Question

Question 19 Not yet answered The following diagram represents a replication bubble. The grey circles represents 4 molecules of DNA polymerase III siting on a template strand and ready to add new nucleotides to the RNA primers (not shown). Which of the 4 DNA pol III molecules will create okazaki fragments? Points out of 2.50 P Flag question A B 5' 3' Select one: o a. Cand D O b. Only A O c. B and C O d. A and B O e. A and D

Answer 1

19) Okazaki fragments are produced on the template strand having polarity 5` to 3`, because DNA polymerase catalyse the polymeisation in 5` to 3` direction, so template strand having polarity 3` to 5` the replication is continous.

here DNA polymerase B and C are on the template strands having polarity 5` to 3`, polarity of the template strand is checked in the direction in which DNA polymerase is moving.

so the answer is c) B and C.

20) enhancer is the DNA sequence where activators bind and increase the transcription of a gene. enhancers can be found thousands of basepairs away from the gene.

e) is a short region of DNA that can be bound by proteins to increase the chances for a gene to be transcribed.

21) during meiosis I homologous chromosomes are separated and during meiosis II sister chromatids are separated, non-disjunction in meiosis I means the homologous chromosomes fail to separate, and non-disjunction in meiosis II means sister chromatids fail to separate.

father is XY and mother is XX

XXY zygote can be formed when X egg is fertilized by XY sperm, in this case non-disjunction occurs in meiosis I in father, so that homologous chromosome X and Y failed to separate.

XXY zygote can be formed when XX egg is fertilized by Y sperm, mother is XX, so non-disjunction in either meiosis I or meiosis II can result in XX egg.

so non-disjunction in meiosis I of father, non-disjunction in meiosis II of mother, non-disjunction in meiosis I of mother are possible.

so the answer is c) more than one of these choices could result in an XXY cell.