Answer: b dead organisms And waste are recycled throughout the tropic levels.
Explanation:
Answer:
All of the statements are true.
The X chromosome is one of the two sex chromosomes of humans and some animals (the other sex chromosome is the Y chromosome). Men have a single X chromosome and women two X chromosomes.
Diseases whose gene is localized on the X chromosome are most often transmitted in the X-linked recessive mode; some are transmitted on the dominant mode related to the X.
In this mode of inheritance, the morbid allele behaves like a recessive trait.
Women heterozygotes are not affected but can transmit the disease; they are aid to be conductive of the disease.
The disese is only manifested in male subjects (XY) with only one copy of the gene (hemizygous subjects)
Answer:
PFFT this might help? sorry if not mate
Explanation:
Cell cycle checkpoint controls play a major role in preventing the development of cancer [see Sherr, 1994, for a more detailed discussion]. Major checkpoints occur at the G1 to S phase transition and at the G2 to M phase transitions. Cancer is a genetic disease that arises from defects in growth-promoting oncogenes and growth-suppressing tumor suppressor genes. The p53 tumor suppressor protein plays a role in both the G1/S phase and G2/M phase checkpoints. The mechanism for this activity at the G1/S phase checkpoint is well understood, but its mechanism of action at the G2/M phase checkpoint remains to be elucidated. The p53 protein is thought to prevent chromosomal replication specifically during the cell cycle if DNA damage is present. In addition, p53 can induce a type of programmed cell death, or apoptosis, under certain circumstances. The general goal of p53 appears to be the prevention of cell propagation if mutations are present. The p53 protein acts as a transcription factor by binding to certain specific genes and regulating their expression. One of these, WAF1 or Cip1, is activated by p53 and is an essential downstream mediator of p53-dependent G1/S phase checkpoint control. The function of p53 can be suppressed by another gene, MDM2, which is overexpressed in certain tumorigenic mouse cells and binds to p53 protein, thus inhibiting its transcriptional activation function. Other cellular proteins have been found to bind to p53, but the significance of the associations is not completely understood in all cases. The large number of human cancers in which the p53 gene is altered makes this gene a good candidate for cancer screening approaches.
Answer - A
Semi-conservative model of replication involves the replication of DNA in all the familiar cells in such a way that each newly synthesized daughter cell contains a double helix with one new strand and one old strand.
