CELL DIVISION
THE CELL CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Mitosis
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Synthesis
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Gap 1
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Gap 2
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Detailed explanation-1: -Following a low dose of UV radiation, DNA replication is inhibited and the cells undergo a transient arrest re-entering the cell cycle by 24 h. Instead, a high dose of UV damage leads to an initial replicative arrest followed by death of the cells by apoptosis.
Detailed explanation-2: -UV irradiation alters the expression of multiple genes that encode functions to repair DNA damage, arrest cell growth, and induce apoptosis. In addition, UV irradiation inhibits protein synthesis, although the mechanism is not known.
Detailed explanation-3: -Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage.
Detailed explanation-4: -In fact, UV-A radiation commonly damages DNA in an oxygen-dependent manner that involves photosensitization. This leads to the production of a free radical that then interacts with and oxidizes DNA bases. These oxidized bases don’t pair correctly during replication, resulting in mutations (Figure 1).