemble, transport, and store molecules
1. Endoplasmic Reticulum – site of cellular chemical reactions. A complex folded membrane that
forms a transport system between the nucleus and the cytoplasm. May be rough (has ribosomes
attached; exports synthesized proteins to golgi apparatus) or smooth (no ribosomes attached,
acts to modify or detoxify lipids).
2. Golgi Apparatus – flattened system of tubular membranes that sort the proteins into packages to
be sent to the appropriate destination.
3. Vacuoles – membrane bound space for temporary storage of materials.
4. Lysosomes – contain digestive enzymes
E. Some organelles provide the cell with energy
1. Chloroplasts – contain chlorophyll, a pigment that traps light energy to produce food that is
stored until a later time.
2. Mitochondria – break down food molecules to release energy that powers most cell activities
F. Some organelles provide support and locomotion for the cell.
1. Cytoskeleton – acts as a scaffold to provide support for the organelles suspended within the
cytoplasm
2. Cilia – short, numerous, hair-like projections that move in a wave-like motion to propel a cell or
aid in feeding.
3. Flagella – long, whip-like projections for movement of the cell.
OBJECTIVE 11: COMPARE AND CONTRAST THE STRUCTURES OF A PLANT AND ANIMAL CELL
A. Plant and animal cells have many of the same organelles as they both need to perform the same
critical functions. (survive, grow, and reproduce).
B. Pant and animal cells do differ in some ways
1. Animal cells have centrioles (used in cellular reproduction)
2. Animal cells usually have many small vacuoles; plant cells usually have on large vacuole
3. Plant cells in general are larger than animal cells.
4. Plants cells have a cell wall( for protection and support) and chloroplasts which contain
chlorophyll.
OBJECTIVE 12: EXPLAIN THE PROCESS AND IMPORTANCE OF DIFFUSION AND PREDICT THE
EFFECT OF A HYPOTONIC, HYPERTONIC AND ISOTONIC SOLUTION OF A CELL
A. Diffusion - Movement of molecules from a higher concentration to a lower concentration
1. Movement will occur if there is a concentration gradient (difference)
2. Movement will continue but eventually there will be no overall change. At this point dynamic
equilibrium has been reached.
B. Movement of water, lipids and lipid soluble substances are some of the compounds that can pass
through the plasma membrane. Movement may or may not require energy
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C. Passive transport: no energy required, just diffusion. Facilitated diffusion uses channel and carrier
proteins, driven by concentration gradient trying to reach equilibrium
D. Osmosis
1. The diffusion of water across a semipermeable membrane. Water will move across a membrane
trying to reach equilibrium (the amount of water being equal on both sides). Water will diffuse
toward the side with the greater concentration of dissolved particles.
2. Effects of osmosis:
a. Isotonic: water is in equilibrium, no net movement, cell retains .normal shape
b. Hypertonic: high concentration of dissolved substances, low amounts of water, water will
move in, cell will swell.
c. Hypotonic: low concentration of dissolved substances, higher amounts of water, water will
move out, cell will shrink
Example: a membrane separates two solutions, one solution is seawater, and the other is
fresh. The seawater is hypertonic to the freshwater, or the freshwater is hypotonic to the
seawater. Which way will the water move?
OBJECTIVE 13: EXPLAIN THE PROCESS OF ACTIVE TRANSPORT AND THE TRANSPORT OF
LARGE MOLECULES
A. Active transport: energy required as molecules move against a concentration gradient. Uses carrier
proteins that bind to the substance. (see fig. 7.26 page 205)
1. Carrier proteins change shape, release substances on the other side of the membrane, then are
restored to its original shape.
2. A common active transport pump in the plasma membrane of animal cells is the sodiumpotassium ATPase pump.
a. Controls the levels of Na+ and K+ inside cells.
b. Allows other substances to “piggy back” their way into or out of a cell by coupling with
another substance that uses an active transport pump. (see page 206.)
B. Some substances are too big to move through the plasma membrane by diffusion or transport
proteins.
1. Exocytosis: cell membrane expels substances (wastes, secrete hormones)
2. Endocytosis: cell membrane engulfs substances, pinocytosis (cell drinking) or phagocytosis (cell
eating) (See fig. 7.29 page 207).
OBJECTIVE 14: Relate DNA to Protein Synthesis and Cellular Activities
A. All cells contain genetic information in the form of DNA.
B. Genes are specific regions within the extremely large DNA molecules that form chromosomes.
1. Genes contain the instructions that code for the information of molecules called proteins,
which carry out most of the work of cells to perform the essential functions of life.
a. Proteins provide structural components, serve as signaling devices, regulate cell
activities, and determine the performance of cells through their enzyme activities.
OBJECTIVE 15: SUMMMARIZE THE NEGATIVE FEEDBACK MECHANISM USING HORMONE
LEVELS IN THE BODY AS AN EXAMPLE
A.
B.
The amount of hormone released from a gland is determined by your body’s demand for that
hormone at a given time. Ensures that the right amount is in your system at all times.
The endocrine system is controlled by negative feedback system, a system in which the
hormones, or their effects, are fed back to inhibit the original signal
1.
If hormone level is too low the glands will start secreting, if the level of hormone is too high, the
gland will stop secreting.
2.
Example is regulation of blood glucose
a. blood: normal glucose levels
b. eat: glucose levels rise in the blood
c. pancreas begins secreting insulin into the bloodstream
d. Insulin causes liver and other tissues to take up more glucose
e. Homeostasis restored, return to normal glucose levels in the blood.
3.
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a.
A and B represent two related metabolic processes. An increase in A causes an
increase in B. However, the change in B also causes a change in A. This is called
feedback. If the change caused by B is opposite to the original change in A, the
feedback is called negative. Negative feedback prevents A from changing very much in
either direction and helps to maintain homeostasis.
SUMMARY: STRUCTURE AND FUNCTION
A. Systems of specialized cells within organisms help them perform the essential functions of life,
Which involve chemical reactions that take place between different types of molecules, such as
water, proteins, carbohydrates, lipids and nucleic acids.
B. Genes are different regions in the DNA that contain instructions that code for the formation of
proteins, which carry out most of the work of cells.
C. Multicellular organisms that a hierarchical structure organization, in which one system is made up
of numerous parts and itself a component of the net level.
D. Feedback mechanisms maintain living system’s internal conditions within certain limits and
Mediate behaviors, allowing it to remain alive and functioning even as external conditions change
within some range.
1. Outside that range (ex. Too high or too low a temperature, with too little food or water
available), the organisms cannot survive.
2. Feedback mechanism can encourage (through positive feedback) what is going on in the
living system.
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