Outline - Inheritance

3.4.U2 Gametes are haploid so contain only one allele of each gene.

3.4.U4 Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.

Outline the possible combination of alleles in a diploid zygote for a gene with two alleles.
Outline the possible combination of alleles in a diploid zygote for a gene with three alleles.

3.4.U5 Dominant alleles mask the effect of recessive alleles but co-dominant alleles have joint effects.

3.4.U6 Many genetic diseases in human are due to recessive alleles of autosomal genes.

Describe why it is not possible to be a carrier of a disease caused by a dominant allele.
Outline inheritance patterns of genetic diseases caused by dominant alleles.
Explain sickle cell anemia as an example of a genetic disease caused by codominant alleles.
Define sex linkage.

3.4.U8 The pattern of inheritance is different with sex-linked genes due to to their location on sex chromosomes.

Outline Thomas Morgan’s elucidation of sex linked genes with Drosophila.
Use correct notation for sex linked genes.
Describe the pattern of inheritance for sex linked genes.
Construct Punnett grids for sex linked crosses to predict the offspring genotype and phenotype ratios.

3.4.U9 Many genetic diseases have been identified in humans but most are very rare.

3.4.U10 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.

3.4.A1 Inheritance of ABO blood groups.

Describe ABO blood groups as an example of complete dominance and codominance.
Outline the differences in glycoproteins present in people with different blood types.

3.4.A2 Red-green color blindness and hemophilia as examples of sex-linked inheritance.

3.4.A3 Inheritance of cystic fibrosis and Huntington’s disease.

Describe the relationship between the genetic cause of cystic fibrosis and the symptoms of the disease.
Outline the inheritance pattern of cystic fibrosis.
Outline the inheritance pattern of Huntington’s disease.
List effects of Huntington’s disease on an affected individual.

3.4.A4 Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

Outline the effects of radiation exposure after nuclear exposure at Hiroshima and Chernobyl.

3.4.S1 Construction of Punnett grids for predicting the outcomes of monohybrid genetic crosses.

Define monohybrid, true breeding, hybrid, F1 and F2.
Determine possible alleles present in gametes given parent genotypes.
Construct Punnett grids for single gene crosses to predict the offspring genotype and phenotype ratios.

3.4.S2 Comparison of predicted and actual outcomes of genetic crosses using real data.

Explain the reason why the outcomes of genetic crosses do not usually correspond exactly with the predicted outcomes.
Describe the role of statistical tests in deciding whether an actual result is a close fit to a predicted result.

3.4.S3 Analysis of pedigree charts to deduce the pattern of inheritance of genetic diseases.