3.4: Inheritance
Teaching time: 4 hours Practical time: 0 hours
key vocabulary
Prior learning & Retrieval practice
Review 3.2 Chromosomes
Review 3.1 Genes
Mendelian Inheritance
Essential idea: The inheritance of genes follows patterns.
NoS: Making quantitative measurements with replicates to ensure reliability. Mendel’s genetic crosses with pea plants generated numerical data. (3.2)
U1: Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.
Exercise 1: Watch these two videos and connect-extend-challenge.
In addition, work through examples of inheritance given in the video using a punnett grid.
Inheritance and Meiosis
U2: Gametes are haploid so contain only one allele of each gene.
U3: The two alleles of each gene separate into different haploid daughter nuclei during meiosis.
U4: Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.
Exercise 2: Answer the following questions:
What does it mean if a cell is "haploid"?
How does meiosis separate alleles into different cells?
What is the connection between meiosis and haploid cells? How are they related?
Why is a zygote diploid? How does a zygote form?
Inheritance in autosomal genes
U5: Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.
A1: Inheritance of ABO blood groups.
Guidance: The expected notation for ABO blood group alleles is:
Phenotype
O
A
B
AB
Genotype
ii
|A| A or | Ai
|B| B or | Bi
|A| B
Multiple Alleles and Inheritance of Gender.pdfExercise 3: Complete the exercises above
Sex-Linkage
U7: Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.
A2: Red-green colour blindness and hemophilia as examples of sex-linked inheritance. Guidance: Alleles carried on X chromosomes should be shown as superscript letters on an upper case X, such as Xh.
Sex Linkage.pdfExercise 4: Complete the exercises above
Genetic diseases
U6: Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.
U8: Many genetic diseases have been identified in humans but most are very rare.
A3: Inheritance of cystic fibrosis and Huntington’s disease.
S1: Construction of Punnett grids for predicting the outcomes of monohybrid genetic crosses.
S2: Comparison of predicted and actual outcomes of genetic crosses using real data.
Huntingdon's and Cystic Fibrosis.pdfExercise 5: Complete the exercises above
Pedigree charts
S3: Analysis of pedigree charts to deduce the pattern of inheritance of genetic diseases.
Exercise 6: Complete these exercises
Pedigree Charts.pdfPractice problems
Exercise 7: Work through these problems.
Genetics practice problems.pdfGenetics Worksheet.pdfPunett Squares 2.pdfMutations
U9: Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.
A4: Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.
Exercise 8: Outline the effects of radiation and mutagenic chemicals on mutation rate and genetic diseases. Outline the consequences of radiation after the nuclear bombing of Hiroshima and the accident at Chernobyl.
