Genetics Answers

What are pyrimidine dimers? Please explain it.

I was reading criteria that a molecule must fulfill before they are regarded as genetic material. There the book said: It should be able to express itself in the form of 'Mendelian Characters'. I couldn't understand this. Could you please explain.

What are the significance of chromosome mapping?

What is Hoogsteen base pairing?

Mia and Kevin’s first child (Ethan) developed problems shortly after birth and was eventually diagnosed with Duchenne muscular dystrophy (DMD). Ethan is now four years old and doing well on a carefully-planned therapy program although DMD cannot currently be cured. Both Mia and Kevin are healthy. Mia just gave birth to a little girl named Daisy. What is the probability that Daisy will be diagnosed with Duchenne muscular dystrophy? Explain. Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. Patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein.

Red-green color blindness is the inability to distinguish between the colors red and green. This characteristic is a X-linked recessive trait in humans and is 16 times more common in males than in females. Two people both have normal color vision have a color-blind son. What are the genotypes of the parents? Be sure to define the allele symbols you chose to use.

One of two major forms of a human condition called neurofibromatosis is inherited as an autosomal dominant gene, although it may range from mild to very severely expressed. Since symptoms of the disease can vary for individuals who have this allele a allele is said to show variable expressivity.
Neurofibromatosis affect a variety of organ systems and can have neurological, musculoskeletal as well as other symptoms.
A man with mild symptoms of Neurofibromatosis (he is heterozygous for the Neurofibromatosis allele) has son with a women who does not have Neurofibromatosis. What is the probability that his son will also develop some form of Neurofibromatosis.

You are working with a family practice group and a couple (Mark and Susan), planning to start a family comes to you for information. Mark was married once before, and he and his first wife had a daughter with cystic fibrosis who died of the age of 6. Susan had a teenage sister with cystic fibrosis who is doing fairly well with intensive medical treatment of her inherited disorder. Susan has no previous children. Both Susan and Mark are healthy and neither one of them has cystic fibrosis. All the members of their family are also healthy. Note that cystic fibrosis is a serious genetic disease caused by an autosomal recessive allele. Heterozygotes have a normal phenotype and show no health problems related to this allele.

If a cell begins G1 with 2 chromosomes, how many chromatids are present during S and G2? How many are in the daughter cells after mitosis?