misconceptions in genetics and in biology

One set of alleles is responsible for determining each trait, and there are only 2 different alleles (dominant and recessive) for each gene. this is completely lie for example cystic fibrosis is known for its allelic heterogeneity meaning more than 100 alleles are known to cause this disease. We have been taught Mendelian inheritance with Punnett square calculating probabilities what kind of color will have child if parents are known. this is misconception because In humans, at least 3 different genes are associated with eye color.For traits that show a Mendelian pattern of inheritance, students often assume that there are only 2 possible alleles for a trait. This is true in some cases, but in many cases, there are more alleles for a trait. In cat-coat-color genetics, 3 different alleles of 1 gene determine the position of pigmentation on the body.

2)chromosome structure

is thought to be this. but actually this X shaped genetic material is 2 sister chromatid. because of we see chromosomes only during mitosis best at meta-phase and during which chromosomes already have replicated and is presented as 2 sister Chromatid, this is the X structure we see in microscope. and this is actual chromosome

3)All mutations are harmful. mutation can be harmful, neutral or beneficial. for example PCSK9 gene which utilizes LDL receptor can be mutated artificially, that will increase quantity of LDL receptor which will in result decrease cholesterol in the blood plasma. but what is PCSK9 for? well... it defends cells from excess cholesterol. in research complete mutation of PCSK9 never shown harmful efects.

4)use terms locus and gene interchangeably. Well locus is where gene is located meaning they are not the same at any way. we can imagine locus as the house where gene lives. and locus is the address of this house. for example are humans and their house addresses the same? of course not :D

5)mitochondrial disease can't be inherited from father. Well mitochondrial DNA can't be inherited from father but disease pretty much yes. because there are actually more nuclear genes that are responsible for TCA cyle's Oxidative phosphorylation than mitochondrial genes itself, meaning nuclear genes can cause mitochondrial disease and since nuclear gene can be inherited from father and mother at same rate Well mitochondrial disease can be inherited from father too.