p2: inheritance and populations Flashcards
define gene
a base sequence of DNA on a chromosome which codes for the amino acid sequence of a polypeptide or functional RNA
define allele
a different version of a gene
define genotype
genetic constitution of an organism
define phenotype
the expression of this genetic constitution and its interaction with the environment
define homozygous dominant
homozygous organism with 2 dominant alleles
define homozygous recessive
a homozygous organism with 2 recessive alleles
define heterozygoous
the allele on each homologous chromosome is different
define monohybrid inheritance
the inheritance of a single gene on an autosome
define dihybrid inheritance
the inheritance of 2 different genes on different chromosomes at the same time
define co-dominant alleles
both alleles are expressed in the phenotypes
define multiple alleles
more than 2 alleles in a population
define sex-linkage
a gene carried on the X chromosome
define autosomal linkage
inheritance of 2 or more genes carried on the same autosome
define epistasis
the allele of one gene affects or masks the expression of another gene
In humans, Huntington’s disease is caused by a dominant mutant allele of a gene. Draw a genetic diagram to show the possible genotypesand phenotypes of the offspring produced between a man with one allele for the disease and woman who does not suffer from the disease.
In cocker spaniels, black coat colour is the result of a dominant allele and red coat colour is the result of a corresponding recessive allele.
Draw a genetic diagram to show a cross between a pure-breeding (homozygous) bitch with a black coat and a pure-breeding (homozygous) dog with a red coat.
In cocker spaniels, black coat colour is the result of a dominant allele and red coat colour is the result of a corresponding recessive allele.
If the offspring of this first cross are interbred, calculate the probabilitythat any one of the offspring will have a red coat. Use a genetic diagram to show your working
