Lecture 7 Flashcards
What are 3 sex limited characters?
determined by autosomal genes
expressed in only one sex
have zero penetrance in opposite sex
What are sex infulenced characters? 3
determined by autosomal genes
inherited according to mendelian prinicples
expressed differently in males and females
What are four characteristics of cytoplamically inherited traits? is it present in males and females?
yes
Cytoplamic inhertd traits…. Is usually inherited how?
from one parent, usually maternal parent
Reciprocal crosses give…. in cytoplamically inherited traits
results
What is a characteristic of cytoplasmically inherited traits?
exhibit extensive phenotypic variation, even within a single family
What is the genetic maternal effect?
phenotype of the offspring is determined by the genotype of the mother
In cytoplasmic inheritance, who is the genes inherited from?
only from one paretn
Who are the genes inherited from in the genetic maternal effect?
are inherited from both parents but the offspring’s phenotype is determined by the mother’s genotype, not its own
What is genomic imprinting ?
Differential expression depending on whether it is inherited from the male or the female parent.
What are examples of genomic imprinting?
prader-willi and angelman syndromes
What is genomic imprinting due to?
DNA methylation differences in sperm and eggs
What are symptoms of Prader-Willi?
small hands and feet short stature poor sexual development mental retardation voracious appetites, usually obese mutations is always inherited from father
What is the genetic variation with prader-willi?
deletion in long arm of chromsome 15
What is the genetic variation for angelman syndrome?
deletion in long arm of chromosome 15
What are the symptoms of angelman syndrome?
exhibit frequent laughter uncontrolled muscle movement large mouth unusual seizures mutation is always inherited from mother
What is the methylation of DNA in mammals?
Methylation is erased in germ cells of each generation and then reestablished in the course of gamete formation
What are the different levels of methlyation?
sperm and eggs undergo different levels of methylation, resulting in the differentail expression of male and female alleles in the offspring
sex linked characteristics
genes located on the sex chromosome
sex influenced characteristic
genes on autosomal chromosomes that are more readily expressed in one sex
sex limited characteristic
autosomal genes whose expression is limited to one sex
genetic maternal effect
nuclear genotype of the maternal parent
cytoplasmic inheritance
cytoplamic genes, which are usually inherited entirely from only one parent
genomic imprinting
genes whose expression is affected by the sex of the transmitting parent
an allele whose product is functional only at certain temps?
temp sensitive allele
