Imagine an organism with mutations in complexes I, III, and IV that prevent pumping of hydrogen ions into the intermembrane space but still allow electrons to pass through the electron transport chain. Which of the following is the most likely consequence of these mutations?
a. the mobile electron carriers q and cyt c will no longer pass electrons through the electron transport chain.
b. oxygen will not accept electrons and combine with 2 h+ to form water at the end of the electron transport chain.
c. atp synthase will not convert adp to atp.
d. nadh and fadh2 will not donate new electrons to the electron transport chain

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.