TOPIC 3:  GENETICS

Topic 3.5:  Genetic engineering
IB topic(s):  2.7 and 3.5
Essential Idea(s):  Biologists have developed techniques for artificial manipulation of DNA, cells and organismsUnderstandings:
  • PCR can be used to amplify small amounts of DNA
  • Gel electrophoresis is used to separate proteins or fragments of DNA according to size
  • DNA profiling involves comparison of DNA
  • Genetic modification is carried out by gene transfer between species
  • Clones are groups of genetically identical organisms, derived from a single original parent cell
  • Many plant species and some animal species have natural methods of cloning
  • Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells
  • Methods have been developed for cloning adult animals using differentiated cells
Applications:
  • Use of DNA profiling in paternity and forensic investigations
  • Gene transfer to bacteria using plasmids makes use of restriction endonucleases and DNA ligase
  • Assessment of the potential risks and benefits associated with genetic modification of crops
  • Production of cloned embryos produced by somatic cell nuclear transfer
Skills:
  • Design of an experiment to assess one factor affecting the rooting of stem cuttings
  • Analysis of examples of DNA profiles
  • Analysis of data on risks to monarch butterflies of Bt crops ​


Lesson 1 (10/4):  Introduction to Biotechnology Applications
Activity:  Read Kognity Topic 3.5.0-3.5.5
Activity:  Read article (linked here).
In class notes, summarize the techniques of Gel Electrophoresis, PCR, Profiling and GMOs. 

Lesson 2:  (10/15):  Biotechnology Applications Continued
Slides
Video: Restriction Enzymes (Animation)

Lesson 3-4 (10/17-10/19):  VNTR analysis.
Lab handouts (procedure) linked here.
DNA fingerprinting scenario (DNA dots handout)  
Link:  TED talk:  Personal DNA Machines (miniPCR) 
HHMI-Origins of Corn
Hand-out GMO foods 

​Lesson 5 (10/23):  PCR amplification of GMO genes
Article:  History of Biotechnology 
Article reading guide questions
Slides 
Hand-outs (DBQs and review questions) 


Topic 3.1:  Genes
Essential Idea:  Every living organism inherits a blueprint of life from its parents.
Understandings:
  • A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic
  • A gene occupies a specific position on a chromosome
  • The various specific forms of a gene are alleles
  • Alleles differ from each other by one or only a few bases
  • New alleles are formed by mutation
  • The genome is the whole of the genetic information of an organism
  • The entire base sequence of human genes was sequenced in the Human Genome Project

Applications:
  • The causes of sickle cell anaemia, including a base substitution mutation, a change to the base sequence of mRNA trancribed from it and a change to the sequence of a polypeptide in haemoglobin
  • Comparison of the number of genes in humans with other species

Skills:
  • Use of a database to determine differences in the base sequence of a gene in two species


Lesson 1 (11/12): Introduction to Genetics  
​Slides
Article:  Oxytricha
Database of human genome sequences (linked here) 
Link:  Video on "Would you want to know?"
Link:  Video on orphan genetic diseases (galactosemia) 
Link:  Video:  "Find your zebra" 

Topic 3.2:  Chromosomes and Genomes
Essential Idea: Chromosomes carry genes in a linear sequence that is shared by members of a species.
Understandings:
  • Prokaryotes have one chromosome consisting of a circular DNA molecule
  • Some prokaryotes also have plasmids but eukaryotes do not
  • Eukaryote chromosomes are linear DNA molecules associated with histone proteins
  • In a eukaryote species there are different chromosomes that carry different genes
  • Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles of those genes
  • Diploid nuclei have pairs of homologous chromosomes
  • Haploid nuclei have one chromosome of each pair
  • The number of chromosomes is a characteristic feature of members of a species
  • A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length
  • Sex is determined by sex chromosomes and autosomes are chromosomes that do not determine sex
Applications:
  • Cairns' technique for measuring the length of DNA molecules by autoradiography
  • Comparison of genome size in T2 phage, Escherichia coli, Drosophila melanogaster, Homo sapiens and Paris japonica
  • Comparison of diploid chromosome numbers of Homo sapiens, Pan troglodytes, Canis familiaris, Oryza sativa and Parascaris equorum
  • Use of karyograms to deduce sex and diagnose Down syndrome in humans
Skills:
  • Use of databases to identify the locus of a human gene and its polypeptide product​
7.3.NOS:  Developments in scientific research follow improvements in computing- the use of commuters has enabled scientists to make advances in bioinformatics applications such as locating genes within genomes and identifying conserved sequences (Oxford Biology Course Companion page 368).
  • Define bioinformatics.
  • Outline why computers are necessary for genome analysis.

Lesson 2 (11/15):  Chromosomes and Genomes
Slides

Topic 3.3:  Meiosis and Genetic Variation
Essential idea: 
Alleles segregate during meiosis allowing new  combinations to be formed by the fusion of gametes
Understandings:
  • One diploid nucleus divides by meiosis to produce four haploid nuclei
  • Separation of pairs of homologous chromosomes in the first division of meiosis halves the chromosome number
  • DNA is replicated before meiosis so that all chromosomes consist of two sister chromatids
  • The early stages of meiosis involve pairing of homologous chromosomes and crossing over followed by condensation
  • Orientation of pairs of homologous chromosomes prior to separation is random
  • The halving of the chromosome number allows a sexual life cycle with fusion of gametes
  • Crossing over and random orientation promotes genetic variation
  • Fusion of gametes from different parents promotes genetic variation
Applications:
  • Non-disjunction can cause Down syndrome and other chromosomal abnormalities
  • Studies showing age of parents influences chances of non-disjunction
  • Description of methods used to obtain cells for karyotype analysis – e.g. chorionic villus sampling and amniocentesis and the associated risks
Skills:
  • Drawing diagrams to show the stages of meiosis resulting in the formation of four haploid cells

3.3.NOS  Making careful observations- meiosis was discovered by microscope examination of dividing germ-line cells.
  • Discuss difficulties in microscopic examination of dividing cells.
  • Describe the discovery of meiosis.

​Lesson 3-4 (11/26):  Meiosis
​Slides 
Interactive:  Karyotyping
Resource:  Bozeman Science Video-Meiosis 

Lesson 5 (11/28):  Linkage (HL)
​Slides 

Lesson 6 (11/30):  Introduction to inheritance
​Slides (mutations, new alleles, cystic fibrosis, Huntington's disease, blood type)
Resource link:  Genetics topics

Lesson 7 (12/4):  Rules of inheritance
Worksheet:  Sickle Cell Anemia and Pedigrees
Link:  Genetics problems 
​Slides  

Lesson 8 (1/8):  Sickle Cell Disease Activity (continued)
Link-article New Research on Sickle Cell Disease 
Link:  Sickle Cell Genetics and Chi Square Analysis