Transcript File - Biology with Radjewski

AP Biology Review – Unit 1
Chapter 1-3
1. Briefly summarize the characteristics of
life shared by all living organisms
a) Common set of chemical components (cells)
b) Contains genetic info (DNA)
c) Convert molecules from environment into new
molecules
d) Extract energy from environment to do work
e) Metabolism
f) Homeostasis
g) Replicate genetic info
h) Share sequence similarities with others
i) evolve
2. How do scientists define a theory?
• Biologists define “theory” as a body of
scientific work which is rigorously tested
and well-established facts
and principles are used to understand, explain,
and make predictions about the natural world.
3. Design an experiment…
1. Testable hypothesis
2. Independent variable – specific to it’s values and
range
3. Dependent variable – specific on how and when
it is being measured.
4. Large sample size or repeat experiment several
times
5. State your control variables
6. Statistical analysis of data
7. State results expected as they relate to
hypothesis
Actual key answer…
•
•
•
•
•
The independent variable is the type of goldfish food. For the sake of this experiment, we will
assume that
feeding goldfish fish flakes is customary or the “control,” while feeding shrimp pellets is the
independent variable.
Hypothesis: Feeding goldfish shrimp pellets instead of fish flakes produce larger fish.
In the experiment, twenty 5-gallon tanks are filled with 5 gallons of water, kept at the same
temperature of 68 degree F. Twenty young goldfish of identical age, which have each been
measured in length prior to
commencement of the experiment, are placed into the tanks, one fish per tank. The water in
each tank is
filtered and aerated with the same type of aeration system, and the tanks are placed near
each other with
equal exposure to periods of light and darkness. In the first ten tanks, the goldfish are fed
shrimp pellets,
according to the directions on the package. In the second group of ten tanks, the control
group, the goldfish are fed fish flakes, also in accordance with package directions.
At the end of each week, the goldfish are carefully removed from their respective tanks and
individually
measured before being returned to the tank. This process is continued for twelve weeks. The
food should be weighed and its nutritional content should be matched between the two
treatments.
*** Many other examples are possible. ***
4. electrons, protons, neutrons,
atomic number
Electrons
Protons
Neutrons
Atomic
Number
Hydrogen
1
1
0
1
Carbon
6
6
6
6
Oxygen
8
8
8
8
Phosphorus
15
15
16
15
Remember protons = atomic number ALWAYS!!
Remember protons = electrons in a NEUTRAL atom.
Remember mass number on periodic table is rounded then subtract
the atomic number to get # of neutrons
5. Strongest  Weakest
• Covalent (sharing of electrons)
• Ionic (transfer of electrons)
• Hydrogen (attraction between partial + and
partial – charges – like between water
molecules)
• Van Der Waals – (weak electric forces)
6. Cation vs. Anion
• Cations are positively charged ions
– Examples are Mg2+, Na+1, Al+3
• Anions are negatively charged ions
– Examples are F-1, O-2, P-3
7. NaCl explanation of ionic bond
• A sodium atom has only one electron
in its outermost shell, which is an
unstable condition.
• A chlorine atom has seven electrons
in its outermost shell, also unstable.
• They achieve stability by transferring
an electron from sodium to chlorine,
making sodium a cation and making
chlorine an anion.
• The electrical attraction between the
anion and the cation is an ionic bond,
which holds these ions together as
dry salts, but this weak bond gives
way when the ions are dissolved in
water.
8. Name that molecule
• Water or H20
• The oxygen molecule in water,
however, has a higher
electronegativity than the
hydrogen molecules. When they
combine to form water, the
electrons involved are
unequally shared, tending to be
nearer to the oxygen nucleus
because of its greater
electronegativity, giving the
oxygen end of the chemical
bond a slightly negative charge
(δ- added to picture) and the
hydrogen end a slightly positive
charge (two δ+ added to
picture).
9. Explain A and B/same vs. different
number of atoms
A. This demonstrates
the formation of a
hydrogenbond
between two water
molecules
B. Thisis an example
of how hydrogen
bonds can form
between different
parts of the
same large molecule.
More atoms are represented in drawing
B because it is a protein and not all of
the atoms are being shown in the
picture.
10. Explain prompts
•
Choice A is more watersoluble because it contains
more polar covalent bonds,
causing it to be hydrophilic or
more attracted to the
hydrogen atoms in water.
•
Choice B is less water-soluble
because it is a nonpolar
molecule, containing mostly
carbon and hydrogen
atoms, which tend to
aggregate with one another
rather than with the more
polar water molecules. This
type of molecule is
hydrophobic.
11. Number carbons and name
12. Label molecule
The hydrophobic tail
includes
Hydrocarbon chains.
The hydrophilic head
includes
Choline and phosphate.
13. Steroids and other fatty
substances pass readily through most
cell membranes because:
• … they are fat soluble. The lipid molecules line
up in a way that the center of the lipid bilayer
(the fatty acid tails) are nonpolar, so they do
not readily interact with polar molecules such
as water.
• Their nonpolar nature makes them
hydrophobic, so they do not dissolve in water.
14. Draw amino acid and label
15. Explain how the diversity of
different proteins is created.
• The primary structure of a
protein/peptide/polypeptide is determined by its
precise linear sequence of amino acids.
• Since there are 20 different amino acids,
combinations of two amino acids could
mathematically generate 400 distinct dipeptides;
combinations of three amino acids could
generate 8,000 tripeptides. Even a small
polypeptide of 100 amino acids has 20100
possible sequences, making the potential
diversity of proteins essentially immense.
16. Explain levels of proteins
•
Primary The primary structure of a protein is established by covalent bonds
between adjacent amino acids. This type of structure is found where amino acid
monomers are joined, forming polypeptide chains. The primary structure
determines the protien’s secondary, tertiary, and quaternary structures.
•
Secondary The secondary structure of a protein consists of regular, repeated
spatial configurations in different regions of a polypeptide chain. The two basic
types are the “alpha helix,” a right-handed coil similar to a wood screw, and “beta
pleated sheet,” formed from two or more polypeptide chains that are extended
and aligned. Many proteins contain both types of secondary structure.
•
Tertiary Tertiary structure is formed when the polypeptide chain is bent at specific
sites and then folded back and forth. This provides the molecule’s specific threedimensional shape, including a buried interior as well as an exposed outer surface.
These folds are stabilized by hydrogen bonds and disulfide bridges.
•
Quaternary Quaternary structure refers to the distinct manner in which two or
more polypeptide chains or subunits bind together and interact, forming even
larger protein molecules.
17. Draw amino acids
17C. Draw dipeptide
18. Leucine substituted for Cysteine
•
Leucine is nonpolar and
hydrophobic, often found clustering
with other similar hydrophobic side
chains in the interior of the protein.
Cysteine, a special type of amino
acid which is not hydrophobic , has a
terminal SH group that can react
with another cysteine side chain to
form a covalent bond, called a
disulfide bridge, which determines
how a polypeptide chain folds.
•
If leucine were to be substituted for
cysteine, the spatial orientation of
the molecule would be affected
because of the loss of hydrophobic
properties, and the folding of the
polypeptide chain would be altered.
Altered shape usually results in
altered functions of proteins.
18. Arginine substituted for Phenylalanine
• Arginine is positively charged,
hydrophilic, and attracts
negatively charged ions of all
sorts. Phenylalanine is
nonpolar and hydrophobic.
• This substitution would likely
cause the molecule to alter its
orientation toward, instead of
away from, water, possibly
reducing the protein’s
solubility in water. The
changed protein would
also tend to more readily
interact with anions.
18. Alanine substituted for Aspartic Acid
• Alanine has nonpolar,
hydrophobic side chains,
whereas aspartic acid is
negatively charged and
hydrophilic.
• Substitution of alanine
for aspartic acid would
likely cause the
molecule to alter its
orientation away from
water. It would also
reduce its tendency to
interact with positively
charged ions.
29. Quaternary? Why?
• “B” shows a quaternary
structure, because the
diagram depicts four
polypeptides (observe
that “B” has 8
terminal amino acids)
associated with each
other, forming a larger
protein molecule. This
example is a tetramer,
made up of four
polypeptide subunits.
30. Explain with terms
• Strongacid is an environmental factor that can result in
the breakdown of a functional protein’s secondary
and tertiary structures, a process also known as
denaturation.
• The introduction of acid alters the concentration of
protons (H+ ) which results in the ionization of exposed
carboxyl and amino groups, thus altering polarity.
• Since the tertiary structure of a protein determines its
three-dimensional shape, the protein loses its original
structure and likely, its original function.
31. How does an enzyme speed up a
reaction between 2 substrate
molecules?
• An enzyme speeds the reaction time between
two substrate molecules by lowering the
activation energy required for a reaction to
occur.
• Substrate molecules bind themselves to a
particular site on the enzyme, called the active
site, where catalysis takes place.
32. Label diagram
33. Cofactors vs. Coenzymes?
• Cofactors are inorganic ions such as copper,
zinc, and iron that bind to certain enzymes.
• A coenzyme differs from a cofactor because it
is an organic molecule that adds or removes
chemical groups from the substrate, although
it does not permanently bind to the active
site.
34. Allosteric Regulation? Why?
• “B” is an example of allosteric
regulation. Allosteric regulation
occurs when a non-substrate
molecule controls enzymatic
activity by binding to or
modifying a site other than the
active site.
• This molecule does not attempt
to replace the substrate on the
active site, but instead binds to
a site away from the active site,
changing the enzyme’s shape so
that the substrate no longer fits.
Identifying Molecules
1.
2.
3.
4.
5.
6.
7.
Carbohydrate Monosaccharide C6H12O6
Carbohydrate Monosaccharide C6H12O6
Carbohydrate Disaccharide
Carbohydrate Monosaccharide, alpha glucose
Carbohydrate Monosaccharide, beta glucose
Carbohydrate polysaccharide, cellulose
Carbohydrate polysaccharide, glycogen or
starch
Continued…
8. Lipid, Steroid
9. Amino Acid
10.Carbohydrate, monosaccharide, pentose –
deoxyribose
11.Carbohydrate, monosaccharide, pentose –
ribose
12.Carbohydrate, polysaccharide
13.Lipid, Triglyceride, saturated
Last page!
14.Lipid, triglyceride, unsaturated
15.Lipid, phospholipid
16.Lipid, steroid
17.Protein, primary
18.Protein, tertiary
19.Protein, quaternary
20.Protein, secondary, alpha helix