Lecture 1 Flashcards

Question

Electronegativities in biochemistry?

Answer 1

Another important factor that makes a difference in biochemistry. Thre important thing is that you want to look ate which atoms are most electronegative and which ones are the least, alongside what that tells you about the element's behaviours and relationships.

Answer 2

Electronegativity is the abiity pof an element to attract a shared pair of electrons toward itself, resulting in partial changes and determining if bonding is ionic or covalent. - The tendency of an atom to hang onto its electrons. (typically a behaviour seen in the upper right side of the PT)

Answer 3

The formation and stability of molecules depends on the fact that atoms like having 8 electrons in their outer valence shell.

Answer 4

Lewis dot symbols represents valence electrons as dots. Ex. Carbon has 4 dots, therefore it will want to make 4 bonds sharing its electrons. - Some only need 2 in their valence shell, but most need 8.

Answer 5

Thinking back to Lewis diagrams helps us understand why some molecules choose to bond with an element over a different one.

Answer 6

Atoms participate in either covalent bonds (sharing of electrons) or ionic bonds (transfer of electrons) to complete their valence shell (2 or 8)

Answer 7

Geometry depends on the number of bonded atoms and electron pairs.

Answer 8

The composition and geometry of a molecule determines if they are polar or non-polar.

Answer 9

Distribution of positive negative and positive charges.

Answer 10

No partial negatives or positives

Answer 11

The answer is.... B! CO2 is the molecule that we anticipate will be non-polar, due to its linear geometry.

Answer 12

Hydrophilic, hydrophobic, or amphipathic.

Answer 13

Amphipathic/amphiphilic molecules contain both polar and non-polar functional groups. Both the hydrophobic and hydrophilic portions are significant in order to be amphipathic.

Answer 14

Poor molecules have an uneven distribution of charge (negative and positive ends). They can be charged but do not need to be ionized (like glucose). Highly electronegative molecules tend to be found in polar molecules/charged molecules (having many electronegative oxygens make it likely to be a polar molecule. DO NOT NEED NET CHARGE TO BE POLAR - just a charge distribution.

Answer 15

Fully nonpola molecules are hard to find inn biochemistry - so we mainly look at mostly hydrophobic molecules. Hard to be found due to the fact that we are mainly made up of water (polar) therefore most molecules will at least have a polar end.

Answer 16

Glucose, Glycine, Aspartate, Lactate, Glycerol

Answer 17

Phenylalanine, Phosphatidylcholine

Answer 18

Typical waxes - long hydrocarbon chains with a tiny polar portion for the purpose of binding in cells (which are majorly polar!!)

Answer 19

Methyl, Ethyl, Hydroxyl, Anhydride, Amido, Amino, Disulfide, Phosphoryl - Huge variety in the polarity of these molecules! A huge factor in this is the electronegativities of these atoms.

Answer 20

2 charged molecules interact.

Answer 21

Uneven charge distribution in a molecule.

Answer 22

2 polar molecules: opposite poles will interact

Answer 23

Charged molecule approaches molecule without charge distribution and induces a charge distribution where you get an uneven distribution of electrons, where the opposite charge is closest to what you get. Ex. positive molecule comes close = relative abundance of electrons come close to positive molecule because they're attracted to that.

Answer 24

A dipole induces another molecule

Answer 25

Random charge distributions that can flicker in time will induce other random charge distributions that are opposite to them, that can flicker in time and cause interactions.

Answer 26

Occur between hydrogen and NOF! Bond length is specific (vary a little bit but stay defined).

Answer 27

Charge-charge Charge-dipole Dipole-dipole Charge-induced dipole Dipole-induced dipole Dispersion Hydrogen Bond

Answer 28

Non-covalent interactions are critically important to biochemistry and determine how molecules fold and associate with one another. Ex. Suppose you have a lot of amino acids that polymerize to form a protein that's a covalent polymer. How it folds into functional form is dependent on non-covalent interactions between different parts of the protein.

Answer 29

Non-covalent interactions weaken over distance (dependent also on the molecules involved).

Answer 30

Covalent - strong in all environments Ionic interactions - very strong in vacuums but not as strong in polar environments like water. Water has high dielectric constant, meaning it shields the charges to some ions that would normally stay together. Hydrogen bonds - relatively weak Van der Waals interaction - very weak one their own.

Answer 31

Due to different dielectric constants (refers to how much a substance can shield electric charge) ionic bond strength varies depending on the solvent. Ex. It is 80 times stronger in a vacuum than in water

Answer 32

- Between peptide groups in polypeptides (amino acids in a protein) - Between complementary bases of DNA

Answer 33

H is shared between two electronegative atoms: strongest when the 3 atoms are in line. - They are non-covalent and reflect the sharing of a hydrogen proton (hydrogen's nucleus) between two electronegative atoms. Kind of like tug of war where 2 atoms share the hydrogen.

Answer 34

Oxygen is highly electronegative form because it is double bonded to carbon and likes to hold onto electrons. Hydrogen is basically a proton because its electron is with nitrogen and held close. The nitrogen is covalently bonded to the hydrogen, keeping the electron from H close to it. - The Oxygen will hydrogen bond with the hydrogen. - Oxygen is the acceptor in this case and Nitrogen is the donator.

Answer 35

- Attractive or repulsive - Strength depends on Coulomb's law (don't need to know) - Weaker in polar environments

Answer 36

- Very weak forces due to dipole or induced dipole interactions of closely spaced atoms - Significant in large numbers, where complementary binding surfaces contribute to biological specificity (can favour specificity) - Includes dipole-dipole, charge-induced dipole, dipole-induced dipole, and dispersion - Include charge, but not permanent charge (partial charge from electron clouding) doesn't mean they're polar, just means there is some polarity at the moment. - Weak on their own but powerful in numbers (breaking one won't do much but breaking all of them will make a difference).

Answer 37

- H shared between two electronegative atoms with partial covalent character. - Strength (5-20kJ/mol) depends on being linear, atom electronegativity, and environment polarity - Very directional: contributes a lot to biological specificity.

Answer 38

Long range: Charge-charge and charge-dipole Short range: Dipole-dipole, charge-induced dipole, dipole-induced dipole, dispersion BONUS - Fixed length: Hydrogen bonds

Answer 39

They have many flat surfaces that maximize interactions with the surface they're on. Their surfaces will also form van der Waals interactions really nicely. - despite VDW being fairly weak, there is power in numbers. Each hairlike structure is host to many many VDW interactions, and there are many of those structures on their feet in general - leading to a strong gripping, therefore the gecko can walk up the wall.

Answer 40

The hydrogens in water are slightly positive while the oxygen is slightly negative due to bonding interactions. This allows the oxygen of one water molecule to accept a hydrogen donated by a separate water molecule (oxygen). - Water is the most important molecule in life as we are 60% water! - Water is also bent and very polar, with a high melting point and the temperature at which water is liquid is lower than other molecules.

Answer 41

Liquid water: fast changes to hydrogen bond pattern (flickering). At any given moment, there's lots of H-bonds but they change quickly and frequently. Ice: fixed hydrogen bonds (stable) where ice has an open lattice structure hence ice is less dense than water. Amorphous/vitreous ice: cool water below glass transition temperature in milliseconds! It is very squashed together and chips into small pieces easily.

Answer 42

No, ammonia cannot form as many hydrogen bonds as water because there are not enough H-bond acceptors. Therefore, it cannot form an ice-like network. NH3 has 3 donors and only 1 acceptor.

Answer 43

H2O forms hydrogen bonds, which impart high melting and boiling points, dielectric constant, surface tension and more. Heat of vaporization is also higher compared to other similarly sized molecules. - H2O gas much more stable forms, which is a huge advantage for life.

Answer 44

Because of cell membranes having the hydrophobic effect!

Answer 45

Water is a good solvent for ionic and polar molcules. Ex. for salt (NaCl) the Cl and H with the Na and O help pull apart the salt crystal and it becomes difficult to get the crystal back together afterwards.

Answer 46

Hydrogen is attracted to the Cl and Na is attracted to the O, which effectively pulls apart the salt crystal, dissolving it in water. - Favourable enthalpathic interactions and gain in entropy of salt overcomes the loss of entropy of solvent water.

Answer 47

The formation of the non polar molecule is fairly disordered and high entropy. The H2O is highly ordered and has low entropy. They will not mix.Hy

Answer 48

The tendency of non polar substances tp aggregate in aqueous solutions.

Answer 49

Any reversible process (A<->B) is or isn't spontaneous according to DG = DH - TDS. - The decreased entropy of water at the non-polar solute interface is not compensated by favourable (lower enthalpy) solute-solvent interactions. - The total area of contact is less in B than A, so b is favoured.

Answer 50

The compartmentalization of cells. - Detergent micelles (polar outside and non-polar inside) - Lipid bilayer (selectively permeable) - Lipid vesicles and cells (aqueous cavity) - Protein folding - Surface tension.

Lecture 1 Flashcards

Aqueous Chemistry (74 cards)