Cellular senescence may have evolved to protect organisms against cancer. Instead of dividing out of control, the cells die. Cellular senescence appears to be regulated by several tumor suppressor genes, especially p53.what is the most appropriate reason behind this,

1) Transcription factor p53 is thought to suppress tumorigenesis by causing cell arrest and senescence in response to short telomeres, DNA damage, and viral or external signals to divide

2) This factor can stop the cell cycle, cause cellular senescence in rapidly dividing cells, instruct genes to initiate cellular apoptosis, and activate DNA repair enzymes.

3) Induction of apoptosis or cellular senescence by p53 always beneficial.

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#Question id: 351

#I Life Science/ Life Sciences Group – I-V

 If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions ________.

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#Question id: 14126

#I Life Science/ Life Sciences Group – I-V

Which of the following statement is incorrect about homology and sequence similarity?

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#Question id: 18688

#I Life Science/ Life Sciences Group – I-V

Match the items in Group 1 with an appropriate description in Group 2 

Group I                                      Group 2 

P. GOR method                           1. Protein structure visualization 

Q. Genome sequencing           2. Sanger method

R. ESTs                                         3. Protein secondary structure prediction

S. RasMol                                    4. gene expressed as cDNA

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#Question id: 16134

#SCPH01 Biochemistry

You obtain 6 BACs (of known order, as shown below) and 7 STSs (of unknown order) that derive from a region of mouse chromosome 16 whose genomic sequence has not yet been finished.   

 

By PCR (using 20-bp primers at either end of each STS), you test each of the 6 BACs for the presence (+) or absence (-) of each of the 7 STSs. You obtain the following results:

 

You determine the DNA sequences of PCR products obtained at STS5 using BACs B, C, D, E, and F as PCR templates. The DNA sequences of PCR products obtained using BACs B and C are identical, but they differ by several nucleotide substitutions from the DNA sequences of PCR products obtained using BACs E and F. Oddly, PCR product obtained using BAC D appears to be a mixture of two sequences – one corresponding to the BAC B/ BAC C sequence and the other corresponding to the BAC E/ BAC F sequence. Briefly account for these findings, and explain how a single PCR assay could amplify two different sequences.

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#Question id: 6972

#I Life Science/ Life Sciences Group – I-V

Sodium ions influx and passive water movement result in fluid-filled blastocoel in __________embryos.