Biology – Genetics Unit
Enduring Understandings
 Cell division allows for the continuity of genetic information.
 The universal structure of DNA allows for diversity among all living things.
 Understanding inheritance patterns is important in predicting future generations.
 DNA controls protein synthesis.
 The applied science of biotechnology can be controversial.
Essential Questions
 How does structure relate to function?
 How is a system regulated?
 How does scientists’ understanding of the world change over time?
 How is information shared?
 Because we can, should we?
What Students Should Know
 Geneticists discovered that Mendel had not determined all of the ways traits are inherited. These
complex patterns of inheritance became known after his work was rediscovered. Animals and
plants have traits that are expressed by complex patterns including codominance, incomplete
dominance, multiple alleles, sex linkage, and polygenic traits.
 When an intermediate phenotype occurs and no allele dominates, incomplete dominance results.
(Codominance occurs when both alleles are expressed in the phenotype.)
 Recombination and mutation provide for genetic diversity. Genetically diverse populations are
more likely to survive changing environments.
 The sorting and recombination of genes in sexual reproduction results in a great variety of gene
combinations in the offspring of any two parents.
 Inserting, deleting, or substituting DNA bases can alter genes. An altered gene or mutation may
be passed on to every cell that develops from it, causing an altered phenotype.
 An altered phenotype may be beneficial or detrimental.
 Sometimes entire chromosomes can be added or deleted, resulting in a genetic disorder such as
Trisomy 21 (Down syndrome).
 Some new gene combinations have little effect, some can produce organisms that are better suited
to their environments, and others can be harmful. Beneficial changes that are genetic and that
remain in a population are known as adaptations.
 DNA technologies allow scientists to identify, study, and modify genes.
 Genetic engineering techniques are used in a variety of industries, in agriculture, in basic
research, and in medicine.
 There is great potential for the development of useful products through genetic engineering (e.g.,
human growth hormone, insulin, and pest- and disease-resistant fruits and vegetables).
 The Human Genome Project is a collaborative effort to map the entire gene sequence of
organisms. This information will be useful in detection, prevention, and treatment of many
genetic disorders.
 Ethical questions can be raised in genetics. These range from the use of genetically modified
foods, profiling people by their genomes, cloning of organisms, and stem cell research.
What Students Should Be Able To Do
 Determine both the genotypes and the phenotypes from descriptive characteristics.
 Set up a Punnett Square to show all possible genotypic combinations of gametes and the possible
resulting combinations in monohybrid crosses.
 Predict possible gametes in a dihybrid cross, given parental genotypes.
 Diagram and label the structure of a DNA nucleotide and a DNA molecule.
 Relate the structure of a DNA molecule to its function.
 Given a DNA sequence, write a complementary mRNA strand.
(ex: DNA = ATCCGGA then the mRNA = UAGGCCU).
 Given an mRNA codon and the corresponding chart, determine the correct amino acid.
 Use Punnett Squares to show all possible combinations of gametes and the likelihood that
particular combinations will occur in crosses involving incomplete dominance (such as flower
color), multiple alleles (such as blood type), and sex-linkage (such as color blindness or
hemophilia).
 Determine the possible results of genetic recombination that occurs through the sorting and
recombination of genes in offspring (especially in sexual reproduction and crossing over in
meiosis) and the insertion, deletion, and substitution of DNA segments.
 Relate the possible effects resulting from an inherited altered gene to its effects on a phenotype
(beneficial or detrimental). Recognize that a beneficial effect might become an adaptation.
 Summarize the potential effects of the deletion or addition of entire chromosomes and the genetic
conditions that may result.
 Evaluate and analyze karyotypes and pedigrees.