Genetics Foundations Flashcards
When does nondisjunction occur?
Anaphase I or Anaphase II
What is Turner Syndrome?
Only 1 X chromosome
What does the law of independent assortment say?
Chromosomes are inherited independently eg. Cystic fibrosis gene inherited separately from Retinoblastoma gene
What genes are exempt from the law of independent assortment?
Linked genes
Is the probability of recombination between two genetic loci is directly proportional to the physical distance that separates them on the chromosome?
Yes
What is incomplete dominance?
2 copies of dominant gene needed for normalcy. e.g. red rose+ white rose = pink rose
What is codominance?
BOTH phenotypes are expressed.
e.g. A parent and B parent = AB child
What is incomplete penetrance?
You won’t necessarily develop the phenotype of your genotype. E.g. certain genotype gives you a 75% chance of developing cancer
What is a phenocopy?
An individual showing features characteristic of a genotype other than its own, but produced environmentally rather than genetically.
What are modifier loci?
Other genes in the genome that modify how a phenotype develops eg. cases of incomplete penetrance
What is pleiotropy?
A single gene having multiple different effects or unrelated outcomes
What are CpG islands?
Enriched regions of methylated cytosines, often found in promoter regions
Can be hemimethylation (just one strand) but an enzyme will find this region and restore symmetry
The methylated regions of DNA tend to be associated with what?
Deacetylated/compact regions of DNA
The unmethylated regions of DNA tend to be associated with what?
Acetylated/open regions of chromatin
What is imprinting?
One one parent’s copy of a gene is methylated (turned off) and one is unmethylated (turned on)
