MVU1 CELL CHEMISTRY AND BIOENERGETICS

Question 1

what is the bond strength?

Answer 1

amount of energy needed to break it

Question 1

in what environment do most reactions in the body take place?

Answer 1

in an aqueous solution

Question 2

how much stronger are covalent bonds compared to non covalent?

Answer 2

100x times stronger

Question 3

what do covalent bonds resist?

Answer 3

they resist being pulled apart by thermal motions

Question 4

what is the only way to break covalent bonds?

Answer 4

only be broken by biologically catalysed chemical reactions

Question 5

how are covalent and non covalent bonds differentiated?

Answer 5

by bond strength

Question 6

what elements make up 99% of the total atoms of the cell?

Answer 6

C, H, N, O

Question 7

what elements make up 0.9% of the total number of atoms in the cell?

Answer 7

P, S, Cl, Na, Mg, K, Ca

Question 8

what are the most common chemical groups in cells?

Answer 8

methyl (CH3)
Hydroxyl (OH)
Carboxyl (COOH)
Carbonyl (C=O)
Phosphate (PO3^-2)
Sulfhydryl (SH)
Amino (NH2)

Question 9

what sorts of molecules can carbon make?

Answer 9

chains and rings, making many combinations

Question 10

how many carbons do organic compounds usually contain?

Answer 10

30 carbons

Question 11

where are organic compounds found?

Answer 11

in free solution = the aqueous solution of the cell

Question 12

what are the 4 major families of organic compounds? and the groups that distinguish them

Answer 12

sugars (hydroxyl)
amino acid (methyl)
fatty acid (carbonyl)
nucleotide (phosphate and amino)

Question 13

what are the two uses of organic compounds?

Answer 13

monomer subunits to construct polymeric macromolecules
energy sources –> broken down and transformed into other small molecules used in metabolic pathways

Question 14

what do the building blocks give?

Answer 14

sugars give polysaccharides, glycogen and starch in plants
fatty acids give fats and membrane lipids (external membrane but also for intracellular organelles)
amino acids give proteins
nucleotides give nucleic acids

Question 15

what are the most abundant carbon containing molecules and what are they?

Answer 15

proteins, the principal building and functional blocks of cells
versatile and perform thousands of functions

Question 16

what is a characteristics of the assembly of macromolecules?

Answer 16

not random but in a sequence, subunits are added in a precise order

Question 17

what do covalent bonds allow for?

Answer 17

allow for rotation
give flexibility which creates different conformations

Question 18

what do non covalent bond do?

Answer 18

stabilise the different conformation, constraint the shape to one conformation

Question 19

what do living cells strive for?

Answer 19

strive to create and maintain order

Question 20

what are the two types of reactions?

Answer 20

anabolic and catabolic

Question 21

what is the anabolic pathway?

Answer 21

creates bonds, we need to provide energy
condensation
energetically unfavorable

Question 22

what is the catabolic pathway?

Answer 22

bonds are broken
energy is released
hydrolysis
energetically favorable

Question 23

what is the second law of thermodynamics? and what does it mean

Answer 23

in any isolated system the degree of disorder always increases
order requires energy, disorder is more likely

Question 24

what is entropy

Answer 24

the amount of disorder in a system
the greater the disorder the greater the entropy

Question 25

what will systems spontaneously arrange towards?

Answer 25

will spontaneously rearrange towards higher S

Question 26

what happens to the environment when you create more order in the cell?

Answer 26

the environment becomes more disordered

Question 27

what is the first law of thermodynamics?

Answer 27

the energy can be converted from one form to the other but cannot be created/destroyed

Question 28

what is released in a catabolic pathway?

Answer 28

heat

Question 29

where is energy stored in biological systems?

Answer 29

in the bonds

Question 30

what is enthalpy and what sort of enthalpy change is more favorable?

Answer 30

energy that can be released from chemical bonds
negative delta H is more favorable

Question 31

what does Gibbs free energy need to be for the reaction to be favorable? and what does that mean in terms of the equation?

Answer 31

delta G has to be negative, therefore entropy has to be greater than the change in enthalpy

Question 32

what is the gibbs free energy equation

Answer 32

delta G= delta H-T(delta S)

Question 33

how can energetically unfavorable reactions happen?

Answer 33

has to be coupled to a second energy favorable reaction

Question 34

what do enzymes do?

Answer 34

lower the activation energy

Question 35

what needs to happen for the system to have a net negative gibbs free energy value?

Answer 35

the energy released by the energetically favorable reaction has to be greater than the energy used for the energetically unfavorable reaction

Question 36

in which bond is the energy stored in ATP?

Answer 36

phosphoanhydride bond

Question 37

what are the two steps of an ATP driven reaction?

Answer 37

step 1: activation
ATP transfers a phosphate to the OH group of one reactant to produce a high energy intermediate
step 2: condensation
the activated intermediate reacts with the hydrogen on the other reactant to form the product A-B accompanied with released of inorganic phosphate

Question 38

what does Acetyl CoA give to the molecule?

Answer 38

gives the acetyl group

Question 39

what does the cell need to be in?

Answer 39

equilibrium

Question 40

what is oxidation?

Answer 40

removal of electrons from an atom, creation of a partial positive charge

Question 41

what is reduction? and what happens with it?

Answer 41

addition of electrons to an atom, creation of a partial negative charge
if a molecule picks up an electron it picks up a hydrogen -> hydrogenation