Lecture 7-8

Question 1

What is retina and what it contains on human eyes?

Answer 1

The retina is located at the back of human eye and it contains photorecptors cells which convert photons into electrical info.

Question 2

What are two types of photoreceptors?

Answer 2

Rod photoreceptors cells (light intensity) and cone photorecptor cells (color vision)

Question 3

What is photoisomerizaiton?

Answer 3

As light triggers a chanfe in molecular configuration on opsin protein.

Question 4

what is phototransduction?

Answer 4

It’s the process by which light detected by photoreceptor cells is converted to electrical impulses before these impulses are then sent to the brain.

Question 5

What is coulomb’s law?

Answer 5

Fe=kq1q2/r^2

Question 6

What forces are included in intramolecular force?

Answer 6

ionic bond, covalent bond, and metallic bond

Question 7

What is electronegativity?

Answer 7

The tendency of an atom to attract a shared pair of electrons

Question 8

What is metallic bonds?

Answer 8

A type of covalent bonding specifically occurs between atoms of metals. Valence electrons are free to move through the lattice.

Question 9

What is Lennard-Jones Potential?

Answer 9

Describes the potential energy of interaction between two nonbonding atoms or molecules based on their distance of seperation.

Question 10

What is the smaller attractive term in LJ potential?

Answer 10

London dispersion force

Question 11

What is the sigma value in L-J potential?

Answer 11

Van der Waals radius.

Question 12

What is short range forces?

Answer 12

Short range forces tend to be repulsive. It happens when the centers of molecules are separated by three angstroms or less.

Question 13

What is long range force?

Answer 13

AKA Van der Waals forces. It happens when three angstrom range are attractive.

Question 14

What is intermolecular force responsible?

Answer 14

Surface tension, friction, viscosity, and differences between behaviour of gases.

Question 15

What are three types of Van der Waals forces?

Answer 15

Dipole-dipole, interactions between dipoles and induced dipoles, LDF

Question 16

What is disulfide bonding?

Answer 16

A covalent bond derived from the oxidation of two S-H group

Question 17

What’s the difference between intramolecular and intermolecular disulfide bridge?

Answer 17

Intra: stabilize the tertiary structure
Inter: stabilize the quaternary structure

Question 18

What is capillary action?

Answer 18

It only occurs when adhesive forces are stronger than cohesive forces.

Question 19

What is surface tension?

Answer 19

It’s the result of cohesive forces between liquid molecules at an interface. It leads to surface film.

Question 20

What is surfactant?

Answer 20

It’s the compound which lower surface tension by disrupting intermolecualr forces at the interface.

Question 21

What is self-assembly?

Answer 21

It’s a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves without external direction.

Question 22

What the condition that self assenbly would occur?

Answer 22

1. it’s a spontaneous process.
2. The product of self-assembly is more thermodynamically stable. The Gibb’s free energy must be less thatn zero, a net gain in entropy.

Question 23

What is super-hydrophobicity?

Answer 23

A result of micro- and even nano-structured patterns. When contanct angle is larger than 90 deg.

Question 24

How to quantifying hydrophobicity?

Answer 24

γSG= γSL+ γLGcosa

Question 25

What is Wenzel regime?

Answer 25

characterized by micro-structures into which the water droplet embeds itself

Question 26

What is cassie-baxter regime?

Answer 26

Characterized by hierarchical nanostructures that water droplet floats above.