Question

24. (15pts) You have a close friend or family member who sends their DNA to a sequencing company, looking for ancestry information. On a whim, your health-conscious friend elects to also receive any medical insight her DNA may provide. She is told that she has a mutation in the gene for an estrogen receptor (ERa, aka estrogen receptor 1, ESR1), located on chromosome 6. This mutation may put her at higher risk for developing ER+ (estrogen receptor-positive, aka hormone receptor-positive, HR+) breast cancer. She is concerned, and has heard of ‘estrogen’, but doesn’t understand what this receptor is or how it relates to cancer. Simply but accurately and thoroughly explain: genetic mutations & how they may change cell function, nuclear receptor transcription factor function, transcription dysregulation, and how disruption in transcription initiation could lead to cancer. Assume your friend is reasonably intelligent, but hasn’t studied science since high school. (For example, your friend has heard the words ‘DNA’, ‘gene’, and ‘chromosome’, and has a vague idea what they are, but doesn’t know the difference between them. You must explain this.)

This answer has to be veryyy thorough and dumbed down enough for a non-scientist person to understand. This is for my class final plz help!

Answer 1

24.

DNA is the genetic material present in every living cell. DNA controls all cellular activities and is passed on from parents to their offspring. It is because of the DNA we resemble out parents which we receive from our parents. DNA has genes on it. Genes are actually small segments of DNA and many genes are present on one DNA molecule. Each gene is capable of synthesising a protein which acts as an enzyme and brings various chemical reactions int eh body. These chemical reactions will result in a cellular activity. This is how a gene regulates a cellular function. That is why genes (DNA) are called the hereditary units of an organism. Chemical nature of DNA is , it is formed of nucleotides (A/G/C/T)

A DNA molecule is folded along with proteins to form chromatin. Chromatin further coils to become thick and short structures called chromosomes. Chromosome are present in the nucleus. So basically it is the chromosome which has DNA (gen) and these chromosomes are inside the nucleus. Gene< DNA<Chromatin< nucleus, this is the order of their size.

Genetic mutations are the changes occuring in the triplet codes which code for the amino acids. One triplet codes for one amino acid. When the triplet code changes, amino acid coded will also change. Amino acids form proteins. Change in one amino acid also can make a protein completely different. Because the proteins control all cellular functions, change in the protein will affect the cellular function. A protein which has changed due to mutation may not be able to function normally. This will change the functioning of the cell and the functioning of an organ as a whole. That is who mutations affect the whole organism and its function.

A receptor molecule is a molecule which can recognize another chemical molecule (ligand) and bind to it. Nuclear receptors are a type of proteins present with in the cytoplasm and attach to a ligand. The complex of the nuclear receptor and the ligand reach the nucleus and bind to a specific gene and affect its functioning by activating or deactivating. ER receptor binds to estrogen and attach to a gene in the nucleus and bring the growht of the breast during puberty, pregnancy ets in a very controlled manner.

When there is a mutation for estrogen receptor gene , then the estrogen receptor may not be formed normally. In which case it does not bind to estrogen which is the ligand and does not regulate the gene concerned. Lack of gene regulation will cause gene dysregulation. ER gene expression is important in breast cancer control. But if an individual is ER + ve , there is a mutation in the ER gene indicating lack of ER gene regulation. There is no regulation of the transcription here, so the cell division occurs continuously and causes tumours and cancers.

Cancer is continuous cell division with out stop and causes tumor or cancer development.