Inheritance Flashcards
What is a gene?
A sequence of DNA that codes for a polypeptide
What is an allele?
A version of a gene that codes for a phenotype
What is dominant?
If present, the allele will always be expressed
What is homozygous?
Alleles for a particular gene are present on both parents
What is heterozygous?
The alleles for a particular gene are different on both parents
How does a test cross/back cross work?
Cross the organism with a homozygous recessive to determine whether the organism was homozygous dominant or heterozygous
What is co dominance?
Both alleles in a heterozygous are expressed individually
What is incomplete dominance?
The offspring phenotype is intermediate between that of the 2 homozygotes
What is the expected ratio for incomplete and co dominance?
1 : 2 : 1
In dihybrid, which seed colour is dominant and which is recessive?
Which seed shape is dominant and which is recessive?
Yellow = dominant
Green = recessive
Round = dominant
Wrinkled = recessive
What should the ratio be in dihybrid crossing if both parents are heterozygous?
9 : 3 : 3 : 1
What is linkage?
Genes that are on the same chromosome = do not segregate independently at meiosis
What are the reasons that the results don’t fit Mendelian’s ratios?
Linkage
What is the null hypothesis in genetics?
The observed results are due to Mendelian inheritance and any deviation from expected ratio is due to chance
