inheritance Flashcards
3.19 what is a gene
a short length of DNA found on a chromosome that codes for a particular characteristic
3.19 genes exist as alternative
forms called alleles
3.19 what are alleles
they are variations of the same gene
3.19 having alleles give rise to
differences in inherited characteristics and variation within species
3.20 what does dominant mean
a dominant allele only needs to be inherited from one parent to show up in the phenotype
3.20 what does recessive mean
a recessive allele needs to be inherited from both parents for the characteristic to show up in the phenotype
3.20 if there is only one recessive allele
it will remain hidden and the dominant allele characteristic will show
3.20 what does homozygous mean
if two alleles of a gene are the same the individual is homozygous
3.20 what does heterozygous mean
if the two alleles of a gene are different the individual is heterozygous
3.20 definition for allele
alleles are different versions of a particular gene
3.20 definition for dominant
a dominant allele is always expressed even if only one copy is present
3.20 definition for recessive
a recessive allele is only expressed if two copies are present
3.20 definition for genotype
the combination of alleles that control each characteristic is called the genotype
3.20 definition of phenotype
the observable characteristics of an organism
e.g. eye colour
3.23 what is monohybrid inheritance
it is the inheritance of characteristics controlled by a single gene
3.23 what is a punnett square
a diagram that shows the possible combinations of alleles that could be produced in the offspring
3.23 how to construct a punnett square
determine the parental genotypes
split the alleles & add them to the square
fill the middle 4 squares working out the possible genetic combinations in the offspring
determine the phenotypes of the offspring
3.25 completing a punnett square allows you
allows you to predict the probability of different outcomes from monohybrid crosses
3.24 what is a family pedigree diagram
diagrams used to trace the pattern of inheritance of a specific characteristic through generations of a family
3.25 monohybrid inheritance is
the inheritance of characteristics controlled by a single gene
3.25 the outcomes of offspring are TT, Tt, Tt and tt
what is the ratio
3:1 of tall : short
3.25 how can you make predictions of the offsprings’ characteristics
if we have the ratio 3:1 of tall : short
probability of being tall is 75%
probability of being short is 25%
