The SA node exhibits automaticity; it can spontaneously generate action potentials without neural input. 

TLS Online TPP Program

#Id: 1478

#Unit 4. Cell Communication and Cell Signaling

Loss of SWI/SNF function, just like loss of Rb function, can lead to overgrowth and cancer.

TLS Online TPP Program

#Id: 1479

#Unit 4. Cell Communication and Cell Signaling

Characterization of the disease-causing deletion showed that the absence of two miRNAs, miR-15-a and miR-16-1, causes chronic lymphocytic leukemia (CLL)

TLS Online TPP Program

#Id: 1480

#Unit 4. Cell Communication and Cell Signaling

The miRNAs miR-15-a and miR-16-1 act like tumor-suppressors; they normally inhibit cell proliferation, and their absence leads to cell growth.

TLS Online TPP Program

#Id: 1481

#Unit 4. Cell Communication and Cell Signaling

Let-7 miRNAs down-regulate the translation of Ras. Thus in the absence of the miRNAs, Ras is constitutively overproduced, contributing to tumorigenesis.

TLS Online TPP Program

#Id: 1482

#Unit 4. Cell Communication and Cell Signaling

Neurofibromatosis, a benign tumor of the sheath cells that surround nerves, is caused by loss of both alleles of NF1, which encodes a RAS GAP-type protein.

TLS Online TPP Program

#Id: 1483

#Unit 4. Cell Communication and Cell Signaling

MYC is translocated close to an antibody gene, leading to overproduction of MYC IN Burkitt’s Lymphoma due to translocation from Chromosome 8 to 14.