Exam 1: Ch 2 Flashcards Preview

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Flashcards in Exam 1: Ch 2 Deck (65):
1

water constitutes what % by weight of cells

70-80%

2

amphipathic

molecules with hydrophilic and hydrophobic regions

3

covalent bond

strongest bond

when 2 atoms share electrons

4

types on noncovalent interaction

ionic bonds

hydrogen bonds

van der waals forces

hydrophobic effect

5

most abundant elements in biological molecules

carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus

6

chirality

asymmetric carbon with 4 different groups around it

makes stereoisomers

7

biochemistry stereoisomers

different arrangement = different molecule

different biological functions b/c arrangement differences cause them to interact with the body differently

8

dipole moment

measure of the strength or extent of charge separation

9

molecular complementarity

lock and key fit of shapes, charges, or other physical properties of molecules

10

3 main types of biological macromolecules

protein

nucleic acids

polysacharides

11

phosphodiester bonds

link nucleotides together

12

purines

adenine

guanine

13

pyrimidines

cytosine

thymine

uracil

14

nucleoside

combination of a base/sugar without a phosphate

15

carbohydrate

covalently bonded combinations of carbon and water in a one to one ratio

16

glycogen

storage of carbohydrate in animal cells

very long highly branched polymer of glucose


10% of liver

17

what is starch, and its 2 forms

storage form of carbohydrate in plants

amylose - unbranched

amylopectin - branched

18

cullulose

major consituent of plant cell walls

19

peptidoglycan

polysaccharide chain cross linked by peptide bridges

rigidity and cell shape

20

glycosaminoglycans

major polysaccharide components of ECM

21

enthalpy and entropy

enthalpy: bond energy

entropy: measure of randomness or disorder

22

carbon fixation

ATP is hydrolyzed to provide energy for conversion of CO2 to hexoses

these sugars are food sources for the plants

23

oxidation of glucose rxn

C6H12O6 + 6 O2 --> 6CO2 + 6H2O

-686 kcal/mol

24

purpose of coenzymes NAD+ and FAD

electron carrying

25

electronegativity

how well an atom can attract an electron

26

van der waals interactions

nonspecific interactions resulting from the momentary random fluctuations in the distribution of the elections of any atom

strength of interaction decreases rapidly with distance

27

acetylation

most common chemical modification of a protein 80%

play an important role in controlling the life span of proteins

nonacetylated proteins are rapidly degraded

28

fatty acid

hydrocarbon chain attached to a carboxyl group

important energy source

esterified with phosphates to form phospholipids

29

microscopic reversibility

ability of a reaction to go backwards

slow at first, but speeds up as concentration of product increases

30

chemical equilibrium

rates of forward and reverse reactions are equal so concentrations of reactants and products stop changing

31

equilibrium constant

Keq is a fixed value that measures the extent to which a rxn occurs by the time it reaches equilibrium

32

standard biological conditions

1atm, 25 celcius

33

steady state

system of linked reactions where production and consumption of products is steady

helps prevent accumulation of potentially toxic intermediates

34

dissociation constant

the reciprocal of the equilibrium constant that describes binding reactions

when half the protein molecules are bound, the concentration of protein is equal to the Kd

35

what do high and low Kds mean

lower Kd means tighter binding: less protein is needed to bind half of its ligand

higher Kd is less tight binding: more protein is needed to bind half of its ligand

36

what is Kd measured in

molarity moles/L

37

pH

concentration of hydrogen ions in solution

negative log of hydrogen ion concentration

pure H2O is 7

38

1 unit difference in pH represents how many fold difference in proton concentration?

tenfold

39

zwitterion

a molecule that has an equal number of positive and negative charge

they are neutral

amino acids are zwitterions (amino end and carboxyl end cancel each other out)

40

Ka

equilibrium constant for acid dissociation HA --> H+ + A-

Ka = [H+][A-] / [HA]

high Ka = low pKa (stronger acid)

41

Henderson Hasselbach

pKa of any acid is equal to the pH when half the molecules are dissociated and half are not

pH = pKa + log [A-] / [HA]

because when [A-] = [HA], log [A-] / [HA] is 0 and then pH = pKa

42

buffer

a reservoir of weak acids and bases that maintain a stable pH by soaking up excess H+ or OH-

must be within 1 pH unit

43

buffering capacity

ability of a buffer to minimize changes in pH

depends on the concentration of the buffer and the relationship between its pKa and pH

44

if pH > pKa

A- dominates

disassociation occurs

45

if pH < pKa

HA dominates

no disassociation occurs

46

kinetic energy

energy of movement

47

potential energy

stored energy

ex. covalent bonds

48

thermal energy

form of kinetic energy: the energy of the motion of molecules

to perform work flows from higher temp to lower temp

49

radient energy

kinetic energy of photons

converted to thermal energy when light is absorbed and moves molecules

change electronic structure of a molecule by moving an electron into a higher energy orbital (photosynthesis)

50

mechanical energy

form of kinetic energy

can result from the conversion of chemical energy

51

electric energy

form of kinetic energy

energy of moving electrons

52

chemical potential energy

energy stored in bonds connecting atoms in molecules

harnessed to do work

ex. ATP

53

concentration gradient and electric potential

ex. ions of different sides of the membrane form [ ] gradient

energy of charge separation occurs on diff sides of membrane too

54

unit of energy

joule or calorie

1 joule = 0.239 calorie

55

calorie

energy required to raise temp of 1 gram of water by 1 celcius

56

exergonic

energy releasing rxn

products contain less energy than reactants

57

endergonic

energy absorbing rxn

products contain more energy than reactants

58

gibbs free energy

all systems change to minimize free energy

describes whether or not the products contain more or less energy than reactants

enthalpy is bond energy

entropy is a measure of disorder or randomness

59

units of gibbs free energy

kilocalorie/mol

60

delta g from standard free energy (delta g not prime)

delta g = standard delta g + RTlnKeq

61

delta g not prime from Keq

delta g not prime = -2.3RTlogKeq

62

transition state

time when system in rxn is at its highest energy level

activation energy is E needed to overcome t.s

63

reduction potential (E) vs. oxidation potential

reduction potential: ease an atom or molecule gains an electron

oxidation potential: ease an atom or molecule loses an electron

both measured in volts

64

in redox rxns electrons move spontaneously toward atoms or molecules with a more _____ reduction portential

positive

65

electric potential delta E

delta G = -n delta E

measured in volts