Question

15) A spontaneous chemical reaction:

a) will never occur on its own

b) could occur on its own, but might take a long time

c) has to occur immediately

13) Disulfide bridges stabilize which of the following levels of protein structure?

a) primary

b) secondary

c) tertiary

d) all of the above

e) none of the above

d) has an overall positive free energy change (ΔG)

e) decreases entropy, according to the 2nd Law of Thermodynamics

14) In your research, you expose a culture of amoebae to mutating radiation and then isolate a mutant cell that is unable to move (it cannot crawl around), but otherwise grows, divides, and appears normal. You suspect that most likely, this cell has a mutation in a gene that encodes a protein involved in:

a) actin filament formation

b) microtubule formation

c) ribosome assembly

d) intermediate filament formation

e) DNA formation

Answer 1

15. Answer c)

• Spontaneous reactions occur under certain condition in which energy is not required.
• In spontaneous reaction energy is released and is exergonic reaction.
• For exergonic reaction, the value of standard free energy change is negative. Thus, it occurs immediately

13. Answer: c

Tertiary Structure:

• Forms the three-dimensional structure by folding of secondary structures.
• Comprises of single polypeptide backbone formed by the secondary structure, which interact to form a stabilized structure.
• The interactions include: Hydrophobic interactions, salt bridges, hydrogen bonds, ionic interactions, Stabilized by Di-sulfide linkages.

14. Answer: a

Cytoskeletons comprises of:

1. Microfilaments or actin filaments-help in rigidity and cellular movements. It is narrowest among microfilaments.
2. Intermediate filaments- bears tension, helps to support the cell junctions and extracellular substances. It is intermediate in size
3. Microtubules- form track for vesicle movements. It is the widest.
4. Actin (F-actin) helps in amoeba movement.