inheritance Flashcards
what is the genotype
the genetic information of an organism and describes all the alleles an organism has
what is phenotype
observable biochemical characteristics of an organism it is the interaction between the genes and the enviroment
what is a gene
a section of dna which codes for a protien
what are allele
different versions of the same gene
what is a locus
the position of a gene on a chromosome
what happens when hetrozygous is present
only one of the alele is shown in the phenotype the allele that is expressed is thought to be dominanes and the not expressed iis recessive
when is reccessive expressed
when the gentype is homologous recesive
what is codominance
when two genes contribute to the phenotype
what is pure breeding
must be homozygous for either recessive or dominant
what is the law of segregation
in diploid organism the characterisitcs are determined by alleles that occur in pairs only one of each pair of allels can be present in one gamete
how to produce 3:1 ratio
when the pure bred reccesive and dominant are bred together, all the offsprings will have a heterozygous genotype and all will have same phenotype, when these f1 generation are bred together will produce a 3:1 ratio
whatis monohybrid
is the inheritance of a single gene
what is dihybrid
two characteristics are determined by two different genes and are inherited located on two different chromosomes
what is the usual dihybrid ration
9:3:3:1
what is multiple alleles
more than two alleles of which only two may be present at the locus of individual homologous chromosome
what are the male sex chromosome
they are x and y
what gamete do women and male produce
females have two x chromosomes so only pass on x chromosomes, males have one x and one y chromosome and there is 50/50 chance that either a y or a x will be passed on so it is 50/50 chance girl or boy
what is sex linked
a gene that carries the x or y chromosome
why is sex linked disease usually seen in boys
the x chromosome is usually longer than the y chromosome which means that for the most of length of the x chromosome there is no equivalent homologous portion of the y chromosome so even when the characteristics are recessive there is no dominant allele to overide the recessive feature
what is haemophillia
the blood clot is slow and infrequent as there may be internal bleeding usually fatal when females mensturate
what is the law of assortment
each member of a pair of allele can randomly combine with another pair
what is autosomal linkage
two gene that occur on the same chromosome is thought to be linked
ration when two hetrozygous parents produce offsprings no crossing over
3:1
what happens when two hetrozygous alleles occur on the same chromosome
produce 2 different gametes
what does a gene determine
the limit of the expresion and the infleuce of the enviroment
what is epistasis
when an allele of one gene masks the expression of another allele
