Essential Idea:  Chromosomes carry genes in a linear sequence that is shared by members of a species.

• Outline answer to each objective statement for topic 3.2 (coming soon)
• Quizlet study set for this topic

At SHS, Topic 3.2 is taught in the following class unit(s):​​​

• Prokaryotic Cells (unit 3)
• Cell Division (unit 6A)
• Genes and Genomes (unit 14)
• Chromosomes (unit 15)

3.2.U1  Prokaryotes have one chromosome consisting of a circular DNA molecule.

• Describe the structure and function of nucleoid DNA.​
• Define the term “naked” in relation to prokaryotic DNA.​
• Compare the genetic material of prokaryotes and eukaryotes. ​

3.2.U2  Some prokaryotes also have plasmids but eukaryotes do not.

• Describe the structure and function of plasmid DNA.​

3.2.U3  Eukaryote chromosomes are linear DNA molecules associated with histone proteins.

• Describe the structure of eukaryotic DNA and associated histone proteins during interphase (chromatin).
• Explain why chromatin DNA in interphase is said to look like “beads on a string.”

3.2.U4  In a eukaryote species there are different chromosomes that carry different genes.

• List three ways in which the types of chromosomes within a single cell are different.
• State the number of nuclear chromosome types in a human cell.​

3.2.U5  Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles of those genes.

• Define homologous chromosome.
• State a similarity and a difference found between pairs of homologous chromosomes.

3.2.U6  Diploid nuclei have pairs of homologous chromosomes.

• Define diploid.
• State the human cell diploid number.
• Outline the formation of a diploid cell from two haploid gametes.
• State an advantage of being diploid.​

3.2.U7  Haploid nuclei have one chromosomes of each pair.

• Define haploid.
• State the human cell haploid number.
• List example haploid cells.​

3.2.U8  The number of chromosomes is a characteristic feature of member of a species.

• State that chromosome number and type is a distinguishing characteristic of a species.
• List mechanisms by which a species chromosome number can change.​

3.2.U9  A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length.

• Describe the process of creating a karyogram.
• List the characteristics by which chromosomes are arranged on the karyogram.​

3.2.U10  Sex is determined by sex chromosomes and autosomes are chromosomes that do not determine sex.

• Outline the structure and function of the two human sex chromosomes.
• Outline sex determination by sex chromosomes.

3.2.A1  Cairns’ technique for measuring the length of DNA by autoradiography.

• Describe Cairn’s technique for producing images of DNA molecules from E. coli.
• Outline conclusions drawn from the images produced using Cairn’s autoradiography technique.  ​​

3.2.A2  Comparison of genome size in T2 phage, Escherichia coli, Drosophila melanogaster, Homo sapiens, Paris japonica.

• Describe the relationship between the genome size of a species and the species complexity in structure, physiology and behavior.​

3.2.A3  Comparison of diploid chromosome numbers of Homo sapiens, Pan troglodytes, Canis familiaris, Oryza sativa, Parascarsis equorum.

• State the minimum chromosome number in eukaryotes.
• Explain why the typical number of chromosomes in a species is always an even number.
• Explain why the chromosome number of a species does not indicate the number of genes in the species.
• Explain the relationship between the number of human and chimpanzee chromosomes.​

3.2.A4  Use karyograms to deduce sex and diagnose Down Syndrome in humans.

• Distinguish between a karyogram and a karyotype.
• Deduce the sex of an individual given a karyogram.
• Describe the use of a karyogram to diagnose Down syndrome.  

3.2.S1  Use of databases to identify the focus of a human gene and its polypeptide product.

• Search NCBI or OMIM for a given gene.
• Determine the gene locus, abbreviated gene name, and description of the gene.​

3.2.NOS  Developments in research follow improvements in techniques- autoradiography was used to establish the length of DNA molecules in chromosomes.

• Outline the advancement in knowledge gained from the development of autoradiography techniques.​

In the News:

• Split-Sex Animals Are Unusual, Yes, but Not as Rare as You’d Think (2019-02-25)
  
• The little piece of DNA that makes girls boys (2018-06-14)
• Secrets of the Y Chromosome (2018-06-11)
• How Cells Pack Tangled DNA Into Neat Chromosomes (2018-02-22)
• Antibiotic-resistant plasmids flourish in hospital plumbing (2018-02-06)
• New butterfly species discovered in Russia with an unusual set of 46 chromosomes (2017-11-27)
• New approach to studying chromosomes' centers may reveal link to Down syndrome and more (2017-11-20)
• Sleep duration may affect the integrity of sperm DNA 2017-10-16)   
• ​A female Viking warrior confirmed by genomics (2017-09-08)
• The Extraordinary Complexity of Sex Determination (2017-09)
• DNA blood test gives women a new option for prenatal screening (2015-01-26)
• ​Reprieve for men: Y chromosome is not vanishing (2014-04-24)
• With Men's Y Chromosome, Size Really May Not Matter (2014-07-28)
• Genghis Khan's genetic legacy has competition (2015-01-23)
• Sex redefined (2015-02-18)
• The Olympic Games and Athletic Sex Assignment (2016-08-04)
• A Gene Mystery: How Are Rats With No Y Chromosome Born Male? (2017-05-12)
• 'Pregnant' housefly males demonstrate the evolution of sex determination (2017-05-24)
• ​​​​Antibiotic resistance persists in bacteria, even absent selection pressure from antibiotics (2016-08-01)
• ​The mystery of cell proliferation: Matching histone to DNA (2014-08-19)​​
• ​​​Rogue chromosome may be behind new contagious cancer striking Tasmanian devils (2017-07-10)​