BIOL 2010 Lecture Notes - Lecture 2: Endergonic Reaction, Collision Theory, Ionizing Radiation

66 views8 pages
Published on 22 Feb 2017
School
TNTECH
Department
Biology
Course
BIOL 2010
Professor
Chapter 2 The Chemistry of Life
Chemistry in A&P?
o You are made of elements
Predominately made of 3 elements (O2, C, H) but even the trace elements
are important for natural physiology
o Some are classified as minerals
Inorganic elements extracted from the soil by plants and then moved up
the food chain
Ca, P, Cl, Mg, K, Na, S, I, Fe, Mn, Zn, Cu
Elements are made of atoms…
o …. And atoms are made of:
Protons
Positive charge
Number determines which element is which
Weight of 1 amu
Neutrons
Neutral charge
Number can vary leading to isotopes
Weight of 1 amu
Electrons
Negative charge
Number normally equals the number of protons
Weight is “negligible”
o Protons and neutrons found in the nucleus while electrons are found in orbits
called shells
Bohr model of atoms is overly simplistic but it will work for us
Isotopes
o Changing the number of neutrons doesn’t affect the bonding behavior of the
atoms
It is the valence electrons that matter there
Does affect their physical behavior and they may be unstable
Stable isotopes do not delay
Radioactive isotopes (radioisotopes) do
Isotopes: Friend or Foe?
o Both.
o Radiation (“the emission of energy as electromagnetic waves”) doesn’t
necessarily mean radioactive isotopes
Light, radiowaves are all types of low energy radiation that do not cause
harm
o Ionizing radiation has a high enough energy to cause electrons to be ejected
Forms ions hence the name
Three kinds of radiation produced by nuclear decay:
Alpha particles
Beta particles
Gamma particles
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in
Half-lives of radioactive chemicals
o Radioactive materials decay (change from one element to another)
o Each radioisotope has a specific half-life
Physical half-live
o Biological half-life refers to how long it will stay in the body
Length of time can be different than physical half-life because it depends
on how the ion behaves in the body
Ex: Cesium-137 has a physical half-life of 30 years but a
biological half-life of 17 days
o Chemically, it acts like potassium in the body and is easily
excreted
Radiation Exposure
o Alpha and beta sources are relatively harmless in small doses and as long as the
ion is outside of the body
Ingesting them can cause issues
o Sieverts (SV, SI unit for radiation) take into account the type and intensity of
radiation on the body
Single doses of 5 SV or more are usually fatal
o Average person receives doses of radiation of 2.4 mSV (0.0024 SV) per year from
natural sources
Another 0.6 mSV from artificial sources like your smoke detector and TV
o Guidelines are in place for workplace exposure to radiation
Healthcare workers who deal CTs, X-rays, etc can get no more than 50
mSV/year
Ions
o Ions are elements or molecules that differ in their numbers of electrons and
protons
o The element/molecule either gained electrons or lost electrons in the ionization
process
o Some elements have multiple ionized states (Fe 2+ or Fe 3+)
o Charge on the ions is called its valence
Electrolytes
o Acids, Bases, and Salts
All of these ionize in water
Conduct electrical current
Allows for the usage of EKGs, EEGs, and other physiological
instrumentation
o Important because:
The reactivity of electrolytes depends on whether or not they are ionized
Ionized forms are the only ones that are biologically active
They influence the osmotic pressure of the body’s various fluids
Their electrical effects play a role in muscle contraction and nervous
system conduction
Free Radicals
o For example: superoxide anion (O2-) versus (O2)
o Produced by both natural and unnatural means
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in
Naturally made in some metabolic reactions
ATP production in mitochondria
Certain WBCs use them to kill bacteria
Radiation can cause the formation of them
UV radiation and x-rays
Chemicals
Nitrates used as preservatives in foods have been shown to do this
Body uses antioxidants to release free radicals
Molecules
o Combining elements results in the formation of molecules
Ex: O2
o Molecular formulae can be helpful in identifying particular compounds but you
have to be careful about structural isomers
o Molecular weight is the sum of the atomic weights of its atoms
o The sharing of electrons doesn’t have to be equal either!
o The most electronegative atom (or molecule) in a compound will draw the
electron density
o Electrons equally shared?
Non-polar covalent bond
o Electrons not equally shared?
Polar covalent bond
Chemical Bonds Hold Molecules Together
o Table 2.3 types of chemical bonds
Hydrogen Bonding
o Intermolecular forces
o Occurs between a polar covalently bonded molecule where that molecule has a
hydrogen has a hydrogen atom attached to a very electronegative atom (usually O,
N, or F)
o The hydrogen is attracted to another electronegative atom or negative ion in
solution
o Hydrogen bonding is involving in:
Protein folding
Holding DNA
Van Der Waals Interactions
o Brief attraction between neutral molecules
o Very weak
o Occurs when electron density randomly shifts in one molecule causing a shift
Importance of Water in the Human Body
o Your body is a mixture of chemical
To be sure, you are more than just a sum of the chemicals in your body
though
Emergent properties as chemical combine
o Water is involved in most of the mixtures in our bodies
o Several important properties of water (all due to its polarity)
Cohesion tendency of molecules of the same time to cling together
Adhesion tendency of molecules of different types to cling together
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Chemistry in a&p: you are made of elements. Predominately made of 3 elements (o2, c, h) but even the trace elements are important for natural physiology: some are classified as minerals. Inorganic elements extracted from the soil by plants and then moved up the food chain. Ca, p, cl, mg, k, na, s, i, fe, mn, zn, cu. Number normally equals the number of protons. Weight is negligible : protons and neutrons found in the nucleus while electrons are found in orbits called shells. Bohr model of atoms is overly simplistic but it will work for us. Isotopes: changing the number of neutrons doesn"t affect the bonding behavior of the atoms. Does affect their physical behavior and they may be unstable. It is the valence electrons that matter there. Isotopes: friend or foe: both, radiation ( the emission of energy as electromagnetic waves ) doesn"t necessarily mean radioactive isotopes.

Get OneClass Grade+

Unlimited access to all notes and study guides.

YearlyMost Popular
75% OFF
$9.98/m
Monthly
$39.98/m
Single doc
$39.98

or

You will be charged $119.76 upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.