Transmission Genetics Part 2 Flashcards
multiple alleles
more than 2 alleles exist for a single gene
- an individual only has 2 copies of each gene, one from each parent
- ex. blood type, rh factor, galactosemia, hlas
galactosemia
- recessive
- body cannot process galactose
- 3 alleles
HLAS
human leukocyte antigen complex which means that each gene contains hundreds of alleles
Codominance
- two different alleles of a gene have equal expression in the phenotype
- ex. blood types and glycoproteins
- polka dots
variable expression
age of onset which is the time when signs and symptoms are first evident
-ex. cancers, hypertension
incomplete dominance
- phenotype is heterozygous all the way
- pink flowers
- ex. sickle cell carriers, familal hyypercholesterolemia
pentrance
dominant gene is present but is not expressed
-ex. dimples
expressivity
how much or degree of phenotypic expression
-ex. polydactyl and dimples
genetic heterogeneity
one phenotype from various genetic causes
-ex. muscular dystrphy, dementia, hemophilia
phenocopy
non genetic condition has similar signs and symptoms to genetic condition
-ex. head trauma and parkingsons or stroke
ecogenetics
interaction of the environment with a gene by changing the genes nucleotides which can cause a new mutation causing a difference in the phenotype
epigenetic
a change in the gene’s function that occurs without a change in the DNA sequence but causes a change in the phenotype
- ex. maternal stress during pregnancy causes a decreased masculation of a male child
- prader willi and angelmans
prader willi
-dominant
exceptionally high levels of growth because of increased ghrelin which causes need to eat
-decreased muscle tone, low IQ
-dad genetic error
angelmans
- very happy, non smooth movement, puppet, low IQ
- mom genetic error
pharmacogenetics
individuals reactions to medications
linked genes
- genes on the same chromosomes
- genes do not always independently assort and tend to travel together on the same chromosome
sex linked genes
- females two X cs are inherited
- males cs genes are hemizygous so all genes on X and Y chromosomes are expressed either dominant or recessive.
x linked genes
- females can carry a recessive x linked gene in the heterozygous state
- father can pass genes on to daughter but not to the son
- males express x linked traits more oftern and they cannot carry sex linked traits
Few bad dominant disorders
- hypophosphatemia which causes bone curvature
- hypertrichosis- excessive hariness
hypophosphatemia
causes bone curvature
-domiant
hypertrichosis
excessive hairiness
-dominant
hemophilia
- recessive
- blood clotting
lesch nyhan syndrome
- recessive
- build up of uric acid which causes spastic movement like uncontrolled chewing
muscular dystrophy
- recessive
- progresive weakness of muscle mass
G-P-PD
- recessive
- defiency causes RBC lysis
red green color defiect
-recessive
Y linked genes
- gene passes from father to son w/o changes or mutation
- few genes are linked to the Y chromosome
- ex. HY cell antigen and SRY gene for the organ reciept
Hardy-Weinberg Law
rules for application
- allele frequencies must remain constant
- large population must exsist
- mating must be random
- p2+2pq+q2=1