Chem/Phys

Question 1

Does a peptide bond have an amine or an amide group ?

Answer 1

amide

Question 2

1. Does Sn1 or Sn2 create a carbocation?
2. Does Sn1 or Sn2 attack tertiary?
3. Does Sn1 or Sn2 create a receamic mixture?

Answer 2

1. Sn1 always creates a carbocation. Sn2 creates a five bond intermediate.
2. Sn1 attacks tertiary because it is able to stabilize the carbocation with its 3 carbons. Sn2 attacks primary and secondary which less steric hinderance and allows the nucleophile to attack from around.
3. Sn1 creates a racemic mixture. Sn2 creates, optrically acitve (achiral) and inverted.

Question 3

In gas-liquid chromatography, what is the mobile and stationary phase? What else can separate the components?

Answer 3

stationary= metal or polar liquid

mobile= inert gas

Size can also separate them if they don’t differ in polarities. The lightest will elute first.

Question 4

what is a Deuterium?

Answer 4

A heavy proton

Question 5

Someone has eye to lens distance is 2 cm, and can only see objects closer to 1 m. What is the strength of the person’s lens?

Answer 5

use strength equation: 1/0 + 1/I = S

1/1 m + 1/ (2/100)m = 51 D

Question 6

what is the index of refraction of the vitreous humor with speed of light of 2.1 x 10^8 m/s?

Answer 6

index of refraction= speed of light/speed in material of interest

3 x 10^8 / 2.1 x 10^8 = 1.4

Question 7

What is intensity of electromagnetic radiation?

Answer 7

The number of photons (energy) emitted per unit time.

Question 8

What is the energy of the photon emitted by LED at a frequency of 610 THz?

Answer 8

E= hf = hc/ λ

E= (6.6 x 10^-34 J.s)(610 THz)

E= (6.6 x 10^-34)(610 x 10^12)

E= about 4 x 10^-19

shortcut= just multiply 6.6 x 6 and choose the answer closer

Question 9

what fraction of a sample decays in 10 min (1/2 life= 2min)

Answer 9

31/32 because question is asking for DECAY.

1/32 of the sample is LEFT.

Question 10

What is the work generated by an adult that circulates 9 L of blood in 10 min?

Answer 10

Question 11

what is the assumption of an ideal gas?

Answer 11

individual molecular volume and intermolecular forces are negligable.

Question 12

What is the function of rods?

Answer 12

To detect detail in dim light . Responsible for night vision.

Question 13

1. Would the recognition site of this molecule be hydrophilic or hydrophobic?
2. What is the hybridization of carbon 6 off the ring?

Answer 13

1. Hydrophobic bc the molecule is mostly composed of hydrogens and carbons making it largely nonpolar.
2. sp2. double bond coutns as one.

Question 14

Rodopsin is phosphorylated by rhodopsin kinase and then binds to arrestin. What is the source of phoshate?

A. rhodopsin kinase

B. ATP

C. arrestin

Answer 14

B. ATP

rhodopsin kinase is the enzyme that cleaves a phosphate from ATP. ATP is the source.

Question 15

1. What is the mechanism of a kinase ?
2. What is the mechanism of a phosporylase?
3. What is the mechanism of a phosphotase?

Answer 15

1. ATP + kinase —> ADP + Pi + substrate-phosphate
2. glucose + phosphorylase + substrate-phosphate —–> glucose-Pi + substrate
3. substrate-Pi + phosphotase + H2O —–>

substrate-OH + Pi

Question 16

What is the funciton fo LipA (lysosomal lipase?

A. ATP hydrolysis

B. Peptide cleavage

C. Hydrolysis of Triglycerides

Answer 16

C. Hydrolysis of Triglycerides.

Answer is in the word itself. LIPASE. no need to interpret graphs.

Question 17

What is the net charge change when going from RKMYI to GDDCM ?

Answer 17

+2 charge going to -2

net change of -4

Question 18

1. what creates the a-1,4 bond?
2. what cleaves the a-1,4 bond?
3. what creates the a-1,6 bond?
4. what cleaves the a-1,6 bond?

Answer 18

1. Glycogen synthase
2. Glygogen Phosphorylase
3. Branching Enzyme
4. Debranching Enzyme

Question 19

What is the structure of ribose?

Answer 19

Question 20

The cathode reduction potential (E^o) is 0.339 V and the anode E^o is -0.127 V. Will this reaction occur spantaneously?

Answer 20

Yes, because E_cell = E^ocathode - E^oanode

Ecell= 0.339 - (-0.127) = 0.466

A (+) Ecell (emf) = spontaneous reaction bc

ΔG= -nFEcell

Question 21

Do microscopes work at visible wavelength?

Answer 21

Yes- at 400-750 nm

Question 22

What will you use to find mechanical work of a spring?

Answer 22

W= (k x²)/2

K can be equal to force

Question 23

Whic of the the following mixtures, with each component present at a concentration of 0.1 M, has a pH closest to 7?

HClO and NaClO

HNO2 and NaNO2

HNO3 and NaNO3

Answer 23

HClO and NaClO

The question says that the components are in equal concentration thus, according to HH equation when HA= A- pH= pKa

HClO is the molecule with pH closest to 7. (trick 8-1)

Question 24

What is the best explanation for the fact that a solution of NaNO2 is basic?

Answer 24

NO2- is hydrolyzed with the formation of OH- when it reacts with water.

Question 25

If something is negatively charged will it be polar or non polar?

Answer 25

It will be polar bc the negative charge can interact with water molecules. eg. SO3-

Question 26

What could be the structure of R1 and R2, considering that this molecule is a lipid on cell membranes? A. CH3 B. NH2 C. (CH₂O)₁₀CH₃ D. (CH₂)₁₅CH₃

Answer 26

D. (CH₂)₁₅CH₃ Since this is a lipid, we should realize that the R1 chain should be a long carbon chain. A- Ch3 is too short

Question 27

Considering the equation below, what will happern to the pH of a soapy solution as a result of this reaction? A. the pH increases as [H+] increases B. The pH is not changes since no acid-base reaction occurs. C. The pH decreases as [Oh-] decreases D. The effect on pH depends on the identyty of M2+

Answer 27

C. The pH decreases as [Oh-] decreases ## Footnote Because A and B are wrong. There is an acid base reaction occuring since a weak base is eliminated. D is wrong bc all metals stated in the passage were 2+ charge. (missed this question bc did not look at correct reaction.)

Question 28

Soaps can be derived from all of the following except: A.fatty acids B.cholesterol C. triaglycerols D.phospholipids

Answer 28

B. cholesterols soaps are structurally different to cholesterol molecules

Question 29

What happens when the OH on carbon-5 attacks the hydroxyl and when OH on carbon 4 attacks the hydroxyl on glucose?

Answer 29

5= pyranose 4=furanose

Question 30

What is the equation for Kcat

Answer 30

Kcat= 1/[S] Vmax= Kcat [E]

Question 31

Does a catalyst Change the transition state of a reaction?

Answer 31

No. It finds alternate pathways with lower transition states.