Gametes are formed through meiosis (reduction division), in which a germ cell undergoes two fissions, resulting in the production of four gametes.
The DNA replication by the action of DNA polymerase takes place in the 3' to 5' direction on the leading strand. The lagging strand which has the opposite orientation or polarity as that of the leading strand requires a more time to get synthesised. The DNA replication of the lagging strand happens in short segments where a RNA primer forms a compliment with a part of the DNA segment on its 3' end. This RNA primer helps initiate the replication of the Okazaki fragments. When the replication on the lagging strand reaches its end, the RNA primer forms a compliment with the last bit of the strand. This small segment gets missed in the end as no more DNA is left to form a RNA primer-DNA compliment. Such shortening of the lagging strand in the replication process is the end-replication problem.
Telomeres are protective ends of the DNA strands. These ends contain a poly-A tail. When the lagging strand replication reaches its end, the RNA primer forms a compliment with the telomere and initiates the replication. This leads to the shortening of the telomere and not the coding segments on the lagging strand of DNA. The telomerase repairs the shortened telomere by re-synthesising it.
It’s E,two independent linear equations,each having at least one of the variables
Oncogenes are most like the gas pedal on a car, while tumor suppressor genes are most like the brakes on a car. Oncogenes and tumor suppressor genes are mutated in cancer cells.
Oncogenes are genes overexpressed in cells in which they should not be expressed, thereby leading to cancer.
Some examples of oncogenes are growth factors such as, for example, the Platelet-derived growth factor (PDGF) or Epidermal growth factor (EGF).
Conversely, tumor suppressor genes are genes that act to regulate cell division and replication, thereby their inactivation also leads to cancer.
A well-known example of a tumor suppressor gene is the p53 gene that acts to control cell division and apoptosis (programmed cell death).
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Answer:
Tibia, Fibula, Interosseous Membrane.
Explanation:
Tibialis posterior muscles originates from the proximal tibia and fibula. The medial origin is on the posterior surface of the interosseous membrane.