Inheritance/ Genetic Disorders Flashcards
When does a recessive allele has control over the development of characteristics?
When the dominant allele is not present and there is homozygous recessive present.
When Mendel published his work on genetics, other scientists did not realize how important it was, why?
Mendels work was not understood by the scientists, and Mendel only worked on pea plants, which the scientists may have thought was not reliable.
Mendel did a large number of offspring plants, how does it improve the investigation?
It increases the validity of the results because of the large number. It identifies any anomalies.
How does the combination of alleles of the parents relate to how some cats have the disease (polydactyl) and some cats don’t in the same generation in the family tree?
The disease is caused by a dominant allele, so the cats must inherit the dominant allele to have the disease.
The parents have heterozygous alleles (Dd) since some cats did not have the disease, however if the parents had homozygous alleles, all the cats would have the disease.
The family tree shows 2 cats without the disease, so the genotype must be heterozygous (Hh)
What is cystic fibrosis
An inherited disorder of cell membranes, mainly affect the lungs and the digestive system.
How is it treated- physical therapy and antibiotics used to clear the lungs from mucus/infections.
What is cystic fibrosis caused by? How can we know if parents are carriers?
By a recessive allele, a child has to inherit both the recessive alleles to get this disorder.
If parents have the heterozygous allele, they’re carriers since they carry the faulty gene and are able to pass it on to their offsprings.
What is polydoctyly?
An inherited disorder where an individual has extra fingers/toes
How is it treated? The extra fingers may be removed by surgery, or may not be removed if it is not a medical concern.
What is polydoctyly caused by
It is caused by a dominant allele. (P,p) (P,P)
How do they test if an embryo is healthy (has no mutations) ?
The embryo cell will be taken from an early stage, embryos will be checked if it has any mutations. If the embryo does, it will be destroyed, if it doesn’t, embryo will be implanted in the woman’s uterus.
One advantage and disadvantage of screening embryos to check for CF-
Ad- CF will be detected
Da- Some embryos will be destroyed due to screening
What does recessive mean?
A gene that will not be expressed due to the presence of a dominant allele.
How can you know if a characteristic is caused by a recessive allele?
When the 2 parents don’t have the characteristic/disease but they’re carries so they produce a child with the disease since recessive alleles always skip a generation.
How can genetic disorder be caused?
Due to dominant and recessive alleles
How can a person with down syndrome have an extra chromosome?
An individual with Down syndrome has three copies of the 21st chromosome rather than two due to the gamete formation having an extra chromosome during meiosis.
Give a reason why a mutation in the gene coding for haemoglobin could be harmful
Mutation can cause less oxygen for aerobic respiration.
