genetics chapter 4.3

lethal allele

allele whose expression results in death at an early stage of development

complete dominance

phenotype of the heterozygote is the same as the phenotype of one of the homozygotes

incomplete dominance

phenotype of the heterozygote intermediate (falls withing the range) between the phenotypes of the two homozygotes

Codominance

phenotype of the heterozygote includes the phenotypes of both homozygotes

multiple alleles

A gene that has more than two alleles

what is an example of multiple alleles?

blodo type

what blood type is codominant?

AB

what blood types are possible among the children of a cross between a man who is blood type A and a woman who is blood type B?

O, A, B, AB

what allele codes for blood type O?

i

epistasis

one gene masks the effect of another gene

sex-linked characteristic

genes located on sex chromosome

sex-influenced characteristics

genes on autosmal chromosomes that are more readily expressed in one sex

sex-limited characteristic

autosomal genes whos expression is limited to one sex

genetic maternal effect

nuclear genotype of the maternal parent

cytoplasmic inheritance

cytoplasmic genes, which are usually inherited entirely from only one parent

genomic imprinting

genes whose expression is affected by the sex of the transmitting parent

through which parent is cytoplasmically inherited characteristics inherited from?

mother

what are the charactersitics of cytoplasmically inherited characteristics?

- present in males and females
- usually inherited from one parent

Where does mitochondrial DNA come from?

mother

if a father has a cytoplasmic disease and the mother doesn't will the child have the disease?

no

genetic maternal effect

the phenotype of the offspring is determined by the genotype of the mother

what is an example of the genetic maternal effect?

dextral and sinistral shell position on snails

what is genomic imprinting?

one form of epigenetic process that invovled methylation of DNA without alternating genetic sequence

where are imprinted genes expressed from?

only one allele

where are epigenetic markers located for genomic imprinting?

the germline

what determines how much methylation occurs in genomic imprinting?

whether the gene passes through the egg or the sperm

what are the environmental effects on the expression of a genotype?

temperature senitive alleles are alleles whose product is functional only at certain temperatures

assume you are looking at a case of lethal alleles. crossing two green corn plants results in 2/3 green progeny and 1/3 white progeny. if you crossed two white progeny with each other, how many of the progeny would you predict to be white?

100%

A child who is blood type A has a mother who is blood type B. In a paternity suit a man is accused of being the father. He has blood type AB. Is he the father?

he cannot be excluded as the father

the difference between dominance and epistasis is that

epistasis maks genes at different loci

what is dominance the relationship between?

2 alleles

what is epistasis the relationship between?

2 different genes

in the ABO blood type phenotype, whihc gene is the most epistatic?

H

Sex-influenced traits are encoded by _____ genes and sex-linked traits are encoded by _____ genes

autosomal; sex-chromosomes

while studying a new human disease you discover that hte disease is linked to a mitochondrial gene. you can be reasonably sure tha thte disease is inherited

from mother to child

syndromes like Prader-Willi are examples of genomic imprinting. What DNA modification is important to understand Prader-Willi syndrome?

methylation