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Copy of AP Bio- Chemistry 1: Atoms, Water, & Carbon
Transcript of Copy of AP Bio- Chemistry 1: Atoms, Water, & Carbon
(worth considering in biology) Two simplistic models of atoms There are ~120 different kinds of atoms ("elements").
Biology is made of 4 major (CHON), ~10 minor, & ~30-50 trace elements electrons (-) Nucleus:
Neutrons(0) electron "orbitals" electron "cloud" Atoms Bond Bonding is accomplished by electrons interacting between atoms (due to valence considerations).
2 major kinds of bonds hold atoms together. Energy & Atoms Energy interacts with atoms in different ways.
Energy holds e-'s to the nucleus.
When atoms absorb energy, e-'s are moved to higher energy levels.
The movement of e-'s back to lower energy levels releases energy (as EM radiation) Ionic Bonds: Transfer of e-'s
Not many possible combinations.
Kind of boring. Covalent Bonds: Sharing of e-'s.
Functionally infinite combinations.
All important biological molecules (eg
glucose, DNA) are covalently bonded Compounds & Emergence The properties of a compound can be very different from the properties of the elements that make them + Sodium: explosive metal Chlorine: toxic gas Delicious table salt! Emergence: increasing levels of complexity in a system can demonstrate novel properties not seen in the levels below them.
Shows up repeatedly in science (especially in biology). Not all bonds are created equal Polarity:
The unequal sharing of electrons in a covalent bond
Leads to unequal distribution of
charge in the molecule Polar Molecules are attracted to other polar molecules.
Hydrogen Bonds: The strongest attractions between the most polar molecules.
Common in Biological Systems All Chemical Reactions result in the breaking and forming of bonds. In any reaction, mass, energy, and charge are conserved. Bonds Determine Shape ...and shape is very, very important in Biology!
Structure & Function are ALWAYS related. Radioactivity Atoms with unstable nuclei are "radioactive"
Radioactive atoms spontaneously emit high energy particles until stability is reached.
Excess radiation is damaging to biological systems (why?) Radiation is used in biology as molecular labels It's a bad scene if you don't get your elements a "goiter" comes from too little iodine in the diet Various nutrient defficiencies in plants Now that we have all these atoms... ...Just what are we supposed to do with them? Kabloom! Make Sure You Can Water Dissociates! Because it is so polar, water can easily break apart.
This produces a hydronium (H3O+) and Hydroxide (OH-) ion.
In pure water, the concentration of these ions is equal.
"Acids"- donate protons: [H3O+] > [OH-]
"Bases"- accept protons: [H3O+] < [OH-] pH: a measure of acidity.
the -log of the [H3O+]
In all aq solutions [H3O+] x [OH-] = 10E-14
You should be able to calculate pH/pOH if given the [H3O+] or [OH-] concentration pH & Biology Biological systems can only tolerate a narrow range of pH.
Extreme variations in pH have bad effects at all levels of organization The effect of ocean acidification on coral reef biodiversity: Healthy Reef Sick Reef Dead Reef Bleaching! Why is water such a big deal? Water ice in the track of a Mars rover Any Questions? Water is needed for life The chemistry of life is a solution-based chemistry
The majority of any organism is water. Earth is unique in its amount of liquid water Water is one of the few substances that exists in all three phases at normal terrestrial conditions Water's Unique Properties There are many.
All of them are due to the polarity of water (and its resulting hydrogen bonds) Cohesion & Adhesion Cohesion: Sticking together
Adhesion: Sticking to other things
Water is both. Why?
Is there anything that water can't stick to? The cohesiveness of water gives it a very high surface tension Transpiration: The movement of water through trees. A BIG Deal! A High Specific Heat Specific heat:
How much heat is absorbed/released before an increase/decrease in temp.
Water: 4.18 J/g C
Ethanol:1.24 J/g C
Iron: 0.449 J/g C
Why so high?
So what? Big What! Evaporative Cooling Water as Temp. Buffer Ice Floats! Solid water is less dense than liquid water (weird!)
What would happen if the reverse were true? Water is a great solvent! There is no "universal solvent"
But water comes close (why?)
Is there anything water can't dissolve? A large protein in solution The "Hydration Shell" Any Questions? The dissolution of salt Getting To Know
The Functional Groups Biology = Carbon Based Why Carbon? 1. It's abundant
2. It's versatile Carbon is tetravalent.
It makes 4 bonds to get stable
This leads to infinite variety There is nothing special about life's building blocks Vitalism- belief in a "life force"
Mechanism- theory that there is nothing special about how life is built.
Simulated Early Earth Conditions
Produced hydrocarbons, amino acids.
So long vitalism (at least as far as molecules go) Stanley Miller Isomerism Isomers- Molecules with the same molecular formula, but different structures
Any molecule more complex than propane has at least one isomer.
Isomerism is another example of an emergent property! 3 Kinds of isomers Structural-
Same formula, different order.
Same formula, different positioning
around a double bond.
Same formula, mirror image
positioning around a central carbon Biological systems tend to use only one of any two enantiomeric forms.
All cells use D-sugars, and L-amino acids
Can you explain why this is? About Enantiomers A little difference goes a long way! Functional Groups modify the properties of organic molecules Teststerone Estrogen The entire difference in the physical appearance of genders is due to the effects of these two hormones! Any Questions? Identify different elements and explain how they are different from each other.
Explain the processes of ionic and covalent bonding and why they occur.
Explain why a compound demonstrates emergent properties.
Compare polar and non-polar bonds and describe how they affect the substances that they occur in.
Explain the relationship between bonding, shape and function of molecules.
Provide some examples of the uses of radioactive isotopes in biology Big Questions Why are you mostly made of water?
How does water function in biological systems?
How does the structure of water determine its properties? Big Questions Why is Carbon a fundamental atom in biological systems?
How does the structure of carbon allow for functionally infinite complexity in the structure of molecules that contain it? Make Sure You Can Explain why water is necessary for biological systems.
Explain why water is polar
Draw a water molecule, assign polarity to the different atoms of the molecule, and show how water molecules hydrogen bond with each other.
Explain how each of the properties of water discussed in this presentation are a function of water's polarity/its capacity for hydrogen bonding.
Provide two examples of how each of the properties of water discussed in this presentation are used by organisms to maintain their homeostasis. Make Sure You Can Explain how the structure of the Carbon atom leads to the emergence of complexity in carbon containing compounds
Identify all of the functional groups discussed in this presentation.
Explain how each of the functional groups discussed contributes to the properties of the molecules that contain them. Alasan Polimer tidak dapat menggunakan teknik biasa
teknik krioskopi, ebulliometri dan titrasi untuk BM rendah Panjang Rantai tidak sama