Lecture 1 Flashcards
The cell as a living system, obeys the same laws of chemistry and physics that influence nonliving systems and reactions. Give examples of the type of principles.
-chemical bonding
- thermodynamics
- ph
What limits the size of the cell?
Rate of diffusion
Evolutionarily diverse organisms have similar characteristics how?
- biological macromolecules, DNA, proteins
- use the same metabolite-same metabolic pathways
What are the three domains of life? what are the differences between the two?
Bacteria, Archea, Eukarya-Prokaryotic cells: lack a nucleus. It consists of bacteria and archaea (lack peptidoglycan).
-eukaryotic cells contain a membrane bound nucleus.
What is the key characteristics of Archea?
microbes are prokaryotic
-lack peptidoglycan
What are the four kingdoms of Eukarya?
protists,fungi, plantae, animalia
What is the characteristic of kingdom protista?
-single cellular with a few multicellular
What are the characteristics of kingdom fungi?
- cell wall contains chitin
- heterotrophic by absorption
- nonmotile
- Haplontic life cycle: adult (n), zygote is diploid (2n)
- energy storage is glycogen
Kingdom plantae
- cell wall containing cellulose
- autotrophic
- nonmotile
- life cycle: alternation of generations
- energy storage: starch
Kingdom Animalia
- cell lacking cell wall
- nutrition: heterotrophic
- motile
- life cycle: diploid adults 2n that produce haploid gametes (n).
- energy storage:glycogen
Energy required to raise the temperature of 1 gram of water 1 degree celcius
Specific Heat
What type of energy are covalent bonds? What about the energy?
The interaction is sharing a pair of electrons. The energy is 355kj/mol
What about Hydrogen bonds? Where are they found
chemical bonds of hydrogen bonds that occur between 2 other electronegative atoms.
4-20 kj/mol
- complementary DNA
- alpha and beta sheets of protein
What about ionic (electrostatic) interaction?
Attraction of opposite charges.
~ 5.8 kj/mol
at active sites of enzymes
Vanderwaals
Interaction: electron clouds. Weak forces due to transient electrostatic interactions
2-4 kj/mol
found on substrate specificity
Hydrophobic interactions
Interaction of nonpolar substances. very weak.
What about covalent bonding?
chemical bond formed between two atoms due to the sharing of pair of electrons. overlapping electron shells.-strong interaction: don’t break spontaneously under physiological conditions
Hydrogen bond
-hydrogen atom is shared between 2 other electronegative atoms.-In DNA H holds bonds together complemetary strands.in proteins, h bonds stabilize alpha helixes and beta sheets.
Know the electronegativity trend.
j
Ionic Bond
chemical bond that occurs between two opposite charges (either full + or - or partial charges)-important interactions at active sites of enzymes
Van der Waals interaction
Weak forces between neutral atoms due to transient electrostatic interactions.-substrate specificity may come from large numbers of van der Waals bonds resulting from matching surfaces.
Hydrophobic Interaction
-nonpolar molecules-water forms cage.-interaction is more energetically favorable-an active cleft may be strongly nonpolar-an active site cleft may be strongly nonpolar, therefore attract nonpolar substrates. Use low free energy, enthalpy but gain in entropy
What is the most important compound? and what are its characteristics?
water:-high specific heat-high heat enthalpy of vaporization-universal solvent-high surface tension-density of solid water is less than water-water ionizes
Specific Heat
-the measure of the amount of heat required to raise 1g of 1 celcius of water.
What is surface tension?
The measure of how difficult it is to break the surface of the liquid
Ex: insects walking on water
Why is water so important for life?
- )water is a liquid at physiological temperatures
- )water has an unusually high boiling point for its mw
- ) water is a good thermal regulator. Large amount of heat is required to change its temperature.
- ) water provides very effective heat dissipation (involves phase change)
Why does water have such unusual properties?
- shape of molecule
- hydrogen bond (requires energy to break)
Know the 4 formulas of pH and OH
1 x 10-14 = [H+][OH]
14 = pH + pOH
pOH = -log [OH-]
pH = -log [H+]
What is the first law of thermodynamics?
The total energy of a system and surrounding is constant; energy can’t be created or destroyed.
What is the second law of thermodynamics?
The total energy of the system plus the surrounding always increases.
Heat (enthalpy) of Vaporization
amount of heat required to convert liquid into gas
