Question

Discussion Question 1

• What are the differences between alkanes, alkenes, and alkynes?
• What are the differences between cis- and trans-isomers of alkenes?
• How are cis-trans isomers used for night vision?

Answer 1

» what are the difference between alkanes, alkenes , and alkynes a. are Alkanes contain saturated single hydsoconbons; means bond (-) it only H 4 1 H-C .C C-H CH₂ - CH₂ - CH₂ propane H H ethane C₂H6 Methane (city) H- H H H-CC-H 1 con 너 methane ethane propane butane CHA 4 when n=1 C₂ Ho s when n=2 Hg a when n=3 Cq HO Cn Man+2 (general formula of alkones) ane are common alkenes are unsaturated double hydso cabbons; means bonds (=) One More general formula CM Mzn 2020-5-21 04:14

Alk enes also called olefins SM ethylene CHA propylene (C+6) GX Н H. H cc. HC-C=C. H - 1 H H H H COCHOWY butооlеhe C4H6 H. H - Chroefp-cow C =C H C=c=0 C=6=c-6-H w H H И both Structure have similar molculas formula cis-trans alkenes H COWG atoms one same С — С cis: same side of ca mce H trans: same atoms ce NOT side On same H B

Alkynes (acetylene) CH₂ H-C = C — Н Alkynes with are also one unsaturated more triple hydrocarbons bonds (=) genedal formula of where n is number alkynes (Costan-2) by presin. identified Diference between cis and trans cis isomers TRANS isomer CIS The The Isom on progize & is desived Latine, it means the some side" som Prefix "trans" is derived -Latin. it means opposite side )) on isomer, Ih the the trans isomer, substituent groups are on different sides placed 2) IN the cis the substituent groups Placed ong one side of double bond Plone non-asomatic cycle bond double Plane of a non-asomatic of cycle CH₃ H. / Н both H C = same H C = C ase side CH3 2020-5-21 04:15 "CH₃ CH3

CIS & The cis isomers DE ON TRANS are The more less Polar than the thans isomers and have a higher boiling point. trains anal isomers ase polas and have boiling point than cis-isomers. lower the & The The cis isomers isomers have trans less symmetrical and higher Symmetty and have have lower meeting a higher melting point point, composed composed cis isomers. less a symmetrical the 70 Hans. more Ih cyclic systems, Ih cyclic systems, the the CIS isomers are trans isomers ose more unstable than stable Hans isomers Trans a cis isomers have solubility lower in isomers have higher solubility inest solvents inert solvents

3.ans:-. Vision involves the isomerization of 11-cis-retinal to all-trans-retinal.

There are three steps in generating a visual signal.

(a) Isomerization of retinal

When a photon hits a rod or cone cell, a π electron is excited to a higher energy level.

This breaks the C=C double bond between C11 and C12 and allows rotation to form the all-trans isomers

(b) Protein conformational changes

The 11-cis-retinal is bound to a protein. When the 11-cis- retinal isomerizes to all trans form, its new shape no longer fits the protein.It adopts an energetically unfavourable conformation, and this triggers a series of changes to expel it from the protein.

(c) Generation of nerve impulses

One of the intermediates formed during the expulsion of all-trans-retinal activates an enzyme that triggers a series of biochemical reaction, ultimately producing a nerve impulse to the brain