Key Ideas

Students should know and understand the following.

Intended Student Learning

Students should be able to do the following.

Get into Genes activity

MACROMOLECULES (M)

Organisation

M1. The chemical unit of genetic information in most organisms is DNA.

M1.1 Model the structure of DNA as a double helix made up of a sequence of complementary bases joined by weak bonds. The bases are attached to a sugar phosphate backbone.

Introductory talk : Structure of DNA and its function as the chemical unit of genetic information is described.

Station 3 : The structure, bonding, and sugar phosphate backbone of DNA is discussed in relation to its charge.

M2. The structural unit of information in the cell is the chromosome.

M2.1 Know that a chromosome is made up of many genes.

M2.2 Explain that each chromosome has genes specific to that chromosome, making it identifiable.

Introductory talk : Students learn that c hromosomes are composed of DNA and that g enes are pieces of DNA (parts of the entire genome) with a particular, identifiable function.

Station 4 : Students learn about the position of genes on the chromosome relative to molecular markers.

M3. The functional unit of information on the chromosome is the gene.

M3.1 Know that a gene consists of a unique sequence of bases that code for a polypeptide or an RNA molecule.

M3.2 Describe how three bases, called a codon in mRNA, code for one amino acid.

Introductory talk : The concept that genes are DNA with a particular, identifiable function is discussed. Also, that A,G,T,C form the DNA code, the the order of which determines the proteins made is addressed.

M4. The flow of information from DNA to protein is unidirectional in most organisms. DNA ->RNA -> protein

M4.1 Describe and illustrate the processes of transcription and translation, including the roles of mRNA, tRNA, and ribosomes.

Introductory talk : These c oncepts are introduced, but not described in great detail.

M6. Polysaccharides and lipids are important macromolecules in cells and organisms.

M6.1 Know that polysaccharides, including cellulose and chitin, and phospholipids, contribute to the structural components of cells and organisms.

Station 2: During the DNA extraction experiment students learn about role of lipids in cell membranes.

Selectivity

M8. Enzymes are specific for their substrate.

M8.1 Describe the induced-fit model of enzyme–substrate binding.

M8.2 Explain how pH, temperature, and chemical inhibitors can alter the binding of enzymes and substrates at the active site.

Station 2 : Students examine the use of enzymes in the DNA extraction experiment. Students explore the concepts of a pH buffer, which is necessary for their experiment to work.

Station 4 : Students explore the use of restriction enzymes and how they cut at sequence specific sites.

Perpetuation

M12. DNA carries genetic information from one generation to the next.

M12.1 Understand that DNA is perpetuated by semi-conservative replication.

Introductory talk: Students are shown that characteristics are passed from one generation to the next, and that DNA determines characteristics.

Station 1 : Students learn that traits are passed from one generation to the next (heredity).

Evolution

M13. The universal presence of DNA is strong evidence for the common ancestry of all living things.

M13.1 Know that DNA is universal to most

living things.

M13.2 Know that DNA has diversified over billions of years.

Introductory talk : The concept that DNA has been manipulated for 1000's of years through breeding techniques is discussed. Students will learn that most living things have DNA – and that this is made of the same code (A, G, T, C)

Concluding talk: Because DNA is made of the same code in all organisms it can be interchanged between species (via Agrobacterium and retro viruses) and through genetic engineering techniques.

M14. DNA and protein sequences usually show greater similarity between closely related groups of organisms than between distantly related groups.

M14.1 Understand that organisms have common features attributable to commonly shared sequences of DNA.

M14.2 Explain why the greater the similarity there is between the sequences of nucleotides in their DNA, the more likely it is that the separation of two species is recent.

Concluding talk: the idea of identifying similar gene sequences within the same family (eg grasses) is discussed.

M15. Change in the base sequence of DNA can lead to the alteration or absence of proteins, and to the appearance of new characteristics in the descendants.

M15.1 Know that changes in the DNA sequence are called ‘mutations'.

M15.2 Know that the mutation rate can be increased by radiation, mutagenic chemicals, and heat.

M15.3 Explain how inheritable mutations can lead to changes in the characteristics of the descendants.

Station 4: Students can observe how a difference of one base can lead to the destruction of restriction enzyme recognition sites as well as change the proteins and traits.

Human Awareness

M16. Human beings can manipulate DNA.

M16.1 Know that the DNA can be extracted from cells.

M16.2 Describe how particular genes can be selected and removed, using probes and restriction enzymes.

M16.3 Describe how selected genes can be transferred between species, using bacterial plasmids, viruses, and microinjection.

M16.4 Discuss the social consequences of the manipulation of DNA

Station 2 : Students extract DNA from wheatgerm

Station 4: Students learn about the EcoRI restriction enzyme. Students learn that restriction enzymes can be used to identify differences in DNA fragments. Students learn about molecular markers and how they are linked with certain genes.

Concluding talk: The concept of transferring genes from one organism to another via Agrobacterium and biolistic transformation is discussed. Relevant examples are given.

M17. Human beings can sequence even small amounts of DNA.

M17.1 Understand that segments of DNA can be multiplied, using the polymerase chain reaction (PCR), and then have their base sequences identified (details are not required).

M17.2 Explain how differences in DNA sequences, identified by DNA fingerprinting, can be used in forensic science.

Station 4: The connection between identifying individuals in a plant breeding program through DNA fingerprinting, and forensic science is explained

CELLS (C)

Organisation

C1. The cell is the unit of structure and function of most organisms.

C1.1 Understand that the cell is the smallest independent unit of life.

Introductory talk: Discussion that all organisms are made of cells.

Human Awareness

C11. Human beings culture cells for a variety of purposes.

C11.1 Understand techniques of cell culture, and discuss some contemporary examples of their use.

Concluding talk: Discussion of cell culture to grow up transformed plants.

C12. Chemicals can interfere with cell metabolism.

C12.1 Discuss possible benefits and/or harmful effects of chemicals that human beings use.

Station 3: Students learn that to visualise DNA it must be stained with ethidium bromide – a carcinogen. The concept of carcinogens is addressed.

ORGANISMS (O)

(Only human examples are required in the organisation and selectivity threads.)

Organisation

O1. There is a hierarchical structure within multicellular organisms.

O1.1 Give examples of cells with identical genetic information that differentiate to produce cells with specialised structures and functions.

Concuding talk: Students learn that we can culture undifferentiated cells and these cells can be used for transformation.

Selectivity

O2. Organisms selectively detect and respond to changes in the internal and external environments.

O2.1 Describe the importance of sensory receptors that detect changes in the external environment.

Station 1 : Students learn that plants have to deal with a range of environmental conditions, some can tolerate these while others perish. Phenotype = genotype + environment is discussed.

Perpetuation

O6. Many organisms reproduce by asexual

means.

O6.1 Understand that, in eukaryotes, asexual reproduction involves mitosis.

O6.2 Explain why the offspring of asexual reproduction are genetically identical to their parent. In asexual reproduction genetic variation occurs only through mutation.

Station 1: Students investigate the reproductive mechanism of cereal crops (i.e. crossing) and learn that cross pollination involves the transfer of pollen from the male flower parts to the female.

Concluding talk: Students learn that through transformation we can produce identical offspring.

O7. Sexual life cycles involve meiosis and fertilisation.

O7.1 Understand that diploid cells contain pairs of homologous chromosomes.

O7.2 Explain why the products of meiosis are haploid cells and contain a single set of chromosomes.

O7.3 Explain the importance of crossing over and independent assortment in meiosis.

O7.4 Know that fertilisation restores the diploid number.

Station 1: Students examine crossing over and independent assortment in relation to plant breeding (crossing)

Evolution

O8. Offspring that are the result of sexual reproduction are usually not genetically identical.

O8.1 Describe how the events in meiosis and fertilisation contribute to variation in offspring.

Station 1: Students investigate the concept of crossing. Students learn that offspring are not genetically identical and that the combination of traits in the new generation occurs at random.

Overall workshop: Students should leave the workshop with the understanding that plant breeding results in variation.

O9. Not all offspring will survive to reproduce.

O9.1 Understand that some genetically controlled characteristics increase the chances of survival and reproduction.

Introductory talk: Students learn that some plants are tough while others are weak – this depends on plants genotype.

Station 1: Students investigate the phenotype of plants (selection) to with traits that would be beneficial for further propagation.

Station 4: Students learn how to use molecular markers to predict which plants will have certain traits.

Human Awareness

O10. Human beings can alter the genetic composition of organisms.

O10.1 Give examples of how human beings use genetic engineering to produce organisms and substances of benefit to them.

O10.2 Discuss ethical issues associated with the genetic manipulation of organisms.

Concluding talk: Students are presented with current research examples of genetic engineering projects that have been designed to produce crops that have increased tolerance to environmental stresses. .

ECOSYSTEMS (E)

Selectivity

E3. Characteristics of communities are determined by environmental conditions.

E3.1 Describe how environmental factors may determine the type of the community.

Introductory talk : Students are introduced to the idea of identifying different plants that may be adapted to different environments

Evolution

E8. Natural selection acts on variation in a population.

E8.2 Know that members of a population show genetic variability.

E8.3 Describe how biotic and abiotic factors contribute to natural selection.

Introductory talk : The concept of variability within a plant population (and that this can be exploited through artificial selection) is introduced.