Question

Transcription, translation and cell signaling within cells is controlled by many different mechanisms.

Name two environmental factors that could possibly increase the amount of mutations in an organism and state how they would affect the organism's genetic code(explain both).

Please be specific and thorough as possible, I will give a thumb up if I like your answer. Thank you.

Answer 1

Mutation is a permanent, heritable alteration to the DNA. Mutations are caused by various environmental and genetic factors.

The two environmental factors that could possibly increase the amount of mutation in an organism are Ionizing radiations and chemical mutagens.

Ionizing radiation such as X-rays, gamma rays and alpha particles create ions or reactive oxygen species that breaks hydrogen bonds between bases or sugar phopshate backbone of the DNA and cause single stranded or double stranded breaks. This breaks in the DNA leads to insertion/deletion of a part of chromosome and cause frameshift mutation that alters the reading frame of the DNA (genetic code). Reactive oxygen species also cause substitution mutations (tranversion and transition). For example, Reactive oxygen species oxidizes guanine and forms 8-oxoguanine that pairs with adenine instead of cytosine. During the replication process, the guanine is replaced by thymine becuase the template strand now has adenine instead of cytosine. This is called as G to T transversion that leads to changes in the genetic code of the organisms and effects the structure and functions of protein.

Chemical mutagens such as base analogs, alkylating agents, DNA crosslinkers and interclating agents cause substitution or frame shift mutation in the DNA. This leads to change in genetic code of the DNA. For example, base analogs such as 5-bromouracil(5-BU) substitute thymine in A-T base pair and forms A-5-BU. During replication, the enol form of 5-BU pairs with guanine and thus replaces AT base pair with GC base pair. This leads substitution mutation in the DNA and changes the genetic code.