Many eukaryotic genes contain a large number of exons. Correct splicing of such genes requires that neighboring exons be ligated to one another; if they are not, exons will be left out. One early proposal suggested that the splicing machinery bound to a splice site at one end of an intron and scanned through the intron to find the splice site at the other end. Such a scanning mechanism would guarantee that an exon was never skipped. This hypothesis was tested with one minigene with a duplicated 5ʹ splice site. Find diagram of the products you expect from minigene if the splicing machinery binds to a 5ʹ splice site and scans toward a 3ʹ splice site.

TLS Online TPP Program

#Question id: 33472

#Unit 2. Cellular Organization

Find correct True and False statements

A. Human females have 23 different chromosomes, whereas human males have 24.

B. In the living cell, chromatin usually adopts the extended “beads-on-astring” form.

C. The four core histones are relatively small proteins with a very high proportion of positively charged amino acids; the positive charge helps the histones bind tightly to DNA, regardless of its nucleotide sequence.

D. Nucleosomes bind DNA so tightly that they cannot move from the positions where they are first assembled.

TLS Online TPP Program

#Question id: 33473

#Unit 2. Cellular Organization

Which of the following specialized DNA sequences and their functions that act to ensure that the number and morphology of chromosomes are constant from one generation of a cell to the next.

 Replication origins B. Centromeres C. Telomeres

TLS Online TPP Program

#Question id: 33474

#Unit 2. Cellular Organization

CTG/CAG trinucleotide repeats (5ʹ- CTG in one strand and 5ʹ-CAG in the other strand) is unusually flexible. What can be their probable role?

TLS Online TPP Program

#Question id: 33475

#Unit 2. Cellular Organization

With pulsed-field gel electrophoresis, which can separate DNA molecules up to 107 bp in length. The results of pulsed-field gel electrophoresis of the DNA from the yeast Saccharomyces cerevisiae are shown in Figure. How many chromosomes does S. cerevisiae have?

TLS Online TPP Program

#Question id: 33476

#Unit 2. Cellular Organization

Find true and false statements

A. The structures of eukaryotic genes show extensive variation. 

B. Some eukaryotic genes are uninterrupted and their sequences are colinear with those of the corresponding mRNAs. 

C. Most multicellular eukaryotic genes are interrupted, but the introns vary enormously in both number and size.

TLS Online TPP Program

#Question id: 33477

#Unit 2. Cellular Organization

Finding: Ancestry have similar organizations with conservation of the positions (of at least some) of the introns.

Example: The globin and DHFR genes are examples of a genes that share a common ancestor