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LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Biology 121 – Biological Foundations for Physiology
Can you organize these units, from smallest to largest?
Here are the answers. Let’s go through each level individually.
7: organism 1: atom 4: cell 5: organ
3: organelle 2: molecules and compounds 6: organ system
“Cell and tissue, shell and bone, leaf and flower, are so many portions of matter, and it is in obedience to the laws of physics that their particles have been moved, moulded, and conformed.”
-D’Arcy Thompson, 1917
from On Growth and Form
Atom – the smallest unit of matter
• Although this is the smallest in the series you had to choose from, we’ll see later that each atom or “element” is actually composed of smaller subunits, called subatomic particles, named protons, neutrons and electrons.
• The atom is the smallest unit of an element
Molecule -- when two or more atoms interact, they form a molecule
• Molecules are formed when individual atoms bond together. This molecule is called ATP (adenosine triphosphate), and is the energy currency for most cells.
• A compound
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Organelle -- many molecules working together to perform a single function
for the cell• This is a photograph of
a mitochondria, one of the organelles present in eukaryotic organisms.
• Cells parcel out their workload to various organelles, or “little organs”.
• Mitochondria are the organelles responsible for making ATP.
Cell – the smallest unit of life
• Organelles work together within a living cell
Tissue -- two or more cells working together to perform a function
• Not a choice in your series! But you will learn a great deal about tissues in Biology 201, Human Anatomy. This hierarchal level and the remaining levels are specific to multicellularorganisms.
Areolar connective tissue
Bone -- the strongest connective tissue
Adipose – storing fat
Organ -- two or more tissues performing a function
• This picture of the lungs also has other organs included --you can see the trachea and the bronchi.
Organ System -- two or more organs performing a function for the organism
• There are 11 organ systems in the human body. You’ll cover them progressively in Biol201 and 202
Organism -- All 11 organ systems working cooperatively to form one individual
• This is an example of a multicellularorganism
• Plants, animals, fungi …
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Population -
• A group of the same type of organism located together in one area
Community
• All populations in one particular location
• Plant community in a prairie
• Microorganism community in our GI tract
Ecosystem
• A community + the physical environment in which it exists and interacts
Biosphere
• All the ecosystems making up the earth
• Earth, water, atmosphere and organisms
Learning Goal: Be able to rank order levels of organization
1. Subatomic particles2. Atoms3. Molecules 4. Organelles5. Cells6. Tissues7. Organs8. Organ systems9. Multicellular Organism10.Population -- a group of the same kind of organisms occupying the
same area11.Community -- Populations of different species occupying the same area12.Ecosystem -- The community AND the physical environment13.Biosphere -- all regions sustaining life
Biol 121 is concerned with Levels 1-5
1. Subatomic particles2. Atoms3. Molecules 4. Organelles5. Cells6. Tissues7. Organs8. Organ systems9. Organism10.Population -- a group of the same kind of organisms occupying the
same area11.Community -- Populations of different species occupying the same
area12.Ecosystem -- The community AND the physical environment13.Biosphere -- all regions sustaining life
5. Cells6. Tissues7. Organs8. Organ systems9. Organism10.Population -- a group of the same kind of organisms occupying the
same area11.Community -- Populations of different species occupying the same area12.Ecosystem -- The community AND the physical environment13.Biosphere -- all regions sustaining life
You would learn about Levels 9-13 in an organismal/environmental biology course like
128 or 1201. Subatomic particles2. Atoms3. Molecules 4. Organelles5. Cells6. Tissues7. Organs8. Organ systems
9. Organism10. Population -- a group of the same kind of organisms
occupying the same area11. Community -- Populations of different species
occupying the same area12. Ecosystem -- The community AND the physical
environment13. Biosphere -- all regions sustaining life
Biology 121Lecture 1.2
Basic ChemistryElectron Shells
Elements
• Fundamental forms of matter
• Can’t be broken apart by normal means
• 92 occur naturally on Earth
• Most common elements in living organisms:
– Oxygen (O)
– Hydrogen (H)
– Carbon (C)
– Nitrogen (N)
Atom
• Smallest particles that retain properties of an element is an ATOM
• Positively charged nucleus surrounded by cloud of negatively charged electrons
• Made up of subatomic particles:
– Protons (+)
– Electrons (-)
– Neutrons (no charge)
• Has mass (we can think of mass as weight)• Occupies space
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Fig. 2-2, p.20
Representing the Hydrogen Atom How Much Do You Know About Atoms?
• Atoms are composed of 3 subatomic particles, called protons, neutrons and electrons.
• Each has a characteristics charge and mass associated with it:
Particle Charge Mass Location
Proton + 1 amu* nucleus
Neutron 0 1 amu nucleus
Electron - 0 amu shells
* 1 Amu is a unit of mass (atomic mass unit), like a pound or gram, but much, much, smaller.
Atomic particles arranged in pattern
• The MASS of the atom is concentrated in its nucleus.– Determined by numbers of protons and neutrons
– Positively charged protons and uncharged neutrons are tightly packed in the nucleus
• The VOLUME of the atom is determined by the negatively charged electrons– Electrons orbit the nucleus in a series of concentric
‘shells’
Atomic Mass
• It’s time to mention another important concept regarding atomic weights……..
6.02 x 1023
What Does It Mean??
• A dozen is………..12
• A gross is…………..144
• A triple is……………..3
• A century is…………….100
• And Avogadro’s Number is…….6.02 X 1023
• In other words……it’s a predetermined, arbitrary number chosen for matters of ‘handiness.’
Why is it handy?
• Avogadro’s Number is a convenient amount of very small things to count out, like 6.02 X 1023 protons
• 6.02 X 1023 protons weigh exactly 1.00 grams.• 6.02 X 1023 H atoms weigh exactly 1.00 grams.• 6.02 X 1023 amu weigh exactly 1.00 grams.• Avogadro’s number relates the mass of a proton,
which is unimaginably and immeasurably small, to something more tangible-- the gram
• 6.02 X 1023 molecules = 1 mole.• More information about Avogadro and his number
• Protons are positively charged subatomic particles that have a mass of 1 amu
• They are located in the nucleus. See the green “dot” at the right? It’s a proton.
• This particular atom contains 1 proton and 1 electron.
Hydrogen
• If a second proton were added to the nucleus, it wouldn’t be H any longer. It’d be Helium. In fact, every atom has its own characteristic number of protons. Each atom has an atomic number, which reflects its proton total.
• For each proton in the nucleus, there must be a corresponding electron in the shell to balance the charges. The atomic number also reflects the number of electrons in a particular atom.
Hydrogen is the simplest atom. H contains one proton
Elements have abbreviations
• Each atom has a one or two letter short hand abbreviation. The first letter is capitalized, the second is small case. They are derived from the name of the atom:
H Hydrogen
He Helium
C Carbon
Co Cobalt
• The Periodic Chart of the elements contains all of the atoms, listed in atomic number order, reading in rows from left to right. In most periodic charts, the atomic number is on the top.
Name that element! Don’t use your periodic chart
• H = Hydrogen• He = ???• Ne = ???• C = ???• Si = ??• P = ??• Na = ???
• Know the symbols for elements 1 through 20
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Name that element!
• H = hydrogen
• He = Helium
• Ne = Neon
• C = Carbon
• Si = Silicon
• P = Phosphorus
• Na = Sodium (from the Latin, Natrium)
Name that Atom!
• Based on the number of protons (dark blue circles), which atom is represented by each picture? For this, you DO need to use your periodic chart.
• Neutrons are subatomic particles that weigh 1 amu (same as a proton),
• but they are neutral,which means they have no associated charge (unlike a proton).
Atomic Mass (Weight)• Since both protons and neutrons (but not electrons…) contribute
mass (weight) to an atom, each atom has a characteristic atomic weight, the total of all its protons and neutrons
• On most periodic charts, that number is written beneath the atom’s symbol
Calculate the atomic mass for these atoms
Hydrogen (H)Carbon (C)
Helium (He)Magnesium (Mg)
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Atomic Mass
Hydrogen (H) has 0 neutrons
and 1 proton
Atomic Weight = 1 amu
Carbon (C) has 6 neutrons
and 6 protons
Atomic weight = 12 amu
Helium (He) has 2 neutrons
and 2 protons
Atomic weight = 4 amu
Magnesium (Mg) has 12 neutrons
and 12 protons
Atomic weight = 24 amu
In Summary…• The atomic number is a whole number, and is equal
to the number of protons in the nucleus of that atom. Since protons and electrons are equal to neutralize charges, it also tells you how many electrons are in the shells.
– Atomic number = number of protons or electrons
• The atomic weight is a decimal number, and is the sum of the protons and the neutrons. You know the number of protons from the atomic number, the number of neutrons is the difference between atomic number and atomic weight.
– Atomic wt – atomic number = number of neutrons
– Atomic wt = no. of protons + no. of neutrons
Problems
• How many neutrons are in one atom of the following elements?
• Need to know 3 things…
Element N Li B F
Atomic Wt
No. Protons
No. Neutrons
Problems
• How many neutrons are in one atom of the following elements?
• Need to know 3 things…
Element N Li B F
Atomic Wt 14 7 11 19
No. Protons 7 3 5 9
No. Neutrons 14-7 = 7 7-3 = 4 11–5 = 6 19-9 = 10
Practice Problems
Atom: C Be
Atomic number: 6 14
Atomic weight: 12 22.99
No. Protons 6 8
No. Neutrons 6 2
No. Electrons 6
Practice Problems - Answers
Atom: C Be Si Na O He
Atomic number: 6 4 14 11 8 2
Atomic weight: 12 9.012 28.09 22.99 16.00 4.003
No. Protons 6 4 14 11 8 2
No. Neutrons 6 5 14 12 8 2
No. Electrons 6 4 14 11 8 2
Know how to calculate these parameters for elements 1 through 20.
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Atomic Mass
• Although atomic numbers are reported as whole digits, atomic weights are generally reported as decimals
• C weighs 12.01 amu
• Al weights 26.98 amu
• H weighs 1.008 amu
• If protons and neutrons each weigh 1.00 amu, where does the extra “weight” of the atom come from?
Atomic Mass
• Atoms can exist in multiple forms in nature, with differing numbers of neutrons. These forms are called isotopes (same atom, different form)
• Isotopes vary in number of neutrons; protons and electrons remain the same.
Atomic Mass -- Part II• Hydrogen typically has 1 proton and 0 neutrons,
weighing a total of 1 amu. • But alternate, isotopic forms of H exist;
– Deuterim, 1 proton and 1 neutron, 2 amu, stable– Tritium, 1 proton and 2 neutrons, 3 amu, unstable or
radioactive
Atomic Mass -- Part II
• Isotopes are indicated by writing the atomic symbol, with the specific weight of that isotope in the upper left hand corner
– 1H is hydrogen
– 2H is deuterium
– 3H is tritium
Deuterium = 2H
Stable
Hydrogen = 1H
Stable
Tritium = 3H
Radioactive
Atomic Mass
• The atomic mass indicated on the periodic chart represents our knowledge about the average mass, distributed among all the known isotopes of each atom, that exist in the universe.
Isotope Rel. Abund. Half-life
12C 98.9% C is stable with 6 neutrons13C 1.1% C is stable with 7 neutrons
14C trace 5730 y
Radioisotopes
• Have an unstable nucleus that emits energy and particles as it ‘decays’
• Radioactive decay transforms radioisotope into a different element
• Decay occurs at a fixed, predictable rate
• Emissions from the radioactive isotope can be detected with special instruments
• Following movement of radioactivity is useful in many areas of biology and health care
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Radioactive Isotopes and Health Care
• Radioactive isotopes have two very special places in the health care industry– Diagnostics
– Therapeutics
• Nuclear Energy Institute’s Informational Website to learn more about Nuclear Medicine– http://www.nei.org/
Isotopes
How many protons?
What element is it?
How many neutrons?
What’s the atomic mass?
What is the isotope?
Isotopes
How many protons? 1 1 1 6 6
What element is it? H H H C C
How many neutrons? 0 1 2 6 8
What’s the atomic mass? 1 2 3 12 14
What is the isotope? 1H 2H 3H 12C 14C
hydrogen deuterium tritium
Biology 121Lecture 1.2
Basic Chemistry
Electron Shells
Electrons -- the Bonding Story
• Electrons are the negatively charged subatomic particles without mass that make up the volume of the atom
• Electrons are SOCIAL -- they prefer:– Being paired– Living in full shells
• Electrons repel each other
• Electrons are attracted to protons in the nucleus• Electrons determine how atoms interact with or
bond with each other.
Electron Shells
• Electrons spin and rotate around the nucleus of an atom, but are constrained to particular paths. They live in shells
• Similar to layers of an onion, or floors of a hotel.
Negatively charged electrons are attracted to the positive charges on the protons
Electron shells
• There are specific places (distances) around the nucleus where the opposing centrifugal forces (away) and charge forces (toward) exactly balance one another.
• These are the “shells” where electrons reside
• Shells closest to nucleus are lower energy and are filled first.
Electron shells
• The first shell, closest to the nucleus, is quite small, only large enough for 2 electrons
►
Electron shells
• The second shell, a bit farther from the nucleus, is a bit larger, and can accommodate 8 electrons
►
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Electron shells
• The third shell, a bit farther from the nucleus, is also a bit larger, but still only accommodates 8 electrons
►
Electron shells
• As we are only dealing with elements 1-20, and we can account for 18 electrons with three shells (2 + 8 + 8), only the last two elements (K and Ca) need to use the 4th shell. ►
Electron shells
• As you might imagine, this ‘shell’ description is a slight oversimplification.
• But that’s all we need for now. We won’t worry about how complicated shells can really be in Biol 121.
Filling electron shells• Helium example:
– Helium has atomic number 2, indicating it has 2 protons and 2 electrons.
– The two electrons will both fit in the first shell.
– The last, outermost shell with an electron in it is the atom’s “valence” or outer shell. The first shell is the valence shell for He.
Filling electron shells• Lithium example:
– Lithium has atomic number 3, indicating it has 3 protons and 3 electrons.
– The first two electrons will both fit in the first shell. The third electron goes into the second shell.
– The second shell is the valence shell for Li.
Filling electron shells
• Draw the electron shells for the following atoms --using your periodic chart.
• Some atoms have full valence shells. They’re called the Noble Gases -- they do not react or bond with other elements. You can find them in a nice neat column on the periodic chart, on the farthest to the right.
Let’s look at another column in the periodic chart….
Sulfur
16e- = 2 in the first, 8 in the second and 6 in the third (valence) shell
Oxygen
8 e- = 2 in the first and 6 in the second (valence) shell
Oxygen and Sulfur are also in the same column (16) of the periodic chart
And O and S have the same number of electrons (6) in their valence shells
Oxygen
8 e- = 2 in the first and 6 in the second (valence) shell
Sulfur
16e- = 2 in the first, 8 in the second and 6 in the third (valence) shell
Periodic Table is organized
• The periodic chart is not a random arrangement of atoms, they are all conveniently arranged for your viewing pleasure,
• Elements in column (we call them groups or families of elements) having the same number of valence electrons.
• Families of elements have similar bonding capabilities
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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Is there a similar significance to the rows on the periodic chart?
Noble Gases
• Remember Helium and Argon, who both had full valence shells? They are the noble gases.
• Noble gases end each row. The next atom is written in the next row (period) of the chart.
• What is the significance of that?
Oxygen and Sulfur have the same number of electrons (6) in their valence shells, but they are
in different shells
Oxygen
8 e- = 2 in the first and 6 in the second (valence) shell
Sulfur
16e- = 2 in the first, 8 in the second and 6 in the third (valence) shell
Oxygen is found in the second period (row), its second shell is occupied
Oxygen
8 e- = 2 in the first and 6 in the second (valence) shell
Sulfur
16e- = 2 in the first, 8 in the second and 6 in the third (valence) shell
Sulfur is found in the third period (row), its thirdshell is occupied
Oxygen
8 e- = 2 in the first and 6 in the second (valence) shell
Sulfur
16e- = 2 in the first, 8 in the second and 6 in the third (valence) shell
In Summary….Location, location, location
LCC Biol 121, Kitty O'Neil, Instructor 1/8/2010
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The period (row) represents which shell is the valence shell
The group (column) represents how many electrons are in that valence shell
Lecture 1.1 and 1.2 Study Guide
• Biology overview and Subatomic particles– Name and describe the characteristics of life
– Know the levels of organization of life from least to most complex
– Know the name, charge, location, and mass of the subatomic particles
– Know the names (spelled correctly!) and symbols for elements 1-20
– Know what a mole is, what Avogadro’s number is and how they are both used