Genetics Difficult Concepts and Diseases - Exam 1

what is independent assortment and when does it occur?

metaphase 1, random alignment, two different genes randomly assort their alleles if unlinked

what is segregation and when does it occur?

anaphase 1, two copies of a gene will separate during transmission from parent to offspring

example of heterozygote advantage

sickle cell anemia, also resistant to malaria

example of incomplete penetrance

polydactyly, many Hh don’t have extra fingers or toes, even though they should

example of incomplete dominance

4 o’clock plant, heterozygote is pink

example of x linked recessive disorder

Duchenne’s Muscular Dystrophy (DMD), males more likely to get because only one copy of X gene

example for lethal allele

Manx cat, dominant negative, homozygous dominant do not survive

example for recessive loss of function disease

Tay-Sachs disease, produces HexA protein, albisim, cystic fibrosis, PKU, sickle cell

haploinsufficiency

heterozygote always shows phenotype, 50% of healthy allele not enough.

example of gain of function mutation

achondroplasia

example of dominant negative mutation

marfan syndrome

what are diseases involving a defective enzyme usually?

autosomal recessive disorder

autosomal dominant inheritance example

huntington’s disease

which disease shows locus heterogeniety?

hemophilia

what kind of test recommended for TSD?

biochemical

how does down syndrome happen?

nondisjunction in meiosis 1, octosis

if son is sick from x linked recessive

has to be from mom

if daughter sick from x linked recessive

both mom and dad sick or carriers

misaligned crossover between homologs

deletion and duplication

rare crossover between non homologs

reciprocal translocation