Inphotos y s temiipsiilightenergy is us edtoproduc

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ep requires an input of energy. Hin t 1. Comparing the energy requirements of chloroplast and mitochondrial electron transport chains In a c hloroplas t, photos y nthetic elec tron trans port between Pq (plas toquinone) and Pc (plas toc y anin) v ia the c y toc hrome c omplex is nearly identic al to the c entral portion of the elec tron trans port c hain in a mitoc hondrion. Rec all that in a mitoc hondrion, onc e elec trons enter the elec tron trans port c hain from NADH, no additional input of energy is needed to power elec tron flow to O2. Think about how this s imilarity applies to the energy requirements of the photos y nthetic elec tron trans port c hain. Hin t 2. How is light energy used in Photosystem II? When light energy is abs orbed by a c hlorophy ll molec ule, an elec tron in the c hlorophy ll is boos ted to a higher energy lev el. This form is c alled the ex c ited s tate of the c hlorophy ll. How is the energy of the excited state of P680 chlorophyll used in Photosystem II? ANSWER: The ex c ited s tate of P680 remov es an elec tron from the primary elec tron ac c eptor. The ex c ited s tate of P680 donates an elec tron to the primary elec tron ac c eptor. The ex c ited s tate of P680 remov es an elec tron from water. Hin t 3. What is the effect of artificially (without light) reducing NADP+ to NADPH? Suppos e that a partic ular c ompound X, when added to a s olution of func tioning c hloroplas ts , c aus es the reduc tion of NADP+ to NADPH in the dark . Howev er, when X is mix ed with NADP+ in the abs enc e of c hloroplas ts , no reduc tion of NADP+ to NADPH oc c urs . In other words , c ompound X c annot direc tly reduc e NADP+ to NADPH. Which of the following m ust also occur when com pound X is added to chloroplasts in order to account for the observed reduction of NADP+ to NADPH in the dark? ANSWER: Elec tron c arriers between PS II and PS I (s uc h as plas toquinone) mus t be reduc ed. In PS I, P700 mus t be ox idiz ed to P700+. Water mus t be ox idiz ed and O2 mus t be...
View Full Document

This document was uploaded on 02/17/2014 for the course BIOCHEMIST 2550 at Ohio State.

Ask a homework question - tutors are online