Transcript Fig. 3-9 - UCR Classes

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Kelli Lauderdale
Office: BSS 1103
Office Hours: W 1pm-3pm
Email: [email protected]
UNLH 1000
Belltower
BSB 1103.
1st Floor
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Attend and be on time to each discussion
section.
Be respectful to your TA and to your fellow
students.
No cell phones.
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Study soon after each
lecture.
Do questions at the end of each
chapter.
Form small study groups.
Supplemental Instruction offered by
the Learning Center.
Ask questions!
Come to lectures, office
hours and discussion
sections and take notes.
Integrate book and
lecture notes into your
own words.
Read the textbook!
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Mini review
In class questions
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Discuss questions and answers
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What is an element?
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What is a compound?
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Element
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a substance that cannot be broken down to other
substances by chemical reactions.
Compound
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a substance consisting of two or more elements in a
fixed ratio
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What is an atom?
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What is the shape of an atom
What defines an atom?
Atomic Number
 Mass Number
 Atomic mass
 Isotopes
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Atom?
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Atomic Number
 # of protons in nuclei. 5B
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Mass Number
 Σ of protons and neutrons in nucleus of an atom.
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10
5
B
Atomic mass
 the atom’s total mass, can be approximated by the mass
number.
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Isotopes
 Same number of protons but different number of
neutrons
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How many protons?
How many neutrons?
How many electrons?
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An atom has 36 protons and 42 neutrons. What
is its atomic number (Z)?
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Atomic number = 36
 131I
is a radioactive isotope of iodine. 131I has an
atomic number (Z) of 53. How many neutrons
are in the 131I nucleus?
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78 neutrons
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Reactivity depends on electrons in outermost
shell [valance electrons].
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Potential energy is greater further away from the
nucleus.
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Rank the following elements commonly found in
biological molecules in order of electronegativity:
S, N, O, P, C, H
What is electronegativity?
- The attraction of a given atom for the electrons of a
covalent bond
Draw two molecules with covalent bonds the first
between two Oxygen and the second with one Oxygen
and two Hydrogen.
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Covalent
 the sharing of a pair of valence electrons by two atoms
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Ionic
Hydrogen Bond
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Single and double bonds
Polar and non polar
hydrogen bond forms when a hydrogen atom
covalently bonded to one electronegative atom is
also attracted to another electronegative atom
Van der Waals
Fig. 3-9
pH Scale
0
1
Gastric juice,
2 lemon juice
H+
H+
Battery acid
+
– H
H+ OH
+
OH– H H+
H+ H+
3 Vinegar, beer,
wine, cola
4 Tomato juice
Acidic
solution
5
Black coffee
Rainwater
6 Urine
OH–
OH–
OH–
OH– OH– +
H+ H+ H
H+
H+
Neutral
solution
Neutral
[H+] = [OH–]
Saliva
7 Pure water
Human blood, tears
8 Seawater
9
10
OH–
Milk of magnesia
OH–
OH– H+ OH–
–
OH– OH
–
OH
+
H
Basic
solution
11
Household ammonia
12
Household
13 bleach
Oven cleaner
14
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Acids (H+
donating)
Bases (H+
reducing)
pH scale
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pH=-log[H+]
10-14=[H+][OH-]
Buffers
o Changes in concentrations of H+ and
OH– can drastically affect the chemistry
of a cell
oThe pH of cellular cytoplasm is
normally about 7.2. Cell organelles,
such as lysosomes, have a much lower
pH of around 5.
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You are handed a bottle of glucose that is made up of
the most common isotopes of carbon (Z = 6), hydrogen
(Z = 1), and oxygen (Z = 8).
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The most abundant isotopes for carbon and oxygen have an
equal number of neutrons and protons while the most
abundant isotope of hydrogen has no neutrons. Calculate the
molecular mass of one glucose molecule.
Assume that one of the carbon atoms of glucose is replaced
with an isotope that has one less neutron.
 What is the molecular mass of that glucose molecule?
 You feed one population of rats a diet that consists of the most
abundant isotope of glucose (the control group) and another
population of rats a diet that consists of the isotope of glucose
that has one less neutron (the experimental group). How will
the metabolic rate of the experimental group differ from the
control group. Explain your reasoning.
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DNA is a nucleic acid that is made up of building
blocks called nitrogenous bases. As the name
suggests, these bases contain nitrogen atoms.
Consider a situation in which you have two
molecules of DNA that have the same sequence of
100,000 nitrogenous bases. However, one of the
strands consists of nitrogenous bases that contain
the most common isotope of nitrogen (Z=7, M=14)
and the other strand contains an isotope that has
one additional neutron. Both isotopes are stable
(i.e., they are not radioactive). How could you
separate the two strands of DNA away from one
another?
The pH scale is typically reported to range
from 1 to 14. Can it be lower than 1? Higher
than 14? What is the theoretical lower limit for
pH?
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The pH scale is logarithmic, one unit of pH change means tenfold
change in the H+ ion concentration.
The pH scale uses Sorensen’s PH definition and concentration is
usually confined to 1 to 14 However the pH can in some, rare
instances be lower and higher while theoretically it is absolutely
possible to have a lower or higher pH.
Remember pH = -log(H+) so,
pH = -log(1) = 0 which is lower than 1 and of course using this
same method you can get a higher pH than 14. Also remember
that although you may be talking about the H+ concentration or
the OH- concentration BOTH are present in the solution.
And after you find the pH for one the pH for the other is easy to
get using the next equation.
pH + pOH = 14
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Resting calcium levels in cells are on the order
of 100nM. What is the pCa in this cell? When a
cell is activated its pCa can rise to 1 uM. What
is the pCa now?
10-2
Centi c
10-3
Milli m
10-6
Micro
µ
10-9
Nano n
10-12 Pico p
pH = -log(H+)
So first you need to convert
 100nM * 10-9 M / nm = 10-7 M
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 pH = -log(10-7) = 7
 For the second part you do not have to convert
so,
 pH = -log(10-6) = 6
 See the pattern after you convert to exponential
for the number is always going to be whatever
your power your 10- is raised to!