Genetics Flashcards
Sex linked recessive :
color blind, hemophilia, muscular dystrophy
autosomal dominant disease
huntington’s
Autosomal dominant tipoff
affected individual has affected parent.
’failure of penetrance’
dominant gene does not express. often happens with syndactyly in parents and then it expresses in child
X-linked dominant example
CGH- hypertrichosis- lots of extra hair on your face- expresses in all the females.
- Characteristic feature of x-linked recessive; expressed more frequently in boys b/c they are____ meaning that _____
hemizygous. if they had a copy of the bad gene, it is not masked by Y, always expressed
atavistic trait
ancestral trait. ex: hair on face, tails
only possibly Y-linked trait
hairy ears.
If more males in a pedigree, the gene inheritance pattern is probably ___ , and recessive. More females- probably ___. Same: probably autosomal
sex-linked
x-linked dominant
if individuals do NOT have affected parents, disease is :
Autosomal recessive
Linked genes
on the same chromosomes. Linkage group: all these genes located on the same chromosomes. affected in crossing over.
phenylketonuria:
missing the enzyme that normally converts phenylalanine to tyrosine- > autosomal recessive disorder -> damage to developing brain-> metabolites spill over into urine. Infants severely mentally retarded ,often die. If you catch it early enough , put them on a phenylalanine free diet, they develop normally. After their brain finishes developing as an adult, they can eat anything. all newborns in the US are screened for PKU.
Achondroplastic dwarfism
- achondroplastic dwarfism is dominant and the most common types of dwarfism.
Primordial dwarfism
7 lb woman
give examples of common dominant genetic traits you’ll see around the classroom
- Widow’s peak: dominant
- Freckles: dominant
- Dimples: dominant
- Brachydactyly:
short stubby fingers + intellectual challenges. Autosomal dominant
Polydactyly:
more than 5 fingers. Classic 6th finger pointing off of pinky.
Marfan syndrome
connective tissue problem. Causes problems with collagen deposits in cells, connective tissue in aorta wall. If you have it, aorta will become really stretched out, so sometimes the walls of your aorta burst unexpectedly.
People normally tall, thin, super long fingers.
When genes are found on different chromosomes or far apart on the same chromosome, they assort independently and are said to be ___
unlinked
When genes are close together on the same chromosome, they are said to be linked. That means that:
the alleles, or gene versions, already together on one chromosome will be inherited as a unit more frequently than not.
how can recombination frequency be useful to us?
shows us if genes are linked
linkage maps
show the order and relative distances of the genes on the chromosome.
When genes are linked, genetic crosses involving those genes will lead to:
ratios of gametes (egg and sperm) and offspring types that are not what we’d predict from Mendel’s law of independent assortment.
When genes are on the same chromosome but very far apart, they assort independently due to
crossing over (homologous recombination).



